Mick Jagger is to become a father for the eighth time at age seventy-two. Stones lead guitarist Ronnie Wood also recently became a father to twin daughters at age sixty-eight. Ronnie’s thirty-eight-year-old wife Sally and the girls are doing fine. I’m sure Mick and twenty-nine-year-old mother-to-be Melanie are full of anticipation. This was widely publicized suggesting that this was big news. Being members of the Rolling Stones had something to do with the publicity, but the fact that Mick and Ronnie are still procreating when most others are attending their grandchildren’s high school graduations probably contributed to making these newsworthy events.
Becoming a father around the age when one starts collecting social security is not terribly uncommon despite the reality that most of the resulting children will be fatherless sooner rather than later. Charlie Chaplin, Robert De Niro, and Pablo Picasso also fathered children later in life. You could argue this is just a phenomenon of the rich and famous. After all, being a wealthy rock star or famous actor must do wonders for your social life. But actually, becoming a father later in life is fairly common among those who don’t have Oscars on their mantels. In fact, older fathers may have contributed to the evolution of some of the very traits that make us human. A better understanding of fatherhood and aging requires us to dust off our anthropologist hats and venture to societies that are not Western, Educated, Industrial, Rich, and Democratic, or WEIRD, as evolutionary psychologist Joseph Henrich has dubbed us.
Demographers often assumed that men generally stopped reproducing around the age of fifty, which coincides with women experiencing menopause. Assuming that most humans, or at least those that are WEIRD, are monogamous, this is a reasonable assumption. The problem with this idea is that many members of our species are not WEIRD, and it is likely that those in our evolutionary past may not have been so devoted to having a single mate.
This includes both males and females, but for now we’re keeping our Darwinian gaze on the men. Evolutionary demographer Shripad “Tulja” Tuljapurkar and colleagues analyzed male fertility in several non-WEIRD societies and found that fatherhood at older ages, say after the age of fifty, was not only evident, but more commonplace compared to WEIRD societies. Therefore one can make the assumption that fatherhood at older ages was likely common in our evolutionary past and that older fathers contributed to the emergence of traits that define us as a species.
The emergence of fatherhood at older ages provides an explanation for the long period of post-reproductive life in women and humans in general. The lifespan of most organisms usually coincides with the loss of their ability to reproduce. In women, that is around the age of fifty with the onset of menopause. However, in humans, almost a third of our lifespan is post-menopausal, which is very unusual regardless of whether you’re WEIRD or not. If men were able to reproduce at older ages, a trait that is very uncommon among primates and animals in general, this may have selected for longevity genes that were passed to both sons and daughters. In other words, older fathers may have contributed to the evolution of long lives in humans. Thank you, Mick and Ronnie.
However, why would younger, fertile women be willing to pair with older guys when there are probably younger and stronger men waiting in the wings? Yes, older guys can have their charm, I suppose, but the George Clooneys of this world are quite rare. A common widespread explanation is based on the social and economic benefits of marrying older men. In many parts of the world now and throughout evolutionary history, wealth has been controlled patrilineally or along male family blood lines so it can be beneficial for women to marry older men who are often wealthier compared to younger men. This is fairly common in pastoral societies with compelling scientific data to support this hypothesis. It is important to note however that some women have little choice and do not have control over their reproductive lives. Arranged marriages are one example of this and beyond the scope of this article but certainly worthy of greater awareness by all.
A complimentary hypothesis that emerges from demographic studies that document the significant number of children fathered by older men, is that during human evolution, older men have provided a resource that is often absent in younger males and actually quite rare among primates and mammals. That resource is childcare and attention to family. While the importance and uniqueness of paternal investment in humans is well known, suggesting that older men leveraged this form of reproductive effort to increase their fitness later in life is a novel idea.
Before I get hate mail from those who are fortunate to be paired with wonderful younger dads or recall their own doting younger fathers, I am not saying that only older men can provide care. Remember that we have to consider non-WEIRD societies in which sexual division of labor is pretty common, with men often taking on the responsibilities of providing resources through hunting, farming, caring for herds, or other physically demanding labor. These tasks require much more physical exertion and strength compared to men like me who sit at a desk and wiggle their fingers in a non-random manner on a keyboard for a living. Youth and vigor do have their advantages in the mating game of course, but, especially in non-WEIRD societies, being an older father with compromised physical strength may make childcare a viable reproductive strategy to attract mates.
Among all great apes, human males have evolved the most flexible range of paternal behaviors that span from being the most doting fathers to being completely neglectful. This plasticity has allowed men to adjust their paternal behaviors in response to social factors and physical changes with age. Despite age-induced declines in muscle mass and growing waistlines, during our evolution older men leveraged paternal care, which not only made them viable mates, but may have allowed natural selection to favor long lives, big brains, and the ability to maintain high fertility compared to other great apes. The accumulation of fat with age may have even created an internal hormonal environment that is conducive to paternal care. Having a paternal caretaker frees up maternal time and energy that can be diverted to additional slow growing, big brained and metabolically expensive offspring that require lots of time and care.
Mick and Ronnie are probably not thinking much about the evolutionary significance of fatherhood late in life or how their hormones contribute to them swooning every time they hold their newborns. But that’s ok. Evolution happens whether we are aware of it or not. Older fathers made a significant contribution to how we evolved the unique suite of traits that define us a species. For us older guys, there is life after fifty even if we can’t play a decent chord or go on world concert tours. A cushy belly for children to snooze on is worthy of applause. Rock on.