minds

Christopher Bird and Nathan Emery (2009) performed a number of tool use experiments on rooks -- birds related to crows (corvids) that do not use tools in the wild. Some other corvids, in particular New Caledonian crows, are expert tool users. People who work with New Caledonian crows compare their tool prowess with the great apes -- they can manufacture novel implements, put together two items into a compound tool, and use tools to make other tools. Each of these is a test that psychologists devised to differentiate human tool manufacture from animals. In each case, apes passed, and then the New Caledonian crows passed.

In the current paper, Bird and Emery find that rooks also can do these things, despite never having been observed to do any of them in the wild. They conclude that the birds likely do not have specialized cognitive adaptations for tool manufacture, but instead that they are solving novel problems using cognitive skills that are also useful for many other kinds of problems -- in short, domain general cognition:

Our results contradict suggestions that tool use was the driving force behind the evolution of advanced physical intelligence (2). It appears more likely that corvid tool use is a useful by-product of a domain-general “cognitive tool-kit” (31) rather than a domain-specific ability that evolved to solve tool related problems. Whether or not each species taps into this capacity for tool use may depend on their ecology (22, 32).

In hominoids, a shared basic ability for tool manufacture goes back at least to the Middle Miocene, based on its phylogenetic distribution. It is an open question whether early apes also were tool users. Some monkeys make and use tools in the wild, and if their abilities are homologous with ours, that would put the cognitive capacity for tool manufacture back into the Oligocene. Bird and Emery go through a similar train of logic for the corvids:

Rooks are highly innovative, social foragers (39), using their cognitive abilities in a number of nontool related ways (40). Our findings provide further support for recent claims of convergent evolution in the cognitive abilities of corvids and apes (31). New Caledonian crows and now rooks have been shown to rival, and in some cases outperform, chimpanzees in physical tasks, leading us to question our understanding of the evolution of intelligence.

The claim is that the cognitive resources useful for tool manufacture are probably also useful for other things, and therefore conserved in many if not all corvids. If they're useful for other things, there's no necessary reason for them to have evolved as adaptations for tool use or manufacture (although tool use in ancestral corvids remains possible). The same may be true of primates. For example, gorillas process some kinds of plant foods in complicated ways, using series of steps comparable in complexity to chimpanzee tool manufacture. But gorillas use tools very sporadically in the wild. Arguably, general-purpose cognitive abilities underlie both kinds of activities -- and social learning would facilitate both kinds of skills.

References:

Bird CD, Emery NJ. 2009. Insightful problem solving and creative tool modification by captive nontool-using rooks. Proc Nat Acad Sci USA 106:10370-10375. doi:10.1073/pnas.0901008106

A reader forwarded me a reference to this website, which is a placeholder for present and future critiques to David Buller's book, Adapting Minds : Evolutionary Psychology and the Persistent Quest for Human Nature:

What about David Buller's book, Adapting Minds?

Cultivating a persona of fairness and impartiality, David Buller has written a critique of theory and results from evolutionary psychology. To those unfamiliar with the primary literature, some of his claims may seem plausible. That has not, however, been the reaction of those who know this literature intimately.

Over the next few months, we will be developing on this website a collective response to Buller. It will be collective because we think each scientist should respond to the research that he or she knows best. We will try to provide links to primary sources, so that interested readers can see for themselves what the literature says.

It will take some time. In the meantime, we will post links to the very short replies to Buller to appear in Trends in Cognitive Sciences...

I want to say first that I am a relative outsider to these exchanges. I study human cognitive evolution, and teach it from a broad perspective. As such, I am fairly well aware of the literature in evolutionary psychology, although clearly not as extensively so as its primary participants.

So my biases are my own, and are idiosyncratic compared to many who may care more about the accuracy of particular predictions of evolutionary psychology. As for myself, I find many of the theoretical underpinnings of EP to be unobjectionable, although I think some are very wide of the mark. In my opinion, Buller does good work exposing these and arguing against them for sound evolutionary reasons.

As someone researching the evolution of the mind, I find a large proportion of the specific hypotheses of EP to be useless to me: they make no substantial testable predictions about human fossils, archaeology, or genetic variation. Moreover, although I think it is possible that such cognitive circuits as a "cheater detection module" may have evolved, I see no necessity on the grounds of evolutionary theory or primate comparative biology to suppose that they should have done so.

Buller attacks hypotheses like the "cheater detection module" idea for reasons that I consider to be well-founded. And he does what I consider to be a remarkable job in showing the actual empirical weakness of the data that are supposed to support such hypotheses. Yet, he does not present much positive evidence in support of his own alternative hypotheses. This, I feel, is a drawback of the book. While he does promote alternatives that, by his account, are better explanations of the data, for the most part these alternatives remain to be tested.

In their website, critics of the book present arguments that Buller has misrepresented the evidence for their evolutionary psychology hypotheses. They claim that he has failed to cite studies -- important studies -- that refute his specific views. If this criticism is true, it is indeed a serious flaw.

But a closer look at their website and Buller's book shows that this criticism just isn't true. Here is what the website says about the "cheater detection" issue (hyperlinks available in original):

Here is our response to Buller's attack on the evidence for cheater detection, based on the book and his article, which appeared in Trends in Cognitive Sciences. Because we were limited to 700 words, we could only address the fact that Buller has ignored 15 years worth of evidence showing that his favored alternative hypothesis is false. As time permits, we will expand this response to deal with the other problems with his argument (see Fiddick, Cosmides, & Tooby (2000) on why logic + background assumptions cannot explain our results) and the other ways in which he has misrepresented the empirical literature (e.g., it is not true indicatives need only be "natural" to elicit good violation detection). For a more complete review of the literature on cheater detection and social exchange reasoning--including a review of the evidence that refutes Buller's alternative, deontic, hypothesis-- see Cosmides & Tooby (2005), Neurocognitive adaptations designed for social exchange. Click here for a more complete (and annotated) set (annotated) of publications on this topic.

Perhaps they don't expect people to actually take them up on their "challenge" to read these papers. Perhaps they haven't read Buller's book themselves. The fact is that Buller does discuss Fiddick, Cosmides, and Tooby (2000) -- in fact he devotes well over a page of discussion to it, along with a prominent role in his later argument. If they don't agree with his assessment of that work, it's one thing, but they cannot say he doesn't treat it seriously.

What I find an insult to my intelligence is their apparent assumption that readers of their website cannot use Google to find the relevant literature that they exclude. For example, why don't they themselves refer to this 2002 comment by Sperber and Giotto that argues against the methods and conclusions of Fiddick, Cosmides, and Tooby (2000)? Abstract:

Sperber, Cara, and Girotto (Cognition 52 (1995) 3) argued that, in Wason's selection task, relevance-guided comprehension processes tend to determine participants' performance and pre-empt the use of other inferential capacities. Because of this, the value of the selection task as a tool for studying human inference has been grossly overestimated. Fiddick, Cosmides, and Tooby (Cognition 77 (2000) 1) argued against Sperber et al. that specialized inferential mechanisms, in particular the "social contract algorithm" hypothesized by Cosmides (Cognition 31 (1989) 187), pre-empt more general comprehension abilities, making the selection task a useful tool after all. We rebut this argument. We argue and illustrate with two new experiments, that Fiddick et al. mix the true Wason selection task with a trivially simple categorization task superficially similar to the Wason task, yielding methodologically flawed evidence. We conclude that the extensive use of various kinds of selection tasks in the psychology of reasoning has been quite counter-productive and should be discontinued.

Why is there no citation to that work in Cosmides and Tooby's (2005) "more complete review"? Why does the "more complete review" fail to discuss the weaknesses of their research with Fiddick? Why does it persist in the fallacy that "social exchange" and "social contracts" are the same thing? Why does it exclude the later argument of Fodor (2000), which ends thusly:

What seems clear, in any case, is that Cosmides and Tooby's original assumption that requirement-hypotheticals and regularity-hypotheticals have the same logical form was unsound. I'm grateful to Beaman for thus demonstrating empirically what I had urged on a priori grounds.

Now all of these arguments could be wrong. Perhaps they really pose no problem to Cosmides and Tooby's preferred interpretation.

But it seems to me that the failure to acknowledge them is not a good sign. Not a single critical article is listed on the "complete (and annotated) set (annotated) of publications". Clearly anyone going to that website is going to get a far more one-sided view of the issue than Buller's book has presented.

They have every right to present whatever they want, but it is especially galling that in a response to a book that does include their arguments, they claim "Buller has ignored 15 years worth of evidence", when they can't appear to be bothered to cite, much less discuss other papers critical of their views.

I'm no shill for Buller. I don't know him, have never met him, and my only extensive experience with his arguments is from reading his book. I have expressed some of my own reservations about his arguments in my reviews, which nevertheless have been broadly positive. As with the weblog in general, these are my mostly unvarnished reactions and notes; if I didn't have a positive opinion, I certainly wouldn't write one.

Whether he is right about every specific hypothesis he critiques remains to be seen, and hopefully tested. But with the exchange developing as it is, I wouldn't lay much money on him being wrong.

Chapter 5 of David Buller's Adapting Minds : Evolutionary Psychology and the Persistent Quest for Human Nature is mostly about the critique of studies that purport to demonstrate human mate preferences, covering males and females in turn. Buller's critique here is not that the theoretical basis for differences in male and female preferences is weak, or that there is no theoretical reason to suppose the mate preferences asserted by evolutionary psychology (males prefer young fertile females, females prefer high-status males). He does argue against both theoretical points later in the book, however, and here he reiterates his doubt that such preferences might be adaptations and part of a universal developmental program.

But the focus here is to refute the specific evidence that is supposed to demonstrate human mate preferences. Most of the chapter therefore takes the form of a batting practice, as Buller takes pitches from many different studies and clubs them down one by one. It's therefore not the most interesting piece of writing, but it does carry a sort of emotional satisfaction -- sort of like a long game of Whack-a-mole.

Now, if the evidence for the claim that females prefer high-status males is as weak as I've made out, why is the claim so widely accepted? I think the reason is that we are captivated by a particular picture of the relation between sex and status among our primate relatives, and this picture affects our perception of human mating. It is widely accepted that among non-human primates high-status males have greater mating success than males lower in the status hierarchy. This belief is due partly to the popularity of the engaging work of the primatologist Frans de Waal, who has been one of the main purveyors of this idea. Once we're convinced of the strength of the correlation between status and mating success among our primate relatives, the standards of evidence that are required to convince us of a correlation in humans get lowered considerably. As de Waal says: "In monkeys and apes there is a clear link between power and sex. High-ranking males enjoy sexual privileges, and are more attractive to the opposite sex. We need only look at recent events in the White House (and at a television spectacular like 'Who Wants to Marry a Multimillionaire') to see how much the link exists in us too." (Buller 2005:250, citing de Waal's 2000 New York Times book review of Thornhill and Palmer's Natural History of Rape)

Buller lists two problems with this viewpoint. First, of course anecdotal evidence is not enough to demonstrate mating preferences in humans generally. Beyond anecdote, there is precious little evidence that female humans actually do prefer high-status mates.

This may sound surprising to anyone cognizant of the literature on mating preferences in humans. As Buller describes, a major confounding factor is that people tend to mate assortitively with others of like backgrounds, interests, and prospects. These include financial prospects. They also include attractiveness, which is correlated with financial prospects in industrialized societies. This means that saying anything generally about female mate preferences must both make sure that the samples are representative (i.e. that they don't include one socioeconomic class to the exclusion of others) and that the confounding factors must be controlled (i.e. that an apparent preference for high status is not actually explained equally well by the preference for attractiveness).

As it turns out, the majority of work attempting to determine female mate preferences in humans has been done by surveying female undergraduate students at universities. Some of this work has been done by surveying women at their sororities! Now, of course female undergraduates including sorority members have mating preferences, and these preferences carry information about the mating preferences of females in society. But the sample of females who attend universities (especially private ones) and who belong to sororities (especially at private universities) is not characteristic of the population at large -- it is a sample biased toward women who expect to achieve high education status, who may have expectations of high income levels, and who disproportionately come from upper middle class backgrounds. That these women may prefer high-status men might be explained by a general preference for high-status men. Or it may be explained by a preference for men with similar interests, education, and prospects to their own.

Buller reviews studies that don't follow this bias and concludes that the evidence for a female mating preference for high-status men is weak or nonexistent. Indeed, reading this section is a bit like reading a slasher-movie as the hypothesis raises up again and again with each new study, and Buller strikes it down once more.

For me reading the book, the message is that data on human psychological preferences (at least for long-term life choices) really are not available in studies of human self-reported preferences or real-world behavior. There are just too many ways that preferences can vary (where studies generally ignore variation in preferences and focus on the averages only) and too many compromises that people must make in their behavior (when they can't get what they might prefer). This is the case in spades when Buller considers male mating preferences -- and the question of whether males prefer young women with waist-to-hip ratios of 0.70. He finds, again, that there is strikingly little evidence in favor of this preference, and that most of the evidence is flawed.

A sophisticated reader might point out that Buller hasn't really refuted the EP interpretations; he has merely provided alternatives that explain the observed data equally well. Buller is able to make these arguments effectively because of the large possible set of confounding factors, and because of the evolutionary psychology focus on averages instead of variation. When more information is available, Buller shows that it fails to support the EP interpretation. When more information is not available, Buller argues that the missing information is necessary to test the EP interpretation. In both cases, he is convincing that the evidence is weak or nonexistent. But Buller actually does note that some studies actively refute the EP expectations -- for example, the study of Kinsey's sexual behavior data that shows greater sexual activity by lower status males.

The other objection to the analogy from primates is that primate studies don't actually show a strong female preference for high-status males. Certainly some studies (on some species) do show this, but others show either no apparent female preference, a slight preference for low-status males, or multiple strategies where some females prefer low-status males at least some of the time. And many of the studies that show a correlation of high-status with male mating success are not demonstrating anything about female preference, but instead about male control of mating access. The idea that primate females generally prefer high-status males is a non-question: some species may show such preferences, others do not, and within species there may be substantial variation in mate preferences among females.

Buller leaves the chapter with one final point: selection might not be able to make a mate preference adaptation like the one proposed by EP anyway. Consider the way such a preference should work: people prefer as good a mate as possible, but since these are in high demand, they may have to settle for less than the prefer. Buller puts people on a scale from 1 to 10 -- the preference hypothesis supposes that everyone wants a 10, but they will tend to be able to mate with 10's themselves, which leaves 9's mating with 9's and 6's mating with 6's. But. says Buller, there's no reason to suppose that 6's have less offspring or lower long-term reproductive success than 10's. In genetic terms, if there is no reproductive benefit to a 6 in mating with a 10, then a 10 preference does not have a selective advantage over a 6-preference, at least as far as 6's are concerned. We might even think that 6's would be better off assessing their mating prospects early on and choosing 6's deliberately, instead of wasting a lot of time trying to attract a 10.

Noting that there may be a limit beyond which settling for a lower-quality mate may negatively impact reproduction, Buller notes:

The real question, then, is whether male status and female youth are characteristics that females and males respectively can "trade down" while still achieving comparable reproductive success. My skeptical argument presupposes that, within limits, they are. Evolutionary Psychology's view of human mate preferences presupposes, in contrast, that male status and female youth are characteristics that couldn't have been traded down by our ancestors without a corresponding decline in reproductive success (Buller 2005:256).

Buller points out that the most EP has to support this hypothesis is hypothetical arguments about the EEA. Indeed, the sort of thing one would have to know is the long-term success over many generations of different mate preferences, the heritability of such preferences within a hypothetical ancient population where they were polymorphic, and the differences between the modern environment where these features were observed and the hypothetical ancient environment where humans evolved. It's all exceedingly tenuous.

More on Adapting Minds

References:

Buller DJ. 2005. Adapting Minds : Evolutionary Psychology and the Persistent Quest for Human Nature. Bradford Books, New York. Amazon