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.)
Stearns' team examined the vital statistics of 2,238 postmenopausal women participating in the Framingham Heart Study, which has tracked the medical histories of some 14,000 residents of Framingham, Mass., since 1948. Investigators searched for correlations between women's physical characteristics - including height, weight, blood pressure and cholesterol levels - and the number of offspring they produced. According to their findings, it was stout, slightly plump (but not obese) women who tended to have more children - "Women with very low body fat don't ovulate," Stearns explains - as did women with lower blood pressure and cholesterol levels. Using a sophisticated statistical analysis that controlled for any social or cultural factors that could impact childbearing, researchers determined that these characteristics were passed on genetically from mothers to daughters and granddaughters.
If these trends were to continue with no cultural changes in the town for the next 10 generations, by 2409 the average Framingham woman would be 2 cm (0.8 in) shorter, 1 kg (2.2 lb.) heavier, have a healthier heart, have her first child five months earlier and enter menopause 10 months later than a woman today, the study found. "That rate of evolution is slow but pretty similar to what we see in other plants and animals. Humans don't seem to be any exception," Stearns says. (See TIME's photo-essay "Happy 200th Darwin Day.")
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.
Steve Jones, an evolutionary biologist at University College London who has previously held that human evolution was nearing its end, says the Framingham study is indeed an important example of how natural selection still operates through inherited differences in reproductive ability. But Jones argues that variation in female fertility - as measured in the Framingham study - is a much less important factor in human evolution than differences in male fertility. Sperm hold a much higher chance of carrying an error or mutation than an egg, especially among older men. "While it used to be that men had many children in older age to many different women, now men tend to have only a few children at a younger age with one wife. The drop in the number of older fathers has had a major effect on the rate of mutation and has at least reduced the amount of new diversity - the raw material of evolution. Darwin's machine has not stopped, but it surely has slowed greatly," Jones says. (See TIME's special report on the environment.)
Despite evidence that human evolution still functions, biologists concede that it's anyone's guess where it will take us from here. Artificial selection in the form of genetic medicine could push natural selection into obsolescence, but a lethal pandemic or other cataclysm could suddenly make natural selection central to the future of the species. Whatever happens, Jones says, it is worth remembering that Darwin's beautiful theory has suffered a long history of abuse. The bastard science of eugenics, he says, will haunt humanity as long as people are tempted to confuse evolution with improvement. "Uniquely in the living world, what makes humans what we are is in our minds, in our society, and not in our evolution," he says.
TIME MAGAZINE
Monday, October 26, 2009
Thursday, October 22, 2009
Tihar Celebration 09
Culture embodies person’s identity. Distance doesn’t matter to preserve and maintain one’s traditions and practices. To maintain the same at the special occasion of auspicious Tihar, NeFE organized Tihar celebration in Matsuyama, Japan. Special Tihar feast was served and best wishes exchanged among the Nepalese residing in Matsuyama. Ladies also performed brief bhaili and exchanged blessings to each other.
Tuesday, September 29, 2009
NeFE observed Dashami Tika
NeFE welcomed New Students
NeFE organized gathering program to welcome new students in Ehime University from Nepal. The gathering provided participants a chance to get introduced with new comers and familiarize them with NeFE family and its programs. New students arrived for the academic session October 09 are:
Mr. Yubaraj Poudel, (Faculty of Engineering, to pursue Doctorate Degree)
Mr. Shankar Dhakal (Faculty of Engineering, to pursue Doctorate Degree)
Mr. Deepak Bhat (Faculty of Engineering, to pursue Masters’ Degree)
Mr. Purshwotam Ghimire (Faculty of Agriculture, to pursue Masters’)
NeFE extends its best wishes to newly arrived students for their productive stay in Japan and successful accomplishments of academic study.The program also observed wish sharing event at the special occasion of national festival, Vijaya Dashami
Friday, September 4, 2009
Farewell Gathering (01/09/09)
NeFE organized a farewell gathering to bid adieu to the Nepali friends who completed their academic career in Ehime University and are returning back to homeland. Three friends received farewell this September namely, Dr. Pashupati Poudel, Dr. Nirmala Bhatta and Mr. Prahlad Uprety.
Dr. Poudel accomplished his doctorate in crop production with special reference to corn production in Nepal and Dr. Bhatta completed her doctorate in irrigation system in Nepal comparing the similar systems in developing and developed countries from Graduate School of Agricultural Science. Similarly, Mr. Uprety successfully accomplished his Masters’ Degree in earthquake prevention and evacuation system from Graduate School of Science and Engineering.
The farewell receivers shared their experience of living in Japan during their study period and talked about their accomplished study in brief. All accentuated in strengthening NeFE solidarity and mutual relationship among all Nepalese in Ehime.
The program was divided into two sessions: formal session followed by the dinner. Farewell receiving guests were granted a token of memory and best wishes certificate from NeFE team. NeFE organizes such kind of farewell gathering to congratulate the graduates for their successful academic accomplishments and to wish success in their future endeavors.
Dr. Poudel accomplished his doctorate in crop production with special reference to corn production in Nepal and Dr. Bhatta completed her doctorate in irrigation system in Nepal comparing the similar systems in developing and developed countries from Graduate School of Agricultural Science. Similarly, Mr. Uprety successfully accomplished his Masters’ Degree in earthquake prevention and evacuation system from Graduate School of Science and Engineering.
The farewell receivers shared their experience of living in Japan during their study period and talked about their accomplished study in brief. All accentuated in strengthening NeFE solidarity and mutual relationship among all Nepalese in Ehime.
The program was divided into two sessions: formal session followed by the dinner. Farewell receiving guests were granted a token of memory and best wishes certificate from NeFE team. NeFE organizes such kind of farewell gathering to congratulate the graduates for their successful academic accomplishments and to wish success in their future endeavors.
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