Why women have the survival advantage in times of crisis

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WOMEN have a longer life expectancy than men do under normal circumstances, and now a new study from Denmark and Germany reveals that women also outlive men even in the worst of times. In the study, which took a look back on historical life expectancies, researchers found that women had, on average, a longer life expectancy when facing the harshest conditions — including famines and epidemics — than men did.
Indeed, the study found that even under extremely harsh and critical conditions, women have a survival advantage, said lead author Virginia Zarulli, an assistant professor at the Institute of Public Health at the University of Southern Denmark.
It’s not clear why women are the “life-expectancy champions,” the study authors wrote, but previous research has suggested that under normal conditions, biological reasons play an important role, along with environmental and behavioral factors.
However, there was little evidence about whether women would have a survival advantage over men under critical, highly life-threatening conditions, Zarulli told Live Science. So, the researchers decided to investigate these situations to tease out whether the differences observed could be explained by biological or environmental factors.
To do so, they analyzed historical data collected between 1772 and 1939 from seven populations facing extreme hardships. Specifically, the researchers looked at data on life expectancy and death rates from groups facing starvation, disease and slavery during times such as the Irish potato famine (1845–1849), measles epidemics in Iceland (1846 and 1882) and plantation slaves in Trinidad (at the beginning of the 19th century).
All seven of the groups involved in the study had an extremely low life expectancy because of the harsh conditions; one or both sexes were not expected to live longer than 20 years during these crises. In the seven crises analyzed, women survived longer than men: The study found that women outlived men by six months to four years, on average, Zarulli said.
For example, the analysis showed that during the Irish potato famine, women typically lived, on average, 22.4 years, while men lived, on average, 18.7 years. (In the years before the famine, the life expectancy for both sexes was about 38 years, according to the findings.) During a measles epidemic in Iceland in 1882, women lived, on average, 18.8 years, compared with 16.7 years, on average, for men. (In the years before the epidemic, the average life expectancy for women was about 44 years and about 38 years for men.)
Most of the female advantage in life expectancy during these crises was due to survival differences in infant mortality, according to the researchers. The findings showed that baby girls survived harsh conditions better than baby boys.