Sunday, October 25, 2009

Humans Still Evolving

begin quote from above article
Evolution: Are Humans Still Evolving?

By EBEN HARRELL Eben Harrell – Sat Oct 24, 10:10 am ET

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," end quote.

So I guess it is the reproductive success among stout, slightly plump(but not obese) women who are successful having more children that are driving human evolution worldwide.

So, if you are a male and are having babies with someone like this then you are driving evolution too with your genes.

Begin quote(same article)

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.")
end quote.

So this study is credible for Framingham because the study has been ongoing since 1948. So the .8 inch shorter and 2.2 pounds heavier with a healthy heart and having her first child 5 months earlier and entering menopause 10 months later than women today can be predicted by 2409. However, it is unlikely to go this way because there are always unexpected events over 300 or 400 years to alter this trend. However, there likely is a probability if no major factors change that this could still happen.

No comments: