Male lifespans trailing behind females'
Modern humans have longer lifespans than every other primate, yet male lifespans lag behind female lifespans across the primate family tree, according to new research. The study, titled “The Emergence of Longevous Populations,” appeared in Proceedings of the National Academy of Sciences. The study included contributors from several U.S. and European universities. The study sought to understand why men tend to have shorter lifespans than women despite the overall lifespan increase.
“We’ve made a bigger journey in lengthening our lifespan over the last few hundred years than we did over millions of years of evolutionary history,” explained Susan Alberts, the study’s co-author and a biology professor at Duke University.
Alberts’ comments related the study’s findings to prior research that was done on the subject, which overall demonstrates that Homo sapiens have been making rapid gains in lifespan that supersede any gains previously seen across all primates. These numbers can be attributed to a mix of factors, which are biological, contextual and social.
To address the possible impact of genetics on longevity, the study traces the lifespans of various populations of primates and compares them to findings from studies that examine the lifespans of various human populations. The findings show genetic differences are correlated to mortality patterns.
The existence of a genetic correlation to lifespan may also help explain lifespan differences between genders of the same species, especially in that of humans. One theory looks at the differences in how genetic material is organized in men and women as a possible explanation—women have two X chromosomes, while men have one.
Genetic problems that appear on one X chromosome can be mitigated to an extent by genetic material on the other X chromosome in women. In men, genetic problems that appear on one of their X chromosomes are more likely to become apparent through health complications.
Factors other than genetics may be involved in lifespan differences as well, such as lifespan quality. For example, lower lifespans are expected in pre-industrialized societies because these societies usually lack medical technology that treats potentially life-threatening illnesses, technology which is more readily available in industrialized societies.
Lifestyle habits, such as farming and diet, and environmental factors, such as access to clean water and exposure to warfare, may affect lifespans. The impact of lifespan quality may help explain the observed gender-related mortality patterns, as social factors like gender norms may also be causing differences in male and female lifespans.
In line with this explanation, the study’s findings show striking lifespan differences between pre-industrialized and post-industrialized populations, which can be attributed to factors other than genetics. The study’s data shows that, while people in modern hunter-gather societies live 10 to 20 years longer on average than other primates, people in industrialized societies live to an average of 40 to 50 years longer.
The study’s authors acknowledge that their research is far from over. Current data shows that a mix of biological, contextual and social factors interact to produce the evolutionary changes that have led to longer lifespans. The full picture is only beginning to emerge. Future studies will be necessary in order to further unravel the sources of longevity and why it differs between men and women.