SAN FRANCISCO, Jan. 9 (Xinhua) -- Women have better chances to survive than men in the worst of circumstances such as famines and epidemics, a new study revealed Tuesday.
Researchers at the U.S. Duke University and the University of Southern Denmark examined about 250 years of mortality data for people whose lives were cut short by famine, disease and misfortunes, to study the life expectancy gender gap between females and males.
Their findings, published in the online edition of Proceedings of the National Academy of Sciences, were released on Tuesday.
The researchers found that the behavioral differences were the least remarkable between both genders in infancy and the fact that females have an edge during that period suggests at least in part that biological factors plays a decisive role in giving women a longer expectancy during adulthood.
The data covered seven populations in which people of both sexes had a hard time in 20 years or less, including famine victims in Sweden, Ireland and Ukraine in the 18th, 19th and 20th centuries.
The mortalities of Icelanders were also studied during the measles epidemics from 1846 to 1882.
They found that more than 40 percent of freed American slaves who were relocated to Liberia in West Africa in the 1800s died from tropical diseases during their first year.
In Europe, the life expectancy of a group of people living in Ireland was cut short by more than 15 years due to an extensive crop failure.
In general, the researchers discovered that women lived longer than men by an average of six months to nearly four years.
The researchers attributed the female advantage in times of crisis to biological factors such as genetics or hormones, including estrogens that provide stronger immune defense against infectious diseases for women.
