Sex, evolution, plasticity and bluebirds

Let me clarify some things.

Stephen Pinker and all his followers seem to be arguing that evolution has created some differences between male and female brains. I agree ““ there almost certainly are some evolved differences. What those differences are, and if they have any real-world significance, is what’s under debate. No one, so far as I know, is arguing that evolution didn’t occur.

However, what evolution means is another question altogether. Many Pinker-ites (and keep in mind, not all evolutionary biologists are Pinker-ites) tend to speak about evolution as if it leads to set-in-stone characteristics: “men evolved this way, so men will always use this reproductive strategy.”? But this is a simplistic and mistaken view of how evolution works: as if animals were simple machines, like toy trains, able to only move dumbly along one train track.

In fact, humans (like many other animals) have also evolved plasticity ““ the ability to alter our behavior in beneficial ways in response to new or changed environments. For example, look at bluebirds. In the wild, suitable spots for bluebird nesting are rare: the mating strategy used by bluebird males is to take a nesting spot and aggressively defend it from other males; the successful males will let a female use the nest in exchange for sex.

Most Pinkerites would look at bluebirds and say: “There, you see? Bluebird males have aggressive competitions, and the females will mate with the male who’s able to win these competitions. If you don’t believe that, then you’re an blank slater who doesn’t believe in evolution.”

But if you put bluebirds in a different environment ““ say, one with plenty of nesting sites, more than the bluebirds would ever need ““ what happens? Bluebird females nest wherever they please. Bluebird males react by trying to help females with their current batch of children ““ in the hope that he’ll be allowed to father her next batch. Same genes, same evolution, but very different mating behaviors.

And if bluebirds can exhibit that kind of plasticity in response to changes in environment, how much plasticity can humans ““ the all-time champions of plasticity in the animal kingdom ““ exhibit? We’re wired to adapt our behavior to our environment. Yet that basic fact of evolution is something that evolutionary psychology’s advocates routinely ignore.

No one’s saying that evolution or genes are entirely unrelated to behavior; plasticity itself is an evolved trait, after all. But although evolution and behavior are undeniably related, they are not related in the simplistic, predictive fashion that Stephen Pinker and his fans seem to believe.

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21 Responses to Sex, evolution, plasticity and bluebirds

  1. 1
    Julian Elson says:

    Of course *some* people are denying evolution. Check Pharyngula out a bit :^).

  2. 2
    Julian Elson says:

    I think that may have come off as a bit condescending, come to think of it. I didn’t mean to imply that Amp was ignorant of real creationism. I was just doing a little “gotcha” in response to “No one, so far as I know, is arguing that evolution didn’t occur.” Which, I think, is largely true as far as this debate.

  3. 3
    jri says:

    I don’t know if you can make the broad brush claim that evolutionary psychologists are routinely claiming that human behavior and potential is any particular thing (placing men above women in some cognitive skills). Particularly when evolutionary psychology must take into account the effect of differing environments (your excellent bluebird example presenting one such conundrum).

    It is usually not the psychologists who are doing the backwards rationalizations of their prejudices and bigotry, and any scientific claim can be warped to justify whatever machination bad actors have in mind.

  4. 4
    jam says:

    nicely said, Mr. Ampersand.

  5. 5
    Jeff says:

    jri: As someone who hasn’t encountered it much out of pop-science interpretations, I’m curious: what parts of evolutionary psychology aren’t “just so stories” to account for (and sometimes to justify) observed behavior?

  6. 6
    Mike Feldgarden says:

    I think one of the problems that evolutionary psychology runs into is irreversibility. It’s very hard to disentangle genetically-based phenotypes from ‘acquired’ ones. For example, if one is starved as a child, the odds of being tall as an adult are very small. This is ‘irreversible’ but not genetic (I’m not arguing that height doesn’t have a genetic basis, this is simply to illustrate a point). Since we can’t do controlled experiments on humans (this is a good thing), disentangling heredity from early development is very hard.

    A second problem is that a trait can be heritable, but very weakly so. There have been some legitimate studies on twins (as well as some falsified one) that indicate a genetic basis for certain psychological characteristics; however, the total amount of variation explained by genetics is typically very small.

  7. 7
    Andras says:

    Well, regarding the argument “[b]ut this is a simplistic and mistaken view of how evolution works: as if animals were simple machines, like toy trains, able to only move dumbly along one train track” I would recommend Valentino Braitenberg’s seminal book “Vehicles: Experiments in Synthetic Psychology”. Obviously, some animals _are_ simple machines; others are much more sophisticated (like Homo sapiens sapiens) – machines never-the-less.

    Positing a radically different environment for a bluebird is a nice thought experiment, but the actual environment of bluebirds is the one we observe them in. The assumption of a radically different environment leading to different behaviour is a fair one – the question(s) then remains: how radically the environment has to differ to lead to the different behaviour and is there an Evolutionarily Stable Strategy which works toward the maintenance of the radically different environment – or are things to drift back toward the “Bad Old Times”. In other words: is there a “bluebird condition” (similarly to the “human condition”).

  8. 8
    PZ Myers says:

    To use a little jargon for what you’re describing here, it’s called norms of reaction: the output of a genetic program is not simply described, but is a complex result of interactions with multiple factors in the environment. It means that adaptive utility can be an extremely difficult thing to assign, and one of the frustrating things about EP is that they treat adaptive utility as something trivially surmised.

  9. 9
    LC says:

    Well, I have a question brought up by Andras’s comment. Your bluebird example, I presume it actually exists? That it isn’t a hypothetical?

    I think that PZ Meyers makes a strong point about one of the problems you often see with EP (especially summaries of EP), that they treat adaptive utility as somewhat trivial.

  10. 10
    mooglar says:

    Is Pinker really an evolutionary determinist to this degree? I’ve only read one of his books, “The Blank Slate,” and it seemed to me that he was refuting the blank slate but not advocating genetic determinism either. It seemed that he acknowledged plasticity in his argument.

    It seemed to me that, in regards to the bluebirds, according to what he says in “The Blank Slate,” that Pinker’s position would be that male bluebirds have, through evolution, developed a propensity for aggressive competition, and will therefore choose aggressive competition over other mating strategies, all things being equal. But, when circumstances warrant, they will adopt other mating strategies.

    Did I misread “The Blank Slate?” Or, perhaps, does Pinker demonstrate greater support for evolutionary/genetic determinism in his other writings and/or public speaking than in “The Blank Slate?”

    Just curious, as I didn’t know this about Pinker and hadn’t divined it from the one book I had read.

  11. 11
    Ampersand says:

    LC: Yes, it’s a true example.

    Mooglar: I haven’t read all of The Blank Slate – I read the section on the wage gap, which I thought was awful. I was basing what I’ve said on the impression I’ve gotten from reading a couple of Pinker’s newspaper articles and also from what I’ve seen many people who constantly cite his work say.

    Of course, that’s not a fair way to judge his work; it’s very possible I’ve been unfair to him.

  12. 12
    LizardBreath says:

    Pinker’s books are oddly like The Bell Curve in that regard (although infinitely more respectable).

    If anyone here read TBC carefully when it came out, rather than articles by people who were touting it as the greatest thing since sliced bread, it didn’t quite make all of the hateful arguments that people took away from it. There were caveats about the measured differences in average black and white IQs not being necessarily genetically caused, everything was hedged, it was very difficult to actually pull out objectionable quotes. But it was written to serve a hateful agenda, and was used as such — racists referred to it as scientific proof that their prejudices were justified, and then the reasonable sounding racists defended it by pointing to all the caveats, and saying that it was really harmless and neutral.

    Pinker, speaking loosely in public, in non-scholarly articles, and in the summary sections of his books, takes the rhetorical position of someone who believes that genetics are the most important factor in determining behavior; and silly people who believe that environment is unimportant and everything is in the genes seize on him as a real scientist who is an ally. The technical portion of his writing takes a much more nuanced and reasonable position, that genes and environment are both important but affect each other in such complex ways that it is impossible to separate out the effects of each.

    I figure Pinker sees the genetic reductionists as political allies, and deliberately lends them cover for that reason, but I could be wrong — it’s possible that his non-technical statements are just consistently misinterpreted.

  13. 13
    sock thief says:

    I have read much of Pinker’s work and never has had said anything that remotely resembles genetic determinism. And in his non-scholarly work I have not come across anything that suggests that either. This sort of allegation was also made against Richard Dawkins. All I can say is read their work.

    I think most people interested in evolutionary psychology take the view presented by Mat Ridley in his book “Nature via Nurture” that human behavior results from the interplay of genes and environment. Interestingly, one of the points people such as Pinker make is that the “environment” is not what it has been traditionally thought of, e.g. the womb is a significant environment but the influence is chemical (not social) and hence genetic.

    To say that Pinker’s believes nature and nurture are related in a “simplistic, predictive fashion” is far from the truth.

  14. 14
    Pete says:

    I have read Pinker’s books and recent writings very closely, and I think the latter of the two explanations from LizardBreath (“..his non-technical statements are just consistently misinterpreted.”) fits better.

    You say “not all evolutionary biologists are Pinker-ites”, but if “Pinker-ite” means a genetic determinist as caricatured above, then not even Pinker is a Pinker-ite.

    I don’t know which newspaper articles gave you which impressions, but I suggest (in addition to going back to The Blank Slate at some point, but skip the art section) reading his entire New Republic article in which, among other things, he says:

    “Of course, just because men and women are different does not mean that the differences are triggered by genes. People develop their talents and personalities in response to their social milieu, which can change rapidly. So some of today’s sex differences in cognition could be as culturally determined as sex differences in hair and clothing.”

    Now, of course, he does use this as a segue to argue against a straw man of his own making, namely ultra-blank-slate-ism, which we are told is “popular among some academics”. Is it really?

    Well, my main point here is that we should separate Pinker from the “Pinker-ites”–since there are some (like, possibly, Summers) who disingenuously use Pinker’s writings to support their politics. This bears some resemblance to the creationists who appropriate Stephen Jay Gould’s writings to support their ravings. But Pinker does risk being called sloppy or worse if he doesn’t rein in these co-opters.

  15. 15
    Dan S. says:

    Orangutans are another example, if I remember correctly. In most natural conditions they’re loners, but in captive situations and certain food-rich? locations, they’re far more social. I’m forgetting all the relevent details, but they’re somewhere on the internet.

  16. 16
    Robert says:

    It would be logical for any large-ish species with slow reproduction to become more gregarious and social when presented with a lush environment with lots of food. When there’s lots of food, animals like that really ought to bump up the old reproductive frequency; turn the dial to 11, as it were. Get while the getting is good.

    This is, of course, a just-so story, but I happen to like just-so stories. ;)

  17. 17
    clew says:

    So from the years the gifts were showered; each
    Took whatever it needed to survive;
    Trout finned as trout, peach molded into peach,
    Bees took the politics that make a hive…

    …And at the end there came a childish creature
    On whom the years could model any feature,
    Who aped with ease a leopard or a dove;
    Who by the lightest wind was rudely shaken,
    And sought the truth, continually mistaken,
    And envied his few friends, and chose his love.


  18. 18
    Tarn says:

    Sockthief said:
    “Interestingly, one of the points people such as Pinker make is that the “environment”? is not what it has been traditionally thought of, e.g. the womb is a significant environment but the influence is chemical (not social) and hence genetic.”

    But this brings us straight back to the environment\biology interaction- the character of the environment in the womb is certainly genetically influenced, but there’s a huge range of socially determined factors that are important too: for example alcohol consumption, thalidiomide use or hormone fluctuations according to nutrition. There’s no clean divide between genetic and social\environmental factors.

    My problem with the bits of Pinker’s work I’m familiar with is that he seems to blends a kind of politics with his actual research- by presenting one position particularly forcefully and often only engaging with a fairly caricatured version of his opponent’s he blurs the line between research and advocacy.

  19. 19
    LizardBreath says:

    Yes — I was simplistic and probably unfair to Pinker.

    I do think he bears a certain amount of responsibility for the fact that he is consistently misinterpreted, in that he doesn’t seem to disassociate himself from the vocal misinterpreters. That is, his chosen opponents, the radical blank slaters, are somewhere between very hard to find and nonexistent, but he argues against them as if they were an influential and intellectually important group. The people Pinker is misinterpreted by, hard-line genetic determinists, are at least far commoner and mistakenly cite him as support, but he appears not to feel the need to correct the misimpression.

  20. 20
    sock thief says:

    LizardBreath, you have misinterpreted Pinker since you thought he was advocating genetic determinism. Is Pinker responsible for this? Time after time people such as Pinker and Dawkins stress that they do believe in a simplistic genetic determinism. It is hardly their fault that some will go on believing this despite the evidence to the contrary.

  21. 21
    Alex Fradera says:

    Hmmm. I have read all of Pinkers books, twice, once straight through for the sheer fun and more critically chapter by chapter (OK, 1 1/2 times then). The Blank Slate is in parts a very good book – particularly when it takes apart the misunderstandings that can fly when genes, determinism, free will and political implications of science are discussed. Then he pisses it all up the wall with his ‘hot buttons’ section, where he takes the credibility that ‘fair and balanced’ Pinker has built up in the first part to promote a conservative agenda. I am not making this up. The book is structured around the chapter ‘Politics’, which thematically if not temporally is the climax of the book, composed of bulletpointed arguments (drawn from every other section) as to why conservatism is more in line with our nature than liberalism. In other words, he moves from his criticism of ‘extreme-blank-slaters’ to dismiss liberal policy and vision under the pretext of scientific authority. It is a pretext, by the way, as most of his arguments really do fall on arguments that don’t live or die on any human-condition type research. The chapter on ‘Violence’, for example, which he uses to bolster his argument for harsh sentencing and policing, is mostly just a description of hobbesian theory and theoretical conflicts, but where it does spill into neuroscience, the veneer to justify its inclusion, it’s just wrong. I’ve written an esay that touches upon this that I might put online at some point – if I do perhaps I’ll let Amp know. Up to then, this old post gives a bit more of my thoughts, though the promised followups are still tantalisingly out of reach.