Women present a lot of paradoxes. For example, they live longer than men yet also experience more frailty later in life. Additionally, extraordinarily fertile females (like queen bees) live considerably longer than non-fertile females and males. But why?
A team led by scientists from the Buck Institute for Research on Aging in California is seeking to reconcile these paradoxes in a new framework called the Reproductive Resilience Hypothesis, published yesterday in the journal Cell.
Under traditional models of aging, reproduction and longevity are often seen as at odds with one another. After all, resources are limited, and those invested in offspring can’t be utilized for regular body maintenance. But it doesn’t explain why women live longer than men, or why queen bees, for example, live for years while drones live only weeks. In fact, in many species, the females that invest more heavily in their offspring also live longer lives.
The Reproductive Resilience Hypothesis proposes that when reproductive fitness is dependent upon surviving longer—either because of more frequent reproduction, caring for offspring, or supporting the following generation—natural selection will favor longer lives. In these organisms, reproduction will be linked with resilience (hence the name).
Read more: “The Longevity Skeptic”
“Our perspective helps explain why female mammals often outlive males, why queen insects can combine extraordinary fertility with longevity, and why male lifespan can equal or exceed female lifespan in species where fathers provide substantial infant care,” study author Parminder Singh explained in a statement.
Take primates, for example. Natural selection has led male great apes to develop larger bodies, more aggression, and higher testosterone levels to compete for mates, but these adaptations come with the cost of an earlier mortality. The reproductive success of females, on the other hand, is subject to an entirely different set of selectional pressures that favor endurance, efficient use of energy, and repeated reproduction.
According to the team, these vastly different selection pressures have important consequences for studying age-related decline. “These divergent evolutionary strategies profoundly shape the biology of aging in each sex and highlight why male and female aging and age-related diseases should not be studied under a unified model,” the researchers write.
But don’t worry guys, it’s not all bad news. Unlocking the secrets of how reproduction allows women to live longer may lead to therapies that benefit both sexes. “Female biology should be prioritized not only to correct a longstanding gap in biomedical research,” Singh explained, “but because it may reveal resilience mechanisms that help us understand how to extend health span in both women and men.” 
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Lead image: Tasnuva Elahi; with images by VectorMine / Adobe Stock
