Women typically outlive men in almost all populations today and new research suggests this may be because they are better equipped to survive a crisis.
Researchers from the University of Southern Denmark examined the survival rates of both sexes under extreme conditions in seven populations and found that women were more likely to survive than men in almost all circumstances.
They analysed 250 years' worth of mortality data, looking at societies plagued by famine and disease epidemics across the world.
This included former slaves working in the US and Trinidad in the 1800s and victims of famine in Sweden and Ireland in addition to those affected by measles epidemics in Iceland.
While the average life expectancy of those analysed was 20 years old, the scientists found that women lived longer than men by an average of up to four years.
For example, during the 1933 famine in Ukraine, girls born during this time lived to the age of 10 whereas boys only made it to seven-years-old on average.
The researchers concluded that this disparity was also apparent in infant mortality rates, as they found that baby girls had higher survival rates in harsh conditions than baby boys.
They noted that in Liberia, where life expectancy is the lowest, newborn girls were “hardier” than newborn boys, giving them an advantage in terms of survival.
“The hypothesis that the survival advantage of women has fundamental biological underpinnings is supported by the fact that under very harsh conditions females survive better than males even at infant ages when behavioural and social differences may be minimal or favour males,” the study states.
“Our findings also indicate that the female advantage differs across environments and is modulated by social factors.”
Hormones might well have a part to play too, given that the female sex hormone oestrogen has been known to boost the immune system.
The Independent UK