Although advances in medical care have improved standards of living over time, humans aren't entirely sheltered from the forces of natural selection, a new study shows.

"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.

The result? Human evolution hasn't ground to a halt. In fact, we're likely to evolve at roughly the same rates as other living things, findings suggest.

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.

"The take-home message is that humans are currently evolving," said Stearns. "Natural selection is still operating."

Source: National Evolutionary Synthesis Center