Hot News Flash: Men Caused Menopause

This is cutting-edge research. We found it in the Telegraph, published in London: Men may be to blame for the menopause. Here are some excerpts, with bold font added by us:

Scientists claim that the menopause, which is thought to be unique to humans, may have evolved due to a preference among men to breed with younger women. A study using computer modelling to assess how such a preference would have driven evolution has now given some weight to the theory.

The cause and effect is not immediately obvious to us. Perhaps that will be explained as we read on:

Professor Rama Singh, from Canada’s McMaster University, said that competition between men for younger mates had left older females with less chance of reproducing. He said: “Menopause is believed to be unique to humans, but no one has yet been able to offer a satisfactory explanation for why it occurs. How do you evolve infertility? It is contrary to the whole notion of natural selection. Natural selection selects for fertility, for reproduction.

If menopause couldn’t have evolved, perhaps — gasp! — it was intelligently designed. This is very confusing. Wait — they just posted about this at PhysOrg: Researchers conclude that what causes menopause is — wait for it — men. Let’s leave the Telegraph for a moment and see what PhysOrg says:

Singh, an evolutionary geneticist, backed by computer models developed by colleagues Jonathan Stone and Richard Morton, has determined that menopause is actually an unintended outcome of natural selection – the result of its effects having become relaxed in older women.

[...]

While conventional thinking has held that menopause prevents older women from continuing to reproduce, in fact, the researchers’ new theory says it is the lack of reproduction that has given rise to menopause.

We still don’t get it. Here’s a link to Singh’s paper, published in PLoS Computational Biology: Mate Choice and the Origin of Menopause. You can read it online without a subscription. Let’s stay with PhysOrg:

The prevailing “grandmother theory” holds that women have evolved to become infertile after a certain age to allow them to assist with rearing grandchildren, thus improving the survival of kin. Singh says that does not add up from an evolutionary perspective.

We never thought much of the grandmother theory. Natural selection seems unlikely to produce infertile nannies. Maybe in an anthill, but mammals aren’t that specialized. Aha — at last, here comes the proposed explanation:

The new theory holds that, over time, competition among men of all ages for younger mates has left older females with much less chance of reproducing. The forces of natural selection, Singh says, are concerned only with the survival of the species through individual fitness, so they protect fertility in women while they are most likely to reproduce. After that period, natural selection ceases to quell the genetic mutations that ultimately bring on menopause, leaving women not only infertile, but also vulnerable to a host of health problems.

Hmmmm. So even when a women had that oddball menopause mutation, she wasn’t selected out of the breeding pool because her reproductive days were already behind her. Okay, that makes sense — but how did that mutation become the common inheritance of all women? The differential breeding success of women with lifelong fertility should have kept menopause a rarity. The article continues:

“This theory says that natural selection doesn’t have to do anything,” Singh says. “If women were reproducing all along, and there were no preference against older women, women would be reproducing like men are for their whole lives.” The development of menopause, then, was not a change that improved the survival of the species, but one that merely recognized that fertility did not serve any ongoing purpose beyond a certain age.

We’re still not persuaded. Here’s one more excerpt:

The consequence of menopause, however, is not only lost fertility for women, but an increased risk of illness and death that arises with hormonal changes that occur with menopause. Singh says a benefit of the new research could be to suggest that if menopause developed over time, that ultimately it could also be reversed.

We wonder if that would cause men to change their ways. Somehow, we doubt it. Meanwhile, back at the Telegraph, we learn this:

Dr Maxwell Burton-Chellew, evolutionary biologist at the University of Oxford, said the study did not explain why the menopause is so rare in the animal kingdom. He said: “The authors argue that the menopause exists in humans because males have a strong preference for younger females. However, this is probably the wrong way round – the human male preference for younger females is likely to be because older females are less fertile.”

It still seems unsettled to us, and we can imagine the creationists making sport of this. We’ll end with a tantalizing incongruity — the extreme opposite of menopause. This is also from PhysOrg: Research shows male guppies reproduce even after death. Maybe there’s an afterlife after all.

After you’ve figured it all out, please explain it to us.

Copyright © 2013. The Sensuous Curmudgeon. All rights reserved.

add to del.icio.usAdd to Blinkslistadd to furlDigg itadd to ma.gnoliaStumble It!add to simpyseed the vineTailRankpost to facebook

. AddThis Social Bookmark Button . Permalink for this article

20 responses to “Hot News Flash: Men Caused Menopause

  1. Ceteris Paribus

    I will wait for the researchers to explain the evolution of the gene mutation that causes the equivalent age male cohort to go out and buy two seater sport cars, and keep serious track of the location of the nearest restroom.

  2. docbill1351

    Like I needed another thing for my wife to blame me for.

  3. The article you link to is in the Torygraph, as indicated at the outset, not the Grauniad, as stated later.

    (Yes, I did type Grauniad deliberately.)

  4. retiredsciguy

    “Hot News Flash: Men Caused Menopause”

    Clever, Curmy, very clever.

  5. It could be argued that the menopause gene proliferated because the post-menopausal women contributed to the child-rearing of their younger relatives, which had the gene.

  6. Thanks, JG. I don’t know why I had the Guardian on my mind.

  7. retiredsciguy says: “Clever, Curmy, very clever.”

    I thought so too, but today I see several newspapers carrying the story with some variation of that in their headlines. We’re all clever guys.

  8. i find it funny when people refer to it as THE menopause. as if there is more than one.

  9. Here is an interesting article on menopause (or lack thereof) in chimps.

    http://news.sciencemag.org/sciencenow/2007/12/13-02.html

    It supports the “Grandmother theory” for human menopause.

  10. I apologize at the outset for being serious. I hope I am not breaking any rules.

    Singe is basically saying that the complex, predictable and uniquely human physiological transformation known as menopause is the result of the chance action of genetic drift of traits freed from natural selection late in life. However, this view ignores the fact that exactly the same argument applies to practically all of god’s creatures, whereas only humans have evolved menopause. Although it is true that young females may be preferentially inseminated in species with harems, in human ancestors, barring evidence to the contrary, older females (like males) probably reproduced as much as physiology allowed. A female who wants a child, whatever the species, can usually find a way to have one.

    The health risks of pregnancy are certainly greater in older individuals. In species in which older females can help care for grandchildren, grandmothering may benefit a female’s fitness more than getting pregnant. (Remember here that grandmothering is not a simple thing: older females must have the brain-power and live in a tight enough social group for a grandmother to use that brain-power to recognize who is and who is not her legitimate grandchild.)

    The onset of menopause is variable, and natural pregnancies in women have been registered almost up until the age of 60. In a pre-technological society, a woman of this age might have difficult in raising to adulthood a newborn child on her own. It could almost be seen as a suicide pact. Depending upon the situation, her genes (including mutations curtailing ovulation) could often be ‘better off’ if instead she babysitted for her daughters.

    One particularly annoying point (see the PhysOrg piece) is Singe’s argument against kin selection for menopause, where he says: “How do you evolve infertility? It is contrary to the whole notion of natural selection. Natural selection selects for fertility, for reproduction—not for stopping it.” Singe has apparently never heard of William Hamilton’s kin selection studies (i.e., a conceptual cornerstone of behavioral evolutionary biology) and seems unaware of worker sterility in ants and bees.

    Singe is basically saying that the complex, predictable and uniquely human physiological transformation known as menopause is the result of the chance action of genetic drift of traits freed from natural selection late in life. However, this view ignores the fact that exactly the same argument applies to practically all of god’s creatures, whereas only humans have evolved menopause. Although it is true that young females may be preferentially inseminated in species with harems, in human ancestors older females (like males) probably reproduced as much as physiology allowed. A female who wants a child, whatever the species, can usually find a way to have one.

  11. Whoa. It’s like deja vu all over again.

  12. Now my terrible joke (above) is even terribler. Also, you should remove the last paragraph from W. Benson’s post (and my posts, please).

  13. longshadow

    “Hot News Flash”? More aptly: “Hot Flash News”

  14. Cheryl Shepherd-Adams

    AHA! I KNEW it was somehow the husband’s fault! And will somebody PLEASE get that thermostat back down to 55F where it belongs????

  15. @Cheryl Shepherd-Adams:

    According to my wife, our thermostat has only two settings: too hot, and too cold.

  16. Curmudgeon: “…we can imagine the creationists making sport of this.”

    You mean another chance to proclaim “‘Darwinists’ disagree! Therefore the theory is dead, dying, falsified and unfalsifiable”? Whereas when “Darwinists” agree they must be “conspiring to censor ‘weaknesses.” Not much sport in “heads, I win, tails you lose.”

  17. It is of course a common creationist claim that evolutionists are making up “just so” stories to explain why this or that trait of biology evolved. It may not always be a totally unjust accusation.

    While I have no relevant credentials myself (just an interested layman), it seems to me that except in the most obvious cases, it must be quite difficult to reconstruct the “rationale” natural selection has for its “decisions”. All the more so when we are talking about complex traits, which represent genetic information generated over thousands of generations. Why the menopause? Why the appendix? Why fuse two chromosomes that are still separate even in chimps? And so on.

    Biologists trying to retrace the route and “causes” of a particular evolutionary pathway would often do well not to sound too cocksure. However, it must be said that if bioloigists properly qualify their statements with phrases like “may have”, “perhaps” and the like, creationists will often seize on this wording as proof that evolutionary science is just pure speculation with no firm facts whatsoever. I recently encountered this rhetorical strategy in “Sowing Atheism” by Johnson jr., for instance.

    I guess people who are into infallible divine revelation will always see it as a weakness of their “opponents” if any uncertainty whatsoever is admitted.

  18. Mark Joseph

    @H.K. Fauskanger:
    I guess people who are into infallible divine revelation will always see it as a weakness of their “opponents” if any uncertainty whatsoever is admitted.

    That’s what people do when they have no facts that might support their beliefs–try to find problems in the beliefs of other people, especially if those people happen to be rational.

  19. Techreseller

    Wait! Male guppies reproduce after death? Sex after death. Where do I sign up?

  20. Techreseller asks: “Sex after death. Where do I sign up?”

    Your former girlfriends think that you’re already there.