john hawks weblog

paleoanthropology, genetics and evolution

evolutionary psychology

  • A new approach to the Prisoner's Dilemma

    Sun, 2012-07-08 15:31 -- John Hawks

    Daniel Lende has described some evolutionary and anthropological import of a recent paper in PNAS on game theory: "Prisoner’s Dilemma and the Evolution of Inequality – Does Unfairness Triumph After All?".

    The paper, by William Press and Freeman Dyson [1], proves that a range of strategies exist for the classic "iterated Prisoner's Dilemma" game that actually allow one player to dominate and determine the payoffs for the other player over the long term. A long history of theory had argued that symmetrical outcomes were stable because one player could always punish another who was trying to impose an unfair outcome. The difference in the current result comes from the mathematical recognition that one player could completely determine the payoffs for the other, over the long term.

    What is surprising is not that Y can, with X’s connivance, achieve scores in this range, but that X can force any particular score by a fixed strategy p, independent of Y’s strategy q. In other words, there is no need for X to react to Y, except on a timescale of her own choosing. A consequence is that X can simulate or “spoof” any desired fitness landscape for Y that she wants, thereby guiding his evolutionary path. For example, X might condition Y’s score on some arbitrary property of his last 1,000 moves, and thus present him with a simulated fitness landscape that rewards that arbitrary property. (We discuss the issue of timescales further, below.)

    The paper deserves a longer commentary, and Lende has provided an interesting one. After considering some ways in which iterated Prisoner's Dilemma has been applied in evolutionary biology, such as life history theory, he suggests:

    In other words, zero-dimensional strategies are a way to think about facultative adjustments that organisms can make in reproductive and life history strategies.

    As just a thought to throw out there, might zero-dimensional approaches shed new light on the epidemiological transition? Has it made sense, where fitness pay-offs are high for offspring through investment and development, to invest more as a parent and thus set the highest set of pay-offs for a child?

    Much more at the link, which provocatively connects the short-term versus long-term strategy discussion in the paper to the emergence of wealth inequality in complex societies.

    Edge has a question-and-answer post with study author William H. Press: "On 'Iterated Prisoner's Dilemma contains strategies that dominate any evolutionary opponent'". The entire interview is very interesting, here's an excerpt that highlights the connection between the reward-payoff game of Prisoner's Dilemma and actual flesh-and-blood evolution:

    Yes, Virginia, you can fool evolution. People do it all the time, nowadays, with directed evolution experiments that fool microbes into doing unnatural things. The trick is to keep adjusting the environment so that the “more fit” organism is the one that bends most to our (unnatural) goal. So, it’s not a surprise that these tricks exist in principle. What is a surprise is that they are so easily exemplified, mathematically, in a game as simple as Iterated Prisoner’s Dilemma – and that this was mathematically obscure enough to escape notice. Do these tricks exist in all mathematical games? Do they exist in reallife competitive scenarios? When both players have a theory of mind (that is, are not just evolving to maximize their own score), are all games, in some deep way, actually Ultimatum Games? These now seem to be interesting questions.

    Personally, I think the Prisoner's Dilemma has been overemphasized in the discussion of the evolution of human cooperation, as many kinds of social interactions in ancient hunter-gatherers would not have fit that dynamic. Nevertheless, we should revisit the literature and revise the assumption that cooperation emerged according to the Prisoner's Dilemma dynamic. In this regard, the most interesting aspect of Press and Dyson's work may be the clear demonstration that short-term and long-term strategies bear a different relation than traditionally thought. Cognitive resources for individual discrimination, tracking of reputation, and memory of previous interactions have evolved over millions of years in primates, and their elaboration in humans may have happened in a very different context than imagined before last month.

    References

    1. Press WH, Dyson FJ. Iterated Prisoner's Dilemma contains strategies that dominate any evolutionary opponent. Proceedings of the National Academy of Sciences of the United States of America. 2012;109(26):10409-13.
    Tags: 
    game theory
    evolutionary psychology
    theory of mind
    minds

  • Leadership prediction and investment risk

    Sat, 2011-10-29 21:06 -- John Hawks

    The Guardian has printed an excerpt of economics Nobelist Daniel Kahneman's new book, Thinking, Fast and Slow. The story addresses the question of why investment bankers believe they are doing anything useful when statistics show they average worse than the market. Kahneman draws upon his own experience as a psychologist in the Israeli Army, predicting leadership:

    We were willing to make that admission because, despite our definite impressions about individual candidates, we knew with certainty that our forecasts were largely useless. The evidence was overwhelming. Every few months we had a feedback session in which we learned how the cadets were doing at the officer training school and could compare our assessments against the opinions of commanders who had been monitoring them for some time. The story was always the same: our ability to predict performance at the school was negligible. Our forecasts were not much better than blind guesses.

    I think the army story is much more interesting than what he describes about his later interactions with investment houses. Using methods developed by the British army, Kahneman's outfit attempted to evaluate leadership potential in candidate officers based on their interactions on a physical task that required teamwork. They believed their assessments to be reliable and based on real data, and yet they did very poorly compared to the officers who ultimately trained the men.

    Predicting leadership seems much more relevant to our evolutionary history than predicting investment returns. In many ways, leadership is a much less predictable game than investment. Kahneman describes the interactions among men who may not have previously worked together. But in the absence of reputation and repeated interactions, some effective strategies for attaining and defending status as a leader simply won't work. More aggressive leadership strategies may work in the short term, while judgment and fairness become important among people who know each other well.

    The usual argument for why we don't predict marginal probabilities well is that we haven't encountered them in nature. But here's a task it seems we ought to be pretty good at. And maybe we aren't. Worth further exploration.

    Tags: 
    evolutionary psychology
    economics
    risk

  • Adapting evolutionary psychology

    Fri, 2011-07-22 14:22 -- John Hawks

    I've been reading the new paper, "Darwin in Mind: New Opportunities for Evolutionary Psychology", in PLoS Biology. The paper, by Johan Bolhuis and colleagues [1], is an extended attack on the methods of analysis that have been most forcefully advanced by John Tooby and Leda Cosmides (mentioned by name) and David Buss (mentioned only by his institution, UT-Austin).

    Bolhuis and colleagues focus on four assumptions that underlie some of the hypotheses promoted by researchers like Buss, Tooby and Cosmides:

    1. Humans were once well adapted to their environment (the "environment of evolutionary adaptedness"), but recent changes to human existence have created a mismatch of some human traits with the current environment.

    2. Human cognitive traits evolve slowly and gradually, so that they cannot be well adapted to recent environmental changes.

    3. Human cognition occurs as an outcome of many specialized "modules" in the brain, not a few coordinated and flexible learning mechanisms.

    4. Humans have the same cognitive processes whoever they are and wherever they live -- in other words, mental adaptations are universal in humans.

    Knowing all of these researchers, I don't think they would agree with all of this characterization. Some aspects are uncontroversial: Many humans display behaviors that appear poorly suited to current environments but may plausibly have been an advantage in past environments. Others are more reasonable than Bolhuis and colleagues present -- for example I know that evolutionary psychologists usually express the "gradualism" assumption in a limited way, assuming that some cognitive adaptations are complex and therefore not likely to have arisen quickly as a result of a simple change in gene frequencies. Likewise, they do not assume that all human psychological traits are universal, but instead that those traits that appear universal are likely to have arisen in ancient environments shared by the ancestors of all humans. In short, I think the paper fails to accurately present the arguments put forward by mainstream evolutionary psychologists.

    I've written on evolutionary psychology at some length, often in a very critical way (for a good example, check out this post about David Buller's critical work and evolutionary psychologists' lame response). But the idea of niche construction irritates me a lot more than evolutionary psychology ever does.

    So I'll take a critical view of the four suggestions put forward by Bolhuis and colleagues as ways to move evolutionary psychology forward:

    i) A modern EP would evaluate the evolution of a character by constructing and testing population genetic models, estimating and measuring responses to selection, exploring the covariation of phenotypic traits or genetic variation with putative selective agents, making comparisons across species and seeking correlates to selected traits in the selective environment, and so forth, as do contemporary evolutionary biologists. In addition to these established tools, researchers can also exploit modern comparative statistical methods applied to cultural and behavioural variation [85] and gene-culture coevolutionary theory [22],[58],[83],[86] to reconstruct human evolutionary histories. The function of reliable aspects of human cognition, and of consistent behavioural patterns, can be explored utilizing the same methods. An important point here is that researchers are not restricted to considerations of the current function of evolved traits, and well-established methods are available to reconstruct the evolutionary history of human cognition.

    Uh...this is a fancy-sounding paragraph with no concrete suggestion. The response to selection, for example, is determined from heritability and differential reproduction in a particular environment. The paragraph specifically mentions that current functions of traits may be irrelevant to their past evolution. Hence, as evolutionary psychologists have argued, today's observed differential reproduction and heritability are of limited relevance to the evolution of a trait. Aside from mentioning technical-sounding jargon, this paragraph is simply suggesting that evolutionary psychologists should do scenario-building based on the assumption of past environments of adaptedness. The only novel suggestion (the "gene-culture coevolutionary theory" idea) is that different populations may have different evolved cognitive adaptations. I don't think many evolutionary psychologists would disagree.

    ii) With regard to functional questions, while EP has stressed the idea that human beings are adapted to past worlds [87], a niche-construction perspective argues that human beings are predicted to build environments to suit their adaptations, and to construct solutions to self-imposed challenges, aided and abetted by the extraordinary level of adaptive plasticity afforded by our capacities for learning and culture [88]. While adaptiveness is far from guaranteed, from this theoretical perspective humans are expected to experience far less adaptive lag than anticipated by EP [88]. If correct, examining the relationship between evolved psychological mechanisms and reproductive success in modern environments will not necessarily be an unproductive task.

    This is an easy empirical question, it seems to me. The "niche-construction perspective" appears to predict that post-agricultural sedentary humans (living in cities and villages, building and living in structures, working long hours, using a monetary economy, and having vastly higher birthrates) have found ways to replicate a hunter-gatherer lifestyle so that their cognitive adaptations will remain well-adjusted to their current environments. Bolhuis and colleagues point out the rapid rate of Holocene population growth as evidence that we may be comparatively well adapted to these changes.

    I disagree. Population growth is merely evidence that our cognitive adaptations have not impeded reproduction. Selection involves differential fertility or mortality, and may be just as strong in a growing population as in a stationary one. I think it is self-evident that some important aspects of the cognitive environment of post-agricultural people are unparalleled in hunter-gatherer societies. I think it is possible that selection has influenced the responses of some people to these environments, and I am very skeptical of the idea of "cognitive universals" in living people. But I don't think that culture promotes a static, hunter-gatherer-like cognitive niche, or that people have constructed their cultural environments to promote stasis.

    The third and fourth points raised by Bolhuis and colleagues are ones with which I basically agree. They note that evolutionary psychologists should do more to investigate the actual neural mechanisms underlying behavior, and that studying development may provide a way to test the evolutionary basis of such mechanisms. These suggestions are non-specific but quite true: To my knowledge, no evolutionary psychologists have ever shown a specific neural mechanism underlying their claims about cognitive "modules". Instead, they argue by analogy to better-understood cognitive and perceptual systems such as face recognition or visual processing. One of the main reasons why I and other people find evolutionary psychology explanations unconvincing -- one that goes back to Gould and Lewontin -- is that they fail to engage at the mechanistic level. If these are truly adaptations, then how are they instantiated.

    So, at the end, what do I think? To be honest, I really don't understand the point of an article like this. Bolhuis and colleagues make some good points, but they fail to produce even a single example of a cognitive or psychological trait in humans that can be fruitfully explained using their approach. Indeed, they do not even bother to present a method of hypothesis testing that could satisfy their criticisms.

    References

    1. Bolhuis JJ, Brown GR, Richardson RC, Laland KN. Darwin in Mind: New Opportunities for Evolutionary Psychology. PLoS Biol [Internet]. 2011;9:e1001109+. Available from: http://dx.doi.org/10.1371/journal.pbio.1001109
    Tags: 
    mind
    evolutionary psychology
    brain
    niche construction
    Synopsis: 
    Bolhuis and colleagues (2011) suggest several "improvements" for evolutionary psychology. I demur.

  • Mental mismatches

    Thu, 2010-09-23 08:30 -- John Hawks

    A Primate of Modern Aspect ("The sexuality wars, featuring apes") writes about some of the reactions to the new book, Sex at Dawn: The Prehistoric Origins of Modern Sexuality. As the subtitle suggests, the book is an account of human sexuality from the viewpoint of evolutionary psychology, written by Christopher Ryan and Cacilda Jethá. Ryan blogs at Sex at Dawn, I'm a frequent reader.

    Anyway, I loved this point about comparative studies:

    [F]or some reason, the only time primate sexuality gets any attention is when we turn it into a debate about how humans should be having sex.

    We never say, “Hey, those muriquis are too promiscuous. Don’t they know that all of their close evolutionary cousins are polygynous? If they just did what came naturally to them, they’d have a lot less psychological stress.” Or, “Those gibbons are so sexually repressed. If they just gave in to their natural predilection for promiscuity, I bet those nasty gibbons would have fewer territorial disputes and gibbon society would be much more peaceful.”

    Why worry about the "echoes" of psychic distress that may linger after the mating system changes? That's a very interesting point; there are unexplored assumptions here about the nature of adaptation and the structure of genetic causation of mental states. Clearly if major aspects of human social life change, we cannot expect people's minds to be perfectly optimized to the new regime. But what is the force of selection? What are the mental "rough spots" that differential fertility will ultimately iron out? How much "mismatch" between mental and social adaptations can persist?

    Primates may not be the best non-human model for such questions. Some domesticates have undergone social changes as great as humans, with strong selection against individuals who buck their human masters. But for many wild primates we may reasonably wonder, to what extent are social dynamics constrained by mental adaptations, and how quickly can mental lives shift under selection to fit a new social system?

    Tags: 
    sexual selection
    behavior
    domestication
    mating
    primates
    brain
    evolutionary psychology
    mind

  • Nowhere the rational man

    Mon, 2010-08-23 08:30 -- John Hawks

    David Sloan Wilson has been posting a series on behavioral economics ("Economics and evolution as different paradigms"). This, broadly speaking, is based on the idea that humans are not rational actors, and the ways that we act irrationally actually matter to the subjects of traditional economics, like markets and

    In Wilson's description, focusing on some recent books, it's a field that badly needs an infusion of evolution:

    As a symptom of the problem, consider the number of times that the word "evolution" is used in the three aforementioned books. It's easy for me to check because I have them on my Kindle. The answer is zero, zero, and two respectively, with the two uses in Animal Spirits tangential. Somehow, these authors think they can identify the real Homo sapiens without consulting the genetic evolution of our species or cultural evolution as an ongoing process. With a handful of exceptions, this is representative of the field as a whole.

    How is this possible? The subtitle of Animal Spirits provides the answer: Behavioral economists consult psychology, not evolution, in their quest to find the real Homo sapiens, and their psychological inquiry does not lead them to consult evolution in any meaningful sense. This is because most psychologists don't consult evolution in any meaningful sense.

    I have seen a number of preprints from people trying to integrate evolutionary perspectives into behavioral economics. A problem is that they are very simplistic on the evolutionary side, in some of the same ways that evolutionary psychology can be. Humans are not rational actors, but neither are they identical to each other. If the model does not entail explanations for variability, then it's not going to explain many interesting phenomena.

    Tags: 
    economics
    metascience
    evolutionary psychology
    psychology

  • Better than a finger in the eye

    Fri, 2010-07-16 15:31 -- John Hawks

    Michael Balter writes in Science about a meeting called "Culture Evolves": "Probing Culture's Secrets, From Capuchins to Children."

    There appears to have been a deliberate ambiguity in the conference title -- is it the evolution of culture, or the evolution of the cognitive abilities underlying culture? Apparently both. Ignoring the distinction usually leads to confusion. Culture does not evolve in the same way as genes do.

    In one group of capuchins, the team's long-term observations have allowed them to witness a rare event: the emergence of a new tradition. In what Perry calls a "bizarre" and "high-risk" ritual, the monkeys poke each other's eyeballs. One monkey will insert his or her long, sharp, dirty fingernail deep into the eye socket of another animal, between the eyelid and the eyeball, up to the first knuckle. In videos Perry played for the meeting, the monkeys on the receiving end of the fingernail, typically social allies, could be seen to grimace and bat their eyelids furiously (as did many members of the audience) but did not attempt to remove the finger or otherwise object to the treatment. Indeed, during these eye-poking sessions, which last up to an hour, monkeys insisted on the finger being reinserted if it popped out of the eye socket.

    Why would the monkeys do something potentially dangerous? Perry suggests that capuchins, which, like humans, are highly cooperative and live in large groups, use this apparently pain-inflicting behavior to test the strength of their social bonds.

    If this were happening in a zoo, wouldn't we call it a behavioral pathology?

    Of course, if it were happening in a fraternity...oh well, never mind.

    A new tradition that appears within one group does not need an adaptive explanation.

    Tags: 
    non-human primates
    behavior
    culture
    evolutionary psychology

  • Depression not adaptation

    Fri, 2010-05-28 12:30 -- John Hawks

    Every so often I see the argument that psychological depression is common because it evolved for a purpose. Usually the idea is that depressive symptoms bring social benefits to the sufferer, as "honest signals" of mental hardship. Less commonly, I see other hypotheses, such as the idea that depression gives people a "breather" to work out their problems. I don't think any of these are convincing, because they don't demonstrate the fitness advantages of the behavior.

    Jerry Coyne has written an essay that puts the problems into better words than I could:

    The evolutionary calculus for depression—as for any psychological “adaptation”—demands an answer to this question: how does that condition affect your expected number of offspring? It is odd that evolutionary psychiatrists neither answer this question nor, with rare exceptions, consider it, especially because data on reproductive output are not hard to gather.

    Clinically defined depression has substantial additive variation in human populations, so evolution is not irrelevant to explaining it. But it doesn't appear to increase fitness, or at least nobody has demonstrated that it does.

    Coyne additionally discusses why an adaptive hypothesis needs to explain the persistence of additive variation. Directional selection is expected to reduce or eliminate additive variation, so additive variation implies non-directional selection, epistasis or other exceptional conditions. I would add one element to his discussion: Many human phenotypes have additive variation today that they may have lacked in the past, because adaptive evolution during the Holocene hasn't come to any kind of equilibrium. There hasn't been time for many genetic changes to be fixed. This explanation for the presence of additive variation doesn't imply that depression is adaptive; only that in the long run we can't expect it to have the same incidence as today.

    Tags: 
    evolutionary psychology
    health

  • Flu blues

    Wed, 2009-10-21 00:45 -- John Hawks

    Will the swine flu lead to the next big evolutionary change for humans? No. But it has already begun to affect the way people interact with each other. I wandered onto campus a couple of weeks ago and saw people wearing face masks! We've been asked to plan for our "essential" classes in the event of a pandemic.

    It's a good time to be on leave. But my kids' school has been closed the rest of the week. It's the flu -- more than a third of the whole school was out sick yesterday.

    In the August Smithsonian magazine, writer Rob Dunn discussed a hypothesis that tries to relate cultural diversity and xenophobia (fear of the other) to the rate of infectious disease ("The culture of being rude"):

    In a series of high-profile papers, Corey Fincher and Randy Thornhill, both at the University of New Mexico, and Mark Schaller and Damian Murray of the University of British Columbia argue that one factor, disease, ultimately determines much of who we are and how we behave.

    Their theory is simple. Where diseases are common, individuals are mean to strangers. Strangers may carry new diseases and so one would do best to avoid them. When people avoid strangers—those outside the tribe—communication among tribes breaks down. That breakdown allows peoples, through time, to become more different.

    Differences accumulate until in places with more diseases, for example Nigeria or Brazil, there are more cultures and languages. Sweden, for example, has few diseases and only 15 languages; Ghana, which is a similar size, has many diseases and 89 languages. Cultural diversity is, in this view, a consequence of disease.

    On the surface, this seems a poor example -- the population has been thin in Sweden relative to Ghana for most of the last 6000 years, until the rise of the Swedish state. It's no surprise that a recent population expansion coupled with political centralization would result in a relatively uniform language and culture area.

    But as the article goes on to explain, some of the theorists think that the rise of states is itself a dependent variable. They would propose that the growth of polities was limited in Ghana because of a high disease load, retaining and fostering a cultural diversity that would have been wiped out by natural political consolidation in a less-disease-prone region of the world.

    That's the logic, at least.

    This kind of topic is interesting but endlessly frustrating. The frustration -- at least for me -- comes from the ready confusion of biological and cultural processes of change. Dunn's article says as much:

    As a rule, it is good to be skeptical of biologists who, like Fincher and Thornhill, propose to explain a whole bunch of things with one simple theory. More so when those biologists are dabbling in questions long reserved for cultural anthropologists, who devote their careers to documenting and understanding differences among cultures and their great richness of particulars. Biologists, and I am no exception, seem to have a willingness–or even need—to see generalities in particulars. Fincher’s new theory would offer an example of these desires (and a little hubris) run amok, of biologists seeing the entire history of human culture through one narrow lens. It would offer such an example, if it didn’t also seem, quite possibly, right.

    As a rule, I'm skeptical of everything. "Wary of strangers" wouldn't keep our school open -- those kids are all catching the flu from their friends. It doesn't take very many contacts between groups of people to spread an epidemic far and wide.

    In that respect, it's a problem for percolation theory. You've got a network of people through which the flu can be transmitted. If the people tend to be highly interconnected, with each other, the flu spreads widely. But even if links between groups are rare, the strong interconnections within a group can keep the epidemic alive long enough to make it to the next hop. At some critical level, the links are no longer enough, and the pathogen can't propagate.

    So does it do you personally much good to be wary of strangers, if you have a few cosmopolitan friends? Everything can make a little difference to the percolation network, but it seems to me that people carrying the "xenophobia" gene would still maintain large social networks including a few people who interacted far and wide with strangers. It's not that the direction of the effect is wrong; it's that a wholesale elimination of stranger contact by an individual may have little effect on her probability of infection, since friends may have gotten the pathogen from strangers.

    It's awful hard for a "xenophobia" gene to get going in that scenario.

    Tags: 
    behavior
    disease
    evolutionary psychology
    health

  • Religion and evolution book showdown

    Wed, 2009-08-12 00:13 -- John Hawks

    William Saletan reviews Robert Wright's book, The Evolution of God, with some discussion of Nicholas Wade's upcoming book, The Faith Instinct: How Religion Evolved and Why It Endures, in the unfortunately-titled article, "Evolution's place in a created universe."

    So who's right in this debate? Is religion a product of natural selection, cultural evolution, or God's truth?

    Here's one possibility: all of the above.

    I agree with Wade that cultural evolution is an exaggerated metaphor. Wright asserts that "just as genes are transmitted from body to body, down the generations, memes are transmitted from mind to mind." But that's a stretch. Memes don't pass from generation to generation the way genes do. One requires only procreation; the other requires parenting and education. For this reason, our cultural inheritance is vulnerable in a way that our biological inheritance isn't.

    An interesting thought. What I'd like to see in any of these "evolution of religion" books, is a testable hypothesis. So far, there's a lot of speculation and storytelling, and extraordinarily little critical thinking, connection with what we know of religion in small-scale prehistoric societies. The review intimates Wright's story, in the end, is that religion is a side-effect of the evolution of other stuff -- an "incidental by-product".

    I've got nothing against that idea, but I'd like to see some development of testable predictions. OK, so religion in humans is a "by-product". By-products (like spandrels) don't vary freely, they have patterns that can be explained in terms of architectural or developmental constraints, in terms of the cognitive features of which they are side effects. The dimension of variation that does exist should vary, in this case among human societies, in ways that reflect demographic and information constraints. Draw out predictions about these things and test them. Let's have some numbers.

    Until then, these books are pretty much the equivalent of "dog IQ" books. There's sure a market for them.

    Tags: 
    behavior
    religion
    symbolic behavior
    evolutionary psychology

  • "Our brains are fluid and plastic"

    Fri, 2009-06-26 21:22 -- John Hawks

    For some reason, it's "bash evolutionary psychology" week. First, Sharon Begley writes a 7-page essay in Newsweek, "Don't Blame the Caveman.", and now David Brooks gamely takes on the subject in the New York Times: "Human Nature Today".

    Brooks' target is Geoffrey Miller's new book, Spent: Sex, Evolution, and Consumer Behavior. I haven't seen Miller's book yet, maybe they'll send me one. I have a feeling there's more to it than Brooks' two-paragraph synopsis.

    We are all narcissists, Miller asserts. We spend much of our lives trying to broadcast our excellence in these traits in order to attract mates. Even if we’re not naturally smart or outgoing, we buy products and brands that give the impression we are.

    It seems to me that an evolutionary analysis of consumer behavior is a tall order. You have to account for the fact that nature didn't set up the mall; a lot of clever advertising people did. Just as David Kessler pointed out for restaurants, stores are busy trying to exploit innate biases toward products and to manipulate learned responses to them. Some of it is a novel environment, other parts are fairly old applications of information foraging. The combinations of old and new, cultural variations, and varying levels of group participation may make cooking a better analogy than foraging.

    Putting the intrinsic challenge aside, I think David Brooks shoots wide of the mark. He lists a catalog of alleged excesses in Miller's book, and tries to pivot into the point that evolutionary psychology in general is overreaching in its interpretations of human behavior. These "criticisms" of evolutionary psychology are hardly new. Some of them may have some force yet, but in Brooks' hands they hardly slap harder than Ann Landers' famous "wet noodle":

    But individuals aren’t formed before they enter society. Individuals are created by social interaction. Our identities are formed by the particular rhythms of maternal attunement, by the shared webs of ideas, symbols and actions that vibrate through us second by second. Shopping isn’t merely a way to broadcast permanent, inborn traits. For some people, it’s also an activity of trying things on in the never-ending process of creating and discovering who they are.

    So what? Many kinds of sexual and status displays in nature are highly learned -- bowerbirds construct displays from physical objects, many songbirds learn songs based on features of the songs they hear. They're all trying to create and discover (which is highfalutin' way to say, learn) what to do. That doesn't mean that the behaviors don't evolve under selection -- it just means that an evolutionary account of the behaviors must explain the learning mechanism.

    In humans, there's no question that status displays are part of mating and social competition. The outcomes of mating and social competition influence fitness. What remains unknown is the extent to which learning may be influenced by innate biases. How do we choose who to copy? Why do we respond to some signals (nowadays, products) and not others? Is familiarity enough -- old-fashioned, blank-slate type learning? How much do developing minds depend on cues other than repetition?

    Nobody really knows the answers to these questions, at least not well enough to persuasively test hypotheses about the evolution of human minds. But Brooks implies that such questions aren't worth asking. He thinks that it's enough to claim that humans aren't "hard-wired" -- as if that (false) dichotomy actually conveys any information. In doing so, Brooks confuses the currency of evolution (that would be, fitness) with the currency of individual fulfillment. They're not the same, and in many cases they work against each other.

    Tags: 
    behavior genetics
    minds
    behavior
    evolutionary psychology

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