Feeling Like a New Woman? That's Evolution

Evolution isn't quite done with us yet, according to researchers from Yale University. As reported in The New Scientist, a recent study of more than 2,200 women in Massachusetts indicates that while advances in health care may have pushed "survival of the fittest" towards extinction, differences in reproduction rates are still nudging human DNA into new directions.

So, who is this new woman? According to researchers, she's a little bit shorter, a couple pounds heavier, has supremely good blood pressure and -- most interestingly -- she has a longer time frame in which to have children.

Of course, the changes aren't happening fast. Stephen Stearns, who headed the project, predicted to New Scientist that it would be 400 years before we see a 2 centimeter drop in the average woman's height and a 1 kilogram gain in weight. In comparison, the changes in fertility seem fast, with Stearns predicting that by the end of the same time period, women will remain fertile 10 months longer than did their ancestors. Stearns also makes another prediction based on the data trends he saw: that women will have their first child approximately five months earlier.

But, I wouldn't start purchasing stock in jogging strollers right away. Here's why: The study looked at the data of women, their daughters and their granddaughters over 60 years, beginning in 1948, and Stearns' predictions assume that trends remain constant. What happened to women in that 60-year time span? As the conversation my colleagues have been having about the period drama "Mad Men" can attest, a lot happened. But, it was also during that time frame that birth control went from something some women whispered about to -- apparently -- the subject of very loud (albeit awkward) night club talk.

Height, blood pressure and length of fertility that Stearns cites are largely linked to genetics, but the age at which a woman has her first child is now typically a matter of choice. And, it's a choice that current data shows most women today are putting off until later, almost across the board.