Shorter, chubbier and having sex earlier
What will the woman of the future look like? Scientists foretell that she will be shorter, chubbier and have babies earlier.
Yale University researchers who traced the effects of natural selection among two generations of women predict that their descendents will be slightly shorter and chubbier.
Shorter, fatter and having babies earlier. Is this the picture of the future woman? Illustration by Mohd Salleh Sapawi
They will also have lower cholesterol and blood pressure and have their first children earlier in life.
The predictions were made at the Proceedings of the National Academy of Sciences recently were based on an analysis of women who took part in the famous Framingham Heart Study which began in 1948.
The results show the medical value of evolutionary biology principles, 150 years after Darwin published The Origin of the Species.
“The idea that natural selection has stopped operating in humans because we have gotten better at keeping people alive is just plain wrong,” said Stephen C. Stearns, senior author of the paper and Edward P. Bass Professor of Ecology and Evolutionary Biology.
Various sizes...the shape of womens' bodies has been changing
Traits that enable women to have children will continue to be subject to selection.
As a first step, the Yale researchers measured the individual reproductive success of two generations of more than 2000 women who took part in the Framingham study and had reached menopause.
They then surveyed the traits that conferred reproductive success. After adjusting for environmental factors such as income, education and lifestyle choices such as smoking, they estimated the heritability of traits by applying correlations among all relatives.
Heritability of traits will also depend on health and lifestyles
They also adjusted for indirect effects of selection by measuring the impacts the traits have on each other – such as whether high blood pressure is correlated with lower or higher age of sexual maturity.
The analysis allowed researchers to predict which traits were likely to be conferred by natural selection upon the third generation of women in the study.
The results showed that the effects of natural selection are slow and gradual, but trend towards shorter, chubbier women with lower blood pressure and cholesterol and who give birth earlier in life.
For instance, the women in the third generation of the study are predicted to begin their periods a month earlier and enter menopause a month later than their mothers and grandmothers.
However Stearns points out that the rate of change driven by natural selection found in this group of women does not differ much from rates observed in nature.
“The paper drives home the point that humans aren’t different, that we are evolving at about the same average rate as other life on the planet,” Stearns said.
Source: Yale University
Published Oct 25 2009
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