Insights: The Trouble with Men; October 2007; Scientific American Magazine; by David Biello; 3 Page(s)

Sons are tough on their mothers. Whether it is heavier birth weights, amplified testosterone levels or simple, hair-raising high jinks, boys seem to take an extra toll on the women who gave birth to them. And by poring over Finnish church records from two centuries ago, Virpi Lummaa of the University of Sheffield in England can prove it: sons reduce a mother's life span by an average of 34 weeks.

The 33-year-old Finnish evolutionary biologist, aided by genealogists, has scoured centuries-old tomes (and decades-old microfiche) for birth, marriage and death records--and clues about the influence of evolution on human reproduction. Historians, economists and even sociologists have long used such tactics to explore their fields, but Lummaa is among the first biologists to enlist Homo sapiens as an animal whose population can be followed over time.