Telling a little girl she’s tough isn’t just an effort in gender-neutral parenting anymore — it’s fact.
All around the world, women’s life expectancy tend to be longer than men’s (in some countries by more than a decade). For years, scientists have been asking what is it that adds these extra, gendered years. But new research suggests that we’ve been looking at the gender gap in life expectancy all wrong — that it’s not about what happens differently at the end, but what happens differently at the beginning.
Three centuries of historical records show that women don’t just outlive men in normal times: They’re more likely to survive even in the worst of circumstances, such as famines and epidemics. And most of that gender gap was due to a female survival advantage in infancy rather than adulthood, the researchers found.
Their conclusion? Newborn girls are simply hardier than newborn boys.
The fact that women have a life expectancy edge in infancy, a time when behavioral differences between the sexes are minimal, supports an at least partly biological explanation, the researchers say. (It’s certainly not societal, given the malingering practice of female infanticide in certain parts of the world.)
Led by Virginia Zarulli, an assistant professor at the University of Southern Denmark, and James Vaupel, a research professor at Duke University, the team analyzed mortality data going back roughly 250 years for people whose lives were cut short by famine, disease or other misfortunes. The data spanned seven populations in which the life expectancy for one or both sexes was a dismal 20 years or less. The populations examined ranged from working and former slaves in Trinidad and the United States in the early 1800s, to famine victims in Sweden, Ireland and the Ukraine in the 18th, 19th and 20th centuries, to freed American slaves who relocated to Liberia in the 1800s (and experienced the highest mortality rates ever recorded, presumably due to tropical diseases they had little resistance to; babies born during that time rarely made it past their second birthday).
Overall the researchers discovered that, even when mortality was very high for both sexes, women still, on average, lived longer than men by six months to almost four years. Girls born during the famine that struck Ukraine in 1933, for example, lived to 10.85, and boys to 7.3 — a 50% difference.
The researchers posit the female advantage in times of crisis may be largely due to biological factors such as genetics or hormones (estrogens, for example, have been shown to enhance the body’s immune defenses against infectious disease).
Don’t mind me, I’ll just be over here listening to “Survivor” on full blast.
