Heterogeneity may be adding years to a female's life

Washington D.C. [USA], Apr 28 (ANI): All across the world, women enjoy longer lifespan. So, why is it so?

A new study has looked at sex differences and mortality in the Eurasian sparrowhawk. It turns out that heterogeneity is what drives longer lives in female sparrowhawks.

Heterogeneity in this context means that female sparrowhawk physiology is more diverse and less average than the males. There are more frail females than frail males, but there are also more robust females than robust males.

The females have a wider range and when it comes to ageing it gives them an advantage, said author Fernando Colchero from the University of Southern Denmark.

With more frail females, there will of course be more early female deaths than male. But this is more than weighed up by the larger number of robust females than males.

According to the study, the life expectancy for the most robust adult females reach up to 4.23 years, while for the most robust adult males it was 2.68 years.

The results are a surprise to the researchers.

This shows us that sexual differences in mortality are not only due to factors like physical size or how much time an individual invests in reproducing. It is also unusual to see shorter life spans in the smaller sex, as we do here; Male sparrowhawks are smaller than the females.

Our results contribute a novel perspective to the ongoing debate about the mechanisms that drive sex differences in vital rates in vertebrates, said Colchero.

It is possible that this phenomenon can be found in other animal species, but it is still uncertain. I suggest that when studying sex differences in mortality, researchers should consider accounting for heterogeneity.

The study also concluded that individuals who spend more energy on reproducing and raising chicks live longer; bigger females are better at reproduction than smaller females; and smaller males have better chances for surviving than bigger males.

The study appears in the Journal of Ecology. (ANI)