It turns out that older men chasing younger women contributes to human longevity and the survival of the species, according to new findings by researchers at Stanford and the University of California-Santa Barbara.
Evolutionary theory says that individuals should die of old age when their reproductive lives are complete, generally by age 55 in humans, according to demographer Cedric Puleston, a doctoral candidate in biological sciences at Stanford. But the fatherhood of a small number of older men is enough to postpone the date with death because natural selection fights life-shortening mutations until the species is finished reproducing.
“Rod Stewart and David Letterman having babies in their 50s and 60s provide no benefit for their personal survival, but the pattern [of reproducing at a later age] has an effect on the population as a whole,” Puleston said. “It’s advantageous to the species if these people stick around. By increasing the survival of men you have a spillover effect on women because men pass their genes to children of both sexes.”
“Why Men Matter: Mating Patterns Drive Evolution of Human Lifespan,” was published Aug. 29 in the online journal Public Library of Science ONE. Shripad Tuljapurkar, the Morrison Professor of Population Studies at Stanford; Puleston; and Michael Gurven, an assistant professor of anthropology at UCSB, co-authored the study in an effort to understand why humans don’t die when female reproduction ends.
Human ability to scale the so-called “wall of death”—surviving beyond the reproductive years—has been a center of scientific controversy for more than 50 years, Puleston said. “The central question is: Why should a species that stops reproducing by some age stick around afterward?” he said. “Evolutionary theory predicts that, over time, harmful mutations that decrease survival will arise in the population and will remain invisible to natural selection after reproduction ends.” However, in hunter-gatherer societies, which likely represent early human demographic conditions and mating patterns, one-third of people live beyond 55 years, past the reproductive lifespan for women. Furthermore, life expectancy in today’s industrialized countries is 75 to 85 years, with mortality increasing gradually, not abruptly, following female menopause.
Grandmother hypothesis
In 1966, William Hamilton, a British evolutionary biologist, worked out the mathematics describing the “wall of death.” Since then, the most popular explanation for why humans don’t die by age 55 has been termed the “grandmother hypothesis,” which suggests that women enhance the survival of their children and grandchildren by living long enough to care for them and “increasing the success of their genes,” Puleston said. However, Hamilton’s work has been difficult to express as a mathematical and genetic argument explaining why people live into old age.
Unlike previous research on human reproduction, this study—for the first time—includes data on males, a tweak that allowed the researchers to begin answering the “wall of death” question by matching it to human mortality patterns. According to Puleston, earlier studies looked only at women, because scientists can reproduce good datasets for humans entirely based on information related to female fertility and survival rates.
“Men’s fertility is contingent on women’s fertility—you have to figure out how they match up. We care about reproduction because that is a currency by which force of selection is counted. If we have not accounted for the entire pattern of reproduction, we may be missing something that’s important to evolution.”
Men and longevity
In the paper, the researchers analyzed “a general two-sex model to show that selection favors survival for as long as men reproduce.” The scientists presented a “range of data showing that males much older than 50 years have substantial realized fertility through matings with younger females, a pattern that was likely typical among early humans.” As a result, Puleston said, older male fertility helps to select against damaging cell mutations in humans who have passed the age of female menopause, consequently eliminating the “wall of death.”
“Our analysis shows that old-age male fertility allows evolution to breach Hamilton’s wall of death and predicts a gradual rise in mortality after the age of female menopause without relying on ‘grandmother’ effects or economic optimality,” the researchers say in the paper.
The scientists compiled longevity and fertility data from two hunter-gatherer groups, the Dobe !Kung of the Kalahari and the Ache of Paraguay, one of the most isolated populations in the world. They also looked at the forager-farmer Yanomamo of Brazil and Venezuela, and the Tsimane, an indigenous group in Bolivia. “They’re living a lifestyle that our ancestors lived and their fertility patterns are probably most consistent with our ancestors,” Puleston said about the four groups. The study also looked at several farming villages in Gambia and, for comparison, a group of modern Canadians.
In the less developed, traditional societies, males were as much as 5-to-15 years older than their female partners. In the United States and Europe, the age spread was about two years. “It’s a universal pattern that in typical marriages men are older than women,” Puleston said. “The age gaps vary by culture, but in every group we looked at men start [being reproductive] later. At the end of reproduction, male fertility rates taper off gradually, as opposed to the fairly sharp decline in female fertility by menopause.”
Despite small differences based on marriage traditions, all women and most men in the six groups stopped having children by their 50s, the researchers found. But some men, particularly high-status males, continued to reproduce into their 70s. The paper noted that the age gap is most pronounced in societies that favor polygyny, where a man takes several wives, and in gerontocracies, where older men monopolize access to reproductive women. The authors also cite genetic and anthropological evidence that early humans were probably polygynous as well.
Older male fertility also exists in societies supporting serial monogamy, because men are more likely to remarry than women. “For these reasons, we argue that realized male fertility was substantial at ages well past female menopause for much of human history and the result is reflected in the mortality patterns of modern populations,” the authors say. “We conclude that deleterious mutations acting after the age of female menopause are selected against … solely as a result of the matings between older males and younger females.”
According to Puleston, the “grandmother hypothesis” may be true, but the real pattern of male fertility extends beyond this explanation. “The key question is: Does the population have a greater growth rate if men are reproducing at a later age? The answer is ‘yes.’ The age of last reproduction gets pushed into the 60s and 70s if you add men to the analysis. Hamilton’s approach was right, but in a species where males and females have different reproductive patterns, you need a two-sex model. You can’t correctly estimate the force of selection if you leave men out of the picture. As a man myself, it’s gratifying to know that men do matter.”
Grants from the U.S. National Institute on Aging supported this study.
hi im 20years old and i like chating with old mens
Very informative article. Thanks for info
I see a claim that most pre-agricutural cultures practiced polygyny:
“early humans were probably polygynous as well.”
If all the women wer impregnated by a smaller number of men, does this mean that there were a large minority, or even a majority of men who did not pass their genes on to the next generation at all? How could a society like that possibly work?
I hate men especialy old men. Men are bullies.
Hee hee hee hee hee ……..
there is only one life stop hurting your feelings if it is such a relationship that gives u the pleasure go for it as long as it is legitimate you all know that what pleases you is what you go for
The real problem is that older women cant accept that men find younger women more attractive they are jealous and bitter. They are sexist against mens nature to desire the more attractive women so they make ageist and sexist remarks against men, because they cant compete. Evolution made us what we are men are supposed to have multiple partners and women are supposed to have children with a successful man- whatever age or race or ethnicity he is. I would tell those bitter women to accept science, and stop making decisions based on your out of control emotions.
heh, good points on this debate here. comments seemed to mostly agree. thanks for posting
Very interesting article, though a bit misogynistic, as others have pointed out! Still, I enjoy reading the Evolutionary Psychology perspective
So, tell me my dear, is biology with all its bio-chemical processes misogynistic?
All up init!!!!!!!!!!!!!!!
that was craxy!
Women are the ones with the power. Men have no power over women.
I see a claim that most pre-agricutural cultures practiced polygyny:
“early humans were probably polygynous as well.”
If all the women wer impregnated by a smaller number of men, does this mean that there were a large minority, or even a majority of men who did not pass their genes on to the next generation at all? How could a society like that possibly work?
Get a perspective!
Get a f****** life old man!
I am a 27 years old doctor, mature and beautiful. and now i am seeking a good older man who can give me
real love, So i got a usename natalieashley —–w w w. ageda te.c0 m —— . It’s the best club for cougar.
Because the most of the members on this website are real and serious. Hurry up! Reply me here, maybe
you wanna check it out or tell your friends.
I am a forty five year old woman who is dating a 75 year old man. This has been the best experience of my life. Sex is great. As a matter of fact, better than any young man I have ever had because an older man is more experienced and knows all the right places to touch. Needless to say, I am a professional and he is a retired professional. He has taught me how to survive in the cutthroat corporate world on a managerial level. We have a meeting of the minds which is why I love him so. I have money and so does he. We just enjoy each others company with no strings attached. So I think that It is all an individual choice. I too made assumptions in the beginning like why would I want to date an old man, but you neve judge a book by its cover. I have been wrong.
So, misogyny is allowed in scientific publications now? And your bloggers are allowed to write like Nuts magazine columnists? Ahem. Content? Style? I thought you had editors for this sort of thing.
Doubt you would call it misandry if the research mentioned in the article ended up with an opposite result.
I’m not really sure why so many people have a problem with older men dating/marrying younger women. If you don’t like it then don’t do it. But who are you to judge anyone else? I am 27 and my husband is 63. We have two children ages 5 & 2 and we couldn’t be happier. We have been together for 9 years so obviously I’m not using him. He isn’t rich, in fact he doesn’t even work! I make the money in our house. I’m not some trailer trash and he isn’t an old horn dog. We are two normal upper class people. I use to feel insulted when people would talk about us but Now I don’t really care what people say. I make a good living as a model/actress which allows my husband to stay home and also takes away the one thing people automaticly assume about us, that I’m a gold digger!
My point is don’t judge a book by it’s cover. Neither of us were planning to marry someone who was 10+ years age gap but it just happened. You can’t always choose who you fall in love with. Keep yourself open to new possibilities and you will be amazed at what life will present you.
You are a model and actor and that is why you are with him. How many men do you sleep with other than him?
Ask this question to yourself….I doubt your intentions….and don’t defend these bloody bastards who eye on the girls their grand daughter’s age.
Very informative,very good
Good post. I’m been looking for topics as interesting as this.
Very informative and information presented very well,
i really liked reading your blog,
thanks for sharingLancaster PA web design
Very informative, thank you. I’ve been blogging on and off for almost 3 years, but have never had much of a focus – I tend to just write about whatever is on my mind when I feel like writing.
Cheers!
I m forty and I found that most of the girl in the 20 are fat and their dress like a man.
I happend to stumble on this post by accident. I can see where it would look awkward for an old man, say someone old enough to be someones father or even older to date someone younger. Yea I can go along with that.
Now I do believe it is another thing for someone just being a little older even if its a 10 year gap dating, being thats a common thing in most healthy normal relationships now. like if someone was 22 and they dated someone 32. No big deal on that one.
I do say all of this on a neutral basis being I don’t judge. Also, if everything is really for the right reason being (TRUE LOVE) then there shouldn’t be no trouble, which I can see thats not the case most of the time.
Thanks everyone, I am just being unbiased, and wanted to put some borders up. :)
Let’s face it, some young women are strange and fancy older men, and some young men are strange and fancy older women. No point in fussing about it unless it is one of your children, then go crazy.