Modern Homo sapiens is still evolving. Despite the long-held view that natural selection has ceased to affect humans because almost everybody now lives long enough to have children, a new study of a contemporary Massachusetts population offers evidence of evolution still in action. A team of scientists led by Yale University evolutionary biologist Stephen Stearns suggests that if the natural selection of fitter traits is no longer driven by survival, perhaps it owes to differences in women's fertility. "Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection," Stearns says. That is, women who have more children are more likely to pass on certain traits to their progeny. (See the top 10 scientific discoveries of 2008.)... Douglas Ewbank, a demographer at the University of Pennsylvania who undertook the statistical analysis for the study, which was published Oct. 21 in the Proceedings of the National Academy of Sciences (PNAS), says that because cultural factors tend to have a much more prominent impact than natural selection in the shaping of future generations, people tend to write off the effect of evolution. "Those changes we predict for 2409 could be wiped out by something as simple as a new school-lunch program. But whatever happens, it's likely that in 2409, Framingham women will be 2 cm shorter and 1 kg heavier than they would have been without natural selection. Evolution is a very slow process. We don't see it if we look at our grandparents, but it's there." Other recent genetic research has backed up that notion. One study, published in PNAS in 2007 and led by John Hawks, an anthropologist at the University of Wisconsin at Madison, found that some 1,800 human gene variations had become widespread in recent generations because of their modern-day evolutionary benefits. Among those genetic changes, discovered by examining more than 3 million DNA variants in 269 individuals: mutations that allow people to digest milk or resist malaria and others that govern brain development. (Watch TIME's video "Darwin and Lincoln: Birthdays and Evolution.") But not all evolutionary changes make inherent sense. Since the Industrial Revolution, modern humans have grown taller and stronger, so it's easy to assume that evolution is making humans fitter. But according to anthropologist Peter McAllister, author of Manthropology: the Science of Inadequate Modern Man, the contemporary male has evolved, at least physically, into "the sorriest cohort of masculine Homo sapiens to ever walk the planet." Thanks to genetic differences, an average Neanderthal woman, McAllister notes, could have whupped Arnold Schwarzenegger at his muscular peak in an arm-wrestling match. And prehistoric Australian Aborigines, who typically built up great strength in their joints and muscles through childhood and adolescence, could have easily beat Usain Bolt in a 100-m dash.
A team of scientists led by Yale University evolutionary biologist Stephen Stearns suggests that if the natural selection of fitter traits is no longer driven by survival, perhaps it owes to differences in women's fertility. "Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection," Stearns says. That is, women who have more children are more likely to pass on certain traits to their progeny. (See the top 10 scientific discoveries of 2008.)...
Douglas Ewbank, a demographer at the University of Pennsylvania who undertook the statistical analysis for the study, which was published Oct. 21 in the Proceedings of the National Academy of Sciences (PNAS), says that because cultural factors tend to have a much more prominent impact than natural selection in the shaping of future generations, people tend to write off the effect of evolution. "Those changes we predict for 2409 could be wiped out by something as simple as a new school-lunch program. But whatever happens, it's likely that in 2409, Framingham women will be 2 cm shorter and 1 kg heavier than they would have been without natural selection. Evolution is a very slow process. We don't see it if we look at our grandparents, but it's there."
Other recent genetic research has backed up that notion. One study, published in PNAS in 2007 and led by John Hawks, an anthropologist at the University of Wisconsin at Madison, found that some 1,800 human gene variations had become widespread in recent generations because of their modern-day evolutionary benefits. Among those genetic changes, discovered by examining more than 3 million DNA variants in 269 individuals: mutations that allow people to digest milk or resist malaria and others that govern brain development. (Watch TIME's video "Darwin and Lincoln: Birthdays and Evolution.")
But not all evolutionary changes make inherent sense. Since the Industrial Revolution, modern humans have grown taller and stronger, so it's easy to assume that evolution is making humans fitter. But according to anthropologist Peter McAllister, author of Manthropology: the Science of Inadequate Modern Man, the contemporary male has evolved, at least physically, into "the sorriest cohort of masculine Homo sapiens to ever walk the planet." Thanks to genetic differences, an average Neanderthal woman, McAllister notes, could have whupped Arnold Schwarzenegger at his muscular peak in an arm-wrestling match. And prehistoric Australian Aborigines, who typically built up great strength in their joints and muscles through childhood and adolescence, could have easily beat Usain Bolt in a 100-m dash.
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er, isn't it "'Is' humans still evolvinv?"
:>) ~"When an inner situation is not made conscious, it appears outside as fate." Karl Jung~
