http://news.nationalgeographic.com/news/2009/06/090619-fathers-day-2009-no-fathers.html
NO-FATHERS DAY: Remote Group Has No Dads, And Never Did
Brian Handwerkfor National Geographic News
June 18, 2009
What would Father's Day—and every other day—be like without fathers? Maybe not so bad, according to experts on the Mosuo culture of the Chinese Himalaya.
The women of this matrilineal society shun marriage and raise their kids in homes with their entire extended families—but no dads.
By most accounts, children seem to do just fine under the arrangement.
"They are a society that we know hasn't had marriage for a thousand years, and they've been able to raise kids successfully," said Stephanie Coontz, family studies professor at the Evergreen State College in Olympia, Washington.
No Fathers: It Makes Genetic Sense?
Men of the Mosuo, who live around Lugu Lake on the border between Yunnan and Sichuan Provinces, do help to raise kids—just not their own, with whom the men typically have only limited relationships.
Instead the men help look after all the children born to their own sisters, aunts, and other women of the family.
Rather than "one father with a kid, it will be four or five uncles. That [father] role is shared among a number of people, and these are very large extended families," explained John Lombard, director of the Lugu Lake Mosuo Cultural Development Association.
The unusual parenting arrangement makes genetic sense, in terms of extending the family line—and many Mosuo men actually think of it that way, Lombard said.
"If you [father] a child with another woman, you can never be absolutely sure that the child really shares your genes," he said. "But if your sister has a child, you can be 100 percent sure that the kid shares some of your genes."
The women of the Mosuo's agricultural villages head the households, make business decisions, and own property, which they pass on to their matrilineal heirs.
In the unique Mosuo tradition called the walking marriage, women invite men to visit their rooms at night—and to leave in the morning.
Women may also change partners as often as they like, and promiscuity carries no social stigma. The practice has made the Mosuo famous, particularly to male Chinese tourists, many of whom see the walking marriages as evidence of sexual liberation and wanton lust, experts say. Though there are tourist-oriented brothels in Mosuo villages, most are staffed with non-Mosuo women and are considered shameful by the Mosuo, according to the the Lugu Lake Mosuo Cultural Development Association Web site.
"I think sometimes the media gets carried away with the possibility that the women can have all these husbands," said filmmaker Xiaoli Zhou, who produced and reported the 2006 documentary on the Mosuo, The Women's Kingdom.
In fact, most Mosuo women don't change walking-marriage partners very frequently. And they rarely carry on more than one romantic relationship at a time.
"Many of the women I interviewed had only had one or two relationships in their lives," Zhou said.
Family First
The lack of live-in fathers shouldn't be taken as evidence that the Mosuo don't value family life, said Lombard, of the Lugu Lake Mosuo Cultural Development Association.
In fact, they value it above all other relationships—particularly those founded on the sometimes fickle feelings of male-female amour, he said.
Extended families of siblings, uncles, aunts, and others are said to be extremely stable, Lombard added.
For example, there are no divorces to destablize the families. And even the death of a child's biological father has little effect on the family, given the father's distance from the family and the extensive support network in the household.
Brent Huffman, co-producer of The Women's Kingdom, said, "The society does kind of create this question: Are fathers really necessary?
"It's hard to think of in Western society, but there, it works."
Friday, June 19, 2009
Having A Higher Purpose In Life Reduces Risk Of Death Among Older Adults
http://www.sciencedaily.com/releases/2009/06/090615144207.htm
ScienceDaily (June 18, 2009) — Possessing a greater purpose in life is associated with lower mortality rates among older adults according to a new study by researchers at Rush University Medical Center.
Patricia A. Boyle, PhD, and her colleagues from the Rush Alzheimer’s Disease Center, studied 1,238 community-dwelling elderly participants from two ongoing research studies, the Rush Memory and Aging Project and the Minority Aging Research Study. None had dementia. Data from baseline evaluations of purpose in life and up to five years of follow-up were used to test the hypothesis that greater purpose in life is associated with a reduced risk of mortality among community-dwelling older persons.
Purpose in life reflects the tendency to derive meaning from life’s experiences and be focused and intentional, according to Boyle.
After adjusting for age, sex, education and race, a higher purpose of life was associated with a substantially reduced risk of mortality. Thus, a person with high purpose in life was about half as likely to die over the follow-up period compared to a person with low purpose. The association of purpose in life with mortality did not differ among men and women or whites and blacks, and the finding persisted even after controlling for depressive symptoms, disability, neuroticism, the number of medical conditions and income. During the study period, 151 participants died.
“The finding that purpose in life is related to longevity in older persons suggests that aspects of human flourishing—particularly the tendency to derive meaning from life’s experiences and possess a sense of intentionality and goal-directedness—contribute to successful aging,” said Boyle.
Significant associations with mortality were found with three specific items on the purpose of life questionnaire to determine the study participants’ agreement with the following statements: “I sometimes feel as if I’ve done all there is to do in life;” “I used to set goals for myself, but that now seems like a waste of time;” and “My daily activities often seem trivial and unimportant to me.”
“We are excited about these findings because they suggest that positive factors such as having a sense of purpose in life are important contributors to health,” said Boyle.
The researchers note that knowledge of the relationship of purpose of life with other demographic characteristics is limited and future studies are needed to examine whether the association of purpose of life with mortality might be modified by other variables not measured in this study, such as how religious a participant may be. In addition, researchers suggest that future studies should examine whether purpose in life can be enhanced in older persons with interventions.
“Although we think that having a sense of purpose in life is important across the lifespan, measurement of purpose in life in older persons in particular may reveal an enduring sense of meaningfulness and intentionality in life that somehow provides a buffer against negative health outcomes,” said Boyle.
The Rush Memory and Aging Project, which began in 1997, is a longitudinal clinical-pathological study of common chronic conditions of aging. Participants are older persons recruited from about 40 continuous care retirement communities and senior subsidized housing facilities in and around the Chicago Metropolitan area. More than 1,200 older persons are enrolled in the study.
The Minority Aging Research Study began in 2004 and is a study of risk factors for cognitive decline in older Blacks. Participants are recruited from community-based organizations, churches, and senior subsidized housing facilities in and around the Chicago Metropolitan Area. More than 350 older persons are enrolled in the study.
The study is published in Psychosomatic Medicine.
Adapted from materials provided by Rush University Medical Center.
ScienceDaily (June 18, 2009) — Possessing a greater purpose in life is associated with lower mortality rates among older adults according to a new study by researchers at Rush University Medical Center.
Patricia A. Boyle, PhD, and her colleagues from the Rush Alzheimer’s Disease Center, studied 1,238 community-dwelling elderly participants from two ongoing research studies, the Rush Memory and Aging Project and the Minority Aging Research Study. None had dementia. Data from baseline evaluations of purpose in life and up to five years of follow-up were used to test the hypothesis that greater purpose in life is associated with a reduced risk of mortality among community-dwelling older persons.
Purpose in life reflects the tendency to derive meaning from life’s experiences and be focused and intentional, according to Boyle.
After adjusting for age, sex, education and race, a higher purpose of life was associated with a substantially reduced risk of mortality. Thus, a person with high purpose in life was about half as likely to die over the follow-up period compared to a person with low purpose. The association of purpose in life with mortality did not differ among men and women or whites and blacks, and the finding persisted even after controlling for depressive symptoms, disability, neuroticism, the number of medical conditions and income. During the study period, 151 participants died.
“The finding that purpose in life is related to longevity in older persons suggests that aspects of human flourishing—particularly the tendency to derive meaning from life’s experiences and possess a sense of intentionality and goal-directedness—contribute to successful aging,” said Boyle.
Significant associations with mortality were found with three specific items on the purpose of life questionnaire to determine the study participants’ agreement with the following statements: “I sometimes feel as if I’ve done all there is to do in life;” “I used to set goals for myself, but that now seems like a waste of time;” and “My daily activities often seem trivial and unimportant to me.”
“We are excited about these findings because they suggest that positive factors such as having a sense of purpose in life are important contributors to health,” said Boyle.
The researchers note that knowledge of the relationship of purpose of life with other demographic characteristics is limited and future studies are needed to examine whether the association of purpose of life with mortality might be modified by other variables not measured in this study, such as how religious a participant may be. In addition, researchers suggest that future studies should examine whether purpose in life can be enhanced in older persons with interventions.
“Although we think that having a sense of purpose in life is important across the lifespan, measurement of purpose in life in older persons in particular may reveal an enduring sense of meaningfulness and intentionality in life that somehow provides a buffer against negative health outcomes,” said Boyle.
The Rush Memory and Aging Project, which began in 1997, is a longitudinal clinical-pathological study of common chronic conditions of aging. Participants are older persons recruited from about 40 continuous care retirement communities and senior subsidized housing facilities in and around the Chicago Metropolitan area. More than 1,200 older persons are enrolled in the study.
The Minority Aging Research Study began in 2004 and is a study of risk factors for cognitive decline in older Blacks. Participants are recruited from community-based organizations, churches, and senior subsidized housing facilities in and around the Chicago Metropolitan Area. More than 350 older persons are enrolled in the study.
The study is published in Psychosomatic Medicine.
Adapted from materials provided by Rush University Medical Center.
Wednesday, June 17, 2009
"Human"-Faced Missing Link Found in Spain?
http://news.nationalgeographic.com/news/2009/06/090610-missing-link-human-face.html
James Owen for National Geographic News
June 10, 2009
Move over Ida—you're last month's news. There's a new (purported) "missing link" in town.
An 11.9-million-year-old fossil ape species with an unusually flat, "surprisingly human" face has been found in Spain. The discovery suggests humans' ape ancestors split from primitive apes in Europe, not Africa—the so-called cradle of humanity—a new study says.
The species, Anoiapithecus brevirostris, may also represent the last known common ancestor of humans and living great apes—including orangutans, gorillas, and chimpanzees—researchers say.
"With this fossil, our opinion is that the origin of our family very probably took place in the Mediterranean region," said study leader Salvador Moyà-Solà of the Catalan Institute of Paleontology in Barcelona.
"Surprisingly Human"
Unearthed at a fossil-rich site near Barcelona in 2004, the fragmented skull remains suggest a species with human-like facial features, Moyà-Solà said.
But a familiar face in and of itself doesn't mean the fossil "has any special specific relationship with modern hominds"—humans and the great apes—the paleontologist added.
Rather, the human-like face is evidence of great diversity among ape species in the Mediterranean region 12 million years ago, he said.
Missing Link?
Resembling both primitive ape species and our early ancestors, Anoiapithecus could be called a missing link.
The ape's wide nose and long palate, for example, resemble those of the ancient apes from which great apes and humans arose, the study says.
But Anoiapithecus' thickly enameled teeth and robust jaw are like those of primitive Kenyapithecus fossil apes, which lived in both Africa and Europe, according to the team.
Kenyapithecus species have been proposed as common ancestors of humans and great apes.
Until now, however, there hasn't been a fossil linking Kenyapithecus to later apes thought to have evolved into more direct human ancestors, according to the study, published last week in the journal Proceedings of the National Academy of Sciences.
The Spanish ape suggests this key evolutionary transition occurred after Kenyapithecus arrived in Europe from Africa some 15 million years ago—likely crossing over before the Mediterranean Sea formed, separating Africa from Europe—Moyà-Solà said.
"The 'folks' that migrated from Africa to the Mediterranean area were in fact completely primitive, without the [hominid] features that identify the members of our family," he said.
"The ancestors of gorillas, chimps, and humans then went back to Africa close to some nine million years ago."
There, they would give rise to the first humans, the thinking goes.
European Interlude
The new study isn't the first to hint at a European origin for hominids.
A similar theory has been advanced, for instance, based on 10- to 13-million-year-old fossils of the chimplike Dryopithecus group from France, Hungary, and Spain.
Anthropologist David Begun of the University of Toronto believes the evolution of African apes can be traced to Dryopithecus species that had migrated from Africa to Europe during the pre-Mediterranean Sea period.
"The new Spanish fossils do indeed support that hypothesis," said Begun, who was not involved in the new study and whose work has been partially funded by the National Geographic Society's Committee for Research and Exploration. (The National Geographic Society owns National Geographic News.)
However Begun "does not see any compelling evidence" linking Kenyapithecus with the newfound Spanish species.
"Frankly, [the new species] does not look like Kenyapithecus to me," he added.
Moyà-Solà, the study leader, doesn't rule out the possibility that each of the great ape species evolved independently from different Kenyapithecus species.
And it's possible that Africa could yet yield a species that, like the new Spanish ape, bridges the gap between early human ancestors and more primitive apes, he admitted.
"It's impossible to test our hypothesis [as of yet], because the fossil record in Africa from this period is very poor," Moyà-Solà said. "We need more and better fossils from Africa."
To that end, he said, the team's next major scientific stop will be somewhere south of the Mediterranean.
Do you think it's a coincidence that a Medeteranian diet is so healthy for us (assuming this is a missing link)? It makes sense to me that if we started our branching out in that area that a diet of foods from that area would be what we were designed to eat, and is now found to be a very healthy diet for us.
James Owen for National Geographic News
June 10, 2009
Move over Ida—you're last month's news. There's a new (purported) "missing link" in town.
An 11.9-million-year-old fossil ape species with an unusually flat, "surprisingly human" face has been found in Spain. The discovery suggests humans' ape ancestors split from primitive apes in Europe, not Africa—the so-called cradle of humanity—a new study says.
The species, Anoiapithecus brevirostris, may also represent the last known common ancestor of humans and living great apes—including orangutans, gorillas, and chimpanzees—researchers say.
"With this fossil, our opinion is that the origin of our family very probably took place in the Mediterranean region," said study leader Salvador Moyà-Solà of the Catalan Institute of Paleontology in Barcelona.
"Surprisingly Human"
Unearthed at a fossil-rich site near Barcelona in 2004, the fragmented skull remains suggest a species with human-like facial features, Moyà-Solà said.
But a familiar face in and of itself doesn't mean the fossil "has any special specific relationship with modern hominds"—humans and the great apes—the paleontologist added.
Rather, the human-like face is evidence of great diversity among ape species in the Mediterranean region 12 million years ago, he said.
Missing Link?
Resembling both primitive ape species and our early ancestors, Anoiapithecus could be called a missing link.
The ape's wide nose and long palate, for example, resemble those of the ancient apes from which great apes and humans arose, the study says.
But Anoiapithecus' thickly enameled teeth and robust jaw are like those of primitive Kenyapithecus fossil apes, which lived in both Africa and Europe, according to the team.
Kenyapithecus species have been proposed as common ancestors of humans and great apes.
Until now, however, there hasn't been a fossil linking Kenyapithecus to later apes thought to have evolved into more direct human ancestors, according to the study, published last week in the journal Proceedings of the National Academy of Sciences.
The Spanish ape suggests this key evolutionary transition occurred after Kenyapithecus arrived in Europe from Africa some 15 million years ago—likely crossing over before the Mediterranean Sea formed, separating Africa from Europe—Moyà-Solà said.
"The 'folks' that migrated from Africa to the Mediterranean area were in fact completely primitive, without the [hominid] features that identify the members of our family," he said.
"The ancestors of gorillas, chimps, and humans then went back to Africa close to some nine million years ago."
There, they would give rise to the first humans, the thinking goes.
European Interlude
The new study isn't the first to hint at a European origin for hominids.
A similar theory has been advanced, for instance, based on 10- to 13-million-year-old fossils of the chimplike Dryopithecus group from France, Hungary, and Spain.
Anthropologist David Begun of the University of Toronto believes the evolution of African apes can be traced to Dryopithecus species that had migrated from Africa to Europe during the pre-Mediterranean Sea period.
"The new Spanish fossils do indeed support that hypothesis," said Begun, who was not involved in the new study and whose work has been partially funded by the National Geographic Society's Committee for Research and Exploration. (The National Geographic Society owns National Geographic News.)
However Begun "does not see any compelling evidence" linking Kenyapithecus with the newfound Spanish species.
"Frankly, [the new species] does not look like Kenyapithecus to me," he added.
Moyà-Solà, the study leader, doesn't rule out the possibility that each of the great ape species evolved independently from different Kenyapithecus species.
And it's possible that Africa could yet yield a species that, like the new Spanish ape, bridges the gap between early human ancestors and more primitive apes, he admitted.
"It's impossible to test our hypothesis [as of yet], because the fossil record in Africa from this period is very poor," Moyà-Solà said. "We need more and better fossils from Africa."
To that end, he said, the team's next major scientific stop will be somewhere south of the Mediterranean.
Do you think it's a coincidence that a Medeteranian diet is so healthy for us (assuming this is a missing link)? It makes sense to me that if we started our branching out in that area that a diet of foods from that area would be what we were designed to eat, and is now found to be a very healthy diet for us.
Apes Laugh, Tickle Study Finds
http://news.nationalgeographic.com/news/2009/06/090604-apes-laugh-tickle-chimps-gorillas.html
Apes Laugh, Tickle Study Finds
Brian Handwerk for National Geographic News
June 4, 2009
What happens if you tickle a gorilla? According to a new study, the ape laughs—which would mean we're not the only animals born with funny bones.
By tickling young gorillas, chimpanzees, bonobos, and orangutans, researchers say they learned that all great apes laugh.
Their findings suggest we inherited our own ability to laugh from the last common ancestor from which humans and great apes evolved, which lived 10 to 16 million years ago.
Primatologist and psychologist Marina Davila Ross of the U.K.'s University of Portsmouth led a team that tickled the necks, feet, palms, and armpits of infant and juvenile apes as well as human babies. The team recorded more than 800 of the resulting giggles and guffaws.
(go to the link to hear laughter recordings)
Mapping the audible similarities and differences in laughs across the five species, the researchers created an acoustic family tree of human and great ape laughter.
The tree, they found, closely matched the standard genetics-based evolutionary tree of primates.
"So we concluded that these vocalizations all share the same common ancestry," Davila Ross explained.
But even the most casual listener can tell a human laugh from an ape laugh. Davila Ross points out that human laughter has distinct differences from ape laughter, most likely because humans have evolved much more rapidly than apes during the past five million years.
And at least one great mystery remains: What purpose does ape laughter serve?
"I'm very keen," Davila Ross said, "on learning how laughter is being used among great apes as compared to humans."
Is It Really Laughter?
It's previously been argued that chimps chuckle, but their method—"laughing" on both the exhale and inhale—had been deemed too different from the human, exhale-only laugh.
The tickle study, however, found evidence that most ape laughter, especially among gorillas and bonobos, shares key traits with human laughter.
Like humans, for example, gorillas and bonobos laughed only while exhaling—leading University of Wisconsin zoologist and psychologist Charles Snowdon, who was not involved in the study, to conclude that, "contrary to current views, the exhalation-only laughter is not uniquely human but is found in our ape ancestors."
Furthermore, gorillas' and bonobos' exhaling breaths during laughter lasted three to four times longer than during normal breathing.
This type of breath control, considered important in speech evolution, had also been thought to be unique to humans.
"Play Faces" to Chimp Chuckles?
Convinced by what he calls an "admirable" study, primatologist Frans de Waal said from now on he'd use "laughter" to describe what scientists have traditionally called a chimp's play face.
The combination of common facial expressions, breathing patterns, and sounds has led de Waal to the conclusion that our laughter has prehistoric, ape-based origins.
What's more, "the primate laugh is given in playful contexts, and as such has a strong similarity to the human laugh," added de Waal, who was not involved in the tickle study.
"Tickling and wrestling are the situations in which primates laugh—and I use the term 'laugh' now advisedly, because the evidence from this study is very strong that their display is evolutionarily related to the human laugh."
Next Up: Rat Laughter?
Primates have apparently packed a lot of laughter into the last 10 to 16 million years, but there's a chance the chuckle originated even earlier: Tickle-induced "laughter" has also been reported in rats.
The idea remains controversial, but it could suggest that our funny bone evolved much closer to the trunk of mammals' evolutionary tree.
SOURCES AND RELATED WEB SITES
University of Portsmouth: Marina Davila Ross
Emory University: Frans B.M. de Waal
University of Wisconsin: Charles Snowdon
Apes Laugh, Tickle Study Finds
Brian Handwerk for National Geographic News
June 4, 2009
What happens if you tickle a gorilla? According to a new study, the ape laughs—which would mean we're not the only animals born with funny bones.
By tickling young gorillas, chimpanzees, bonobos, and orangutans, researchers say they learned that all great apes laugh.
Their findings suggest we inherited our own ability to laugh from the last common ancestor from which humans and great apes evolved, which lived 10 to 16 million years ago.
Primatologist and psychologist Marina Davila Ross of the U.K.'s University of Portsmouth led a team that tickled the necks, feet, palms, and armpits of infant and juvenile apes as well as human babies. The team recorded more than 800 of the resulting giggles and guffaws.
(go to the link to hear laughter recordings)
Mapping the audible similarities and differences in laughs across the five species, the researchers created an acoustic family tree of human and great ape laughter.
The tree, they found, closely matched the standard genetics-based evolutionary tree of primates.
"So we concluded that these vocalizations all share the same common ancestry," Davila Ross explained.
But even the most casual listener can tell a human laugh from an ape laugh. Davila Ross points out that human laughter has distinct differences from ape laughter, most likely because humans have evolved much more rapidly than apes during the past five million years.
And at least one great mystery remains: What purpose does ape laughter serve?
"I'm very keen," Davila Ross said, "on learning how laughter is being used among great apes as compared to humans."
Is It Really Laughter?
It's previously been argued that chimps chuckle, but their method—"laughing" on both the exhale and inhale—had been deemed too different from the human, exhale-only laugh.
The tickle study, however, found evidence that most ape laughter, especially among gorillas and bonobos, shares key traits with human laughter.
Like humans, for example, gorillas and bonobos laughed only while exhaling—leading University of Wisconsin zoologist and psychologist Charles Snowdon, who was not involved in the study, to conclude that, "contrary to current views, the exhalation-only laughter is not uniquely human but is found in our ape ancestors."
Furthermore, gorillas' and bonobos' exhaling breaths during laughter lasted three to four times longer than during normal breathing.
This type of breath control, considered important in speech evolution, had also been thought to be unique to humans.
"Play Faces" to Chimp Chuckles?
Convinced by what he calls an "admirable" study, primatologist Frans de Waal said from now on he'd use "laughter" to describe what scientists have traditionally called a chimp's play face.
The combination of common facial expressions, breathing patterns, and sounds has led de Waal to the conclusion that our laughter has prehistoric, ape-based origins.
What's more, "the primate laugh is given in playful contexts, and as such has a strong similarity to the human laugh," added de Waal, who was not involved in the tickle study.
"Tickling and wrestling are the situations in which primates laugh—and I use the term 'laugh' now advisedly, because the evidence from this study is very strong that their display is evolutionarily related to the human laugh."
Next Up: Rat Laughter?
Primates have apparently packed a lot of laughter into the last 10 to 16 million years, but there's a chance the chuckle originated even earlier: Tickle-induced "laughter" has also been reported in rats.
The idea remains controversial, but it could suggest that our funny bone evolved much closer to the trunk of mammals' evolutionary tree.
SOURCES AND RELATED WEB SITES
University of Portsmouth: Marina Davila Ross
Emory University: Frans B.M. de Waal
University of Wisconsin: Charles Snowdon
Why Do We Choose Our Mates? Ask Charles Darwin, Prof Says
http://www.sciencedaily.com/releases/2009/06/090615185428.htm
ScienceDaily (June 17, 2009) — Charles Darwin wrote about it 150 years ago: animals don't pick their mates by pure chance – it's a process that is deliberate and involves numerous factors. After decades of examining his work, experts agree that he pretty much scored a scientific bullseye, but a very big question is, "What have we learned since then?" asks a Texas A&M University biologist who has studied Darwin's theories.
Adam Jones, an evolutional biologist who has studied Darwin's work for years, says that Darwin's beliefs about the choice of mates and sexual selection being beyond mere chance have been proven correct, as stated in Darwin's landmark book The Descent of Man, and Selection in Relation to Sex.
Bottom line: It's no accident that certain peahens submit to gloriously-colored male peacocks, that lions get the females of their choice or that humans spend hours primping to catch the perfect spouses – it's a condition that is ingrained into all creatures and a conscious "choice" is made between the two so the romantic fireworks can begin.
Jones says Darwin set the standard for original thinking about animal reproduction and was first scientist to propose plausible mechanisms of evolution, and from there he took it one step further – he confirmed that animals' mating choices can drive evolutionary change.
"He noticed that birds, especially, seemed to be a bit picky about who they mated with," Jones explains. "He discovered that birds – especially females – had preferences and that they did not just choose a mate randomly. He believed this is due to beauty of the plumage, that females usually selected the most colorful males.
"That was an important first step, and it's given us models to work from to try to answer other big questions."
Those include determining methods to find out the actual criteria used in choosing a mate, what methods work and which do not, and the passing of genes on to the next generation, a field of study Jones says gained popularity in the 1970s and 1980s.
"Another big recent advance was the development of molecular markers, which allow us to perform paternity testing," Jones adds.
"These markers can be applied to animal populations, and they give us a definitive record of who is mating with whom and what offspring resulted from the mating events. And also, what is the driving force behind sexual selection? We have an unprecedented ability to document mating patterns but we still don't completely understand why some populations experience strong sexual selection and others don't."
Jones notes that other key questions Darwin's work uncovered but has not yet answered include the role of population characteristics and the environment and how they work together to produce strong sexual selection, and also what determines whether or not female choice will evolve in a particular species.
And perhaps the biggest question of all: How does all of this pertain to humans?
"Darwin concluded that sexual selection existed in the animal world and that humans definitely followed a similar process," Jones confirms.
"But he realized he had to explain it first as it related to animals. Darwin thought that sexual selection was an important process in humans, both for males and females. But how much has sexual selection acted on males versus females in humans? Today, while we are celebrating the 200th year of the birth of Charles Darwin, we know sexual selection occurs and is very important but there are still many unanswered questions about precisely why and how it works, especially in humans."
Journal reference:
. Mate Choice and Sexual Selection: What Have We Learned Since Darwin? Proceedings of the National Academy of Sciences, June 16, 2009
Adapted from materials provided by Texas A&M University, via EurekAlert!, a service of AAAS.
ScienceDaily (June 17, 2009) — Charles Darwin wrote about it 150 years ago: animals don't pick their mates by pure chance – it's a process that is deliberate and involves numerous factors. After decades of examining his work, experts agree that he pretty much scored a scientific bullseye, but a very big question is, "What have we learned since then?" asks a Texas A&M University biologist who has studied Darwin's theories.
Adam Jones, an evolutional biologist who has studied Darwin's work for years, says that Darwin's beliefs about the choice of mates and sexual selection being beyond mere chance have been proven correct, as stated in Darwin's landmark book The Descent of Man, and Selection in Relation to Sex.
Bottom line: It's no accident that certain peahens submit to gloriously-colored male peacocks, that lions get the females of their choice or that humans spend hours primping to catch the perfect spouses – it's a condition that is ingrained into all creatures and a conscious "choice" is made between the two so the romantic fireworks can begin.
Jones says Darwin set the standard for original thinking about animal reproduction and was first scientist to propose plausible mechanisms of evolution, and from there he took it one step further – he confirmed that animals' mating choices can drive evolutionary change.
"He noticed that birds, especially, seemed to be a bit picky about who they mated with," Jones explains. "He discovered that birds – especially females – had preferences and that they did not just choose a mate randomly. He believed this is due to beauty of the plumage, that females usually selected the most colorful males.
"That was an important first step, and it's given us models to work from to try to answer other big questions."
Those include determining methods to find out the actual criteria used in choosing a mate, what methods work and which do not, and the passing of genes on to the next generation, a field of study Jones says gained popularity in the 1970s and 1980s.
"Another big recent advance was the development of molecular markers, which allow us to perform paternity testing," Jones adds.
"These markers can be applied to animal populations, and they give us a definitive record of who is mating with whom and what offspring resulted from the mating events. And also, what is the driving force behind sexual selection? We have an unprecedented ability to document mating patterns but we still don't completely understand why some populations experience strong sexual selection and others don't."
Jones notes that other key questions Darwin's work uncovered but has not yet answered include the role of population characteristics and the environment and how they work together to produce strong sexual selection, and also what determines whether or not female choice will evolve in a particular species.
And perhaps the biggest question of all: How does all of this pertain to humans?
"Darwin concluded that sexual selection existed in the animal world and that humans definitely followed a similar process," Jones confirms.
"But he realized he had to explain it first as it related to animals. Darwin thought that sexual selection was an important process in humans, both for males and females. But how much has sexual selection acted on males versus females in humans? Today, while we are celebrating the 200th year of the birth of Charles Darwin, we know sexual selection occurs and is very important but there are still many unanswered questions about precisely why and how it works, especially in humans."
Journal reference:
. Mate Choice and Sexual Selection: What Have We Learned Since Darwin? Proceedings of the National Academy of Sciences, June 16, 2009
Adapted from materials provided by Texas A&M University, via EurekAlert!, a service of AAAS.
We Help Friends Due To Empathy; Relatives Due To Expectation Of Reciprocity
http://www.sciencedaily.com/releases/2008/03/080321114214.htm
ScienceDaily (Mar. 24, 2008) — Empathy is an emotional reaction to the plight of others. Empathy can lead to altruistic behaviour, i.e. helping someone with the sole intention of enhancing that person’s wellbeing. If we see people in difficulty, for example, we feel the same emotions, and this may prompt us to help them. Yet the relationship between empathy and altruism is still far from clear. Psychologist Lidewij Niezink has researched this subject. She concluded that when we help friends in need, we are prompted by feelings of empathy, and that when we help relatives we do so because we have expectations of reciprocity.
Niezink will receive her PhD on 27 March 2008 at the University of Groningen. She measured the empathic responses by telling the participants in the study about a young woman who is in a wheelchair following a serious accident. The participants then had to answer a series of questions designed to show how much they sympathise and identify with the woman.
Social comparison
Among other things, Niezink studied the empathetic reactions of people who often compare themselves with others. ‘We all compare ourselves with the people around us, but some people do this more than others. When the people in this group compare themselves with someone in a worse position, they often experience negative emotions such as tension, agitation, anxiety and irritation.’ Niezink discovered that these negative emotions are actually an expression of empathy. These people feel involved with the person in need, and identify with him/her. The negative emotions are a way of expressing this.
Family and friends
Niezink also studied the role of empathetic feelings in relationships with friends and family members. She discovered that we help friends for different reasons than family members. ‘People help friends out of feelings of empathy, but they help family members because they have expectations about reciprocation.’ This result is surprising, because it was always assumed that empathy was primarily a characteristic of family relationships. ‘But it is logical when you think about it. When you move house, it’s always your brother who comes to help. You can usually rely on family. We do not choose our families, but we do choose our friends. We feel a greater sense of connection with friends, so feelings of empathy are more important.
Altruistic options model
Niezink also compared various studies of empathy, and concludes that the methods varied quite considerably. ‘They are not talking about the same concept. That makes it more difficult to study altruism.’ Niezink then developed the ‘altruistic choice model’. The model works as follows. You see the suffering of others and this leads to a feeling of empathy, over which you have no control. This can be followed by various emotional responses: sympathizing/identifying with the person in question, concern or ‘softheartedness’ (tender feelings). These are responses that we can influence. These responses, in turn, can lead to compassion and altruism, i.e. understanding the other person’s suffering and the willingness to alleviate it. According to Niezink: ‘Altruism is a choice and something that we can actively cultivate when we observe others in need.’
Negative perception unjustified
Niezink is surprised about the fact that altruism is undervalued in our society. ‘We are pack animals. We cannot exist in isolation, so it is no scandal if we are willing to help each other. I’m not saying we must, but we can. Altruism makes the world a more pleasant place.’ It is rewarding to help someone. ‘Some people say, therefore, that helping others is based on selfish motives. If you help someone and it has positive consequences for you, that does not mean to say that your underlying motives are not altruistic.'
Adapted from materials provided by University of Groningen.
ScienceDaily (Mar. 24, 2008) — Empathy is an emotional reaction to the plight of others. Empathy can lead to altruistic behaviour, i.e. helping someone with the sole intention of enhancing that person’s wellbeing. If we see people in difficulty, for example, we feel the same emotions, and this may prompt us to help them. Yet the relationship between empathy and altruism is still far from clear. Psychologist Lidewij Niezink has researched this subject. She concluded that when we help friends in need, we are prompted by feelings of empathy, and that when we help relatives we do so because we have expectations of reciprocity.
Niezink will receive her PhD on 27 March 2008 at the University of Groningen. She measured the empathic responses by telling the participants in the study about a young woman who is in a wheelchair following a serious accident. The participants then had to answer a series of questions designed to show how much they sympathise and identify with the woman.
Social comparison
Among other things, Niezink studied the empathetic reactions of people who often compare themselves with others. ‘We all compare ourselves with the people around us, but some people do this more than others. When the people in this group compare themselves with someone in a worse position, they often experience negative emotions such as tension, agitation, anxiety and irritation.’ Niezink discovered that these negative emotions are actually an expression of empathy. These people feel involved with the person in need, and identify with him/her. The negative emotions are a way of expressing this.
Family and friends
Niezink also studied the role of empathetic feelings in relationships with friends and family members. She discovered that we help friends for different reasons than family members. ‘People help friends out of feelings of empathy, but they help family members because they have expectations about reciprocation.’ This result is surprising, because it was always assumed that empathy was primarily a characteristic of family relationships. ‘But it is logical when you think about it. When you move house, it’s always your brother who comes to help. You can usually rely on family. We do not choose our families, but we do choose our friends. We feel a greater sense of connection with friends, so feelings of empathy are more important.
Altruistic options model
Niezink also compared various studies of empathy, and concludes that the methods varied quite considerably. ‘They are not talking about the same concept. That makes it more difficult to study altruism.’ Niezink then developed the ‘altruistic choice model’. The model works as follows. You see the suffering of others and this leads to a feeling of empathy, over which you have no control. This can be followed by various emotional responses: sympathizing/identifying with the person in question, concern or ‘softheartedness’ (tender feelings). These are responses that we can influence. These responses, in turn, can lead to compassion and altruism, i.e. understanding the other person’s suffering and the willingness to alleviate it. According to Niezink: ‘Altruism is a choice and something that we can actively cultivate when we observe others in need.’
Negative perception unjustified
Niezink is surprised about the fact that altruism is undervalued in our society. ‘We are pack animals. We cannot exist in isolation, so it is no scandal if we are willing to help each other. I’m not saying we must, but we can. Altruism makes the world a more pleasant place.’ It is rewarding to help someone. ‘Some people say, therefore, that helping others is based on selfish motives. If you help someone and it has positive consequences for you, that does not mean to say that your underlying motives are not altruistic.'
Adapted from materials provided by University of Groningen.
The Dark Side Of Gifts: Feeling Indebted May Drive People To The Marketplace
http://www.sciencedaily.com/releases/2009/06/090615171632.htm
ScienceDaily (June 17, 2009) — You need to move out of your apartment. Do you call in your friends and family to haul boxes and furniture or contact a moving company? A new study in the Journal of Consumer Research shows that sometimes the emotions connected with asking for favors can actually drive people to the market.
According to the study's author, Jean-Sébastien Marcoux (HEC Montréal), many researchers romanticize gift-giving. "They praise it for humanizing market relationships, for making the market meaningful, and for providing an escape from the commodifying logic of capitalist exchanges," Marcoux writes. Other researchers have examined the dark side of gift giving: the troublesome feelings that arise from social indebtedness. But Marcoux's research examines how feelings of perpetual obligation affect people's attitudes toward the market.
Marcoux conducted a ten-year (1997-2007) ethnographic study in Montréal on moving. His methods involved interviews, observations, photography, and even moving furniture. He chose to study moving because it's an act that can involve the market, the "gift economy," or both. "Moving is a social event particularly favorable to the emergence of reciprocal relations," writes Marcoux. "Moreover, many people who move use both the gift economy and the market to do so."
By studying moving, Marcoux got an in-depth look at people who were often in the midst of traumatic life events, such as divorce, job loss, separation, or death of a loved one. Marcoux found that the guilt and obligation connected with asking for help from family and friends often drove people to seek the simpler transactions of the marketplace.
"It is important to recognize that withholding requests for gifts, services, and favors from significant others can be a driving force for using the market," writes Marcoux. "People use the market to free themselves from the straitjacket of social expectations—from the sense of indebtedness and emotional oppression—which constrains them in their reciprocity relations inside the gift economy," Marcoux concludes.
Journal reference:
Jean-Sébastien Marcoux. Escaping the Gift Economy. Journal of Consumer Research, 2009; 090603081616048 DOI: 10.1086/600485
ScienceDaily (June 17, 2009) — You need to move out of your apartment. Do you call in your friends and family to haul boxes and furniture or contact a moving company? A new study in the Journal of Consumer Research shows that sometimes the emotions connected with asking for favors can actually drive people to the market.
According to the study's author, Jean-Sébastien Marcoux (HEC Montréal), many researchers romanticize gift-giving. "They praise it for humanizing market relationships, for making the market meaningful, and for providing an escape from the commodifying logic of capitalist exchanges," Marcoux writes. Other researchers have examined the dark side of gift giving: the troublesome feelings that arise from social indebtedness. But Marcoux's research examines how feelings of perpetual obligation affect people's attitudes toward the market.
Marcoux conducted a ten-year (1997-2007) ethnographic study in Montréal on moving. His methods involved interviews, observations, photography, and even moving furniture. He chose to study moving because it's an act that can involve the market, the "gift economy," or both. "Moving is a social event particularly favorable to the emergence of reciprocal relations," writes Marcoux. "Moreover, many people who move use both the gift economy and the market to do so."
By studying moving, Marcoux got an in-depth look at people who were often in the midst of traumatic life events, such as divorce, job loss, separation, or death of a loved one. Marcoux found that the guilt and obligation connected with asking for help from family and friends often drove people to seek the simpler transactions of the marketplace.
"It is important to recognize that withholding requests for gifts, services, and favors from significant others can be a driving force for using the market," writes Marcoux. "People use the market to free themselves from the straitjacket of social expectations—from the sense of indebtedness and emotional oppression—which constrains them in their reciprocity relations inside the gift economy," Marcoux concludes.
Journal reference:
Jean-Sébastien Marcoux. Escaping the Gift Economy. Journal of Consumer Research, 2009; 090603081616048 DOI: 10.1086/600485
Same-sex Behavior Seen In Nearly All Animals, Review Finds
http://www.sciencedaily.com/releases/2009/06/090616122106.htm
ScienceDaily (June 17, 2009) — Same-sex behavior is a nearly universal phenomenon in the animal kingdom, common across species, from worms to frogs to birds, concludes a new review of existing research.
"It's clear that same-sex sexual behavior extends far beyond the well-known examples that dominate both the scientific and popular literature: for example, bonobos, dolphins, penguins and fruit flies," said Nathan Bailey, the first author of the review paper and a postdoctoral researcher in the Department of Biology at UC Riverside.
There is a caveat, however. The review also reports that same-sex behaviors are not the same across species, and that researchers may be calling qualitatively different phenomena by the same name.
"For example, male fruit flies may court other males because they are lacking a gene that enables them to discriminate between the sexes," Bailey said. "But that is very different from male bottlenose dolphins, who engage in same-sex interactions to facilitate group bonding, or female Laysan Albatross that can remain pair-bonded for life and cooperatively rear young."
Published June 16 in the journal Trends in Ecology & Evolution, the review by Bailey and Marlene Zuk, a professor of biology at UCR, also finds that although many studies are performed in the context of understanding the evolutionary origins of same-sex sexual behavior, almost none have considered its evolutionary consequences.
"Same-sex behaviors—courtship, mounting or parenting—are traits that may have been shaped by natural selection, a basic mechanism of evolution that occurs over successive generations," Bailey said. "But our review of studies also suggests that these same-sex behaviors might act as selective forces in and of themselves."
A selective force, which is a sudden or gradual stress placed on a population, affects the reproductive success of individuals in the population.
"When we think of selective forces, we tend to think of things like weather, temperature, or geographic features, but we can think of the social circumstances in a population of animals as a selective force, too," Bailey said. "Same-sex behavior radically changes those social circumstances, for example, by removing some individuals from the pool of animals available for mating."
Bailey, who works in Zuk's lab, noted that researchers in the field have made significant strides in the past two and a half decades studying the genetic and neural mechanisms that produce same-sex behaviors in individuals, and the ultimate reasons for their existence in populations.
"But like any other behavior that doesn't lead directly to reproduction—such as aggression or altruism—same-sex behavior can have evolutionary consequences that are just now beginning to be considered," he said. "For example, male-male copulations in locusts can be costly for the mounted male, and this cost may in turn increase selection pressure for males' tendency to release a chemical called panacetylnitrile, which dissuades other males from mounting them."
The review paper:
Examines work done to test hypotheses about the origins of same-sex behavior in animals.
Provides a framework for categorizing same-sex behavior, for example, is it adaptive, not adaptive, occurs often, infrequently?
Discusses what has been discovered about the genetics of same-sex behavior, especially in the model organism, the fruit fly Drosophila, and in human beings.
Examines connections between human sexual orientation research, and research on non-human animals, and highlights promising avenues of research in non-human systems.
The reviewers expected the research papers they read for their article would give them a better understanding of the degree to which same-sex behaviors are heritable in animals.
"How important are genes to the expression of these behaviors, compared to environmental factors?" Bailey said. "This is still unknown. Knowing this information would help us better understand how the behaviors evolve, and how they affect the evolution of other traits. It could also help us understand whether they are something that all individuals of a species are capable of, but only some actually express."
Bailey recommends that fellow evolutionary biologists studying same-sex behavior in animals adopt some of the research approaches that have been successful in human studies.
"We have estimates, for example, of the heritability of sexual orientation in humans, but none that I know of in other animals," he said. "Scientists have also targeted locations on the human genome that may contribute to sexual orientation, but aside from the fruit fly, we have no such detailed knowledge of the genetic architecture of same-sex behavior in other animals."
Next in their research, Bailey and Zuk plan to begin experimentally addressing some of the many issues raised in their review.
Said Bailey, "We want to get at this question: what are the evolutionary consequences of these behaviors? Are they important in the evolution of mating behavior, or do they just add extra 'background noise'? We are pursuing work on the Laysan Albatross, in which females form same-sex pairs and rear young together. Same-sex behavior in this species may not be aberrant, but instead can arise as an alternative reproductive strategy."
The UCR Academic Senate funded the one-year study.
ScienceDaily (June 17, 2009) — Same-sex behavior is a nearly universal phenomenon in the animal kingdom, common across species, from worms to frogs to birds, concludes a new review of existing research.
"It's clear that same-sex sexual behavior extends far beyond the well-known examples that dominate both the scientific and popular literature: for example, bonobos, dolphins, penguins and fruit flies," said Nathan Bailey, the first author of the review paper and a postdoctoral researcher in the Department of Biology at UC Riverside.
There is a caveat, however. The review also reports that same-sex behaviors are not the same across species, and that researchers may be calling qualitatively different phenomena by the same name.
"For example, male fruit flies may court other males because they are lacking a gene that enables them to discriminate between the sexes," Bailey said. "But that is very different from male bottlenose dolphins, who engage in same-sex interactions to facilitate group bonding, or female Laysan Albatross that can remain pair-bonded for life and cooperatively rear young."
Published June 16 in the journal Trends in Ecology & Evolution, the review by Bailey and Marlene Zuk, a professor of biology at UCR, also finds that although many studies are performed in the context of understanding the evolutionary origins of same-sex sexual behavior, almost none have considered its evolutionary consequences.
"Same-sex behaviors—courtship, mounting or parenting—are traits that may have been shaped by natural selection, a basic mechanism of evolution that occurs over successive generations," Bailey said. "But our review of studies also suggests that these same-sex behaviors might act as selective forces in and of themselves."
A selective force, which is a sudden or gradual stress placed on a population, affects the reproductive success of individuals in the population.
"When we think of selective forces, we tend to think of things like weather, temperature, or geographic features, but we can think of the social circumstances in a population of animals as a selective force, too," Bailey said. "Same-sex behavior radically changes those social circumstances, for example, by removing some individuals from the pool of animals available for mating."
Bailey, who works in Zuk's lab, noted that researchers in the field have made significant strides in the past two and a half decades studying the genetic and neural mechanisms that produce same-sex behaviors in individuals, and the ultimate reasons for their existence in populations.
"But like any other behavior that doesn't lead directly to reproduction—such as aggression or altruism—same-sex behavior can have evolutionary consequences that are just now beginning to be considered," he said. "For example, male-male copulations in locusts can be costly for the mounted male, and this cost may in turn increase selection pressure for males' tendency to release a chemical called panacetylnitrile, which dissuades other males from mounting them."
The review paper:
Examines work done to test hypotheses about the origins of same-sex behavior in animals.
Provides a framework for categorizing same-sex behavior, for example, is it adaptive, not adaptive, occurs often, infrequently?
Discusses what has been discovered about the genetics of same-sex behavior, especially in the model organism, the fruit fly Drosophila, and in human beings.
Examines connections between human sexual orientation research, and research on non-human animals, and highlights promising avenues of research in non-human systems.
The reviewers expected the research papers they read for their article would give them a better understanding of the degree to which same-sex behaviors are heritable in animals.
"How important are genes to the expression of these behaviors, compared to environmental factors?" Bailey said. "This is still unknown. Knowing this information would help us better understand how the behaviors evolve, and how they affect the evolution of other traits. It could also help us understand whether they are something that all individuals of a species are capable of, but only some actually express."
Bailey recommends that fellow evolutionary biologists studying same-sex behavior in animals adopt some of the research approaches that have been successful in human studies.
"We have estimates, for example, of the heritability of sexual orientation in humans, but none that I know of in other animals," he said. "Scientists have also targeted locations on the human genome that may contribute to sexual orientation, but aside from the fruit fly, we have no such detailed knowledge of the genetic architecture of same-sex behavior in other animals."
Next in their research, Bailey and Zuk plan to begin experimentally addressing some of the many issues raised in their review.
Said Bailey, "We want to get at this question: what are the evolutionary consequences of these behaviors? Are they important in the evolution of mating behavior, or do they just add extra 'background noise'? We are pursuing work on the Laysan Albatross, in which females form same-sex pairs and rear young together. Same-sex behavior in this species may not be aberrant, but instead can arise as an alternative reproductive strategy."
The UCR Academic Senate funded the one-year study.
Thursday, June 11, 2009
Close Social Ties Make Baboons Better Mothers, Study Finds
http://www.sciencedaily.com/releases/2009/06/090610091429.htm
ScienceDaily (June 11, 2009) — Baboons whose mothers have strong relationships with other females are much more likely to survive to adulthood than baboons reared by less social mothers, according to a new study by researchers at UCLA, the University of Pennsylvania and other institutions.
"If you're a baboon, the strength of your mother's relationship with other females is the best predictor of whether you'll live to have children yourself," said Joan Silk, the study's lead author and a UCLA professor of anthropology. "The study adds to mounting evidence of the biological benefits of close relationships among females."
The findings are significant because "survivorship to reproduction is the gold standard in evolutionary biology," said co-author Dorothy Cheney, a professor of biology at the University of Pennsylvania. "Females who raise offspring to a reproductive age are more likely see their genes pass along, so these findings demonstrate an evolutionary advantage to strong relationships with other females. In evolutionary terms, social moms are the fittest moms — at least when it comes to baboons."
The study appears online in the Proceedings of the Royal Society B, a peer-reviewed journal published by the national academy of science of the United Kingdom and the Commonwealth.
Silk, Cheney and seven other researchers from the University of Pennsylvania, the University of Michigan and the University of St. Andrews in Kenya analyzed 17 years worth of records on more than 66 adult female baboons in the Moremi Game Reserve, a 2,000-square-mile national park in Botswana that teems with wildlife.
Collected on the ground by primatologists who tracked the baboons six days a week, 12 months a year, the records reflected the sex and survival rates of baboon offspring, as well as telling details of the mothers' social lives, including their ranking within the group, as measured by the direction of approach/retreat interactions, and the amount of social interactions they had with each of the group's other females.
In addition to showing how often one animal approached another, the records of social interactions included details of grooming, which is known to be the primary form of social interaction in Old World monkeys. The researchers noted how much time — frequency and duration — the females spent grooming each other and how often they solicited grooming from other females.
Of all the factors studied, the strength of a mother's social bonds with another female had the most significant effect on the survival rates of offspring. A mother's dominance rank proved to have no affect on the survival rate of her offspring.
"We really expected dominance status to be more influential than it proved to be," Silk said.
Offspring from the most social mothers turned out to be about one-and-a-half times more likely to survive to adulthood than offspring from the least social mothers.
The strongest social bonds were measured between mothers and adult daughters, followed by sisters and all other potential relationships, including aunts, nieces, cousins and baboons with no familial ties. Bonds between mothers and adult daughters proved to be three times stronger than those between sisters and 10 times stronger than relationships with other females.
"What really matter to these girls are mother-daughter bonds," Silk said. "They're really strong, and they last forever. If your mom is alive, she's one of your top partners, always. But more importantly, it's the strength of these bonds, because females whose bonds with their mothers and daughters were strong had higher offspring survival than females whose bonds with these relatives were weak."
Silk's past research with Jeanne Altmann, the Eugene Higgins Professor of Ecology and Evolutionary Biology at Princeton University, and Susan C. Alberts, a professor of biology at Duke University, on baboons in the Amboseli Basin of Kenya had found a higher survival rate for baboons with social mothers, but the research only tracked offspring through the first year of life.
For the new study, researchers followed offspring from 1 year of age through sexual maturity — roughly 5 years of age. The new study also differs from past baboon research by focusing on the strength and duration of relationships between pairs of females rather than on the amount of social interactions in general.
"The benefit comes not from being wildly social — it's about having close social bonds," said Cheney, who runs the Moremi baboon-tracking project with University of Pennsylvania psychology professor Robert M. Seyfarth.
"These females form strong relationships with particular partners," Silk said. "They don't treat everyone the same. They spend a lot more time with — and a lot more time grooming — some females than others, and these relationships tend to be very long-lasting."
Additional research is needed to determine how the female bonds improve infant survival, but it may have to do with such stress hormones as cortisol, Silk said. Research has shown that prolonged elevations of stress hormones in primates can lead to cardiovascular disease and other serious health problems. Research has also shown that grooming tends to lower these stress hormones in baboons.
"Our research suggests that somehow there is a link between the kind of social relationships you form and the natural, normal stresses that occur in everyday life, and that seems to have — at least in baboons — a long-term effect on reproductive success," Silk said.
Said to share 92 percent of their DNA with humans, baboons are close relatives of humans. Baboons and humans last shared a common ancestor about 18 million years ago. The new findings on social interactions among mothers parallel recent research that has shown health benefits for humans who enjoy particularly close social networks.
"Our findings suggest benefits from forming close relationships are built into us from a long way back," Silk said.
The research received funding from the National Geographic Foundation, the Research Foundation of the University of Pennsylvania, the Institute for Research in Cognitive Science at the University of Pennsylvania, the National Institute of Health and the National Science Foundation.
ScienceDaily (June 11, 2009) — Baboons whose mothers have strong relationships with other females are much more likely to survive to adulthood than baboons reared by less social mothers, according to a new study by researchers at UCLA, the University of Pennsylvania and other institutions.
"If you're a baboon, the strength of your mother's relationship with other females is the best predictor of whether you'll live to have children yourself," said Joan Silk, the study's lead author and a UCLA professor of anthropology. "The study adds to mounting evidence of the biological benefits of close relationships among females."
The findings are significant because "survivorship to reproduction is the gold standard in evolutionary biology," said co-author Dorothy Cheney, a professor of biology at the University of Pennsylvania. "Females who raise offspring to a reproductive age are more likely see their genes pass along, so these findings demonstrate an evolutionary advantage to strong relationships with other females. In evolutionary terms, social moms are the fittest moms — at least when it comes to baboons."
The study appears online in the Proceedings of the Royal Society B, a peer-reviewed journal published by the national academy of science of the United Kingdom and the Commonwealth.
Silk, Cheney and seven other researchers from the University of Pennsylvania, the University of Michigan and the University of St. Andrews in Kenya analyzed 17 years worth of records on more than 66 adult female baboons in the Moremi Game Reserve, a 2,000-square-mile national park in Botswana that teems with wildlife.
Collected on the ground by primatologists who tracked the baboons six days a week, 12 months a year, the records reflected the sex and survival rates of baboon offspring, as well as telling details of the mothers' social lives, including their ranking within the group, as measured by the direction of approach/retreat interactions, and the amount of social interactions they had with each of the group's other females.
In addition to showing how often one animal approached another, the records of social interactions included details of grooming, which is known to be the primary form of social interaction in Old World monkeys. The researchers noted how much time — frequency and duration — the females spent grooming each other and how often they solicited grooming from other females.
Of all the factors studied, the strength of a mother's social bonds with another female had the most significant effect on the survival rates of offspring. A mother's dominance rank proved to have no affect on the survival rate of her offspring.
"We really expected dominance status to be more influential than it proved to be," Silk said.
Offspring from the most social mothers turned out to be about one-and-a-half times more likely to survive to adulthood than offspring from the least social mothers.
The strongest social bonds were measured between mothers and adult daughters, followed by sisters and all other potential relationships, including aunts, nieces, cousins and baboons with no familial ties. Bonds between mothers and adult daughters proved to be three times stronger than those between sisters and 10 times stronger than relationships with other females.
"What really matter to these girls are mother-daughter bonds," Silk said. "They're really strong, and they last forever. If your mom is alive, she's one of your top partners, always. But more importantly, it's the strength of these bonds, because females whose bonds with their mothers and daughters were strong had higher offspring survival than females whose bonds with these relatives were weak."
Silk's past research with Jeanne Altmann, the Eugene Higgins Professor of Ecology and Evolutionary Biology at Princeton University, and Susan C. Alberts, a professor of biology at Duke University, on baboons in the Amboseli Basin of Kenya had found a higher survival rate for baboons with social mothers, but the research only tracked offspring through the first year of life.
For the new study, researchers followed offspring from 1 year of age through sexual maturity — roughly 5 years of age. The new study also differs from past baboon research by focusing on the strength and duration of relationships between pairs of females rather than on the amount of social interactions in general.
"The benefit comes not from being wildly social — it's about having close social bonds," said Cheney, who runs the Moremi baboon-tracking project with University of Pennsylvania psychology professor Robert M. Seyfarth.
"These females form strong relationships with particular partners," Silk said. "They don't treat everyone the same. They spend a lot more time with — and a lot more time grooming — some females than others, and these relationships tend to be very long-lasting."
Additional research is needed to determine how the female bonds improve infant survival, but it may have to do with such stress hormones as cortisol, Silk said. Research has shown that prolonged elevations of stress hormones in primates can lead to cardiovascular disease and other serious health problems. Research has also shown that grooming tends to lower these stress hormones in baboons.
"Our research suggests that somehow there is a link between the kind of social relationships you form and the natural, normal stresses that occur in everyday life, and that seems to have — at least in baboons — a long-term effect on reproductive success," Silk said.
Said to share 92 percent of their DNA with humans, baboons are close relatives of humans. Baboons and humans last shared a common ancestor about 18 million years ago. The new findings on social interactions among mothers parallel recent research that has shown health benefits for humans who enjoy particularly close social networks.
"Our findings suggest benefits from forming close relationships are built into us from a long way back," Silk said.
The research received funding from the National Geographic Foundation, the Research Foundation of the University of Pennsylvania, the Institute for Research in Cognitive Science at the University of Pennsylvania, the National Institute of Health and the National Science Foundation.
Thursday, June 4, 2009
Males, females swap sex-role stereotypes
http://www.sciencenews.org/view/generic/id/43212/title/Males%2C_females_swap_sex-role_stereotypes
Analysis finds that mating strategies are not universal
By Bruce Bower
May 23rd, 2009; Vol.175 #11 (p. 5)
SEX ROLES IN SOCIETIES A new cross-cultural study finds that men and women in monogamous societies, such as Pitcairn Islanders (left), and some polygynous societies, including the Aka in the Central African Republic (right), have overlapping ranges of number of offspring. Luis Marden/National Geographic/Getty; Barry Hewlett
Chuck that nonsense about “men are from Mars, women are from Venus.” Here on Earth, the sexes play the mating game with a flexible set of rules. A new study suggests that scientists should abandon the idea that males evolved to be promiscuous and females to be selective. Combined data from 18 modern and traditional societies show greater overall variation in reproductive success for men than for women — with some men producing lots of children with multiple partners and other men conceiving few or no children, say psychologist Gillian Brown of the University of St. Andrews in Fife, Scotland, and her colleagues. Women tend to have a handful of children.
In the past, researchers have treated this pattern as a sign of universal mating tendencies, with women limiting how many children they bear and men conceiving as many children as possible.
Yet the same pattern of distinctive male and female sex roles doesn’t appear when many of these same 18 societies are examined individually, Brown’s group reports in the June Trends in Ecology & Evolution. In monogamous societies and even in some polygynous ones, where men can have more than one wife or mate, men and women can have similar variation in the number of children they produce, the scientists find.
Monogamous societies in the new study included Pitcairn Islanders in the South Pacific, Dobe !Kung hunter-gatherers in southern Africa and 19th century Swedes. Polygynous societies displaying comparable or only slightly unequal patterns of reproductive success for men and women included Aka hunter-gatherers in central Africa, Hadza hunter-gatherers in southern Africa and nomadic Yomut Turkmen in Iran.
Looking at the data all together, patterns of reproductive success were skewed by data from a few polygynous societies in which small numbers of men conceived the bulk of the offspring, the researchers contend. Examples of this pattern came from the Dogon and Kipsigis, both in Africa.
“Half of the populations we studied had similar variations in male and female reproductive success, which is inconsistent with universal stereotypes of passive, discriminating females and promiscuous males,” Brown says.
These scientific generalizations originated with fruit fly studies conducted by English geneticist Angus Bateman in 1948. He reported that male flies exhibited greater variation than females in numbers of sexual partners and offspring. Females mating with several males showed less of an increase in the number of offspring than males mating with many females.
Bateman concluded that it was more costly for females to produce a single egg than for males to produce a single sperm, leading to “discriminating passivity” among female flies and “undiscriminating eagerness” among male flies.
But in the past decade or so, studies of fruit flies and other animals have documented considerable variation in numbers of sexual partners and offspring for both sexes. Situational factors shape animals’ mating decisions, Brown asserts. Investigations suggest that females often get choosy when outnumbered by males or required to raise offspring alone. Males become picky when outnumbered by females or when required to help raise offspring. In small, spread out populations with roughly equal numbers of males and females, both sexes tend to mate indiscriminately.
Brown and her colleagues provide initial evidence that the “astonishing flexibility” of mating strategies also applies to people, remarks behavioral ecologist Stephen Emlen of Cornell University.
“A lot of nonhuman animals that are thought of as innately controlled robots actually perform sophisticated cost-benefit analyses of different choices and adjust their behavior based on flexible rules of thumb,” asserts Emlen, who studies mating decisions in birds. Emlen says it would be surprising if people didn’t have even more variable mating strategies than other animals.
Anthropologist Lee Cronk of Rutgers University in New Brunswick, N.J., says that he hopes the study “will have a major impact on future evolutionary work on human mating patterns.”
Cronk still thinks that universal mating strategies exist for men and women and were genetically ingrained during the Stone Age. But these strategies can play out in a variety of ways depending on the cultural, social and demographic features of modern societies.
Brown sees the situation differently. Disparities in learned mating strategies and cultural beliefs that have developed among groups over the past 50,000 years or so have also led to genetic differences among those populations, not to universal mating tendencies, she suspects.
Brown’s group analyzed information on reproduction and mating in hunter-gatherer, farming and industrialized societies from already published studies. Although these studies depended on women’s reports of who fathered their children, Brown regards the reliability of such evidence as comparable between monogamous and polygynous societies.
Scientists must now try to estimate and compare numbers of sexual partners, as well as offspring, for individuals in different societies, she says. Doing so will be challenging, since attempts to establish the numbers of sexual partners for men and women have relied on self-reports that are unreliable, Brown asserts.
She and her colleagues remain cautious about assuming that men always have more sexual partners than women in polygynous societies. In about half of polygynous societies, most men still take no more than one wife, they note. In others, women as well as men conceive children with two or more partners.
Thorough cross-cultural studies would likely reveal a great variety of mating strategies that respond to local conditions, predicts behavioral ecologist Mhairi Gibson of the University of Bristol in England. “Unfortunately, few anthropologists continue to collect such quantitative data on human behavior,” she says.
Source: Adapted from Brown et al.
Analysis finds that mating strategies are not universal
By Bruce Bower
May 23rd, 2009; Vol.175 #11 (p. 5)
SEX ROLES IN SOCIETIES A new cross-cultural study finds that men and women in monogamous societies, such as Pitcairn Islanders (left), and some polygynous societies, including the Aka in the Central African Republic (right), have overlapping ranges of number of offspring. Luis Marden/National Geographic/Getty; Barry Hewlett
Chuck that nonsense about “men are from Mars, women are from Venus.” Here on Earth, the sexes play the mating game with a flexible set of rules. A new study suggests that scientists should abandon the idea that males evolved to be promiscuous and females to be selective. Combined data from 18 modern and traditional societies show greater overall variation in reproductive success for men than for women — with some men producing lots of children with multiple partners and other men conceiving few or no children, say psychologist Gillian Brown of the University of St. Andrews in Fife, Scotland, and her colleagues. Women tend to have a handful of children.
In the past, researchers have treated this pattern as a sign of universal mating tendencies, with women limiting how many children they bear and men conceiving as many children as possible.
Yet the same pattern of distinctive male and female sex roles doesn’t appear when many of these same 18 societies are examined individually, Brown’s group reports in the June Trends in Ecology & Evolution. In monogamous societies and even in some polygynous ones, where men can have more than one wife or mate, men and women can have similar variation in the number of children they produce, the scientists find.
Monogamous societies in the new study included Pitcairn Islanders in the South Pacific, Dobe !Kung hunter-gatherers in southern Africa and 19th century Swedes. Polygynous societies displaying comparable or only slightly unequal patterns of reproductive success for men and women included Aka hunter-gatherers in central Africa, Hadza hunter-gatherers in southern Africa and nomadic Yomut Turkmen in Iran.
Looking at the data all together, patterns of reproductive success were skewed by data from a few polygynous societies in which small numbers of men conceived the bulk of the offspring, the researchers contend. Examples of this pattern came from the Dogon and Kipsigis, both in Africa.
“Half of the populations we studied had similar variations in male and female reproductive success, which is inconsistent with universal stereotypes of passive, discriminating females and promiscuous males,” Brown says.
These scientific generalizations originated with fruit fly studies conducted by English geneticist Angus Bateman in 1948. He reported that male flies exhibited greater variation than females in numbers of sexual partners and offspring. Females mating with several males showed less of an increase in the number of offspring than males mating with many females.
Bateman concluded that it was more costly for females to produce a single egg than for males to produce a single sperm, leading to “discriminating passivity” among female flies and “undiscriminating eagerness” among male flies.
But in the past decade or so, studies of fruit flies and other animals have documented considerable variation in numbers of sexual partners and offspring for both sexes. Situational factors shape animals’ mating decisions, Brown asserts. Investigations suggest that females often get choosy when outnumbered by males or required to raise offspring alone. Males become picky when outnumbered by females or when required to help raise offspring. In small, spread out populations with roughly equal numbers of males and females, both sexes tend to mate indiscriminately.
Brown and her colleagues provide initial evidence that the “astonishing flexibility” of mating strategies also applies to people, remarks behavioral ecologist Stephen Emlen of Cornell University.
“A lot of nonhuman animals that are thought of as innately controlled robots actually perform sophisticated cost-benefit analyses of different choices and adjust their behavior based on flexible rules of thumb,” asserts Emlen, who studies mating decisions in birds. Emlen says it would be surprising if people didn’t have even more variable mating strategies than other animals.
Anthropologist Lee Cronk of Rutgers University in New Brunswick, N.J., says that he hopes the study “will have a major impact on future evolutionary work on human mating patterns.”
Cronk still thinks that universal mating strategies exist for men and women and were genetically ingrained during the Stone Age. But these strategies can play out in a variety of ways depending on the cultural, social and demographic features of modern societies.
Brown sees the situation differently. Disparities in learned mating strategies and cultural beliefs that have developed among groups over the past 50,000 years or so have also led to genetic differences among those populations, not to universal mating tendencies, she suspects.
Brown’s group analyzed information on reproduction and mating in hunter-gatherer, farming and industrialized societies from already published studies. Although these studies depended on women’s reports of who fathered their children, Brown regards the reliability of such evidence as comparable between monogamous and polygynous societies.
Scientists must now try to estimate and compare numbers of sexual partners, as well as offspring, for individuals in different societies, she says. Doing so will be challenging, since attempts to establish the numbers of sexual partners for men and women have relied on self-reports that are unreliable, Brown asserts.
She and her colleagues remain cautious about assuming that men always have more sexual partners than women in polygynous societies. In about half of polygynous societies, most men still take no more than one wife, they note. In others, women as well as men conceive children with two or more partners.
Thorough cross-cultural studies would likely reveal a great variety of mating strategies that respond to local conditions, predicts behavioral ecologist Mhairi Gibson of the University of Bristol in England. “Unfortunately, few anthropologists continue to collect such quantitative data on human behavior,” she says.
Source: Adapted from Brown et al.
Wednesday, June 3, 2009
Women May Not Be So Picky After All About Choosing A Mate
http://www.sciencedaily.com/releases/2009/06/090603101406.htm
ScienceDaily (June 2, 2009) — Men and women may not be from two different planets after all when it comes to choosiness in mate selection, according to new research from Northwestern University.
When women were assigned to the traditionally male role of approaching potential romantic partners, they were not any pickier than men in choosing that special someone to date, according to the speed dating study.
That finding, of course, is contrary to well established evolutionary explanations about mate selection. An abundance of such research suggests that women are influenced by higher reproductive costs (bearing and raising children) than men and thus are much choosier when it comes to love interests.
The new study is the latest research of two Northwestern psychologists whose well-reported work on speed dating offers unparalleled opportunities for studying romantic attraction in action.
Deviating from standard speed-dating experiments – and from the typical conventions at professional speed-dating events -- women in the study were required to go from man to man during their four-minute speed dates half the time, rather than always staying put. In most speed-dating events, the women stay in one place as the men circulate.
"The mere act of physically approaching a potential partner, versus being approached, seemed to increase desire for that partner," said Eli Finkel, associate professor of psychology in the Weinberg College of Arts and Sciences at Northwestern and co-investigator of the study.
Regardless of gender, those who rotated experienced greater romantic desire for their partners, compared to those who sat throughout the event. The rotators, compared to the sitters, tended to have a greater interest in seeing their speed-dating partners again.
"Given that men generally are expected -- and sometimes required – to approach a potential love interest, the implications are intriguing," Finkel said.
"Let's face it, even today, there is a huge difference in terms of who is expected to walk across the bar to say 'hi,'" added Northwestern's Paul Eastwick, the study's other co-investigator.
Three hundred fifty undergraduates were recruited for the study's speed-dating events. In half of the events, the men rotated while the women sat. In the remaining events, the women rotated. Following each four-minute "date," the participants indicated their romantic desire in that partner and how self-confident they felt. Following the event, the students indicated on a Website whether they would or would not be interested in seeing each partner again.
When the men rotated, the results supported the long-held notion of men being less selective. When the women rotated, this robust sex difference disappeared.
The study draws upon embodiment research that suggests that physical actions alter perception. In one such study, for example, participants who were told to pull an unrelated object toward themselves while evaluating Chinese ideographs rated them as prettier than participants who pushed an unrelated object away from themselves while viewing the symbols.
"The embodiment research shows that our physical activity and psychological processes interface in ways that are outside our conscious awareness," Finkel said. "In conjunction with this previous embodiment research, our speed-dating results strongly suggest that the mere act of approaching a potential love interest can boost desire."
The researchers suggest that confidence also may have affected the results. Approaching a potential date increases confidence, which in turn makes the approacher less selective.
The study presents a clear example of how inconspicuous gender norms (having men rotate and women sit) can not only affect the outcome of a study, but also skew the chances of a speed dater walking away with a potential match.
"Our society is structured in gendered ways that can be subtle but very powerful," Eastwick concluded. The study has implications both for companies that capitalize on the business of dating and for researchers concerned with how social norms may affect research.
ScienceDaily (June 2, 2009) — Men and women may not be from two different planets after all when it comes to choosiness in mate selection, according to new research from Northwestern University.
When women were assigned to the traditionally male role of approaching potential romantic partners, they were not any pickier than men in choosing that special someone to date, according to the speed dating study.
That finding, of course, is contrary to well established evolutionary explanations about mate selection. An abundance of such research suggests that women are influenced by higher reproductive costs (bearing and raising children) than men and thus are much choosier when it comes to love interests.
The new study is the latest research of two Northwestern psychologists whose well-reported work on speed dating offers unparalleled opportunities for studying romantic attraction in action.
Deviating from standard speed-dating experiments – and from the typical conventions at professional speed-dating events -- women in the study were required to go from man to man during their four-minute speed dates half the time, rather than always staying put. In most speed-dating events, the women stay in one place as the men circulate.
"The mere act of physically approaching a potential partner, versus being approached, seemed to increase desire for that partner," said Eli Finkel, associate professor of psychology in the Weinberg College of Arts and Sciences at Northwestern and co-investigator of the study.
Regardless of gender, those who rotated experienced greater romantic desire for their partners, compared to those who sat throughout the event. The rotators, compared to the sitters, tended to have a greater interest in seeing their speed-dating partners again.
"Given that men generally are expected -- and sometimes required – to approach a potential love interest, the implications are intriguing," Finkel said.
"Let's face it, even today, there is a huge difference in terms of who is expected to walk across the bar to say 'hi,'" added Northwestern's Paul Eastwick, the study's other co-investigator.
Three hundred fifty undergraduates were recruited for the study's speed-dating events. In half of the events, the men rotated while the women sat. In the remaining events, the women rotated. Following each four-minute "date," the participants indicated their romantic desire in that partner and how self-confident they felt. Following the event, the students indicated on a Website whether they would or would not be interested in seeing each partner again.
When the men rotated, the results supported the long-held notion of men being less selective. When the women rotated, this robust sex difference disappeared.
The study draws upon embodiment research that suggests that physical actions alter perception. In one such study, for example, participants who were told to pull an unrelated object toward themselves while evaluating Chinese ideographs rated them as prettier than participants who pushed an unrelated object away from themselves while viewing the symbols.
"The embodiment research shows that our physical activity and psychological processes interface in ways that are outside our conscious awareness," Finkel said. "In conjunction with this previous embodiment research, our speed-dating results strongly suggest that the mere act of approaching a potential love interest can boost desire."
The researchers suggest that confidence also may have affected the results. Approaching a potential date increases confidence, which in turn makes the approacher less selective.
The study presents a clear example of how inconspicuous gender norms (having men rotate and women sit) can not only affect the outcome of a study, but also skew the chances of a speed dater walking away with a potential match.
"Our society is structured in gendered ways that can be subtle but very powerful," Eastwick concluded. The study has implications both for companies that capitalize on the business of dating and for researchers concerned with how social norms may affect research.
Feeling Close To A Friend Increases Progesterone, Boosts Well-being And Reduces Anxiety And Stress
http://www.sciencedaily.com/releases/2009/06/090602171941.htm
ScienceDaily (June 3, 2009) — Why does dishing with a girlfriend do wonders for a woman's mood?
A University of Michigan study has identified a likely reason: feeling emotionally close to a friend increases levels of the hormone progesterone, helping to boost well-being and reduce anxiety and stress.
"This study establishes progesterone as a likely part of the neuroendocrine basis of social bonding in humans," said U-M researcher Stephanie Brown, lead author of an article reporting the study findings, published in the current (June 2009) issue of the peer-reviewed journal Hormones and Behavior.
A sex hormone that fluctuates with the menstrual cycle, progesterone is also present in low levels in post-menopausal women and in men. Earlier research has shown that higher levels of progesterone increase the desire to bond with others, but the current study is the first to show that bonding with others increases levels of progesterone. The study also links these increases to a greater willingness to help other people, even at our own expense.
"It's important to find the links between biological mechanisms and human social behavior," said Brown, is a faculty associate at the U-M Institute for Social Research (ISR) and an assistant professor of internal medicine at the U-M Medical School. She is also affiliated with the Ann Arbor Veterans Affairs Hospital. "These links may help us understand why people in close relationships are happier, healthier, and live longer than those who are socially isolated."
Progesterone is much easier to measure than oxytocin, a hormone linked to trust, pair-bonding and maternal responsiveness in humans and other mammals. Oxytocin can only be measured through an invasive spinal tap or through expensive and complex brain imaging methods, such as positron emission tomography scans. Progesterone can be measured through simple saliva samples and may be related to oxytocin.
In the current study, Brown and colleagues examined the link between interpersonal closeness and salivary progesterone in 160 female college students.
At the start of the study, the researchers measured the levels of progesterone and of the stress hormone cortisol in the women's saliva, and obtained information about their menstrual cycles and whether they were using hormonal contraceptives or other hormonally active medications.
To control for daily variations in hormone levels, all the sessions were held between noon and 7 p.m.
The women were randomly assigned to partners and asked to perform either a task designed to elicit feelings of emotional closeness or a task that was emotionally neutral.
In the emotionally neutral task, the women proofread a botany manuscript together.
After completing the 20-minute tasks, the women played a computerized cooperative card game with their partners, and then had their progesterone and cortisol sampled again.
The progesterone levels of women who had engaged in the emotionally neutral tasks tended to decline, while the progesterone levels of women who engaged in the task designed to elicit closeness either remained the same or increased. The participants' cortisol levels did not change in a similar way.
Participants returned a week later, and played the computerized card game with their original partners again. Then researchers measured their progesterone and cortisol. Researchers also examined links between progesterone levels and how likely participants said they would be to risk their life for their partner.
"During the first phase of the study, we found no evidence of a relationship between progesterone and willingness to sacrifice," Brown said. "But a week later, increased progesterone predicted an increased willingness to say you would risk your life to help your partner."
According to Brown, the findings are consistent with a new evolutionary theory of altruism which argues that the hormonal basis of social bonds enables people to suppress self-interest when necessary in order to promote the well-being of another person, as when taking care of children or helping ailing family members or friends.
The results also help explain why social contact has well-documented health benefits---a relationship first identified nearly 20 years ago by U-M sociologist James House.
"Many of the hormones involved in bonding and helping behavior lead to reductions in stress and anxiety in both humans and other animals. Now we see that higher levels of progesterone may be part of the underlying physiological basis for these effects," Brown said.
ScienceDaily (June 3, 2009) — Why does dishing with a girlfriend do wonders for a woman's mood?
A University of Michigan study has identified a likely reason: feeling emotionally close to a friend increases levels of the hormone progesterone, helping to boost well-being and reduce anxiety and stress.
"This study establishes progesterone as a likely part of the neuroendocrine basis of social bonding in humans," said U-M researcher Stephanie Brown, lead author of an article reporting the study findings, published in the current (June 2009) issue of the peer-reviewed journal Hormones and Behavior.
A sex hormone that fluctuates with the menstrual cycle, progesterone is also present in low levels in post-menopausal women and in men. Earlier research has shown that higher levels of progesterone increase the desire to bond with others, but the current study is the first to show that bonding with others increases levels of progesterone. The study also links these increases to a greater willingness to help other people, even at our own expense.
"It's important to find the links between biological mechanisms and human social behavior," said Brown, is a faculty associate at the U-M Institute for Social Research (ISR) and an assistant professor of internal medicine at the U-M Medical School. She is also affiliated with the Ann Arbor Veterans Affairs Hospital. "These links may help us understand why people in close relationships are happier, healthier, and live longer than those who are socially isolated."
Progesterone is much easier to measure than oxytocin, a hormone linked to trust, pair-bonding and maternal responsiveness in humans and other mammals. Oxytocin can only be measured through an invasive spinal tap or through expensive and complex brain imaging methods, such as positron emission tomography scans. Progesterone can be measured through simple saliva samples and may be related to oxytocin.
In the current study, Brown and colleagues examined the link between interpersonal closeness and salivary progesterone in 160 female college students.
At the start of the study, the researchers measured the levels of progesterone and of the stress hormone cortisol in the women's saliva, and obtained information about their menstrual cycles and whether they were using hormonal contraceptives or other hormonally active medications.
To control for daily variations in hormone levels, all the sessions were held between noon and 7 p.m.
The women were randomly assigned to partners and asked to perform either a task designed to elicit feelings of emotional closeness or a task that was emotionally neutral.
In the emotionally neutral task, the women proofread a botany manuscript together.
After completing the 20-minute tasks, the women played a computerized cooperative card game with their partners, and then had their progesterone and cortisol sampled again.
The progesterone levels of women who had engaged in the emotionally neutral tasks tended to decline, while the progesterone levels of women who engaged in the task designed to elicit closeness either remained the same or increased. The participants' cortisol levels did not change in a similar way.
Participants returned a week later, and played the computerized card game with their original partners again. Then researchers measured their progesterone and cortisol. Researchers also examined links between progesterone levels and how likely participants said they would be to risk their life for their partner.
"During the first phase of the study, we found no evidence of a relationship between progesterone and willingness to sacrifice," Brown said. "But a week later, increased progesterone predicted an increased willingness to say you would risk your life to help your partner."
According to Brown, the findings are consistent with a new evolutionary theory of altruism which argues that the hormonal basis of social bonds enables people to suppress self-interest when necessary in order to promote the well-being of another person, as when taking care of children or helping ailing family members or friends.
The results also help explain why social contact has well-documented health benefits---a relationship first identified nearly 20 years ago by U-M sociologist James House.
"Many of the hormones involved in bonding and helping behavior lead to reductions in stress and anxiety in both humans and other animals. Now we see that higher levels of progesterone may be part of the underlying physiological basis for these effects," Brown said.
Myth About 'Dirty Old Men' Supported By Science
http://www.sciencedaily.com/releases/2008/12/081204074654.htm
ScienceDaily (Dec. 4, 2008) — Middle-aged men want younger women, often touting their intelligence and their high income. This is shown in research at Gothenburg University and Oxford University that studied 400 lonely hearts ads to see how men and women choose partners.
Research in the theory of evolution includes a number of accepted theories about how men and women choose their partners. Among the more established ones is that men place more emphasis on attractive appearance, whereas resources and social status are more important to women.
By examining lonely hearts advertisements, researchers at the University of Gothenburg and the University of Oxford have now tested how valid these presumed preferences are when modern individuals choose partners.
In the study, published in the journal Evolutionary Psychology, the researchers looked at 400 lonely hearts ads in the Swedish newspapers Göteborgs-Posten and Aftonbladet and on the Websites Spraydate and match.com.
To some extent, the findings support established theories:
Women, more than men, look for solid resources and social status. As a result men also offer this in their ads, through formulations like ‘large house’ and ‘economically independent.’
Men in all categories prefer younger partners. Of a total of 97 men who mentioned age in their ads, only three were looking for an older partner – among men aged 40 to 59, only one out of 67.
Younger women, on the other hand, prefer older men: fully 14 of 16 women aged 20-39 were looking for an older partner. Among women over 60, however, the majority were looking for a younger man.
Another point of departure for the study was that men are more fixated on appearance than women are. This turned out not to be the case.
“When it comes to physical characteristics, it turned out that men and women were the same. Both used words like, ‘athletic,’ ‘beautiful,’ ‘pretty,’ ‘tall,’ ‘handsome,’ and ‘trim’ to the same extent, and this goes both for their descriptions of themselves and for the characteristics they were looking for in a partner,” says Jörgen Johnsson at the Department of Zoology, University of Gothenburg, one of the researchers behind the study.
“This might indicate that men have learned to respond to women’s interest in looks, therefore stressing to the same extent their attractiveness in the ads. The fact that both sexes focus on looks may also be influenced by our times, with the great fixation on appearance in the media.”
The study is an elaboration of an undergraduate paper at the Department of Zoology, written by Linda Gustavsson. The associate at the University of Oxford is Tobias Uller.
ScienceDaily (Dec. 4, 2008) — Middle-aged men want younger women, often touting their intelligence and their high income. This is shown in research at Gothenburg University and Oxford University that studied 400 lonely hearts ads to see how men and women choose partners.
Research in the theory of evolution includes a number of accepted theories about how men and women choose their partners. Among the more established ones is that men place more emphasis on attractive appearance, whereas resources and social status are more important to women.
By examining lonely hearts advertisements, researchers at the University of Gothenburg and the University of Oxford have now tested how valid these presumed preferences are when modern individuals choose partners.
In the study, published in the journal Evolutionary Psychology, the researchers looked at 400 lonely hearts ads in the Swedish newspapers Göteborgs-Posten and Aftonbladet and on the Websites Spraydate and match.com.
To some extent, the findings support established theories:
Women, more than men, look for solid resources and social status. As a result men also offer this in their ads, through formulations like ‘large house’ and ‘economically independent.’
Men in all categories prefer younger partners. Of a total of 97 men who mentioned age in their ads, only three were looking for an older partner – among men aged 40 to 59, only one out of 67.
Younger women, on the other hand, prefer older men: fully 14 of 16 women aged 20-39 were looking for an older partner. Among women over 60, however, the majority were looking for a younger man.
Another point of departure for the study was that men are more fixated on appearance than women are. This turned out not to be the case.
“When it comes to physical characteristics, it turned out that men and women were the same. Both used words like, ‘athletic,’ ‘beautiful,’ ‘pretty,’ ‘tall,’ ‘handsome,’ and ‘trim’ to the same extent, and this goes both for their descriptions of themselves and for the characteristics they were looking for in a partner,” says Jörgen Johnsson at the Department of Zoology, University of Gothenburg, one of the researchers behind the study.
“This might indicate that men have learned to respond to women’s interest in looks, therefore stressing to the same extent their attractiveness in the ads. The fact that both sexes focus on looks may also be influenced by our times, with the great fixation on appearance in the media.”
The study is an elaboration of an undergraduate paper at the Department of Zoology, written by Linda Gustavsson. The associate at the University of Oxford is Tobias Uller.
Sexual Partner Status Affects A Woman's, But Not A Man's, Interest In The Opposite Sex
http://www.sciencedaily.com/releases/2009/05/090528120657.htm ScienceDaily (June 3, 2009) — A study by Indiana University neuroscientist Heather Rupp found that a woman's partner status influenced her interest in the opposite sex. In the study, women both with and without sexual partners showed little difference in their subjective ratings of photos of men when considering such measures as masculinity and attractiveness. However, the women who did not have sexual partners spent more time evaluating photos of men, demonstrating a greater interest in the photos.
No such difference was found between men who had sexual partners and those who did not. "These findings may reflect sex differences in reproductive strategies that may act early in the cognitive processing of potential partners and contribute to sex differences in sexual attraction and behavior," said Rupp, assistant scientist at The Kinsey Institute for Research in Sex, Gender and Reproduction.
For the study, 59 men and 56 women rated 510 photos of opposite-sex faces for realism, masculinity/femininity, attractiveness, or affect. Participants were instructed to give their "gut" reaction and to rate the pictures as quickly as possible. The men and women ranged in age from 17 to 26, were heterosexual, from a variety of ethnic backgrounds and were not using hormonal contraception. Of the women, 21 reported they had a current sexual partner; 25 of the men reported having a sexual partner. This is the first study to report whether having a current sexual partner influences interest in the opposite sex. Other studies have demonstrated that hormones, relationship goals and social context influence such interest.
"That there were no detectable effects of sexual partner status on women's subjective ratings of male faces, but there were on response times, which emphasizes the subtlety of this effect and introduces the possibility that sexual partner status impacts women's cognitive processing of novel male faces but not necessarily their conscious subjective appraisal," the authors wrote in the journal article. The researchers also note that influence of partner status in women could reflect that women, on average, are relatively committed in their romantic relationships, "which possibly suppresses their attention to and appraisal of alternative partners."
No such difference was found between men who had sexual partners and those who did not. "These findings may reflect sex differences in reproductive strategies that may act early in the cognitive processing of potential partners and contribute to sex differences in sexual attraction and behavior," said Rupp, assistant scientist at The Kinsey Institute for Research in Sex, Gender and Reproduction.
For the study, 59 men and 56 women rated 510 photos of opposite-sex faces for realism, masculinity/femininity, attractiveness, or affect. Participants were instructed to give their "gut" reaction and to rate the pictures as quickly as possible. The men and women ranged in age from 17 to 26, were heterosexual, from a variety of ethnic backgrounds and were not using hormonal contraception. Of the women, 21 reported they had a current sexual partner; 25 of the men reported having a sexual partner. This is the first study to report whether having a current sexual partner influences interest in the opposite sex. Other studies have demonstrated that hormones, relationship goals and social context influence such interest.
"That there were no detectable effects of sexual partner status on women's subjective ratings of male faces, but there were on response times, which emphasizes the subtlety of this effect and introduces the possibility that sexual partner status impacts women's cognitive processing of novel male faces but not necessarily their conscious subjective appraisal," the authors wrote in the journal article. The researchers also note that influence of partner status in women could reflect that women, on average, are relatively committed in their romantic relationships, "which possibly suppresses their attention to and appraisal of alternative partners."
Orangutans Communicate As If They Were Playing Charades
http://www.sciencedaily.com/releases/2007/08/070802091437.htm
ScienceDaily (Aug. 2, 2007) — When using gestures to get their points across, orangutans rely on the same basic strategy that humans follow when playing the popular game and intentionally modify or repeat hand (or other) signals based on the success or failure of their first attempt.
Professor Richard Byrne of the School of Psychology said, "We were surprised that the orangutans' responses so clearly signaled their assessment of the audience's comprehension. Looking at the tapes of the animal's responses, you can easily work out whether the orangutan thinks it has been fully, partially, or not understood, without seeing what went before."
"This means that, in effect, they are passing information back to the audience about how well they are doing in understanding them, hence our 'charades' analogy. In playing the game, you want primarily to convey your meaning non-verbally - as does the orangutan - but secondarily to help the team get your meaning by giving them hints as to how well they are doing."
To find out whether orangutans intentionally communicate with people through gestures - a skill earlier attributed to chimpanzees - PhD student Erica Cartmill and Professor Byrne presented six orangutans in Jersey and Twycross Zoos with situations in which one tempting and one not-so-tempting food item had to be reached with human help.
But to test the orangutans' strategy, there was a catch. Rather than play along all the time, the experimenter sometimes purposefully misunderstood the orangutan's requests, providing them with only half of the delicious treat in some cases and, in others, handing over the less pleasant alternative instead.
When the person they were trying to communicate with did not meet orangutans' aims, they persisted with further attempts, the researchers reported. When partially understood, the animals narrowed down their range of signals, focusing on gestures already used and repeating them frequently. In contrast, when completely misunderstood, orangutans elaborated their range of gestures, avoiding repetition of 'failed' signals.
"The response showed that the orangutan had intended a particular result, anticipated getting it, and kept trying until it got the result," Cartmill said. "The orangutans made a clear distinction between total misunderstanding, when they tended to give up on the signals they'd used already, and use new, but equivalent, ones to get the idea across, and partial misunderstanding, when they tended to repeat the signals that had already partially worked, keeping at it with vigor. The result was that understanding could be achieved more quickly."
The orangutans' charades-like strategy is one way to construct shared meaning from learned or ritualised signals in the absence of language, the researchers concluded. Further investigation of communication among apes may therefore provide insight into the pre-linguistic devices that helped construct the very earliest forms of hominid language.
The findings are published in Current Biology (2 August 2007).
ScienceDaily (Aug. 2, 2007) — When using gestures to get their points across, orangutans rely on the same basic strategy that humans follow when playing the popular game and intentionally modify or repeat hand (or other) signals based on the success or failure of their first attempt.
Professor Richard Byrne of the School of Psychology said, "We were surprised that the orangutans' responses so clearly signaled their assessment of the audience's comprehension. Looking at the tapes of the animal's responses, you can easily work out whether the orangutan thinks it has been fully, partially, or not understood, without seeing what went before."
"This means that, in effect, they are passing information back to the audience about how well they are doing in understanding them, hence our 'charades' analogy. In playing the game, you want primarily to convey your meaning non-verbally - as does the orangutan - but secondarily to help the team get your meaning by giving them hints as to how well they are doing."
To find out whether orangutans intentionally communicate with people through gestures - a skill earlier attributed to chimpanzees - PhD student Erica Cartmill and Professor Byrne presented six orangutans in Jersey and Twycross Zoos with situations in which one tempting and one not-so-tempting food item had to be reached with human help.
But to test the orangutans' strategy, there was a catch. Rather than play along all the time, the experimenter sometimes purposefully misunderstood the orangutan's requests, providing them with only half of the delicious treat in some cases and, in others, handing over the less pleasant alternative instead.
When the person they were trying to communicate with did not meet orangutans' aims, they persisted with further attempts, the researchers reported. When partially understood, the animals narrowed down their range of signals, focusing on gestures already used and repeating them frequently. In contrast, when completely misunderstood, orangutans elaborated their range of gestures, avoiding repetition of 'failed' signals.
"The response showed that the orangutan had intended a particular result, anticipated getting it, and kept trying until it got the result," Cartmill said. "The orangutans made a clear distinction between total misunderstanding, when they tended to give up on the signals they'd used already, and use new, but equivalent, ones to get the idea across, and partial misunderstanding, when they tended to repeat the signals that had already partially worked, keeping at it with vigor. The result was that understanding could be achieved more quickly."
The orangutans' charades-like strategy is one way to construct shared meaning from learned or ritualised signals in the absence of language, the researchers concluded. Further investigation of communication among apes may therefore provide insight into the pre-linguistic devices that helped construct the very earliest forms of hominid language.
The findings are published in Current Biology (2 August 2007).
Ape Gestures Offer Clues To The Evolution Of Human Communication
http://www.sciencedaily.com/releases/2007/04/070430181209.htm
ScienceDaily (May 1, 2007) — Researchers at the Yerkes National Primate Research Center, Emory University, have found bonobos and chimpanzees use manual gestures of their hands, feet and limbs more flexibly than they do facial expressions and vocalizations, further supporting the evolution of human language began with gestures as the gestural origin hypothesis of language suggests. This study appears in the current issue of the Proceedings of the National Academy of Sciences.
Working with two groups of bonobos (13 animals) and two groups of chimpanzees (34 animals), Yerkes researchers Amy Pollick, PhD, and Frans de Waal, PhD, distinguished 31 manual gestures and 18 facial/vocal signals. They found both species used facial/vocal signals similarly, but the same did not hold true for the manual gestures. Rather, the researchers found both within and between species the manual gestures were less closely tied to a particular emotion and, thereby, serve a more adaptable function. For example, a single gesture may communicate an entirely different message depending upon the social context in which it is used.
"A chimpanzee may stretch out an open hand to another as a signal for support, whereas the same gesture toward a possessor of food signals a desire to share," said Pollick. "A scream, however, is a typical response for victims of intimidation, threat or attack. This is so for both bonobos and chimpanzees, and suggests the vocalization is relatively invariant," Pollick continued.
By studying similar types of communication in closely related species, researchers are able to determine shared ancestry. We know gestures are evolutionarily younger than facial expressions and vocalizations, as shown by their presence in apes and humans but not in monkeys. "A gesture that occurs in bonobos and chimpanzees as well as humans likely was present in the last common ancestor," said Pollick. "A good example of a shared gesture is the open-hand begging gesture, used by both apes and humans. This gesture can be used for food, if there is food around, but it also can be used to beg for help, for support, for money and so on. It's meaning is context-dependent," added de Waal.
Looking for further distinctions between species, the researchers found bonobos use gestures more flexibly than do chimpanzees. "Different groups of bonobos used gestures in specific contexts less consistently than did different groups of chimpanzees," said Pollick. The researcher's findings also suggest bonobos and chimpanzees engage in multi-modal communication, combining their gestures with facial expressions and vocalizations to communicate a message. "While chimpanzees produce more of these combinations, bonobos respond to them more often. This finding suggests the bonobo is a better model of symbolic communication in our early ancestors," concluded Pollick.
ScienceDaily (May 1, 2007) — Researchers at the Yerkes National Primate Research Center, Emory University, have found bonobos and chimpanzees use manual gestures of their hands, feet and limbs more flexibly than they do facial expressions and vocalizations, further supporting the evolution of human language began with gestures as the gestural origin hypothesis of language suggests. This study appears in the current issue of the Proceedings of the National Academy of Sciences.
Working with two groups of bonobos (13 animals) and two groups of chimpanzees (34 animals), Yerkes researchers Amy Pollick, PhD, and Frans de Waal, PhD, distinguished 31 manual gestures and 18 facial/vocal signals. They found both species used facial/vocal signals similarly, but the same did not hold true for the manual gestures. Rather, the researchers found both within and between species the manual gestures were less closely tied to a particular emotion and, thereby, serve a more adaptable function. For example, a single gesture may communicate an entirely different message depending upon the social context in which it is used.
"A chimpanzee may stretch out an open hand to another as a signal for support, whereas the same gesture toward a possessor of food signals a desire to share," said Pollick. "A scream, however, is a typical response for victims of intimidation, threat or attack. This is so for both bonobos and chimpanzees, and suggests the vocalization is relatively invariant," Pollick continued.
By studying similar types of communication in closely related species, researchers are able to determine shared ancestry. We know gestures are evolutionarily younger than facial expressions and vocalizations, as shown by their presence in apes and humans but not in monkeys. "A gesture that occurs in bonobos and chimpanzees as well as humans likely was present in the last common ancestor," said Pollick. "A good example of a shared gesture is the open-hand begging gesture, used by both apes and humans. This gesture can be used for food, if there is food around, but it also can be used to beg for help, for support, for money and so on. It's meaning is context-dependent," added de Waal.
Looking for further distinctions between species, the researchers found bonobos use gestures more flexibly than do chimpanzees. "Different groups of bonobos used gestures in specific contexts less consistently than did different groups of chimpanzees," said Pollick. The researcher's findings also suggest bonobos and chimpanzees engage in multi-modal communication, combining their gestures with facial expressions and vocalizations to communicate a message. "While chimpanzees produce more of these combinations, bonobos respond to them more often. This finding suggests the bonobo is a better model of symbolic communication in our early ancestors," concluded Pollick.
New Hominid 12 Million Years Old Found In Spain, With 'Modern' Facial Features
http://www.sciencedaily.com/releases/2009/06/090602083729.htm
ScienceDaily (June 2, 2009) — Researchers have discovered a fossilized face and jaw from a previously unknown hominoid primate genus in Spain dating to the Middle Miocene era, roughly 12 million years ago. Nicknamed "Lluc," the male bears a strikingly "modern" facial appearance with a flat face, rather than a protruding one. The finding sheds important new light on the evolutionary development of hominids, including orangutans, chimpanzees, bonobos, gorillas and humans.
In a study appearing in the Proceedings of the National Academy of Sciences, Salvador Moyà-Solà, director of the Institut Català de Paleontologia (ICP) at the Universitat Autònoma de Barcelona, and colleagues present evidence for the new genus and species, dubbed Anoiapithecus brevirostris. The scientific name is derived from the region where the fossil was found (l’Anoia) and also from its "modern" facial morphology, characterized by a very short face.
The research team at the ICP also includes collaborator David M. Alba, predoctoral researcher Sergio Almécija, postdoctoral researcher Isaac Casanovas, researcher Meike Köhler, postdoctoral researcher Soledad De Esteban, collaborator Josep M. Robles, curator Jordi Galindo, and predoctoral researcher Josep Fortuny.
Their findings are based on a partial cranium that preserves most of the face and the associated mandible. The cranium was unearthed in 2004 in the fossil-rich area of Abocador de Can Mata (els Hostalets de Pierola, l’Anoia, Barcelona), where remains of other fossilized hominid species have been found. Preparing the fossil for study was a complicated process, due to the fragility of the remains. But once the material was available for analysis, the results were surprising: The specimen (IPS43000) combined a set of features that, until now, had never been found in the fossil record.
Anoiapithecus displays a very modern facial morphology, with a muzzle prognathism (i.e., protrusion of the jaw) so reduced that, within the family Hominidae, scientists can only find comparable values within the genus Homo, whereas the remaining great apes are notoriously more prognathic (i.e., having jaws that project forward markedly). The extraordinary resemblance does not indicate that Anoiapithecus has any relationship with Homo, the researchers note. However, the similarity might be a case of evolutionary convergence, where two species evolving separately share common features.
Lluc's discovery may also hold an important clue to the geographical origin of the hominid family. Some scientists have suspected that a group of primitive hominoids known as kenyapithecines (recorded from the Middle Miocene of Africa and Eurasia) might have been the ancestral group that all hominids came from. The detailed morphological study of the cranial remains of Lluc showed that, together with the modern anatomical features of hominids (e.g., nasal aperture wide at the base, high zygomatic rood, deep palate), it displays a set of primitive features, such as thick dental enamel, teeth with globulous cusps, very robust mandible and very procumbent premaxilla. These features characterize a group of primitive hominoids from the African Middle Miocene, known as afropithecids.
Interestingly, in addition to having a mixture of hominid and primitive afropithecid features, Lluc displays other characteristics, such as a very anterior position of the zygomatic, a very strong mandibular torus and, especially, a very reduced maxillary sinus. These are features shared with kenyapithecines believed to have dispersed outside the African continent and colonized the Mediterranean region, by about 15 million years ago.
In other words, the researchers speculate, hominids might have originally radiated in Eurasia from kenyapithecine ancestors of African origin. Later on, the ancestors of African great apes and humans would have dispersed again into Africa -- the so-called "into Africa" theory, which remains controversial. However, the authors do not completely rule out the possibility that pongines (orangutans and related forms) and hominines (African apes and humans) separately evolved in Eurasia and Africa, respectively, from different kenyapithecine ancestors.
The project at els Hostalets de Pierola is continuing and, the researchers anticipate, more fossil remains will be found in the future that will provide key information to test their hypotheses.
ScienceDaily (June 2, 2009) — Researchers have discovered a fossilized face and jaw from a previously unknown hominoid primate genus in Spain dating to the Middle Miocene era, roughly 12 million years ago. Nicknamed "Lluc," the male bears a strikingly "modern" facial appearance with a flat face, rather than a protruding one. The finding sheds important new light on the evolutionary development of hominids, including orangutans, chimpanzees, bonobos, gorillas and humans.
In a study appearing in the Proceedings of the National Academy of Sciences, Salvador Moyà-Solà, director of the Institut Català de Paleontologia (ICP) at the Universitat Autònoma de Barcelona, and colleagues present evidence for the new genus and species, dubbed Anoiapithecus brevirostris. The scientific name is derived from the region where the fossil was found (l’Anoia) and also from its "modern" facial morphology, characterized by a very short face.
The research team at the ICP also includes collaborator David M. Alba, predoctoral researcher Sergio Almécija, postdoctoral researcher Isaac Casanovas, researcher Meike Köhler, postdoctoral researcher Soledad De Esteban, collaborator Josep M. Robles, curator Jordi Galindo, and predoctoral researcher Josep Fortuny.
Their findings are based on a partial cranium that preserves most of the face and the associated mandible. The cranium was unearthed in 2004 in the fossil-rich area of Abocador de Can Mata (els Hostalets de Pierola, l’Anoia, Barcelona), where remains of other fossilized hominid species have been found. Preparing the fossil for study was a complicated process, due to the fragility of the remains. But once the material was available for analysis, the results were surprising: The specimen (IPS43000) combined a set of features that, until now, had never been found in the fossil record.
Anoiapithecus displays a very modern facial morphology, with a muzzle prognathism (i.e., protrusion of the jaw) so reduced that, within the family Hominidae, scientists can only find comparable values within the genus Homo, whereas the remaining great apes are notoriously more prognathic (i.e., having jaws that project forward markedly). The extraordinary resemblance does not indicate that Anoiapithecus has any relationship with Homo, the researchers note. However, the similarity might be a case of evolutionary convergence, where two species evolving separately share common features.
Lluc's discovery may also hold an important clue to the geographical origin of the hominid family. Some scientists have suspected that a group of primitive hominoids known as kenyapithecines (recorded from the Middle Miocene of Africa and Eurasia) might have been the ancestral group that all hominids came from. The detailed morphological study of the cranial remains of Lluc showed that, together with the modern anatomical features of hominids (e.g., nasal aperture wide at the base, high zygomatic rood, deep palate), it displays a set of primitive features, such as thick dental enamel, teeth with globulous cusps, very robust mandible and very procumbent premaxilla. These features characterize a group of primitive hominoids from the African Middle Miocene, known as afropithecids.
Interestingly, in addition to having a mixture of hominid and primitive afropithecid features, Lluc displays other characteristics, such as a very anterior position of the zygomatic, a very strong mandibular torus and, especially, a very reduced maxillary sinus. These are features shared with kenyapithecines believed to have dispersed outside the African continent and colonized the Mediterranean region, by about 15 million years ago.
In other words, the researchers speculate, hominids might have originally radiated in Eurasia from kenyapithecine ancestors of African origin. Later on, the ancestors of African great apes and humans would have dispersed again into Africa -- the so-called "into Africa" theory, which remains controversial. However, the authors do not completely rule out the possibility that pongines (orangutans and related forms) and hominines (African apes and humans) separately evolved in Eurasia and Africa, respectively, from different kenyapithecine ancestors.
The project at els Hostalets de Pierola is continuing and, the researchers anticipate, more fossil remains will be found in the future that will provide key information to test their hypotheses.
When Evolution Is Not So Slow And Gradual
http://www.sciencedaily.com/releases/2009/06/090602133551.htm
ScienceDaily (June 3, 2009) — What's the secret to surviving during times of environmental change? Evolve…quickly.
A new article in The American Naturalist finds that guppy populations introduced into new habitats developed new and advantageous traits in just a few years. This is one of only a few studies to look at adaptation and survival in a wild population.
A research team led by Swanne Pamela Gordon from the University of California, Riverside studied 200 guppies that had been taken from the Yarra River in Trinidad and introduced into two different environments in the nearby Damier River, which previously had no guppies. One Damier environment was predator-free. The other contained fish that occasionally snack on guppies.
Eight years after their introduction, the team revisited the Damier guppies to see what adaptive changes they might have picked up in their new environments. The researchers found that the females had altered their reproductive effort to match their surroundings. In the environment where predators were present, females produced more embryos each reproductive cycle. This makes sense because where predators abound, one might not get a second chance to reproduce. In less dangerous waters, females produced fewer embryos each time, thus expending fewer resources on reproduction.
Finally, the researchers wanted to see if these adaptive changes actually helped the new population to survive. So they took more guppies from the Yarra, marked them, and put them in the Damier alongside the ones that had been there for eight years. They found that the adapted guppies had a significant survival advantage over the more recently introduced group.
In particular, juveniles from the adapted population had a 54 to 59 percent increase in survival rate over those from the newly introduced group. In the long run, survival of juveniles is crucial to the survival of the population, the researchers say.
The fact that fitness differences were found after only eight years shows just how fast evolution can work—for short-lived species anyway.
"The changes in survival in our study may initially seem encouraging from a conservation perspective," the authors write. "[B]ut it is important to remember that the elapsed time frame was 13-26 guppy generations. The current results may therefore provide little solace for biologists and managers concerned with longer-lived species."
ScienceDaily (June 3, 2009) — What's the secret to surviving during times of environmental change? Evolve…quickly.
A new article in The American Naturalist finds that guppy populations introduced into new habitats developed new and advantageous traits in just a few years. This is one of only a few studies to look at adaptation and survival in a wild population.
A research team led by Swanne Pamela Gordon from the University of California, Riverside studied 200 guppies that had been taken from the Yarra River in Trinidad and introduced into two different environments in the nearby Damier River, which previously had no guppies. One Damier environment was predator-free. The other contained fish that occasionally snack on guppies.
Eight years after their introduction, the team revisited the Damier guppies to see what adaptive changes they might have picked up in their new environments. The researchers found that the females had altered their reproductive effort to match their surroundings. In the environment where predators were present, females produced more embryos each reproductive cycle. This makes sense because where predators abound, one might not get a second chance to reproduce. In less dangerous waters, females produced fewer embryos each time, thus expending fewer resources on reproduction.
Finally, the researchers wanted to see if these adaptive changes actually helped the new population to survive. So they took more guppies from the Yarra, marked them, and put them in the Damier alongside the ones that had been there for eight years. They found that the adapted guppies had a significant survival advantage over the more recently introduced group.
In particular, juveniles from the adapted population had a 54 to 59 percent increase in survival rate over those from the newly introduced group. In the long run, survival of juveniles is crucial to the survival of the population, the researchers say.
The fact that fitness differences were found after only eight years shows just how fast evolution can work—for short-lived species anyway.
"The changes in survival in our study may initially seem encouraging from a conservation perspective," the authors write. "[B]ut it is important to remember that the elapsed time frame was 13-26 guppy generations. The current results may therefore provide little solace for biologists and managers concerned with longer-lived species."
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