A new review (and critique) of Richard Prum’s book on sexual selection

I’ve now read Richard O. Prum’s new book, The Evolution of Beauty: How Darwin’s Forgotten Theory of Mate Choice Shapes the Animal World—and Us (I’d highlighted the work earlier in my critique of his NY Times article about the book). Click on the screenshot to go to the book’s Amazon site. (Prum is a professor of ornithology, ecology, and evolution at Yale.)

The review I want to highlight was published in the journal Animal Behaviour, but I’ll get to that in a minute. First, I want to give my own brief take on the book.

The Evolution of Beauty is in fact a mixed bag, but for me the problems outweigh the good parts. First, though, what’s good, and a bit of background.

Prum’s purpose is to explicate a theory of sexual selection that was suggested by geneticist Ronald Fisher eighty years ago and was elaborated much more recently by my colleagues Russell Lande and Mark Kirkpatrick. (Prum also draws a line of descent to this theory from Darwin’s own views of sexual selection published in 1871.)

This theory—the “runaway model”, called by Prum the “Beauty Happens” model—tries to explain why males are ornamented and show displays, while females choose among those males. This is sexual selection, which Prum (mistakenly, in my view) says is qualitatively different from natural selection (see my earlier post for my take on this pseudo-distinction). Prum’s view is that the runaway process, in which females evince randomly generated “aesthetic” preferences for male traits, have been the “ubiquitous” cause of sexual ornamentation and displays in animals. (His examples are drawn largely from birds, but he applies them to humans in the book’s final chapters.) The male traits and female preferences get exaggerated because they are genetically correlated: those females with preferences mate with males having the preferred trait, and the offspring carry genes for both the preference and the male trait. This causes a snowballing process that exaggerates both trait and preference to the extremes that we often see in nature.

Prum contrasts the runaway process with other forms of sexual selection in which females choose males not because they’re “beautiful” (to Prum that word that simply means “what appeals to females”), but because the offspring of females get benefits from her choice: either genetic benefits (“good genes” models) or “direct benefits” (healthy males can better take care of offspring or don’t pass parasites onto the mother and hence onto her young). These models, in which male traits and behaviors indicate the health or genetic quality of a male, are known as “indicator models”.

There are also other models that are either well known and substantiated (“male-male competition”, which causes sexual dimorphism and ornamentation, including antlers in deer, larger body size in competing male elephant seals, and so on), or more speculative but still credible models (“sensory exploitation,” in which female preferences are a byproduct of behaviors that existed for other reason, like preferring colors that resemble berries). There is in fact evidence for nearly every model of sexual selection, but it’s so hard to do this kind of work that we simply cannot say, as does Prum, that one scenario is “ubiquitous.” It’s early days here, and Prum’s suggestion that we know the answer is premature, though in the end he may be right. Or other models may be right. Or the answer may be that different models contribute to sexual dimorphism in varying degrees, or act together. We just don’t know.

The good aspects of Prum’s book include a historical overview of the difference between Darwin and A. R. Wallace in their views of sexual selection, and a critique of the many modern behavioral ecologists who uncritically adopt “good genes” models as the default explanation for sexual dimorphism. Further, Prum’s descriptions of male traits and behaviors, most seen by him in the field, are superbly written and often mesmerizing.

The book’s problem is that it is tendentious. Prum doesn’t describe the issues with his favored runaway model; he mistakenly regards it as a “null model” against which other models must be tested since, he wrongly claims, it makes no assumptions (he also claims that his null model can neither be proven nor disproven, which makes it non-scientific); he neglects other forms of sexual selection; he does not recognize that various models can work together and likely do work together; he ties “good genes” models to eugenics and even Nazi eugenics, unfairly tarring sexual selection theory with the residue of an unsavory past; and he claims that female choice of mates, which he calls “sexual autonomy”, somehow vindicates feminism in our own species.

The tie to feminism is a particularly invidious way to sell his theory, as female choice in birds is a direct product of evolution, while human feminism is a rational conclusion our species draws to improve society by treating people equally. Feminism should not be buttressed by biology, as that makes it susceptible to further knowledge from biology. If you study other species, for example, you could draw other conclusions and support other forms of sexual behavior in humans. Many species, for instance, have “traumatic insemination,” in which the male simply bypasses female choice by either forced copulation or, in the case of bedbugs and some invertebrates, injects the sperm directly into the body cavity, bypassing her genitalia and often injuring or killing her. Here are two bedbugs going at it, with the smaller male sticking his genitals directly into the female body cavity; you can see the puncture wound he’s making. (The sperm somehow still find their way to the eggs.)

If you studied deer or elephant seals, you might find support for the existence of harems in humans, in which powerful males, by virtue of their status, are able to dominate and mate with many women, while the “losers” go childless. This underscores the big mistake of using your favorite brand of biology to support ideological or moral conclusions. (I note that biology can, however, inform some aspects of morality: learning about fetal pain may, for instance, affect one’s views about abortion.)

Nevertheless, the problems with Prum’s book are so serious that it distresses me that it’s gotten such good and uncritical reviews. The New York Times, which gave it a glowing and uncritical review, selected it as one of the Ten Best Books of 2017.  It was also one of three finalists for the 2018 Pulitzer Prize in General Nonfiction (it didn’t win), which convinces me that those who choose these candidates don’t know much about the books’ subjects. I’m starting to realize that magazines and websites should choose scientists, or at least people who deeply understand the science at issue, to review trade books about science.

But enough; I will likely give a fuller explication of my views in the future. For now I want to highlight a newly published critique of Prum’s book by Gerald Borgia and Gregory Ball, two researchers from the University of Maryland who work on mate choice in bowerbirds. (Borgia is my former colleague.) Their review of The Evolution of Beauty occupies a page and a half in the latest issue of Animal Behaviour. The reference with link (also here) is below, and the pdf is here; both are free to me with Unpaywall, but if you can’t download them, a judicious inquiry might yield you a pdf.

Borgia and Ball’s criticisms are similar to mine, but as they are experts, they go far beyond what I’ve written above. If you know about sexual selection it may be an easier read, but if you’re interested in sexual selection I suggest you give it a try. At any rate, at the end of their review, Borgia and Ball raise the feminism and eugenics angles, and the excerpt below should be comprehensible to everyone. I’ve put in bold a particularly misguided quote from Prum:

In the last chapter of Beauty, Prum reveals the political view that has shaped the core arguments in this book. Prum’s style and message is a rerun of Gould and Lewontin’s divisive writings from 40 years ago, in which they unfairly associated adaptationism with genetic determinism, eugenics and Nazi atrocities (Allen et al.,1975, p. 186). Prum applies similar arguments to sexual selection, associating good genes and adaptive mate choice hypotheses with eugenics and Nazi violence. He states: To permanently disconnect evolutionary biology from our eugenic roots, we need to embrace Darwin’s aesthetic view of life and fully incorporate the possibility of nonadaptive, arbitrary aesthetic evolution by sexual selection. “…Accordingly, evolutionary biology should adopt the nonadaptive, Beauty Happens null model of the evolution of mating preferences and display traits by sexual selection”(page 331).

That’s incredibly dumb. What it says is that we should adopt one scientific theory over others (surprise!—it’s Prum’s favored theory) not for scientific and evidential reasons, but simply because that theory can’t be tied to discredited views of eugenics. Borgia and Ball continue:

Prum’s conflation of eugenics and genocide with adaptive mate choice is a disservice to his readers and colleagues for several reasons. First, this argument is wrong. Mate choice represents individual, and especially female, reproductive freedom, whereas eugenics and genocide represent a restriction by the state on an individual’s ability to live and reproduce. It is not more moral to choose a mate  for arbitrary reasons, as Prum suggests, than to choose one to enhance the success of one’s offspring. Consistently across societies, parents support the interests of their offspring, suggesting that adaptive mate choice may be viewed as morally superior. Second, Prum’s mistaken association of eugenics with adaptive/good genes mate choice represents a threat that can limit free scientific discussion of important issues, and this should be resisted. Third, science validates or rejects hypotheses based on evidence, not on potential or contrived historical associations, altruistic intent, or political belief.

We offer two key takeaways from this book. First, contrary to Prum’s claims, LK [“Lande-Kirkpatrick”] runaway selection has enjoyed a privileged position, including being prominently presented in evolution and behaviour textbooks despite a lack of supporting evidence. Perhaps the most significant implication of Beauty comes from Prum’s inability to make a credible case for LK runaway sexual selection in this book’s 448 pages, suggesting that it may be time to shift focus to other, better-supported models. Second, Prum’s (and other, earlier) efforts to inject politics into science commonly distort the science to justify political goals. We should have all learned by now that science is about understanding what nature is, not what we want it to be. The arguments in Beauty that suggest otherwise should be rejected.

That’s a fine ending of a good review—and by that I mean a thoughtful review.

Here’s a 7-minute Big Think video in which Prum explains his views. His drawing a connection between eugenics and adaptive theories of mate choice begins about 2:10. He continues, tying the theories he opposes to eugenics and racism (and to his view that sexual selection differs from natural selection), at about 4:50.

h/t: Nilou, Tami Mendelson

________

Borgia, G. and G. F. Ball. 2018. Review of The evolution of beauty: how Darwin’s forgotten theory of mate choice shapes the animal world—and us.  Animal Behaviour 137:187-188.

 

 

52 Comments

  1. Bruce Lyon
    Posted August 30, 2018 at 9:36 am | Permalink

    Thanks for this great review Jerry. A bit of history explains why Prum loves the runaway model—he has always been quite anti-adaptation (he has mellowed a bit recently) and I think the runaway model fits his world view that we can explain lots of evolution without needing to invoke adaptation. I am not sure why he was initially anti-adaptation but it is something I have seen in others who were trained early in cladistic perspectives. I suspect there was a camp early on in systematics that embraced anti-adapationism but that is clearly not the case any more.

    • Christopher
      Posted August 30, 2018 at 10:10 am | Permalink

      Setting Prum aside, could you explain this adaptation/anti-adaptation split? What, in general, is the reason some would be against the idea that evolution doesn’t need adaptation?

      As for filtering scientific ideas through political ideologies, I’m afraid we are going to be fighting anew wave of this for a generation or more, considering the mood on the campuses in regards to gender/sex, the new feminism, and the regressivist racism running rampant in the minds of so many students and younger professors.

      • Posted August 30, 2018 at 10:39 am | Permalink

        SJWs’ hold visceral disgust for adaptionism and natural selection because those entail quite broad ranges of inherent traits leading to disparate success among individuals. As this is anathema to their tenet of equality of outcome, SJWs readily fall into the moralistic fallacy.

        • Posted October 13, 2018 at 12:18 pm | Permalink

          And, by doing this, they start to resemble the religious nuts.

      • Graham
        Posted August 30, 2018 at 6:56 pm | Permalink

        Too which I will add I have personal encounters with people who have believed in the heritability of traits like racism and sexism, with the first being linked to the ‘white’ gene and the second to the Y Chromosome.

  2. pierluigi Ballabeni
    Posted August 30, 2018 at 9:48 am | Permalink

    Thank you for this review. The (available time)/(number of evolution-ecology books) ratio is small and reviews like this one are very useful for filtering what to read.

    • Posted October 13, 2018 at 12:18 pm | Permalink

      Yes, I also do not intend to read it.

  3. stevenjohnson
    Posted August 30, 2018 at 10:01 am | Permalink

    “First, this argument is wrong. Mate choice represents individual, and especially female, reproductive freedom, whereas eugenics and genocide represent a restriction by the state on an individual’s ability to live and reproduce. It is not more moral to choose a mate for arbitrary reasons, as Prum suggests, than to choose one to enhance the success of one’s offspring. Consistently across societies, parents support the interests of their offspring, suggesting that adaptive mate choice may be viewed as morally superior.”

    Historically, parents choose mates for women in most technologically advanced cultures. (Is the issue debatable for technologically primitive cultures?)This has no discernible relationship to feminism. The notion that adaptive mate choice may be morally superior truly is lapse into the naturalistic fallacy. Even worse, it is not at all clear how these reviewers know that parent choice of mates is adaptive. I suggest it is a mere assertion based on unexamined prejudices.

    “Second, Prum’s mistaken association of eugenics with adaptive/good genes mate choice represents a threat that can limit free scientific discussion of important issues, and this should be resisted.” The proposition that in human populations adaptive fitness both varies widely and is identifiable to simple inspection is at first glance a proposition necessary to both adaptive mate choice and eugenics. Adaptationism as it is currently represented in the popular literature substitutes natural selection for “God” as the cause of perfection. It is not clear that species go extinct because they were ousted by more perfect competitors. Nor is it clear that population size (of course including zero, that is, extinction) is not a question for evolutionary theory.

    “Third, science validates or rejects hypotheses based on evidence, not on potential or contrived historical associations, altruistic intent, or political belief.” This is just the second objection, rephrased as the self-flattering implication they are the ones who have the objective science. It’s not clear why ideas about morality shouldn’t be based on the way the world works, rather than the supernatural free will of superior souls who can rise above mere nature. But it’s not at all clear that the reviewers have achieved the objectivity. They claim that non-adaptive sexual selection is favored view despite having no evidence to support it. This is certainly not true in the popular literature!

    • Posted August 30, 2018 at 10:27 am | Permalink

      “Adaptationism as it is currently represented in the popular literature substitutes natural selection for “God” as the cause of perfection.”

      Not exactly sure what you’re driving at here. But nowhere in adaptationism is ‘perfection’ suggested — ‘good-enough-ism’, more like.

      • mikeyc
        Posted August 30, 2018 at 10:37 am | Permalink

        That’s right. That’s why I shake my head whenever I read some “cdesign proponentsist” knob on about design – nature uses kludgy, inefficient, “good-enough” solutions to adaptive pressures. Not at all the way a god or any competent human designer would approach the problem.

        • Posted August 30, 2018 at 10:40 am | Permalink

          It’s kludges all the way down.

          • mikeyc
            Posted August 30, 2018 at 11:01 am | Permalink

            BTW, I don’t wish to change the subject, but just wanted to put this out to you. Awhile ago in a different WEIT thread you suggested that men are equally the victims in interpersonal (domestic) violence. I said I was skeptical of that claim and asked for evidence. You gave some, but in case you’ve missed it, here’s more I just came across that supports your claim;

            *https*://news.ubc.ca/2018/08/29/teen-dating-violence-is-down-but-boys-still-report-more-violence-than-girls/

            (remove ** because I don’t trust my embedding skills)

            In that thread you and others pointed out that most interpersonal violence goes unreported and the less severe forms even more so, so this kind of evidence is hard to come by. But that’s some right there.

            Sorry to derail.
            ….back to our regularly scheduled programming…

            • Posted August 30, 2018 at 12:17 pm | Permalink

              Thanks for the link and the willingness to explore this thorny subject.

              One of the authors of the study you cite writes:

              “It could be that it’s still socially acceptable for girls to hit or slap boys in dating relationships….”

              A 2007 Jezebel article*, reacting to a CDC survey** that found 71% of nonreciprocal IPV was perpetrated by women, reported with glee and approval that several Jezebel staff had physically assaulted their male partners.

              Despite the considerable stigma to men reporting IPV, the CDC self-report survey on IPV has at least twice (2011 & 2014) recorded greater numbers of male victims than female.

              For a thoughtful analysis of reporting concerns and data interpretation, cf.
              http://www.saveservices.org/2012/02/cdc-study-more-men-than-women-victims-of-partner-abuse/

              * Have You Ever Beaten Up A Boyfriend? Cuz, Uhh, We Have
              https*://jezebel.com/294383/have-you-ever-beat-up-a-boyfriend-cause-uh-we-have

              ** Men Shouldn’t Be Overlooked as Victims of Partner Violence
              https*://psychnews.psychiatryonline.org/doi/full/10.1176/pn.42.15.0031a

              • Christopher
                Posted August 30, 2018 at 3:33 pm | Permalink

                Interesting. I once’s witnessed female on male domestic violence (he was fleeing across a parking lot, she was running after, hitting him) and called th cops. Before the trial, she was blaming him and accusing him of the same stuff…until her lawyer was informed that I had shown up. Evidence is a funny thing that way.

              • Posted October 13, 2018 at 12:23 pm | Permalink

                I cannot imagine how these relationships lasted.

        • Nicolaas Stempels
          Posted August 30, 2018 at 1:44 pm | Permalink

          I like the way ‘Smilodon’s Retreat’ formulated that: “it is not about ‘the survival of the fittest’ but about ‘the reproduction of the fit enough’ “.
          Prumm is right that Darwin himself proposed this ‘runaway’ mechanism, based on random aesthetics, but I always found it a bit, how shall I say, lacking in knowledge about what the ‘trigger’ was, if I may express myself that way.
          Completely random ‘runaway’ sexual preferences always appeared unsatisfactory to me. I keep thinking ‘what was the trigger for that particular runaway process?’

          • rickflick
            Posted August 30, 2018 at 9:04 pm | Permalink

            I don’t fine it hard to imagine a trigger, if you mean a starting point for sexual dimorphism. A subtle color difference in male plumage could become noticed and a trigger for female attention. This color pattern could then become enhanced over time as their genotypes shift.

  4. Posted August 30, 2018 at 10:21 am | Permalink

    Prum’s dogged insistence on distinguishing between survival and reproduction is maddening. I would very much like to ask him what is the purpose of survival in & of itself. It also leads me to wonder whether Prum is an individual selectionist.

    In a piece for the like-minded readers of the New Yorker, Prum unabashedly reveals how feminist ideology drives his scientific research and dictates his conclusions.
    https://www.newyorker.com/tech/elements/duck-sex-and-the-patriarchy

    Very discouraging to see this level of lysenkoism both tolerated in the academic community, and celebrated by the lay public.

    • rickflick
      Posted August 30, 2018 at 9:08 pm | Permalink

      I eagerly read his book and was also maddeningly annoyed by his inability to clearly make his case. I see from your report of his NY piece where all this comes from.

  5. mikeyc
    Posted August 30, 2018 at 10:33 am | Permalink

    Politics, likes religion, poisons everything.

    • Historian
      Posted August 30, 2018 at 11:07 am | Permalink

      Aren’t you being a little cynical or hyperbolic here? Politics is the means by how people decide how they will be governed, including what people or group have the power. Perhaps you have a different or more unsavory definition of the word “politics.” In all societies, the political process is often corrupt, inefficient, unfair and tyrannical. But, it is part of human nature. While we can envision the day when religion as we know it disappears or is insignificant, politics will never go away, no matter how you define it.

      • mikeyc
        Posted August 30, 2018 at 11:15 am | Permalink

        It is also true of religion, no? Despite it “poisoning everything”, positive things like succor in times of grief, providing some with heritage, community and tradition (not that any of that is inherently good), etc, can accrue from religion. Same with politics – some good, eventually, can come out of the process.

        But especially when it is applied to something like science where it has no place, politics and religion really do poison every thing they touch.

        MOOC

      • Posted October 13, 2018 at 12:27 pm | Permalink

        Let’s say, then, that “politics poisons everything outside of the legitimate political sphere”.
        In my country, everything was politicized between late 1944 and late 1989, and it brought disaster.
        I recently asked a student from another EU country what had prompted him to study in Bulgaria. He said that university teachers in his country were strongly politicized and some even demanded from students to pledge allegiance to their favorite party, as a precondition to pass.

  6. Posted August 30, 2018 at 10:37 am | Permalink

    Reblogged this on The Logical Place.

  7. Posted August 30, 2018 at 11:11 am | Permalink

    “It is not clear that species go extinct because they were ousted by more perfect competitors.”

    I would say that it is rarely the case that species go extinct because they were ousted by more perfect competitors. Mostly species go extinct as a result of arbitrary disruptions to their environment (comet strikes, arrival of humans within their range, climate change…). However, this has little to do with the discussion as to the mechanisms of sexual selection which reflect selection at the level of individuals not species or populations.

    “The notion that adaptive mate choice may be morally superior truly is lapse into the naturalistic fallacy”. This is no more or less true than to suggest that the runaway model of mate choice is morally superior because of its supposed disconnection from eugenics – which is Prum’s explicit position.

    The reviewers are surely correct to argue that “science validates or rejects hypotheses based on evidence, not on potential or contrived historical associations, altruistic intent, or political belief.” You choose to reflect this back them as them as a “self flattering implication that they are the ones who have the objective science” but it is not a comment on their science – they are reviewing Prum’s book, no-one else’s and it is a matter of objective fact that Prum argues in favour of non adaptationist runaway sexual selection because it will “permanently disconnect evolutionary biology from our eugenic roots”.

    • Posted August 30, 2018 at 11:14 am | Permalink

      this was intended to be a reply to 3.

    • darrelle
      Posted August 30, 2018 at 1:42 pm | Permalink

      And, don’t species also go extinct simply because they evolve into other species? I mean, not because they couldn’t adapt to new environmental conditions or new competition but simply because of the inevitable changes that slowly accumulate given enough time? There often isn’t really a distinct line between a precursor species and successor species unless you look at it from far enough away in time, or with low enough resolution. If you look up close at any point in the evolutionary history of a lineage it’s all the same species.

      • Christopher
        Posted August 30, 2018 at 3:48 pm | Permalink

        And let us not forget great extinction events such as the end Cretaceous, where 75% of species went extinct but for reasons unclear at this time. Would it not be safer to say that most extinctions are from as yet unknown causes, others are actually evolution, some are certainly via competition (thinking about species accessing a new environment, like the joining of north and south America) and then there’s us. We, by out-competing other species, over-exploitation of food species, and moving around other species.

    • Posted October 13, 2018 at 12:29 pm | Permalink

      I wouldn’t say “rarely”. Migrating and introduced species have caused countless extinctions.

  8. darrelle
    Posted August 30, 2018 at 11:24 am | Permalink

    I am always kind of surprised when an expert seems to exhibit multiple common fallacies while arguing within their own area of expertise. The same kind of fallacies you commonly see among lay-folk.

    Naturalistic fallacy, Straw Man, Black & White fallacy, Red Herring.

    • caracal
      Posted August 30, 2018 at 2:25 pm | Permalink

      Yep, and add “You can’t get an ought from an is” (David Hume – good discussion here: https://en.wikipedia.org/wiki/Is%E2%80%93ought_problem)

      From the review: “We should have all learned by now that science is about understanding what nature is, not what we want it to be.”

  9. Dick Veldkamp
    Posted August 30, 2018 at 11:29 am | Permalink

    Dear PCC(E),

    Could you (or somebody else) shortly explain what the arguments against the runaway model are? Richard Dawkins made a case for it in “The Selfish Gene”, and his reasoning seemed quite convincing to me.

    What are we missing?

    • Bruce Lyon
      Posted August 30, 2018 at 11:45 am | Permalink

      In short, there is no direct evidence for it, unlike all of the other mechanisms. If the assumptions all hold then perhaps it might work. I think the point that the Borgia and Ball review makes is a good one: if it is so ubiquitous, where is all the evidence. The fact that it could logically work does not mean that it does work.

    • Posted August 30, 2018 at 12:02 pm | Permalink

      Also, the model is very sensitive to direct selection on the female preference (e.g. natural selection of some sort). If that selection is reasonably strong, the runaway won’t work. As far as I remember, Prum doesn’t even mention that caveat in the book. And it’s reasonable to expect some selection on the preference, as preferences have costs–in time spent looking for mates, not getting food, and exposing oneself to predators.

  10. Curtis
    Posted August 30, 2018 at 11:45 am | Permalink

    The other thing that bothered me was that Prum claimed his ideas were radical and new. He was the superior scientist for being the first to truly understand evolution. He continually bad mouthed other scientists including Richard Dawkins.

    One of his examples was a quote from either Darwin and Wallace disagreeing about sexual selection. Prum claimed to be the first to see the light in 150 years. Then I read something by Dawkins with the same quote and the same conclusion.

    Having said that I am glad I read the book. There was a lot interesting stuff about sexual selection in birds.

    • Posted August 31, 2018 at 12:51 pm | Permalink

      In her The Ant and the Peacock (published 1991), Helena Cronin described at great length the sexual selection debate between Darwin & Wallace. But I’m sure Cronin is persona non grata to Prum.

      It’s likely no coincidence that I picked up a Ray Comfort vibe of smugness in Prum.

      • Posted October 13, 2018 at 12:32 pm | Permalink

        Somebody should point out how Prum neglected the contribution of Cronin, and based on this, attack him as a toxic sexist white male :-).

  11. Joe Dickinson
    Posted August 30, 2018 at 11:55 am | Permalink

    I already had decided to skip this one because of the outrageous claim, in the title, that this was a “forgotten theory”.

    • Posted August 31, 2018 at 12:07 pm | Permalink

      That was my question too – did Darwin have a theory of sexual selection that was different than the current ones? Reading that part of the Origin as a layperson I didn’t notice anything that wasn’t covered in the intro bio courses at various levels I did. (So I am naive, but not *completely* so. :))

  12. Steve Pollard
    Posted August 30, 2018 at 12:17 pm | Permalink

    Not remotely qualified to comment; just to say thanks for this well-argued review and the additional material from Borgia and Ball. The whole thing has made it worth logging on today!

  13. Roo
    Posted August 30, 2018 at 12:33 pm | Permalink

    I’m confused about what point is being made here. Some reviews of Prum’s book say he proposes a / the driving force in mate selection as simply the ‘female love of beauty’, although perhaps they are not interpreting correctly. If this is true, however, it is a non-explanatory statement, akin to saying “It is what it is”. I mean, yes, technically true, but it doesn’t say anything about causal chains. In terms of approach / avoidance behaviors, female animals presumably feel some form of ‘love’ (i.e., attraction / approach behavior,) for whatever traits they select for, regardless of the reason. There may be an interesting philosophical musing in there about what love means to a bird at a behavioral and felt level, but either way, it seems as if the bird’s subjective experience of that process is secondary.

    By way of example – I ‘love’ ice cream for what are likely purely (previously) adaptive reasons. I ‘love’ cracking my knuckles due to what I assume is a fluky, random mis-calibration of the neurotransmitters or wiring in my particular brain, as it serves no real purpose but no real harm either. I love my friends due to complex and not fully understood processes involving mirror neurons and shared affect and communication that are probably a mix of adaptive traits as well as spandrels of those traits. If you want to get into quasi-mystic territory, I think humans may love certain types of art based on universal mathematical forms that we innately recognize as ‘truth manifest’ or some such thing. But however functional or romantic you want to get with it, there is always a reason involved. Unless you remove it from causal chains (a la the reasoning of ‘free will’), then saying “Mate selection is based on what females think is beautiful” is akin to saying “They like it because they like it.” At least in my reading, maybe I’m not understanding the core concept here. Does Prum propose some mechanism by which aesthetic preferences arise?

    • Curtis
      Posted August 30, 2018 at 3:16 pm | Permalink

      I think “It is what it is” is exactly what Prum means. He argues against any reason that relies on fitness or a marker for fitness . Peahens like peacock tails because they like them i.e. Beauty happens.

      I am not a biologist but this view seems reasonable for some of his examples of female preferences in birds.

      • Concobus
        Posted August 30, 2018 at 3:35 pm | Permalink

        I think Prum deeply confuses a few things in his book.

        He conflates:
        * The nature of the signal
        * The intensity of the signal
        * The signal acting as a means of species discrimination.

        In my view, the exact nature of a signal is probably quite arbitrary a lot of the time. Males of one species may have red feather tips and another might have yellow. Female preferences for the species-specific signal are maintained by hybrid sterility (if they mate with an individual of the wrong species) and because females who choose the “wrong” males will have ugly sons with lower mating success.

        The intensity of the signal (whatever the signal happens to be), is probably driven by natural selection on female choice: there is selection on females to be able to discern-high quality males. Signal intensity is an honest indicator of male quality.

        So in my opinion, the nature of the signal is probably random but the intensity of the signal is driven by selection.

      • Roo
        Posted August 30, 2018 at 10:44 pm | Permalink

        Hmm. I guess the determinist in me doesn’t like the vagueness of “it is what it is”, however, I can see how in the context of his position it *might be a moot point (I say might because I’m not entirely sure I understand all the nuances here.) Meaning, it doesn’t matter if true ‘randomness’ exists or what the underlying mechanisms at play are in this particular case, it’s enough to say that small, chance fluctuations in the environment (a color resembling a favored berry, as Jerry discussed above,) in a myriad of different contexts could more or less represent ‘randomness’ in Prum’s paradigm, and it wouldn’t change the essentials of the point he’s making (that being, I think, that if sexual selection is not controlled by survival, it can be set off on many different courses by many chance happenings, and the details of said happenings are not particularly important, just the fact that they can be rather small and not tied to survival/fitness.)

        Whether or not this is true, I don’t know. I do think a common mistake in thinking about evolution (I say that because it’s a mistake that I, as a casual reader and layperson, find myself making a lot,) is to ascribe a sort of religious “God’s Perfect Plan-esque” nature to it, as if it explains anything and everything perfectly in terms of survival and fitness. In truth, as I understand it, evolution is a rather ‘sloppy’ process (as would be expected,) and contains all sorts of offshoots / spandrels / spectrums that go awry (i.e., autism and schizophrenia,) / features that aren’t helpful but remain because they aren’t harmful either / etc.

        In that sense, I find Prum’s hypothesis interesting, if unproven. I do think that his ponderings on eugenics seem a bit uncomfortably nihilistic (a term I use in place of ‘relativism’, as I think relativism is misunderstood,) however. The unstated flip-side that follows from his argument is that when women today engage in the ‘eugenics’ of mate selection (i.e., when a women says that she hopes to marry a man who is kind, funny and smart; vs. racist, homophobic, and with a long criminal record,) that they are engaging in a sort of random, chance whim that has nothing to do with anything. Maybe I am just a Good Enculturated Little Moralist over here, but that feels (as a woman, btw,) wrong to me. That gets into a sort of moral nihilism that I certainly hope is incorrect.

        • darrelle
          Posted August 31, 2018 at 7:18 am | Permalink

          “I do think a common mistake in thinking about evolution (I say that because it’s a mistake that I, as a casual reader and layperson, find myself making a lot,) is to ascribe a sort of religious “God’s Perfect Plan-esque” nature to it, as if it explains anything and everything perfectly in terms of survival and fitness.”

          Interesting that you mention this (which I agree with) because Prum himself makes exactly this mistake, except he’s an expert and should know better. Either he’s made a mistake or he is rather dishonestly using that claim because it rather egregiously misrepresents the consensus of his profession. As pointed out somewhere above, and as you apparently already know, Evolution doesn’t generate perfection but simply good enough for the moment.

  14. Concobus
    Posted August 30, 2018 at 2:45 pm | Permalink

    The strict distinction between natural selection and sexual selection as survival vs. mating success doesn’t even really make sense from a historical standpoint.

    Darwin coined the process “natural selection” in analogy to the “artificial selection” conducted by animal breeders. But artificial selection mostly proceeds not by killing certain individuals, but choosing which individuals you allow to breed.

    So “artificial selection” mostly reflects mating success, as Darwin noted when he repeatedly called it “selective breeding”. So Darwin’s own thinking was fuzzy on the matter of natural vs. sexual selection. And Prum’s is far worse.

    I greatly disliked this book. For me, there was one particular point early in the book when I knew Prum was talking nonsense. When discussing Zahavi’s Handicap Principle, Prum asks why animals never seem to evolve true handicaps such as missing limbs. Either he is being totally disingenuous there, or else he proves that he knows literally nothing about honest signalling theory. The entire point is that that “honest” signals have to be hard to fake! Any individual with miserable genetics can develop a missing limb. It’s not hard to fake at all.

    • Posted August 31, 2018 at 12:58 pm | Permalink

      Any handicap for signaling by necessity would need be a surmountable one. An insurmountable handicap would, uhh, send the wrong signal.

      Hard to determine whether Prum is disingenuous, blinded by zealotry, or just a complete airhead.

  15. Saul Sorrell-Till
    Posted August 30, 2018 at 3:17 pm | Permalink

    Interesting. THe anti-adaptationist standpoint always struck me as politically motivated. I remember my first exposure to it, back when I was devouring everything evolution-related in every library I could find, was in a small book by Mary Midgley. The sheer sulphurous hatred that burned off the page was enough to tell me that this was not an intellectual argument – it was emotional, at least on one side.

  16. dani
    Posted August 30, 2018 at 6:27 pm | Permalink

    I bought this book and as soon I started reading it, I regreted buying it.

    • Concobus
      Posted August 30, 2018 at 8:34 pm | Permalink

      I’m not sure if you finished it or not, but if not, you missed out on some real aggravation toward the end of the book. Particularly once he starts talking about humans and he eschews sociobiology while advancing his own sociobiological theories. Prum’s lack of self-awareness in the human sections is breathtaking.

      In particular, in the chapter regarding homosexuality. He starts to talk about how the “Good Uncle” hypothesis is likely nonsense and we need a less adaptationist approach to discussing the persistence of homosexuality. I thought I was going to be in for a good, informative read and someone finally saying that perhaps we don’t need to explain homosexuality from an evolutionary standpoint because selection against it is negligible. But nope. MATE CHOICE AGAIN. And he immediately starts saying that homosexuality evolved because homosexuality is positively genetically correlated with pro-social behaviour or some such nonsense.

      At points, he admits that he hasn’t actually done the mathematical models yet so he doesn’t know if what he’s suggesting is even possible, but then the very next paragraph will say that “humans likely [this]” and “humans likely [that]”. I found it all terribly irresponsible. Lucky for Prum, his opinions are politically correct, so they attract praise rather than condemnation.

      Toward the end of the book, he tells the parable of the hedgehog and the fox and criticizes adaptationists as being hedgehogs for seeing natural selection as the solution to everything. But it’s clearly the opposite. Prum is the hedgehog. He sees mate choice in everything even in ridiculous places there’s no evidence it is related to like the evolution of homosexuality.

      As you can tell, I really didn’t like this book.

      • Posted August 30, 2018 at 8:40 pm | Permalink

        Yes, I read that last part (I read the whole book), and the stuff on homosexuality is really stupid. But, as you say, his opinions are politically correct so he doesn’t suffer. He’s virtue signaling throughout, and the readers like to feel virtuous, too.

      • Posted October 13, 2018 at 12:37 pm | Permalink

        I expect a strong selection against homosexuality, because it makes individuals seek sex partners with whom they cannot reproduce.


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