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Context and Variation


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Ladybusiness Anthropologist Throws Up Hands, Concedes Men Are the Reason for Everything Interesting in Human Evolution

The views expressed are those of the author and are not necessarily those of Scientific American.


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Like most modern anthropologists, I have challenged the idea that human evolution is entirely motivated by men’s desires, interests, behaviors and strategies. But feelings of doubt have nagged at me for years – impostor syndrome, internalized sexism, and just a general feeling of inferiority and small-brainedness. Then, PLoS Computational Biology published a piece by Morton et al (2013) suggesting that men’s preferences for younger women are what drove the evolution of menopause.

Despite citing the overwhelming literature on the topic, these authors situate human menopause as an “evolutionary puzzle.” They then point out that a model that recognizes male mating preferences for younger women, with a splash of infertility-causing mutations, produces the evolution of menopause. What this suggests is that if men choose to mate with younger women, female-specific, infertility-causing mutations that affect later reproduction could build up, since those women aren’t reproducing. Ergo, the uselessness and undesirability of older women – we all know how that is – leads to their becoming infertile and menopausal.

I can’t believe my feminism blinded me to such a raw, important truth. I now realize that, throughout the hominin lineage, the women were just sitting silently to the side, quivering, reproducing when commanded but otherwise riding the coattails of man’s evolution.

In order to understand this revelation, and the contribution Morton et al. are making to reinforce cultural bias the reality of the patriarchy, we need to walk through existing hypotheses of human longevity, menopause, and post-reproductive life. Even if, of course, we then discard them as frivolous lady ideas.

My understanding of menopause, before I realized my grave error

Morton et al. are basing their work, in part, on models that came before them. When trying to understand why humans have menopause, a related question is why we live so long and have these post-reproductive lives at all. Hamilton was the first (1966), and he created a model of human longevity that only used females, since they’re the ones who make the babies and thus set the pace of fertility (what a closet feminazi!). Tuljapurkar et al. (2007) took Hamilton’s old model, and added men to it. They found that the fact that men were able to continue to increase their reproductive success in later life was evidence that older male fertility was at least a partial driver of why we live so long. However, this is not the same thing as saying that men prefer younger women, nor that they drove the evolution of menopause, and the authors are careful to make those distinctions and be clear about social variables that affect mating preferences.

Wimps.

I used to think that part of the reason humans are menopausal may not be because menopause serves a particular purpose, but because we have extended lifespans. We may have extended lifespans not because longevity is selected for, but because longer periods of childhood and social learning were selected for. The thinking goes, if you stretch human lifespan out just at one end, you end up lengthening the whole thing, like silly putty. That said, there is at least one paper that shows practice doesn’t necessarily make people better at skills necessary for survival (Jones and Marlowe 2002).

Female reproduction is also functionally constrained. In order to select really nice eggs that make really nice babies in whom we will want to invest, we have to make all our eggs at once, at about five months gestation. This is a time that we’re protected from all sorts of environmental factors that could make our eggs wonky, and it gives us time to have a few massive culling events so we use our very best eggs for ovulation. The problem is, if you make all your eggs at once, then they are all going to expire at about the same time, putting a limit on how long women are fertile.

Before my revelation that the men are all who matter, I would have also favored the grandmother hypothesis. This hypothesis isn’t mutually exclusive with the others. Originally the grandmother hypothesis contended that post-reproductive life evolved because grandmothers are important to the reproductive success of their offspring (Hawkes 2003; Hawkes et al. 1998; Hawkes et al. 1997). Much of the first research into the grandmother hypothesis happened among the Hadza, where grandmothers do a lot of provisioning and helping. Subsequent work among other modern and historical populations have shown that grandmother presence can have a more variable influence on infant mortality and child health (Jamison et al. 2002; Ragsdale 2004; Sear et al. 2000). In a few studies, paternal grandmothers – so a mother’s mother-in-law – have a negative effect on their grandchildren (Strassmann et al. 2006; Voland and Beise 2002).

Even if human longevity and ovarian expiration dates are the reason for post-reproductive life, still, what you do with that post-reproductive life can have consequences for reproductive success and thus the gene frequencies of future generations. In some populations grandparents may influence the timing of birth: the presence of paternal grandparents increase the likelihood that the mother will give birth, and the presence of maternal grandparents can decrease it (Sear et al. 2003). This could be due to support in the form of provisioning or cooperative breeding… or it could be pressure from in-laws to make babies.

Finally, it might not be that one of these hypotheses is right, but that all of them make a contribution. You need to combine the major hypotheses in order for menopause models to work, and this has been done with theoretical modeling as well as using Sear and Mace’s empirical data from the Gambia (Shanley et al. 2007).

The proponents of these hypotheses would have you believe they are the most consistent with the physiological, primatological, and fossil evidence, but we can dispense with that. I’d rather go with my biases gut, and favor the Playboy Mansion Model.

Putting “men” back in “menopause:” the Playboy Mansion Model

Hugh Hefner and some of his earlier feminine companions. Being a proper male, he has of course traded them in for younger ones.

Hugh Hefner and some of his earlier feminine companions. Being a proper male, he has of course traded them in for younger ones. (Public domain, via Wikimedia Commons.)

There’s “men” in the name, and yet precious few menopause hypotheses put men front and center (well, except for (Marlowe 2000)). Thankfully, Morton et al. are helping to right this wrong.

Like I said before, Morton et al. created a model with strong male mating preferences for younger women, and added in some infertility-causing mutations. What this means is that, as they ran the model, the selection for younger women as mates caused the older women to be less and less important to natural selection. So the infertility-causing mutations could accumulate in older women, eventually leading to menopause. It seems like this would really only work if the model was fashioned after Hugh Hefner, since men would have to be continually trading in for a younger model for the older women to be selected for only rarely. And it would only work if the way something like menopause could evolve is through infertility-causing mutations, as opposed to issues of functional constraint and expiration dates.

Now, I know my silly little mind trails behind the dudely movers and shakers of human evolution, but I am having a bit of trouble with this. The model requires that fertility into old age is part of our ancestral history if menopause is to eventually evolve, yes? Then probably our closest living relatives, like say chimpanzees, don’t have menopause, unless it independently evolved more than once of course.

Wait, you mean there is controversy here, and some papers provide evidence to suggest chimpanzees have menopause, just not the long post-reproductive life spans (e.g., Hawkes et al. 2009)? Well, then surely chimpanzee males prefer young females, just like human males, which is why it evolved in them as well.

Wait, chimpanzee males prefer older females, the ones with established fertility (Muller et al. 2006)? (And this is not uncommon among many other species?) Well, crap.

So either menopause evolved a few times in our lineage, or it was already there near the start (because of the whole physiological inevitability thing). But if it evolved independently in chimps and humans, the reasoning must be totally different for each species, since male chimps don’t prefer young females and so don’t fit the model.

In evolutionary theory, we have this thing we tend to look for, called parsimony. What fits the data best? And it might be my feeble female mind, but I have a hard time reconciling the evidence suggesting chimpanzees have menopause with chimpanzee preferences for older females.

If men like Hugh Hefner did not drive the evolution of menopause, there are still many opportunities for men to insert themselves in human evolution. Here, I’ve thought of a few, to soothe the wounds of those who wanted an evolutionary Playboy Mansion to be a thing.

The complete irrelevance of women to human evolution

Maybe men provisioned women, which allowed them to stay at home – er, at the campsite – so they could care for offspring. That’s a way more important component of cooperative breeding than care among peers or by grandmothers, right? So men are why we were able to have altricial, big brained infants.

Maybe man the hunter is what got humans up on two legs, jogging around in their fancy barefoot sneakers, I mean, their bare feet. They’re the ones who sexily heft a spear to demonstrate our interesting shoulder girdle and capacity to throw. And of course, they must be the only ones who made stone tools.

Maybe the male gaze is the reason we ladies have breasts and butts that look the way we do. You know we wouldn’t carry all this around if we didn’t have to. And let’s not forget, female pleasure is really just a byproduct of the male drive to reproduce: the clitoris is just a woman’s adorably ineffective attempt at a penis.

So really, even if men had little to do with menopause, they get… well, they get pretty much everything else, so long as you whiz by several decades of egalitarian anthropology research. Which is fun, like roller skating!

And girls just want to have fun!

Acknowledgements

Thanks to Bastard Colleague from Hell – er, Charles Roseman – for reading an earlier draft of this post and providing comments.

References

Hamilton WD. 1966. The moulding of senescence by natural selection. J Theor Biol 12:12-45.

Hawkes K. 2003. Grandmothers and the evolution of human longevity. American Journal of Human Biology 15(3):380-400.

Hawkes K, O’Connell JF, Blurton-Jones NG, Alvarez H, and Charnov EL. 1998. Grandmothering, menopause, and the evolution of human life histories. Proceedings of the National Academy of Sciences, USA 95:1336-1339.

Hawkes K, O’Connell JF, and Blurton Jones NG. 1997. Hadza women’s time allocation, offspring provisioning, and the evolution of long postmenopausal life spans. Current Anthropology 38(4):551-577.

Hawkes K, Smith KR, and Robson SL. 2009. Mortality and fertility rates in humans and chimpanzees: How within-species variation complicates cross-species comparisons. American Journal of Human Biology 21(4):578-586.

Jamison CS, Cornell LL, Jamison PL, and Nakazato H. 2002. Are all grandmothers equal? A review and a preliminary test of the “grandmother hypothesis” in Tokugawa Japan. American Journal of Physical Anthropology 119(1):67-76.

Jones NB, and Marlowe FW. 2002. Selection for delayed maturity – Does it take 20 years to learn to hunt and gather? Human Nature-an Interdisciplinary Biosocial Perspective 13(2):199-238.

Marlowe F. 2000. The patriarch hypothesis – An alternative explanation of menopause. Human Nature-an Interdisciplinary Biosocial Perspective 11(1):27-42.

Morton RA, Stone JR, and Singh RS. 2013. Mate Choice and the Origin of Menopause. PLoS Comput Biol 9(6):e1003092.

Muller MN, Thompson ME, and Wrangham RW. 2006. Male chimpanzees prefer mating with old females. Current Biology 16(22):2234-2238.

Ragsdale G. 2004. Grandmothering in Cambridgeshire, 1770-1861. Human Nature-an Interdisciplinary Biosocial Perspective 15(3):301-317.

Sear R, Mace R, and McGregor IA. 2000. Maternal grandmothers improve nutritional status and survival of children in rural Gambia. Proceedings of the Royal Society of London Series B-Biological Sciences 267(1453):1641-1647.

Sear R, Mace R, and McGregor IA. 2003. The effects of kin on female fertility in rural Gambia. Evolution and Human Behavior 24(1):25-42.

Shanley DP, Sear R, Mace R, and Kirkwood TBL. 2007. Testing evolutionary theories of menopause. Proceedings of the Royal Society B: Biological Sciences 274(1628):2943-2949.

Strassmann BI, Hug BF, and Welch K. 2006. A new twist on the grandmother hypothesis: adverse impact of paternal grandmothers on Dogon grandsons. American Journal of Human Biology 18(2):275-276.

Tuljapurkar SD, Puleston CO, and Gurven MD. 2007. Why Men Matter: Mating Patterns Drive Evolution of Human Lifespan. PLoS One 2(8):e785.

Voland E, and Beise J. 2002. Opposite effects of maternal and paternal grandmothers on infant survival in historical Krummhorn. Behavioral Ecology and Sociobiology 52(6):435-443.

Kate Clancy About the Author: Dr. Kate Clancy is an Assistant Professor of Anthropology at the University of Illinois. She studies the evolutionary medicine of women’s reproductive physiology, and blogs about her field, the evolution of human behavior and issues for women in science. Find her comment policy here. Follow on Twitter @KateClancy.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Kathy K. 4:57 pm 06/29/2013

    OMG- Your perspective is crystal clear and hilarious!
    I’m in total agreement.

    From a totally non-scientific standpoint, we post menopausal women are living our lives free from the drag of a monthly period, and are better for it. I like to think of it as our reward for years of service.

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  2. 2. bwana 6:33 pm 06/29/2013

    “…Men Are the Reason for Everything Interesting in Human Evolution.” Sounds like a good conclusion!

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  3. 3. marclevesque 6:44 pm 06/29/2013

    I loved your post.

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  4. 4. marclevesque 7:02 pm 06/29/2013

    I really liked that.

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  5. 5. Cotesia1 8:38 pm 06/29/2013

    I hope you had as much fun writing this as I had reading it. “Egg expiration date” – seems like the most logical explanation. Physiology, y’all!

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  6. 6. Suttkus 4:11 am 06/30/2013

    I was trying to figure out why it is that some women remain fertile well into their 30′s, long after they’ve started to go a bit stale in the looks department (amirite!), when clearly all normal, well-adjusted males, the only important source of evolutionary innovation, are interested only in 15-25 year-olds. Then it struck me. I vaguely recall reading some research that suggested that some men actually form emotional attachments to women, besides just wanting their youthful hotness (I KNOW!). Admittedly, such freaks must be rather rare, but it’s possible that they were able to influence the gene pool enough for menopause to be delayed beyond the evolutionarily expected occurrence about about 30.

    The really baffling question here is why haven’t women evolved to stay sexy longer? Given their primary purpose is clearly making men all excited, why aren’t they better suited for it? Some women aren’t even all that hot during their years before the use-by date has passed. It seems inexplicable by male-centric evolutionary theory.

    Well, I’m off to download porn. Please remember to send me my Nobel Prize when my observations rewrite sociology.
    [/snark]

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  7. 7. Percival 4:35 am 06/30/2013

    To me, the single most relevant study you cite is Muller et. al.- it would seem reasonable that early humans could be expected to have formed social groups and habits comparable to those of chimps since both we and they evolved from a common ancestor species, but I note that the chimp study investigated only pan troglodytes, not pan paniscus. The latter subspecies is well-known to be nearly as promiscuous as humans are, and I’d be interested to know what their male’s preferences are when seeking mates (if they have a preference, that is).

    Sometimes I think I must have a lot of one kind or another of chimp in me; when I finally got around to marrying I chose a woman a mere year younger than myself; I like to “brag” that I didn’t marry a girl, I married a full-grown woman. Why did I do that? I wanted a mate who knew who she was; who had some experience and competence. We’re grandparents now and indeed do a lot of “provisioning and helping” with the grandkids.

    As an aside, what about male external secondary sexual characteristics? Why should human males have such huge penises compared to other primates unless human females selected for them?

    Also, while I agree this was a fun article to read, I disagree with the title and “conclusion”; the mythical patriarchy/matriarchy debate aside, obviously both men and women determined the course of social evolution to this point and will do so into the future. Gender differences may not give the Earth its angular momentum, but they keep things interesting.

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  8. 8. Moulton 5:14 am 06/30/2013

    Kate Clancy omitted from her biography her most important biological (genetically inherited) trait, which also explains why her legacy to humankind is more than her genetic offspring. Human evolution is not just biological evolution. Anyone affiliated with Scientific American knows full well that the story of human evolution is primarily the story of our cultural evolution, as passed down through our memes. Unlike the gene pool, which is fairly static, the meme pool is expanding by leaps and bound. Some of us are more focused on contributing to the meme pool, as that is our personal legacy to the advance of civilization.

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  9. 9. jvkohl 8:16 am 06/30/2013

    Thanks for an accurate portrayal of evolutionary theory. For comparison to the silly models of evolutionary theorists, see: Kohl, J.V. (2013) Nutrient-dependent/pheromone-controlled adaptive evolution: a model. Socioaffective Neuroscience & Psychology, 3: 20553. http://dx.doi.org/10.3402/snp.v3i0.20553

    Concluding sentence: “Minimally, this model can be compared to any other factual representations of epigenesis and epistasis for determination of the best scientific ‘fit’.”

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  10. 10. rich lawler 1:27 pm 06/30/2013

    It’s interesting that most evolutionary-based discussions of senescence and post-reproductive lifespan start with Hamilton and work under the paradigm that senescence is inevitable, when various theoretical studies have shown that senescence is not inevitable. Hamilton’s model is all too often given dogma-status. More generally, when you start with Hamilton’s model, a post-reproductive lifespan becomes a “problem” to explain away. When you start with an entirely different model (e.g., an optimization model or even a stage, not age, based demographic model) then this post-reproductive lifespan is not necessarily the looming problem that it seems, as many of these latter types of models predict mortality plateaus, post-reproductive lifespans, and even negative senescence. Of course, whether these latter models actually capture the biology of humans better than a strict age-specific force of selection model is the key question–they probably don’t (though it’s possible to rederive Hamilton’s own model to show that it doesn’t yield the senescence that we often think of as inevitable).

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  11. 11. Veganmochi 3:30 pm 06/30/2013

    That’s one pissed off lady anthropologist… Who’s right on. Thanks for posting.

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  12. 12. rkipling 12:22 pm 07/1/2013

    A quick search turned up a 2011 article on a study by Erik Trinkaus at Washington University in St. Louis. The study of early modern humans reported an estimate of only 25% of adults survived past 40 (40,000 years ago.) Assuming that estimate of survival past 40 is representative of most of human evolution, then about 75% of early modern women wouldn’t have experienced menopause. I guess 25% would be high enough to effect evolution?

    From the response by some commenters, who I assume are students of anthropology, study of anthropology must make this post more humorous. If men are responsible for menopause, my contribution was completely unintentional I assure you.

    I had no idea there was so much research on grandmothering. The one titled Grandmothering in Cambridgeshire, 1770-1861 was probably riveting.

    Does your epiphany mean you will have to change the context of your blog?

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  13. 13. wbailey77 3:47 pm 07/1/2013

    After reading this I went and found the original article, eager to experience the misogynistic bastards in their original language. I came away disappointed.
    Not only did I not get to revel in smugness, but I was almost embarrassed at the incredible lack of understanding demonstrated by the anthropologist above. She seems to not know the difference between scientific data and social commentary, and treats one result of a hypothetical mathematical model as unforgivable slander on half the human population.

    If you bother to read the original, you’ll see that the authors put dozens of genetic and behavioral variables into a very complex mathematical model, ran a bunch of different combinations, and then looked to see what scenario(s) produced stable reproducing populations where females had fertility decline long before mortality. The model demonstrated that it was mathematically possible to create a scenario where a certain combination of genetic conditions and male behaviors create a menopausal time period in females over evolutionary time scales.

    All they showed is that social contributions are not an essential variable in every single possible scenario that could ever create the life history event known as human female menopause. Yet the author above is railing against them for saying women contribute no value to society. Can someone please explain that pseudo-intellectual leap to me? Are we on Fox News or something??

    Let’s look at this from a different perspective. Take man pigs and womyn goddesses out of it altogether. Imagine if a computer model demonstrated that it was possible to make vegan chocolate cake. (which I hope you all know is utterly real and absurdly delicious…but I digress) By Dr. Clancy’s logic, eggs and butter worldwide should rise up in offense and write snarky rebuttals accusing the chefs of ignoring dairy’s essential role throughout history!

    Um, no. Sorry. Does not compute.

    I’d also like to point out this, from the original paper: “We emphasize that the role of the sexes would be reversed in this model if the matrix were to encode female preference for younger males (rather than male preference for younger females) and that the current role of the sexes may be interpreted equivalently as older females being out-competed completely by younger females, their dominant behavior driving the decline in female fertility.”

    This research is not misogynistic social commentary. It is a report on a mathematically plausible scenario as illustrated by a computer model. They fed it variables. It spat out results. That’s all.

    One final note: Dr. Clancy’s repeated references to “expiration dates” on eggs are in total agreement with hypotheses that there may exist genetic mutations that reduce fertility after a certain point. Why would eggs have expiration dates if not for mutations that reduce fertility long in advance of mortality?? Physiology comes from our evolutionary heritage, people, and our evolutionary heritage is determined by gene flow, which is determined *in part* by behavior…this is just science and math, so please exercise the critical thinking endowed upon you by your evolution, and get a grip.

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  14. 14. wbailey77 3:48 pm 07/1/2013

    http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1003092 Here’s the link to the original article, for anyone who wants to actually investigate the source and decide for themselves.

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  15. 15. Kate Clancy in reply to Kate Clancy 5:13 pm 07/1/2013

    Oh, I see wbailey77. Since the authors did math, I shouldn’t worry my pretty lady head about this paper. That’s so great! I also love the ways that you conflate the way I satirize the sexism that can occur in my field (and mainstream media reporting of it) with the criticisms I have with the paper. Funny, most people could tell what I was trying to do here. You must just be willfully ignorant.

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  16. 16. Scottcha 6:38 pm 07/1/2013

    Wonderful article! But don’t worry about the central role of females. As Carl Sagan pointed out, “Despite many claims to the contrary, life does not begin at conception: It is an unbroken chain that stretches back nearly to the origin of the Earth, 4.6 billion years ago.” That unbroken chain is composed of eggs, and that’s why we men are so jealous.
    We can’t make babies, but we can make some pretty convoluted theories!

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  17. 17. lynnoc 8:03 pm 07/1/2013

    Raising homo sapiens children takes a fantastic amount of labor, for a long long time, and the grandmother hypothesis makes total sense. As you mention there is some evidence for it. There is also some evidence that men in fact do not do most of the provisioning in many hunter-gatherer cultures –women (grandmothers included) do, gathering and hunting as well, taking down small game –while men fairly regularly fail to succeed at the “hunt.” Further, older men are more likely to have babies with genetic problems, with higher incidences of serious mental disorders, etc. Men lusting after younger women is a status thing, as well as about success in reproduction. And I’m not sure that every single culture finds exactly the same preferences. We have to re-analyze and carefully review many conclusions by male-centric evolutionary psychologists. It’s sort of like homosexuality in non-human animals, i.e. non-reproductive uses of sex. We’re not the only ones who engage in non-reproductive sex. Turns out homosexuality is really common in non-human animals, but the mostly male ethologists/biologists didn’t notice it until relatively recently. Finally, older men begin to be treated like women. They don’t like it, it’s humiliating. Lusting after young women has a non-reproductive purpose. That doesn’t mean it isn’t important to our evolution –it’s not only procreating that is supported by evolutionary forces. What happens to the babies after birth is important, who brings in provisions is important. In contemporary urban societies there is some evidence that the presence of grandparents may make a real difference, helping to insure the success of the children growing up and themselves reproducing. You may have it backwards, women may be the sex that is most important from an evolutionary perspective.

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  18. 18. DrDemento 8:09 pm 07/1/2013

    This made my day. Thank goodness I went the wet bench route. Please keep up the great posts. :)

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  19. 19. grosas2 8:33 pm 07/1/2013

    I’m so glad that Wbailey set the record straight. Can you imagine the insolence of thinking that feminist anthropological criticism could have something valuable to the debates about women’s bodies? I’m so glad that you cleared that up for all of us. She was just be silly. Wasn’t she?

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  20. 20. Don Quixote 9:30 pm 07/1/2013

    Hmmmm…my sarcasm alarm is clanging loudly, but my man-mind isn’t seeing it :-) (just kidding…seriously, I’m just kidding).

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  21. 21. Kate Clancy in reply to Kate Clancy 9:15 am 07/2/2013

    rich lawler – thanks so much for your comment. I’m not an expert on the senescence stuff by any means, but instead was going off the models Morton et al themselves claimed to use. From talking to some other folks it sounds like they (and I) should have gone back to Medawar, but also looked at fertility patterns of modern foragers to see how terribly wrong the model is.

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  22. 22. rkipling 10:11 am 07/2/2013

    It seems that the Morton piece was just an opportunistic foil for your humorously sarcastic restatement of your general views. Given that approach, I doubt anyone expected you to examine the Morton paper seriously. So, I suggest there is no need to defend your post as an objective critique of the paper.

    In my view, your many and laudable accomplishments are a stronger assertion of feminism than anything you could write. Having said that, in academic context, it may be valuable to consider if you are a scientist first or a feminist. You probably do that. For a well written and really funny post like this it doesn’t matter.

    My guess is that your lectures draw overflow crowds of students.

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  23. 23. britbacca 11:11 am 07/2/2013

    Fabulous article. As someone who worked in an evolutionary psych lab in college, I can attest that the majority of (mostly male) researchers are oblivious to anything that challenges their conveniently constructed patriarchal Pleistocene paradise. However, there are occasionally some good reads out there, and on the topic of menopause, I’d encourage you to check out this article: http://shell.newpaltz.edu/jsec/articles/volume4/issue4/ReiberVol4Iss4.pdf

    The author (Reiber, 2010) looks at ovulation from a gamete competition model, arguing that women enter menopause because “female gametes are competing to achieve ovulation, and the high rate of gamete loss that results leads directly to the follicular depletion that triggers menopause.” While I haven’t had the chance to really research her hypothesis, I do fondly remember the author (an anthropologist) speaking at a evolutionary psychology conference and talking about the scientific and medical literature that always frames female reproduction passively, and how that influences the models we have about female agency and evolution right down to our gametes. If anything, it’s a breath of fresh air in a field full of toxic garbage like the article you discussed.

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  24. 24. Buzz Parsec 3:04 pm 07/2/2013

    In comment 6, Suttkus asked:

    “The really baffling question here is why haven’t women evolved to stay sexy longer? Given their primary purpose is clearly making men all excited, why aren’t they better suited for it? Some women aren’t even all that hot during their years before the use-by date has passed. It seems inexplicable by male-centric evolutionary theory.”

    You answered the question in your first paragraph. Obviously, evolving is another thing that men are really good at but women not so much.

    P.S. This is the first time I’ve posted here. Do I need to add <snark> tags so people will know I’m not serious?

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  25. 25. =8)-DX 5:20 am 07/3/2013

    Lovely article =>
    I’m no scientist, but I always used to feel that coupling high mortality rates and the high risk of childbirth with the value of “tribal elders”, it wouldn’t make sense evolutionarily to have 70-year-old grandmothers dying off in childbirth instead of contributing to their offspring’s developement =S.
    But then science-based and parsimonious explanations are the best, thanks for the good summary of the research.

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  26. 26. archmeg 3:27 pm 07/3/2013

    Kate, thank you so much for this response. I was so frustrated with the NPR blog I read about this article, but I don’t have the expertise you do to so nicely critique it!

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  27. 27. karenl1234 6:05 pm 07/3/2013

    Funny! Thanks for writing and posting and everyone knows the best hunter gets the best looking female. In modern times the rich and fab get everything from all ages and it is legal and we think hooray for them! In society it is all about looks and acquisition and money how shallow is humankind. How about the guy that fathers 15 kids with 13 women and pays zero for any of them! Who care you can get a surrogate or adopt, when I look at the Rock I get all warm and tingly! Ha Ha

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  28. 28. karl 7:34 pm 07/4/2013

    I loved your article, (even if I can’t drive something more complex than a car, much less evolution), The only thing I didn’t catch (male brains here) is the name of the researcher, is it MorTon or without the T?
    I guess that having a baby is as easy as making a hot dog, because it requires almost no effort, no calcium loss, metabolism compromises, nutrition and weigh almost nothing to the mother, (silly me, that has nothing to do with creating a new life anyway), therefore that has nothing to do with menopause, the baby of a 90 year old woman also would have the same chances a baby from a 20 year old woman of having a mother untill reaching adultness, which means that genes allowing that would be preserved if not for the watchfull allmighty males.
    I don’t seem to recall, but do other animals remain fertile until old age? because it is a known fact that men remain functional until a Hefner age and viagra is just a breath freshener.
    then taxonomically speaking what about Cougars?

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  29. 29. karl 8:51 pm 07/4/2013

    Cooling off a bit, mathematical models aren’t nearly definitive, (I had a math teacher that refused to take drugs like aspirin because you never got quite rid of the stuff, as shown on a half life decay model, even when if you have half a molecule of something you don’t have said thing), and the fact that 2+3 = 5 doesn’t mean that 4+1 isn’t 5, both are equally valid.

    If men selecting younger women was somehow forcing the evolution of menopause, why the same reasoning hasn’t affected the hymen (a superior notsayinisgodbutgod thing needs to put a “tamper proof” seal on women?)

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  30. 30. taffazull 1:04 am 07/9/2013

    The reason for the breasts and butts of ladies may be that fats produce 9Kcal/gram while carbs can provide a mere 4 Kcal/gram.Thus advertising ample fat stores may be a way to ensure greater reproductive success.Higher calorific value of fats may also explain menopause. As fat stores get depleted with age reproduction which needs a lot of calories would be adversely affected.Indeed if fat stores are low menarche may be greatly delayed in growing girls. Natural selection is impersonal and perhaps thermodynamics is what drives everything including men’s gazing proclivities..

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  31. 31. rkipling 5:54 am 07/9/2013

    I understand this is off topic, but I’m curious what a labor activist advocates for nowadays? I read about Mother Jones marching to Theodore Roosevelt’s house, but what do you consider is left to accomplish?

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  32. 32. ramacm 1:23 am 10/22/2013

    Great Insight!

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  33. 33. DoubleHelixATCG 8:35 am 10/22/2013

    I don’t think you’ve fully engaged with the data. There is a marked difference between menopause in humans and chimpanzees. Their maximum lifespan in captivity is around 60, and they can continue to ovulate into their late 40s or even 50s (Herdon et al., 2013). Thus, their fertility declines when their other physiological systems are deteriorating. You can’t explain away the hypothesis of this study in reference to chimpanzees. Killer whales and pilots whales are perhaps the only non-human animals observed to experience long post-reproductive periods. As with humans, research has focused on their social structures, providing evidence for the mother hypothesis (Ward et al., 2009; Foster et al., 2012). Further, as its known that for example blue whales can give birth up until their maximum lifespan of 90, fertility decline can’t simply be a by-product of living a long life.

    As you’ve stated, it’s not inconceivable that the origin of menopause is multifactorial. I don’t see how mate choice and adaptive explanations for menopause involving inclusive fitness are mutually exclusive. It seems to me that there might be confirmation bias at work in your dismissal of mate choice. Either that, or you interpreted the characteristics of menopause in chimpanzees in a way that fit your narrative.

    Foster, E.A., Franks, D.W., Mazzi, S., Darden, S.K., Balcomb, K.C., Ford, J.K.B., and Croft, D. P. (2012). Adaptive prolonged postreproductive life span in killer whales. Science, 337(6100), 1313.

    Herndon, J.G., Paredes, J., Wilson, M.E., Bloomsmith, M.A., Chennareddi, L., and Walker, M. L. (2012). Menopause occurs late in life in the captive chimpanzee (Pan troglodytes). American Aging Association, 34(5), 1145-1156.

    Foster, E.A., Franks, D.W., Mazzi, S., Darden, S.K., Balcomb, K.C., Ford, J.K.B., and Croft, D. P. (2012). Adaptive prolonged postreproductive life span in killer whales. Science, 337(6100), 1313.

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  34. 34. DoubleHelixATCG 8:46 am 10/22/2013

    Missing reference: Foster, E.A., Franks, D.W., Mazzi, S., Darden, S.K., Balcomb, K.C., Ford, J.K.B., and Croft,D.P. (2012). Adaptive prolonged postreproductive life span in killer whales. Science, 14(337), 1313.

    Again, I’m not explicitly arguing for the mate choice hypothesis. I just think you owe it to your audience to present an accurate account of the research.

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  35. 35. DoubleHelixATCG 8:47 am 10/22/2013

    Sorry…

    Ward, E.J., Parsons, K., Holmes, E.E., Balcomb, K.C., and Ford, J.K.B. (2009). The role of menopause and reproductive senescence in a long-lived social mammal. Frontiers in Zoology, 6(4), doi:10.1186/1742-9994-6-4.

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  36. 36. Kate Clancy in reply to Kate Clancy 2:07 pm 10/22/2013

    DoubleHelix — thanks for your perspective and citations, they are sincerely appreciated. Maybe you would consider changing your tone next time, though. I tend not to be a fan of being told I haven’t “fully engaged with the data,” nor what I do or do not “owe” my audience.

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  37. 37. kemprl 5:30 pm 10/23/2013

    I REALLY enjoyed reading this article. I have never laughed so much while conducting research.
    I found that it very accurately represented the finding of the research by Morton, Stone, & Singh (2013). You explained the methodology of the study and the results in a very clear and concise manner, with an enjoyable touch of humour.
    I particularly like that you showed where the results of this study were consistent with human evolution by mentioning that hunting men may be the reason that humans are bipedal and that male choice has is the reason that women carry excess weight in their breasts and bums. That male behaviour and choices have driven human evolution for many traits. It is entirely feasible that they could have driven the selection for menopause.
    The only recommendation I would make is to insert the word ‘MAY’ into your headline. Men MAY be the reason for everything interesting in human evolution. The conclusions of the study by Morton et al. (2013) are not definitive as assumptions are made. The researchers presented a theory about the origin of menopause. The theory is yet to be extensively tested or replace the grandmother hypothesis as a widely accepted reason for the production of menopause.

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  38. 38. kathedwards 6:49 pm 10/23/2013

    Although humorous, and certainly written with personality, you aren’t presenting the original work adequately.

    Throughout Morton et al. are suggested to have misogynistic biases, you called wimps, made fun of their Hefner inspired model, but you didn’t give their hypothesis a fair chance. You certainly didn’t present it with the same level of scientific rigor you provide for the counter arguments.

    Considering their authors background is in evolutionary biology I assume they are not making broad underlying statements about the cultural relevance of this sexual-selection model. They have simply proven it is a possible, to reach fixation of a later life sex-specific infertility allele, when one sex is selecting for younger mates (which could have and theoretically could still cause male fixation). You nor anyone else has to agree this is the way menopause evolved, but it’s a valid a argument just like grandmothering, and follicular depletion hypothesis.

    I also agree with wbailey77 in that one of the hypothesis you counter with, the expiration date on gametes, can be theoretically explained through the accumulation of deleterious alleles, opposed to a predetermined functional constraint on viable eggs.

    Finally, menopause is a puzzle! It’s a natural phenomenon, almost completely limited to humans. How and why populations that live beyond their reproductive lifespan evolved is a mystery, that almost defies natural selection. Unless of course we explain it through processes such as grandmothering or even the controversial sexual-selection model.

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  39. 39. Anoniemous 10:56 pm 10/23/2013

    This was a really enjoyable read! It’s always good to see humour in a critique.
    The one thing I do not agree with you on is the degree of importance Morton et al. placed on male mate choices in the development of the menopause. Morton et al. did not claim that only males were important in the development of the menopause; they clarified that if females preferred older males, men would have been the ones to experience the menopause instead. However, I can see where you’re coming from—the paper did neglect to explain how female mating preferences could have played a role in the development of the menopause in women. Such topics could have been quite appropriate in the introduction or discussion.
    You proposed several valid critiques, as well. Functional limitations in women would indeed prevent them from being fertile throughout their lifetime. However, perhaps male mating preferences would have removed the genes that produced those constraints. In fact, when the Morton et al. paper ran a simulation in which males preferred all women, they did not observe the menopause. However, their model included the initial assumption that lifetime fertility was possible, and did not address the subsequent chicken-egg problem. I also agree with your claim that a large reproductive advantage for younger females would have required a male to have offspring with several young women in favour of an older woman. In contrast, it is more adaptive for a monogamous male to reproduce with his mate throughout their lives. It’s hard to take a clear stand on this matter though, since whether human males were monogamous or polygynous in evolutionary history is unclear (Strehler, 1979; Reno, Meindl, McCollum, & Lovejoy, 2003). Nevertheless, the goal of science is to generate questions and discussion, and I think both you and Morton et al. have done well on that.

    Works Cited:
    Reno, P. L., Meindl, R. S., McCollum, M. A., & Lovejoy, C. O. (2003). Sexual dimorphism in Australopithecus afarensis was similar to that of modern humans. Proceedings of the National Academy of Sciences, 100(16), 9404-9409.

    Strehler, B. L. (1979). Polygamy and the evolution of human longevity.Mechanisms of ageing and development, 9(3), 369-379.

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  40. 40. morettba 11:45 pm 10/23/2013

    Hey Kate:
    Your article is too witty for its own good. I really enjoyed reading your commentary. I agree that the male-mating hypothesis has quite a few holes, including the lack of female participation in mate-selection (I assume women have some options). They also fail to identify any unique human selective pressures that chimpanzees do not have to explain their difference in mate-selection. However – being the staunch anti-feminist that I am – I do believe you misrepresent the central hypothesis of Morton et al.’s paper to a certain extent. The authors’ computational model first assumes that mutation(s) causing female-infertility in old age. As infertility increased in older women, male-mating preference became more biased towards younger women. This preference propagated the late-onset mutation(s) in the population which in turn further drove men towards younger women. To say that the authors believe men are responsible for menopause is a tad excessive (they don’t need that much credit). After all, men only work with the mutations women are given.

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