A team of researchers at the Max Planck Society, Germany, have given an insight into why females live longer than males.
The Max Planck Society conducts basic research in the natural sciences, life sciences, humanities, with 31 Nobel Laureates among the ranks of its scientists.
Among other institutes, it operates another 20 Max Planck Centers with research institutions such as Princeton University in the USA.
Its partners also include the Paris University Science Po in France, the University College London in UK, and the University of Tokyo in Japan.
The team led by Dr Johanna Stärk, Department of Department of Primate Behaviour and Evolution, relied on data from the Species360 Zoological Information Management System of over 1,176 birds and mammal species in zoos worldwide.
They found that in most mammals 72 per cent females lived longer than males by on average twelve per cent.
They said their findings also showed that environmental and social pressures were not overly responsible for the gap in life span.
“A long-standing idea is that environmental pressures—such as predation, pathogens, or harsh climates—drive the observed gaps between males and females.
“To test this, the researchers turned to zoo populations, where such pressures are largely absent.
“They found that lifespan gaps persisted even under these protected conditions. Comparing zoo and wild populations showed that the gaps were often smaller in zoos but rarely disappeared,” the report said.
It said it mirrored the human case, where advances in medicine and living conditions have narrowed but not eliminated the lifespan gap.
“One genetic explanation, the heterogametic sex hypothesis, points to differences in sex chromosomes.
“In mammals, females have two X chromosomes, while males have only one X and one Y (making them the heterogametic sex).
“Some research suggests that having two X chromosomes may protect females from harmful mutations, offering a survival advantage,” the study said.
Chromosomes are structures within cells that contain a person’s genes.
Although the reverse is the case for birds, however, the life span margin is lower at about 5 per cent in favour of females.
“In birds, males are the homogametic sex, while females are heterogametic.
“Males in polygamous species with strong competition tend to die earlier than females. In monogamous species, males often live longer. The sex that invests more in raising offspring tends to live longer,’’ it stated.
The study suggests that the lifespan gap between male and females was deeply rooted in evolutionary processes and would likely continue to exist.
While advances in medicine and living conditions have narrowed the gap, it’s unlikely to disappear completely.
The research team believes that both genetic and environmental factors contribute to the discrepancy in life expectancy.
This study provides valuable insights into the biology of aging and could have implications for understanding human lifespan and health.
The researchers also found that sexual selection plays a major role in the female-male lifespan gap.
Sexual selection is a process by which members of one sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex.
“The new study supports this assumption: In polygamous mammals with strong competition, males generally die earlier than females.
“Many birds, on the other hand, are monogamous, which means that competitive pressure is lower and males often live longer.
“Overall, the differences were smallest in monogamous species, while polygamy and pronounced size differences were associated with a more pronounced advantage for females,” the study said.
The study suggested that sexual selection could drain potential lifespan of birds as they use too many resources to develop and maintain traits that give them an edge in attracting mates.