Thank you, Rod Stewart. Seriously.

Earlier this year, Rod Stewart married model Penny Lancaster, promising to love and honor the latest version of his eerily uniform young-blonde-wife prototype. The new Mrs. Stewart is younger than Stewart's own young daughter, and at this rate, it's hard to believe the deeply lined rocker won't end up dating his own distant, blonde descendants. But it turns out, Rod, you are to be thanked. And the pre-menopausal ladies you callously jilted? They should thank you most of all. No, not because they don't have to sleep with you anymore, but for something much more important. Scientists say, in not exactly these words, that it is the old goats who keep the human race alive for longer.

Generally, it's thought that the more fertile you are, the likelier you are to survive. Additionally, the older you are, the higher your chances of dying. Common sense seems to bear this theory out. Yet there's an unexplained mystery about the length of women's lives. Once their ability to have children shuts down, there is no obvious reason for their biology to resist all the forces that conspire to take them down. Indeed, according to demographic models, women over 50 should hit a "wall of death." But they don't. Why not?

Scientists at Stanford and the University of California at Santa Barbara have developed a model to resolve the anomaly. The problem arises, they say, because accounts of the human lifespan have only focused on one or the other sex. If you look at both men and women together, the paradox disappears. The new model, published at the Public Library of Science, confirms the idea that, yes, for as long as people reproduce, they are better able to resist random harmful mutations that might kill them. Evolutionary forces have already weeded out the individuals who weren't so good at doing this, and accordingly they did not have many children to then pass their vulnerabilities on. Once people stop being fertile, all bets are off. There is little payoff for the species as a whole if everyone stays alive long after they can have children. This is why you see a decline in health after reproduction ends. The kicker is this -- women get a free ride into old age because they have the same genes as men who -- I'm looking at you, Rod -- have children later than women.

The fact that men's fertility tapers off around 60 or 70 explains why there is no sudden drop-off in the quality of life for men or women. Our lives taper off as well. How odd that you only need to have one sex to stay fertile in order for both to live longer lives.

In order to prove that much older fathers were not a rare occurrence or just a rock & roll legend, the researchers gathered data from many different cultures all over the world, including the Dobe !Kung in the Kalahari, the hunter-gatherer Ache in Paraguay and modern-day Canada. Examples of men who were over 55 and up to 70-years-old fathering children with younger women were found in all cases. In modern day Germany and Japan, the reproduction of men aged 65 was found to be the same as that of women aged 45. The finding was true for monogamous as well as polygamous societies. One of the ways that men end up being reproductive longer in a monogamous society like ours, say the researchers, is that they are more likely than women to remarry after divorce. Crucially, the researchers suggest that the pattern of very old dads was common in prehistoric times as well.

The new demographic solution is basically a mathematical theory, which means that even though it explains the facts nicely, it may not be what actually happened. Still if it is right, the fact that women survive at all beyond menopause is a byproduct of men's ability to father children into advanced old age, which, this is sticking in my craw, means that the human race really needs its randy geezers. As for the Penny Lancasters, they are taking it for the whole team.

What of the death-defying older women? Why don't they have children in their 70s? And why would they even evolve something as bothersome as menopause? One theory is that more of a woman's descendants will survive if she shuts down her own fertility and focuses on helping the children of her children. So even if older women got a leg up in the survival stakes because of older men, they play an indispensable role in perpetuating the human race when they become grandmothers. Thanks, grandma.

Christine Kenneally is the author of The First Word.

Comments

[Guitarsandmore]

There actually is wisdom in years and we need some of the old farts around for them to share their wisdom with the younger of us.

[Guitarsandmore]

If we could only get pregnant for a few short years the chances for survival of the species would drop dramatically.

That a man’s sexual peak is at 19 and a women’s peak is at 37 seems like an odd twist of fate at first. But then consider that the odds of pregnancy go up when there are two different peaks of interest and the range of interest is spread out over the years.

When a man maintains an interest in sexual activities for many years then opportunities that were missed earlier for one reason or another might pose no obstacle later in life.

A spouse or child might die but if the sexual interest is still there the species could start again with another spouse.

[anniepema]

Not good for the offspring though, de novo Alzheimer's, autism, schizophrenia,type 1 diabetes, MS, prostate cancer, breast cancer, heart defects, leukemias, Duchennes, hemophilia, progeria, de novo Hungtington's chorea etc. etc. all rise in offspring of older fathers and older maternal grandfathers. The life span of daughters decreases when the father is 45 and over. Thanks to fathers over 32 and older all kinds of genetic disease increase in offspring. Wondering where the genetic disease in your family came from?

[jaybird6239]

What's the purpose of a woman beyond childbeari­ng/reprodu­ction? Once women get beyond these roles and no longer has to deal with issues of pregnancy/­menstratio­n they have time to really enjoy the word "freedom." Why do you think so many women dump husbands after menopause and embark on new careers/lifestyles? I predict baby boomer women will redefine the role of women beyond reproduction and certainly the world will be a better place because of it. This is no time for sissys, so let men like Rod Steward, who perhaps isn't comfortable dealing with a strong willed mature woman, mate with younger women.

[blooddoc]

Studies have shown that females are much more picky in the selection of a mate than males - has to do with the perceived quality of genes that might be passed on to offspring. An older, still healthy male might be perceived to have better genes for survival, including the ability to accumulate more food for winter (i.e., $$$$). Rod certainly fills that prescription well.

[JonathanDS2U]

Natural selection, evolution, it may be real, but it makes me sick. You want to know why babies are cute? Because ugly babies couldn't win the support needed to stay alive from the adults around them. So natural selection increased the likelihood that the genetics of survivors would produce cute babies. We're seeing show biz survival increasingly mirror this. There was a time when a lot of less sexy but talented people made it. And look at Romney, I can't. His brand of politics is, "I've got a winning smile, what more do I really need?", and it's all too telling of what the a large part of the public is looking for. Rod Stewart, with the mole on his face, I think he must have been psychologically brow-beaten until he needed to perpetually reaffirm his sex appeal. Oh well, too bad his soul lost the battle.

[JimReed]

"Why don't they have children in their 70s? And why would they even evolve something as bothersome as menopause?"

Older women might not be fertile, but they might make a good president.

[sneezeguard]

Rod Stewart, James Garner and Michael Douglas should get together to form the group The Three Tremors.

[bimplebean]

Then again there's the new study that indicates rock stars tend to die younger than normal people... perhaps Rod is bucking one trend in order to reinforce another.

I like what Keith Richards says... "I'm happy to be here... then again, given my life I'm happy to be anywhere..."

[PaulGaskin]

elr50,

Focusing on cognitive abilities is another kind of "materialism", because it isn't love and it isn't really virtue of character to be well-educated or cognitively gifted.

[Ani]

Aside from the Rod Stewart eewww factor, this is a truly lovely post. I've long maintained that we need to honor the wisdom of our elder women, rather than freak out when we find our first wrinkle or gray hair. I'll leave the breeding to the young females. I'm busy passing on some wisdom!

[Danothemoderateguy]

Men are genetically programed to be attracted to women of child-bearing age. Just just can't beat that awful evolution!

[marcain]

When Rod sang the line in Maggie May, 'The morning sun when it's in your face really shows your age /
But that dont worry me none in my eyes you're everything' That was a lie.

[JimR]

LOL

[richw23]

It was a song.

[jhNY]

Isn't it more pertinent to say that we as a species presently have no need for randy old men? We have obviously overpopulated the planet and must soon suffer a reduction of our number by some means, natural or self-induced.

I say free cigarettes for everybody and the drinks are on the house with plenty of giveaway firearms for the kiddies. And heroin. Lots of heroin all around. That way we're at least helping the economy of Afghanistan get back on its wobbly feet.

Once the population has thus reduced itself to but a shadow of its former overblown self, there may well again be need for the over-50 breeder man. As a fellow in that envied demographic, I will be available for love, or at the very least the act of love, and I hereby offer to sire the offspring of all women I find attractive, even if it means working round the clock, as I am but an average citizen who, ladies, just wants to do his part. With your parts.

[cktirumalai]

I know of single men and women who retain their youthful vitality well into old age, only they have chosen not to have children and have instead put their energy into other nurturing functions. In this context, Richard Dawkins's distinction between the gene and the meme is worth looking into.