How Darwin caused global warming with his theory of sexual selection

July 9, 2022 • 12:00 pm

Yet another letter has appeared in the Guardian about Stephen Buranyi’s misleading “long read” on the site, “Do we need a new theory of evolution?” (Buranyi says “yes”). I’ve mentioned the problems with Buranyi’s article before, and three of us even wrote a letter about the article’s flaws that the Guardian published.

Apparently, though, the fracas hasn’t died down, because another one just appeared, this time on sexual selection. The letter is by anthropologist Heather Remoff, who wrote a book on sexual selection mentioned at the bottom of her letter.

Here’s the letter (click to go to the Guardian site), and my take on it is below:

There’s a lot to “unpack” here, and I’ll try to be brief.

First, the letter doesn’t address Burayni’s claims, which was that the modern theory of evolution was incomplete and perhaps obsolete. He was not referring to Darwin’s theory of evolution but to Darwin’s theory as it has been updated and expanded in light of modern research. Darwin’s failure to understand everything does not mean that the modern theory of evolution is woefully lacking, for we’ve had more than a century and a half of work on evolution since The Origin.

Ergo, showing that Darwin’s theory of sexual selection was incomplete—and yes, it was his theory, rejected even by A. R. Wallace (except in humans!)—does not support Buranyi’s thesis. That theory was published in 1871, and now it’s 150 years on. Modern evolutionary biology has added tons of knowledge and theory about sexual selection. There are entire books on the topic (here’s one) that go far beyond Darwin’s ideas. But showing that “Darwin’s theory was incomplete” doesn’t say anything about the modern theory of evolution, which is what this whole controversy is about.

Darwin actually had two theories of sexual selection, one involving male-male combat for females, and the other involving female preference for “beauty”. The former theory, which Darwin called the “law of combat”, explains the evolution of weapons like antlers in male deer—weapons far less developed in females because they’re not used.  Darwin’s second theory is that females have an aesthetic sense that males appeal to with ornaments, striking colors, extreme behaviors, or lovely calls. This causes female-imposed natural selection on males, which, thought Darwin, explains sexual dimorphism in appearance, behavior, calls, and so on.

Note first that, contra Remoff, female preference was already a crucial part of Darwin’s theory, for without that preference we wouldn’t have the striking sexual dimorphism we see in many animals. Even though male-male competition remains an important explanation for male-limited weapons or competitive behaviors, Darwin had already diagnosed a large portion of the sexually dimorphic world using the lens of female preference.

But Darwin’s theory was incomplete in a way Remoff fails to mention. Exactly why do males compete for females? Darwin had no answer, and you don’t find an answer simply by viewing the issue through the female lens. In general, biologists agree that sexual selection results from this:  female investment in offspring is often much larger than that of males. When females have to do the hard work of gestation and rearing of offspring, as well as contributing metabolically expensive large gametes (eggs), while male investment is often limited only to a small amount of tiny sperm, an asymmetry in the interests of the sexes arises. Evolutionarily, males can leave more of their genes by copulating with any female they can, while it pays for females to be choosy about her mates, since once she mates, she’s made a huge investment that has to be tended. A good choice by a female often means her offspring have a better change of surviving, ergo it pays to be picky.  A male fly can mate with 20 females in a few days and have 20 batches of offspring, but a female fly who mates with 20 males within a few days doesn’t have many more offspring than if she copulated only once. It thus pays the males to be profligate and the females to be choosy.

I often use this example in evolution class to show the asymmetry (see this page for the records). This is what your body is capable of producing if you’re a woman or a man:

Record number of children produced by one mother: 69 (many twins and triplets birthed by a Russian woman)

Record number of children produced by one father: 1000-2000 by Genghis Khan (estimated) or, in more modern times, over 868 fathered by Moulay Ismail Ibn Sharif, a Sultan of Morocco, in the 18th century.

A male can have more than ten times as many offspring over his life than can a woman! Of course the average number of offspring has to be the same for men and women (after all, each child has one mother and one father), but the variation is such that while women produce relatively comparable numbers of offspring, a lot of males produce just a few and a few males produce many. That is, males have a much higher variance in offspring number. And that is the basis for sexual selection. (This difference in variance is seen in humans as well as in many other species.)

The asymmetry between the sexes, then, rests on the best way to choose. For males it’s not evolutionarily “wise” to be choosy (I am generalizing here, for of course there are cases in which males should also be choosy), while for female it pays to make sure you choose well, as you don’t have as many shots as being a parent. As I said, this is a short explanation for sexual selection that has exceptions, but it’s the going explanation for why, when the sexes differ in ornamentation, behavior, or calls, it is males who show elaborated traits.

This asymmetry is critical in understanding the whole process of sexual selection, and it rests not on seeing it through a female lens, but seeing it through a lens that looks at what both sexes have to gain from behaving in various ways. In the end, it’s largely based on gamete size. That was what Darwin missed, but we understand it now and can test it.

Further, since Darwin’s time we have new theories of sexual selection that have been mathematically elaborated: the runaway model (Richard Prum has used this to update Darwin’s “beauty” hypothesis), the “honest signalling” model, the “sexy son” hypothesis, and so on. Some of these models overlap.  All of them consider female preference.

Now I’ve said in the past that, in my view, one of the contributions of the “female view” of biology has been an increased emphasis on female choice in sexual selection, for the process involves an interaction between males and females. Some women (but not solely women) helped direct research by emphasizing female preference. And that’s understandable; you don’t want your sex and its importance in evolution to be overlooked.

That said, though, both men and women have made important contributions to the modern theory of sexual selection; it was not incomplete because the “female lens” was totally overlooked by patriarchal male biologists. And, as I said, female behavior—aesthetic preference—was absolutely critical for the “beauty” aspect of Darwin’s original theory.

As for the “genetic breakthoughs” that have led to a new understanding of sexual selection, particularly when viewed through that female lens, I am stymied. I don’t know what breakthroughs Remoff is talking about. Perhaps she’s referring to this:

The evolutionary moonshot that enabled Homo sapiens to go where other species have failed to follow has its roots in a reproductive mutation – concealed ovulation and continuous sexual receptivity – that dramatically increased the strategic agency employed by females.

Concealed ovulation and continuous sexual receptivity (the latter is possessed by many animals) are not “mutations”; they are traits, likely ones that arose via many mutations of small effect. And yes, these traits have obviously changed the playing field for sexual selection. But whether they have been  “moonshot” that has enabled us to go where other species have not, well, other species have had their own “moonshots”, like hypodermic insemination in some invertebrates, the “pseudopenis” of the female hyena,”and the male pouches of pipefish and seahorses.

The last trait gives male seahorses most of the investment in offspring (males, in effect, get “pregnant”, and females, who can produce lots of eggs, must compete for limited male pouch space). The result that in this group it’s most often females rather than males who are ornamented. This reversal of investment, coupled with a reversal of the sexual dimorphism, is striking support for the “differential investment” theory of sexual selection.

Sexual selection operates in different ways in different species, and, truth be told, we don’t understand the details that have led to the evolution of most sexually dimorphic traits. not involved in male-male competition. We know the basis for the evolutionary process—differential investment in offspring—but we don’t know why particular traits are chosen and whether they are indicators of fitness or of something else. If you ask me why the peacock has a long tail instead of a big head crest, and what information that elaborate tail conveys to females, I wouldn’t be able to tell you. We do know that the more spots a male peacock has on his tail, the more likely he is to be chosen as a mate, but we don’t know the advantage accruing to females that have such a preference.

And no, sexual selection does not “establish the origins of everything that defines human exceptionalism”. Semantic language? Bipedality and manual dexterity? Our remarkably complex brain? Did all those traits rest on sexual selection? I think not.

Remoff ends with a paragraph that is pure hyperbole:

Why does all this matter? Because humans are facing an environmental disaster of our own making. Only by developing an accurate understanding of the factors that shaped human species-specific behaviour will we be able to avert the rapidly approaching climate apocalypse. Sexual selection may have shaped us, but our failure to take an unbiased look at ourselves could be handing natural selection the power to eliminate us.

Will understanding sexual selection, or human evolution in general, help us stave off climate change? Again I think not. Only by limiting carbon emissions will we be able to avert climate change. And that does not depend on understanding human evolution, much less sexual selection.

In the end, Remoff is tilting at two windmills that have already fallen. Her attack on Darwin is wrongheaded since Darwin’s correctness is not the issue in Buranyi’s piece and because female preference was already a crucial part of Darwin’s theory. And her claim that it was only the “female lens”, used recently, that helped us understand sexual selection, is also misleading. Female preference has been considered by evolutionists since 1871.

44 thoughts on “How Darwin caused global warming with his theory of sexual selection

  1. At first it’s puzzling to imagine how a competent editor could let this get past the front gate. But, then you’ve got to realize there is natural selection in publishing newspapers too. The Guardian has mutated its standards in hopes of survival.

    1. Nice meta-level thought there. It’s even possible that it survives only because it mutated its standards in ways that the environment supported–though since papers can consciously evolve (or at least those who run them can make them evolve) it’s probably a bit of both, I guess. Meanwhile, those papers that are careful, staid, sober, and emphasize clarity over hyperbole, and won’t publish matter that is without merit, don’t get shared on social media, don’t get clicked, don’t show up high on Google searches…and so go out of business. Alas.

    2. Sorry for the reply; I can’t figure out how to post a new comment.

      “That is, males have a much higher variance in offspring number. And that is the basis for sexual selection. (This difference in variance is seen in humans as well as in many other species.)”

      As a statistician, I think this misattributes causality. Variance is just a description of a system and cannot be the cause of itself, although it could cause other things. So it’s really the opposite way around: sexual selection is the basis for a high variance in the number of offspring for males. The high variance is a consequence of males competing for females. Why do they compete? My guess is that males who don’t compete simply don’t pass on their genes, and so over time a species gets more competitive as the “docile” ones have no or fewer offspring.

      1. The high variance in offspring number is based on gamete size, so I’m not sure that you can say that “sexual selection” is the basis for the high variance in offspring number. But in a sense it is correct, too, and I wrote my big awkwardly

  2. I would appreciate suggestions as to how we can most effectively voice our opinions about these horrible Guardian articles.

  3. Heather Remoff’s description by Shepheard-Walwyn states: “Heather spent the next forty years involved in research, writing, and economic activism.”

    Activism, in my opinion, is always a bad advisor when it comes to scientific research. It clouds objectivity and promotes bias.

    1. As far as I am aware, Remoff does not have an academic appointment, but I was very amused by the comment on one of her publisher’s website that “She lives in Arlington, Massachusetts, where the proximity to Harvard, Radcliffe, and The Massachusetts Institute of Technology enables her to attend a variety of exciting public lectures that keep her current on recent scientific breakthroughs.”

      I’m sure that most of us would prefer to keep current in our fields by attending “exciting public lectures” rather than the harder slog of reading scores of journal articles, attending conferences, etc. I was reminded of the neat little book by Harry Collins: Are We All Scientific Experts Now?

      1. Thank you for pointing that out. But then why does the editor’s description of Remoff sound like she actually did research? Do they consider her to be an independent scholar?

        1. Good question — my least charitable response might be that “research” covers a wide range of activities, many of which do not resemble the traditional stereotypes in any way….

  4. Ah yes. The “Look at yet another topic Darwin was SO wrong about” bandwagon. Based on most sources I’ve seen (and considering the cultural, religious, and technological state of affairs of his era), I’m still often amazed at all the things he was CORRECT about.

  5. You have the patience of a saint (if you’ll pardon the expression) for taking this nonsense to task point by agonizing point. After reading Remoff’s letter it seemed to me that she felt left out and wanted to get her own knock into the mix.

    Regarding the “female lens,” it’s great to see so many women getting their PhD’s and becoming biological scientists. I’m sure that the great majority are not using science as a tool to push a political agenda. No one is an island and we all have our biases. But Remoff’s piece is so blatantly poisoned by ideology (and falsehoods) that she should have recognized it and self-censored.

  6. …viewing the process through a female lens…

    Am I the only one who doesn’t like the “lens” analogy that is so often used? Lenses are designed to see things clearly, and distortion in a lens is regarded as a flaw. The correct analogy here should be “filter.” Filters are used to purposely distort and change what you are seeing for a desired effect.

  7. With regards to climate change, perhaps Remhoff is referring to human males’ tendency to purchase gas-guzzling sports cars and pickup trucks as a way of attracting females. If human male hair grew in bright orange and stood straight up, perhaps our output of greenhouse gasses would be smaller. 🙂

    1. Understanding human evolution will help us avert global warming? Helluva non-sequitur! I’m so tired by the left (my camp) constantly talking in terms of a human apocalypse if we don’t contain global warming. We’re one of the most adaptive species ever so I think humans will manage even with higher sea levels, more intense storms, and war stemming from limited resources. Millions could die but with >7.9B people, I think we’ll get through it OK. Of course we should try to transition our economies off of petroleum ASAP but all this hyperbole of the human race going extinct from global warming sounds like religious, end-of-days apocalyptic bullshit.

    2. It can’t be denied – human males are overwhelmingly responsible for the creation of “science” and the technology that underpins the modern world.
      We are responsible for global warming, habitat destruction etc.
      But I don’t think she’d want to frame it that way.

  8. To Remoff’s point that sexual selection is exclusively Charles’ theory, not Erasmus’, here is a brief counterpoint:

    I haven’t ready Zoonomia so can’t speak to the detail with which Erasmus described sexual selection but it is strange to me Remoff felt a need to even make the claim that sexual selection is unique to Charles. It seems irrelevant to the article as a whole and appears to be false with a simple internet search.

    1. I have a smattering of knowledge to add about Darwin, which was although he described sexual selection in a language that seems old-fashioned today, for this time it was rather shocking to some to learn that females could effect much of anything. As a case in point, he and his stalwart collaborator Alfred Wallace had a definite separation of views on the matter since Wallace could not get his head around the idea that females could so completely manipulate males!

    2. Humans may “manage” or “get through it OK,” but the mammals we depend upon to live will likely not.

      1. Cows and pigs and sheep and goats and llamas and chickens (honorary mammals because agricultural) are going to be driven to extinction by global warming? Honestly, Su, that’s the first time I’ve ever heard that claim made. I know climate advocates want us to stop eating them because raising them emits greenhouse gasses, but that would be due to imposed policy. It’s not a case of their not surviving climate change.

  9. … the “sexy son” hypothesis …

    I believe the great Chicago bluesman Willie Dixon elaborated on this:

    1. It is said in the abstract of that article that sexual selection is more Wallacean than Darwinian, but the article itself does not give any clear support for that notion.
      I think the truth is probably in between: sexual selection often is ‘honest signalling’, at least initially, but Fisher’s runaway mechanism from there (yes, female preference) is probably the reason that definitely non-adaptive traits can prevail. I would call that pretty Darwinian, and less Wallacean.
      As I said earlier, I think it is human exceptionalism to deny an aesthetic sense to non-human animals. Where would our aesthetic sense come from in the first place?

  10. It’s really a nonsensical letter.

    This is a bit of a derail, but I can think of one area where a female lens might help dispel what I see as an absurd take: the purported mystery of the female orgasm. It’s supposed to be a mystery because it doesn’t have an obvious function, whereas the male orgasm’s raison d’être is supposedly self-evident, given that it goes hand in hand with the vital process of ejaculation. This take confuses the mechanics of copulation and reproduction with the pleasure involved. Just like we don’t feel anything as our heart pumps blood, men could in theory ejaculate without feeling much of anything. Thus the male orgasm doesn’t need any less explaining than the female one just because it happens to coincide with a vital function.

    1. Men wouldn’t hang out in bars buying drinks for strangers who don’t like them if ejaculation produced no more pleasure than cardiac output does. I read somewhere recently that orgasm in women alters the orientation of the uterine cervix in such a way that sperm can more easily pass through the os. The well-known ability of many women to achieve orgasm repeatedly in a short period of time would be adaptive here, giving multiple serial enjoyable copulations all a leg up to produce fertilization. This finding elicited the expected exasperated sigh that men couldn’t be satisfied with just letting women enjoy pleasure. No, they had to find something that it was good for. Point taken.

    2. The female orgasm probably exists because the male one does, and became reinforced as long-term pairing (dare I say love) became more important in humans. As is often the case in evolution, current function doesn’t necessarily reflect origin. One could make the same argument with respect to male nipples. In fact, Stephen Jay Gould did, in an essay called “Male nipples and clitoral ripples”. In a footnote, he pointed out that the original, obvious title—tits and clits—had been rejected.

  11. I think she really wanted to write about the patriarchy, and needed to wrap it in the currently most fashionable wrapping paper, which was the Guardian article.

    Imagine when the post-modernists completely go after all areas of education about sex and the sexes. Then, articles and maybe even text books about reproduction, venereal diseases, sexual selection, and all the rest will have fully laundered language. In all references to females we will see “uterus bearers”. All reference to males will be “ejaculators”, to borrow a clever point made in a recent post.

  12. By the way, here is a very interesting new paper by Paul Griffiths, in which he discusses the fundamental conceptual question in the context of the (evolutionary) biology of sex: “What are biological sexes?”
    The preprint of the paper is freely available:

  13. Poor Darwin! He gathered facts & thought a lot before coming to his conclusions. It seems churlish to blame him for having ideas that she does not accept either in part or total. It is merely bashing someone who has no possibility of responding, so makes an easy target. He did not claim to have every answer.

    He would undoubtedly have been delighted to learn how we have progressed with our understanding of evolution & all the new aspects that have been drawn out.

  14. Remoff’s letter is full of nonsense like “Sexual selection…establishes the origins of everything that defines human exceptionalism.”

    Humans are actually much less sexually dimorphic as measured by body size compared to orangutans (very dimorphic), gorillas, and bonobos. Chimpanzees are barely dimorphic, about the same as humans.

    That pattern suggests that humans have experienced less sexual selection (at least on relative male body size) than those other anthropoids, and suggests humans are not exceptional in that way.

    But Remoff’s view is the kind of thing that passes for comparative biology among anthropologists like her whose training is mostly in sociology and who have only vaguely heard of things like chimps.

      1. Now I wonder about her motivations – !

        “Although present in both sexes, each sexual selection component has different relative importance in each sex. Artisticality functions to attract and maintain long/short-term partners, and to compete with mating rivals.”

        To seek prestige or to stand out from the crowd, as so many of us do. I attribute my failure to mate & produce offspring, to lack of access to females when I was at my reproductive peak, & at my economically most attractive. Those two peaks were far apart, & then I was too fussy. I am a Darwinian failure!

    1. Yes could be helpful. Cordelia Fine is a blank slateist who doesn’t think there are any biological differences in behavior between women and men. She & Remoff could both be wrong.

      Those posts by Jerry (and the comments) from five years ago are prescient about the consequences of spreading ideological biases in science and science writing.

      1. Useful links, thanks, and I also checked out the King review of TR. I agree with you that it is useful to look back over a lot of writing about gender in the last twenty years and ask what directions they set us on. I didn’t read TR as an argument for the “blank slate”, but rather a critique of how we read and make sense of science, which can apply equally to Progressive and Conservative ideologies being brought into the scientific arena. Fine’s own words are probably most helpful in clarifying her position on some of this:
        Fine, C. (2020). Constructing unnecessary barriers to constructive scientific debate: A response to Buss and von Hippel (2018).Archives of Scientific Psychology, 8(1), 5–10.

    1. Sorry but he made several fundamental mistakes. But the one you cite does NOT overturn the notion that mutations are random at all. It shows that mutations are less likely to occur in regions where they could cause more damage, but not that the mutations that do occur tend to enhance fitness at a frequency more than that ofmutations in other regions.

      Further, the paper you cite refers only to the plant Arabidopsis, yet you talk as this phenomenon is general in all species. In fact, tests in other species show that you’re wrong.

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