http://www.sciencedaily.com/releases/2009/05/090525105435.htm
ScienceDaily (May 25, 2009) — New light has been thrown on how humans choose their partners, according to new findings presented May 25 at the annual conference of the European Society of Human Genetics.
Professor Maria da Graça Bicalho, head of the Immunogenetics and Histocompatibility Laboratory at the University of Parana, Brazil, says that her research had shown that people with diverse major histocompatibility complexes (MHCs) were more likely to choose each other as mates than those whose MHCs were similar, and that this was likely to be an evolutionary strategy to ensure healthy reproduction.
The MHC is a large genetic region situated on chromosome 6, and found in most vertebrates. It plays an important role in the immune system and also in reproductive success. Apart from being a large region, it is also an extraordinarily diverse one.
Females' preference for MHC dissimilar mates has been shown in many vertebrate species, including humans, and it is also known that MHC influences mating selection by preferences for particular body odours. The Brazilian team has been working in this field since 1998, and decided to investigate mate selection in the Brazilian population, while trying to uncover the biological significance of MHC diversity.
The scientists studied MHC data from 90 married couples, and compared them with 152 randomly-generated control couples. They counted the number of MHC dissimilarities among those who were real couples, and compared them with those in the randomly-generated 'virtual couples'. "If MHC genes did not influence mate selection", says Professor Bicalho, "we would have expected to see similar results from both sets of couples. But we found that the real partners had significantly more MHC dissimilarities than we could have expected to find simply by chance."
Within MHC-dissimilar couples the partners will be genetically different, and such a pattern of mate choice decreases the danger of endogamy (mating among relatives) and increases the genetic variability of offspring. Genetic variability is known to be an advantage for offspring, and the MHC effect could be an evolutionary strategy underlying incest avoidance in humans and also improving the efficiency of the immune system, the scientists say.
"Although it may be tempting to think that humans choose their partners because of their similarities", says Professor Bicalho, "our research has shown clearly that it is differences that make for successful reproduction, and that the subconscious drive to have healthy children is important when choosing a mate."
The scientists believe that their findings will help understanding of conception, fertility, and gestational failures. Research has already shown that couples with similar MHC genes had longer intervals between births, which could imply early, unperceived miscarriages. "We intend to follow up this work by looking at social and cultural influences as well as biological ones in mate choice, and relating these to the genetic diversity of the extended MHC region", says Professor Bicalho.
"We expect to find that cultural aspects play an important role in mate choice, and certainly do not subscribe to the theory that if a person bears a particular genetic variant it will determine his or her behaviour. But we also think that the unconscious evolutionary aspect of partner choice should not be overlooked. We believe our research shows that this has an important role to play in ensuring healthy reproduction, by helping to ensure that children are born with a strong immune system better able to cope with infection."
Showing posts with label furture planning. Show all posts
Showing posts with label furture planning. Show all posts
Thursday, May 28, 2009
Wednesday, May 27, 2009
Are Humans Genetically Programmed To Care About Long-term Future And Climate Change?
http://www.sciencedaily.com/releases/2009/05/090527105711.htm
ScienceDaily (May 27, 2009) — Humans may be programmed by evolution to care about the future of the environment, suggests new research.
Dr Peter Sozou suggests that individuals may have an innate tendency to care about the long-term future of their communities, over timescales much longer than an individual’s lifespan. This in turn may help to explain people’s wish to take action over long-term environmental problems.
The findings are published in the Proceedings of the Royal Society B, in a paper entitled "Individual and social discounting in a viscous population."
Dr Sozou, of the University of Warwick’s Medical School and the London School of Economics and Political Science, uses a mathematical model of a population of individuals living in communities with limited migration between them.
The study examines what weight individuals should attach to future benefits. It is shown that the answer depends on whether the future benefits are social benefits for their community or private benefits for themselves. Individuals should be expected to take a long-term view of benefits for their community, but a more short-term view of private benefits to themselves. Humans, like all creatures, generally value a reward today more highly than a reward tomorrow – in other words they discount future benefits. But the model shows that the discount rate is lower for social, rather than individual, benefits.
Dr Sozou said: "This analysis shows that the social discount rate is generally lower than the private discount rate. An individual’s valuation of a future benefit to herself is governed by the probability that she will still be alive in future. But she may value future benefits to her community over a timescale considerably longer than her own lifespan.
"Evolution is driven by competition. Caring about the future of your community makes evolutionary sense to the extent that future members of your community are likely to be your relatives."
However this evolutionary logic does not apply, at first glance, in the case of a global threat such as climate change where the ‘community’, the planet, is not in competition with other communities. "In the absence of this competition," says Dr Sozou, "there is no direct basis for evolution to select behaviours which benefit the planet as a whole, and therefore no evolutionary basis for directly determining a social discount rate for global welfare."
In which case why do we care at all about the long-term future of humanity? The answer, Dr Sozou suggests, is that we have evolved to value social benefits because in our ancestral environment they tended to deliver local benefits – helping our kin to survive. However in the modern age, it is this biological preference for social good which gives us an interest in the future of the planet: "In the modern, global environment, such preferences may cause people to care about global problems such as climate change.
"This issue is particularly important for economics as it has a bearing on decisions about public investments and environmental protection measures - actions which typically involve paying a cost today in order to produce a public benefit tomorrow."
Adapted from materials provided by University of Warwick
ScienceDaily (May 27, 2009) — Humans may be programmed by evolution to care about the future of the environment, suggests new research.
Dr Peter Sozou suggests that individuals may have an innate tendency to care about the long-term future of their communities, over timescales much longer than an individual’s lifespan. This in turn may help to explain people’s wish to take action over long-term environmental problems.
The findings are published in the Proceedings of the Royal Society B, in a paper entitled "Individual and social discounting in a viscous population."
Dr Sozou, of the University of Warwick’s Medical School and the London School of Economics and Political Science, uses a mathematical model of a population of individuals living in communities with limited migration between them.
The study examines what weight individuals should attach to future benefits. It is shown that the answer depends on whether the future benefits are social benefits for their community or private benefits for themselves. Individuals should be expected to take a long-term view of benefits for their community, but a more short-term view of private benefits to themselves. Humans, like all creatures, generally value a reward today more highly than a reward tomorrow – in other words they discount future benefits. But the model shows that the discount rate is lower for social, rather than individual, benefits.
Dr Sozou said: "This analysis shows that the social discount rate is generally lower than the private discount rate. An individual’s valuation of a future benefit to herself is governed by the probability that she will still be alive in future. But she may value future benefits to her community over a timescale considerably longer than her own lifespan.
"Evolution is driven by competition. Caring about the future of your community makes evolutionary sense to the extent that future members of your community are likely to be your relatives."
However this evolutionary logic does not apply, at first glance, in the case of a global threat such as climate change where the ‘community’, the planet, is not in competition with other communities. "In the absence of this competition," says Dr Sozou, "there is no direct basis for evolution to select behaviours which benefit the planet as a whole, and therefore no evolutionary basis for directly determining a social discount rate for global welfare."
In which case why do we care at all about the long-term future of humanity? The answer, Dr Sozou suggests, is that we have evolved to value social benefits because in our ancestral environment they tended to deliver local benefits – helping our kin to survive. However in the modern age, it is this biological preference for social good which gives us an interest in the future of the planet: "In the modern, global environment, such preferences may cause people to care about global problems such as climate change.
"This issue is particularly important for economics as it has a bearing on decisions about public investments and environmental protection measures - actions which typically involve paying a cost today in order to produce a public benefit tomorrow."
Adapted from materials provided by University of Warwick
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