Monday, October 19, 2009

Humans still evolving, etc.   posted by Razib @ 10/19/2009 04:26:00 PM

Are Humans Still Evolving? Absolutely, Says A New Analysis Of A Long-term Survey Of Human Health:
"There is this idea that because medicine has been so good at reducing mortality rates, that means that natural selection is no longer operating in humans," said Stephen Stearns of Yale University. A recent analysis by Stearns and colleagues turns this idea on its head....

Taking advantage of data collected as part of a 60-year study of more than 2000 North American women in the Framingham Heart Study, the researchers analyzed a handful of traits important to human health. By measuring the effects of these traits on the number of children the women had over their lifetime, the researchers were able to estimate the strength of selection and make short-term predictions about how each trait might evolve in the future. After adjusting for factors such as education and smoking, their models predict that the descendents of these women will be slightly shorter and heavier, will have lower blood pressure and cholesterol, will have their first child at a younger age, and will reach menopause later in life.

Since large numbers of humans forgo reproduction in an evolutionary sense they might as well have died (excluding some inclusive fitness effects). If reproductive variance and heritable variation in traits correlated with that variance continues then naturally selection will be an operative phenomenon.

The paper is coming out in PNAS, so no guarantee when it'll be online, Byars, S., D. Ewbank, et al. Natural selection in a contemporary human population. Proceedings of the National Academy of Sciences, 106(42) DOI: 10.1073_pnas.0906199106.

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