Note: The primary target of the post is not professional, academic evolutionary psychology. Rather, I am primarily cautioning amateurs (such as LW regulars) about some of the caveats involved in (armchair) evpsych and noting the rigor required for good theories. While the post does also serve as a warning to be cautious about sloppy research (or sloppy science journalism) that doesn't seem to be taking these issues into account, I do believe that most of the researchers doing serious evpsych research are quite aware of these issues.

Evolutionary theories get mentioned a lot on this site, and I frequently feel that they are given far more weight than would be warranted. In particular, evolutionary theories about sex differences seem to get mentioned and appealed to as if they had an iron-cast certainty. People also don't hesitate to make up their own evolutionary psychological explanations. To counterbalance this, I present a list of evolutionary psychology-related problems, divided into four rough categories.

Problems in hypothesis generation

Rationalization bias. We know that human minds are very prone to first deciding on a desired outcome, then coming up with a plausible-sounding story of why it must be so. In general, our minds have difficulty noticing faulty reasoning if it leads to the right conclusion. It's easy and tempting to come up with an ad-hoc evolutionary explanation for any behavior, regardless of whether or not it actually has any biological roots.

Over-attributing meaning. Humans also have a strong tendency to attribute meaning to random chance. We might easily come up with explanations that are unnecessarily complex, and try to make everything into an evolved adaptation. For instance, humans tend to avoid thinking about unpleasant thoughts about themselves. A contrived evpsych explanation might be that this is evolved self-deception: by not acknowledging our own faults, it makes it easier for us to deceive others about them. But mental unpleasantness tends to be correlated with harmful experiences: we avoid situations where we'd be afraid, and fear is correlated with danger. It could just as well be that the mechanism for avoiding mental unpleasantness evolved from the mechanism for avoiding physical unpleasantness, and we avoid thinking unpleasant thoughts of ourselves for the same reason why we avoid poking our fingers at hot stoves. (Example courtesy of Anna Salamon.)

Alternative ways of reaching the goal. Eliezer previously gave us the example of the scientists who thought insects would under the right circumstances limit their breeding, but the insects ended up eating their competitors' offspring instead. We can only cover a limited part of the space of all possible routes evolution could take. While ”but another hypothesis might explain it better” is admittedly a problem all scientific disciplines face, it is especially acute here, since we have very little knowledge of what life in the EEA was actually like.

Problems in background assumptions

Did a genetic path to the adaptation exist? Evolution works by the rule of immediate advantage: for mutation X to reach fixation, it has to provide an immediate advantage. It's well and good to propose that under specific circumstances, organisms that developed a specific behavior would have gained a fitness advantage. But that, by itself, tells us nothing about how many mutations reaching such a behavior would have required. Nor does it tell us anything about whether all of those intermediate stages actually conferred the organism a fitness benefit, making it possible for the final form of the adaptation to actually be reached.

Was there enough genetic variance of the right kind? For an adaptation to evolve, there had to be enough genetic variance for evolution to feed on at the right time. Again, postulating that an adaptation could have been useful tells us next to nothing about whether or not the variation needed to make it real existed.

Problems in verification

Memetic pressures shaping cultures. When trying to show the existence of biological sex differences, evolutionary psychologists sometimes appeal to cross-cultural studies that show sex differences across a wide variety of cultures. But while this is certainly evidence towards the differences being biological in origin, it's rather weak evidence. Pretty much all cultures in the world tend to be more or less patriarchal in nature. This could be caused by biological causes, but it's equally plausible that it was caused by a memetic selection pressure acting on non-psychological sex differences. Women have less strength than men and are the ones who bear children, which could easily have affected their social position even without drastic psychological differences.

Is something an adaptation? We consider the possibility that certain specific aspects of the faculty of language are “spandrels” — by-products of preexisting constraints rather than end products of a history of natural selection (39). This possibility, which opens the door to other empirical lines of inquiry, is perfectly compatible with our firm support of the adaptationist program. Indeed, it follows directly from the foundational notion that adaptation is an “onerous concept” to be invoked only when alternative explanations fail (40). The question is not whether FLN [the Faculty of Language in a Narrow sense] in toto is adaptive. By allowing us to communicate an endless variety of thoughts, recursion is clearly an adaptive computation. The question is whether particular components of the functioning of FLN are adaptations for language, specifically acted upon by natural selection—or, even more broadly, whether FLN evolved for reasons other than communication.

An analogy may make this distinction clear. The trunk and branches of trees are near-optimal solutions for providing an individual tree’s leaves with access to sunlight. For shrubs and small trees, a wide variety of forms (spreading, spherical, multistalked, etc.) provide good solutions to this problem. For a towering rainforest canopy tree, however, most of these forms are rendered impossible by the various constraints imposed by the properties of cellulose and the problems of sucking water and nutrients up to the leaves high in the air. Some aspects of such trees are clearly adaptations channeled by these constraints; others (e.g., the popping of xylem tubes on hot days, the propensity to be toppled in hurricanes) are presumably unavoidable by-products of such constraints.
(Hauser, Chomsky & Fitch 2002)

What is something an adaptation for? For instance, it might seem intuitively obvious that language evolved as a way to communicate. But language also has plenty of other uses, including functions like problem-solving, enhancing social intelligence by rehearsing the thoughts of others, memory aids, focusing attention, and so on. There is evidence that even animals without human language can, for instance, do things such as discriminate various phonemes, suggesting that many key components of language may have evolved as general cognitive capabilities. Human language may then primarily be a result of many non-language related adaptations happening to combine in the appropriate way. It's an empirical question which, if any, of these functions has been the primary force driving the evolution of language. (For a debate on this, see Hauser, Chomsky & Fitch 2002; Pinker & Jackendoff 2005; Fitch, Hauser & Chomsky 2005; Jackendoff & Pinker 2005.)

In the same manner, bats use echolocation to find and capture prey (feeding), to navigate, to find mates, and to engage in aerial dogfights with competitors. We can study bats to obtain plenty of information about how the bat sonar physically and cognitively works and how bats use it. Yet its evolutionary history and the functions that the sonar's early stages were the most useful for are questions that we are mostly incapable of answering. For the most part, such knowledge wouldn't even tell us anything we couldn't more reliably discover via other means. Our inability to verify theories about the adaptive origin of various traits weakens the faith we can place on such theories.

Problems in modern-day meaningfulness

Evolution did not stop after the Pleistoscene. This was covered in more detail in my review of The 10,000 Year Explosion. We know that new adaptations such as the one for lactose tolerance have shown up in the last 8,000 years. We also know that hundreds of "gene sweeps" of specific alleles increasing their frequency in the population are still going on today. While the full functions of these alleles are still not known, it is known that most involve changes in metabolism and digestion, defenses against infectious disease, reproduction, DNA repair, or in the central nervous system. And so on; see the link for more.

The modern environment may alter our biology. To name one example, hormones have a strong impact on human psychology. Yet especially women are likely to have very different hormonal activity than they used to have. We have less children, and have them at a later age we probably did in the EEA. The Pill basically works by screwing up the normal hormonal balance. Some extra hormones are fed to livestock and find their way to our bodies via our food. Even ignoring that possibility, our modern-day diet is very much unlike the one we used to have. We also get far less exercise, and so on. Our environment is likely making our brains different from the way they used to be.

Evolution may have exploited gene-environment relationships that no longer exist. This one is huge. For instance, we know that daylight has a role in regulating our sleep patterns. Now that artificial lightning exists, we routinely stay up for far longer than we would if we had to only go by the sun. More generally, the environment has a massive role in influencing how our brains develop. Children raised by animals do not, as a rule, ever reach a level where they could fully adjust to human society. As our whole society works in a completely different way than it used to, it's nearly certain to have broken numerous relationships that regulated the adaptations in the EEA.

”Human universals” mainly apply on a cultural level.  Even behaviors that were very widespread may or may not apply to any particular individual. Lists of ”human universals” will tell us that members in every tribe found so far will interpret facial expressions, love their children, tell stories, feel pain, experience emotions, and so on. But there are also individuals who do not know how to read facial expressions, do not care for their children, are not interested in stories, do not experience pain or emotions, and so on. Sexuality is one of the drives that would have had the strongest selection pressures operating on it, but we regardless have people who have no interest in sex, are mainly interested in sex with things that you cannot reproduce with (same-sex partners, children, cars...), or prefer to just masturbate.

Conclusion. Evpsych can certainly point us towards interesting novel hypotheses about human behavior. When such hypotheses turn out to be true, then there's indeed a strong possibility that they evolved as adaptations. But it's important to note that while science can provide us strong evidence about the existence of some behavior, it is incapable of providing strong evidence about the evolutionary origins of that behavior. Behavior, as a rule, does not leave convenient fossils behind.

There are basically two kinds of ev-psych explanations: one proposing an evolutionary origin for a present-day trait (an explanation) and one proposing a previously unknown trait based on evolutionary considerations (a prediction). Of these, explanations seem to only have limited value. To make a typical evolutionary psychological claim about the origins of something is to assume, among other things, that the thing in question is an adaptation, that its suggested origin was the primary driver of selection pressure for the adaptation's evolution, that a genetic path existed to the adaptation and there was enough genetic variation to make it possible. These are all claims that are almost impossible to verify or falsify. In most cases, it is better to merely talk about what empirical research has revealed about the thing in question, without giving too much weight to its (unverifiable) evolutionary origins.

Evpsych is more useful for predictions. And it does occasionally produce results you'd never have thought of to test otherwise. Still, even if there seemed to be a very strong case for selection pressures to have existed towards something becoming an adaptation, this tells us next to nothing about whether it actually ended up evolving. Even if we can ascertain that this kind of an effect seems to be prevalent in the world, evolutionary psychology alone cannot tell us the degree to which the effect is amenable to environmental conditions. That sort of information can only be found by ordinary empirical research, and ordinary empirical research doesn't need evolutionary psychology for anything else than suggesting interesting hypotheses.

Evpsych should primarily be used for helping build coherent explanatory frameworks for human behavior and for coming up with new predictions. But someone arguing in favor of some behavior being universal or biologically determined in the modern day shouldn't appeal to evpsych for support, for evpsych can at most weakly suggest such things.

Acknowledgements. Part of the content in this article was adapted from the materials of the Cognitive Science 121 course at University of Helsinki, written by Otto Lappi and Anna-Mari Rusanen.

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Your title "Problems in Evolutionary Psychology" is a bit ambiguous. Does it mean problems with the field of evolutionary psychology, or does it mean problems in the field of evolutionary psychology that evolutionary psychologists themselves are grappling with?

This post introduces some of the issues in studying evolutionary psychology, but off the top of my head, my reading on the subject suggests that evolutionary psychologists are aware of most of them and have taken them into account. So the second meaning would make more sense to me.

Either way, I think it would be useful to discuss what evolutionary psychologists think are the inherent difficulties in their fields (and how they propose to deal with them), and how they answer broad criticisms directed at the field. Evolutionary psychologists have been criticized a lot, and have spilled gallons of ink explaining their views in journals. I will try to find something that's a good introduction and that isn't behind a paywall.

In particular, evolutionary theories about sex differences seem to get mentioned and appealed to as if they had an iron-cast certainty.

Could you give an example of someone making this error?


... (read more)

Could you give an example of someone making this error?

Robin Hanson does this on a pretty regular basis. Most of his reasoning about gender is based on a male provider, female nurturer model. He is very much not alone.

I should have made it more clear in the post that the primary target of the post was not professional, academic evolutionary psychology. Rather, I was primarily cautioning amateurs (such as LW regulars) about some of the caveats involved in evpsych and noting the rigor required for good theories. While the post does also serve as a warning to be cautious about sloppy research (or sloppy science journalism) that doesn't seem to be taking these issues into account, I don't question the claim that the people doing serious evpsych are aware of all the issues I mentioned, and are probably taking them into account.

Could you give an example of someone making this error?

My wording was probably a bit too strong. Anyway, I'll try to look up some examples once I wake up.

Ah, but why do women have less strength, and men have more? See the excerpts from David Geary's Male, Female here arguing that greater male strength is related to sexual selection. (The mere fact that females have the babies isn't enough, because many monogamous primates exhibit minimal dimorphism.)

We know that there were different selection pressures on men and women. It doesn't make sense to believe that these selectio

... (read more)
Given two groups there are probably mental differences. More interesting is are the distributions bimodal and how much have they changed in e.g. last 100 years. If the distributions are not bimodal or change relatively strong with time then a simplistic view of "women X, men Y" won't work.
Agreed. I'm very tired of articles which say "Hey look! There's a difference" without getting into the amount of individual difference or group overlap.
I agree. I'm also tired of "Hey look! There's overlap between the distributions, so let's pretend the difference doesn't matter!"

A simple example is height. On average men are taller than women.

But most of the time making a men=tall, women=short simplification does not make sense. It makes more sense to provide multiple sizes for both women and men.

And if providing only a very limited selection of sizes (e.g. hospital clothing) it makes sense to provide different unisex sizes rather than one for men and one for women.

And while we're busy being tired, I'm really tired of no research by anybody (so far as I know) about keeping reactions to ideas one has about group differences in proportion to what one actually knows instead of exaggerating the size or extent of the differences. It took rather a lot of hammering to get to the idea of atypical women.
It seems that the ideal evolutionary psychology research paper would start with some well-known fact about human nature - a fact empirically verified by ordinary psychologists. From this fact, plus the fact of evolution under natural selection, plus the fact that none of our fellow apes exhibit this human idiosyncrasy, the paper would infer some hypothesis about our recent selective environment - a plausible hypothesis, given what we already know from physical anthropology. Then, assuming that our hypothesis about the past is true, the paper would reason forward to some new, previously unsuspected hypothetical fact about modern human nature. Finally, the paper would conclude with new empirical research showing that human nature really is like that. A hypothesis about the present generated by evolutionary psychology is found to be true by the methods of ordinary psychology. That would be great. That would be science. Does anyone have a citation to such a paper?
What do you think of the experiment cited in this post of Eliezer's?
I've seen one source claim that people of the same size with the same training will end up with the same strength. The book I've gotten it from shows signs of a lot of research (who knew there'd been so much research on sex differences in throwing?), but I've got the claim filed under "very interesting if true, wait on more evidence". And of course, there are average size differences between men and women. I have no idea whether height differences are a result of arbitrary sexual selection. It's fading a little, I think, but there's a cultural assumption that in couples, the man should be taller than the woman. Again, it's been faded somewhat, but there's been a strong cultural assumption, not just that men and women are mentally different from each other, but that they should be different, that men and women should be fairly close examples of ideal types. This means that some fraction of behavior is going to be the result of cultivation rather than genetically forced. I haven't seen any discussion of why men and women aren't more different than they are. As species go, humans are only fair-to-middling sexually dimorphic.

People of the same size with the same training do not end up with the same strength; look at the scoresheet for a powerlifting meet. A 135-pound man is stronger than a 135-pound woman who trains exactly the same way. Hormonally, men are set up to have a higher percentage of muscle mass. I don't know enough biology to describe it in more concrete detail, though.

Edit: I assume everyone knows enough stats to understand that this does not mean a female athlete can't outperform most men. I'm also not saying that women shouldn't challenge themselves athletically. I like the general thesis of "The Frailty Myth" and I think women could be better off training a lot harder than they generally do at present, and that a certain amount of female physical weakness is self-imposed. But there's also a biological difference.

Another huge problem is that popular evolutionary psychology completely ignores the effect of gene drift. There are biologists who think that the amount of genetic changes due to gene drift that differentiate us from chimpanzee are roughly the same as the amount of genetic changes due to natural selection.

I'm for example wary to believe that we are really better of because we can't produce vitamin C ourselves anymore. I rather think that we lost the ability because of gene drift than think that we lost it due to natural selection.

Another frequent sin - not necessarily an inherent one - of the enterprise is to explain phenomena by reference to a virtus dormitiva - to say "here is an observed fact x about humans/undergraduate psychology majors, here is a plausible story for why evolution would select for x," and thus conclude that x occurs because of an x instinct or x module. This is equivalent to saying that we observe x, here is a plausible story for why capitalism/patriarchy/society at large stands to benefit from x, so capitalism &c. creates a "social process" to realize x. That's not an explanation; it's not even a hypothesis. You have to talk about mechanisms.

Again, this isn't inherent in evolutionary psychology, but I think until our understanding of behavioral genetics becomes much better it will be a more common vice than its equivalent in social explanations. If we found ways to genetically reconstruct our ancestors at various points in our specific development that would go a long way as well.

Mechanisms -- good point. I have another way of putting it. In TV police shows, detectives try to establish a suspect's means, motive, and opportunity for committing a crime.Sloppy detectives (and jurors!) tend to focus just on motive and its lurid details. In evolutionary bio/psych, we try to establish genetic variation, selective advantage, and heritability. Sloppy evolutionary hypotheses tend to focus just on the selective advantage and ignore the other two. People are drawn to stories. We give evidence extra weight if it comes in the form of a good narrative. (Is there a name for that bias?)

I'm somewhat frustrated by the frequent posts warning us about the dangers of Ev. Psych reasoning. (It seems like we average at least one of these per month).

It seems like a lot of this widespread hostility (the reaction to Harald Eia's Hjernevask is a good example of this hostility) stems from the fact that ev. psych is new. New ideas are held to much higher standard than old ones. The early reaction to ev. psych within psychology was characteristic of this effect. Behaviorists, Freudians, and Social Psychologists all had created their own theories of &q... (read more)

Wow, who downvoted this, and why?

It seems like a lot of this widespread hostility (the reaction to Harald Eia's Hjernevask is a good example of this hostility) stems from the fact that ev. psych is new.

Not just that; certain political positions believe (correctly or incorrectly) that sociobiology or evolutionary psychology is counter to their worldviews. See Defenders of theTruth by Ullica Segerstrale.

While it may be true that some writing about evolutionary psychology (particularly in the popular press) deserves rationalist scrutiny, certain forms of opposition to evolutionary psychology also deserve rationalist scrutiny for their long track record of putting badly-though-through social values above scientific inquiry.

So much junk opposing evolutionary psychology has been written that anyone casually investigating the subject can easily have screwed up priors and be infected with biases and misconceptions about the field. The best way to evaluate evolutionary psychology is to read what people in the field write in peer-reviewed publications (not popular books) and assess their reasoning for yourself.

Could you explain why you hypothesize that opposition to evolutionary psychology stems from the youth of the discipline? Or better yet, don't try to explain your own thought processes and instead try reading what the critics write and assessing their arguments rather than imagining their motivations. Yes, much of the opposition to sociobiology was based on political ideology. That has mostly passed. But the opposition to evolutionary psychology is based on epistemology. It just is not a respectable empirical science.

Could you explain why you hypothesize that opposition to evolutionary psychology stems from the youth of the discipline?

That was knb's hypothesis, not mine.

Or better yet, don't try to explain your own thought processes and instead try reading what the critics write and assessing their arguments rather than imagining their motivations.

Or even better, don't accuse me of imagining people's motivations when I've already given a citation about the politics around sociobiology and evolutionary psychology that informs my view: Defenders of theTruth by Ullica Segerstrale.

I have read plenty of criticism of evolutionary psychology. I've also read plenty of defenses of evolutionary psychology.

Yes, much of the opposition to sociobiology was based on political ideology. That has mostly passed.

On the contrary, I've seen plenty of opposition to evolutionary psychology from certain political ideologies. I'm not "imagining" these motivation. Are you not familiar with the opposition, or do you not think it comprises the bulk of opposition to evolutionary psychology?

But the opposition to evolutionary psychology is based on epistemology. It just is not a respectable empirical s

... (read more)
Whoops, sorry. Now I feel like an idiot for reasons beyond squandering all my karma on this crusade. I've read Segerstrale. I agree that the opposition to Sociobiology was unjustified. But I still claim that what Buller calls "EP" (as opposed to "ep") is pseudo-science - not because it tells us something unwelcome about ourselves, but rather because it tells us next to nothing about ourselves. Ah! That may explain our disagreement. I don't know what standards are expected in sociology or psychology. I was thinking in terms of the standards expected in evolutionary biology. I thought I stated that in my initial comment.
See what you think of Delton, Robertson, and Kenrick's discussion of "Evolutionary Psychology" vs. evolutionary psychology: See also Machery and Barrett's response:
What do I think? I think these are rhetorically effective critical reviews. Without reading Buller's book or any of the reviews by biologists and philosophers of biology, I have no idea whether they are fair reviews. However, I have read enough by Cosmides, Tooby, and by their critics and defenders to form the opinion that what the critics say about their work is entirely fair.

New ideas are held to much higher standard than old ones... Behaviorists, Freudians, and Social Psychologists all had created their own theories of "ultimate causation" for human behavior. None of those theories would have stood up to the strenuous demands for experimental validation that Ev. psych endured.

I'm not sure what you mean. Are you saying that standards of evidence for new ideas are higher now than they have been in the past, or that people are generally biased in favor of older ideas over newer ones? Either claim interests me and I'd like a bit more explanation of whichever you intended.

In general, I think scientific hypotheses should invite "strenuous demands for experimental validation", not endure them.

I checked the list of posts tagged with evpsych, and there weren't all that many posts about the dangers of evpsych. Nor do I remember seeing many. Part of the reason why I wrote the post was precisely because there seems to be a lot of support for evpsych on the site, but little criticism. I'm not saying evpsych is necessarily wrong or useless, but people should at least be aware of what the criticisms are.
Relatively few posts are tagged "evpsych", but there still has been much criticism of ev. psych here, most of it highly repetitive and derivative. Wrongbot wrote several posts criticizing ev psych. During the "PUA wars" there were many posts written criticizing ev. psych. Recently Wrongbot wrote his post about "thoughts too dangerous to think" where he basically said ev. psychology would turn you into a sexist, so you should avoid thinking about the subject. Yes, Kaj, I know you haven't said it was useless. If you read my comment, you'll notice that I never said you said that. What I am saying is that, since there has been an ongoing effort to discredit ev. psych from the very beginning, it is unlikely anyone significantly interested in ev. psych has not run into these criticisms. You also never gave any evidence that a significant number of people on Less Wrong really are making overconfident, novel claims based on ev. psych reasoning.
My sequence on Sex at Dawn isn't a criticism of ev psych as a discipline. It's a criticism of certain conclusions drawn (mostly) by popular science writers, and offering a different set of conclusions that are themselves based (in part) on ev psych. That's a massive over-simplification, and ev psych was never implicitly or explicitly called out as part of the danger. If anything, I am one of the people making "overconfident, novel claims based on ev. psych reasoning." I'm not even sure I could disagree with that description of my ev psych posts to date, though I'd probably include a caveat about the degree of my apparent overconfidence.
I really never got the impression of overconfidence from your Sex at Dawn series. I think you did a good job of including the necessary caveats and cautions. I'm sorry that I misunderstood your intention. However, I do think that if one takes your line of argument seriously, it wouldn't lead to ignoring ev. psych--which more than any other area of research addresses sex differences.
I would expect to get much more credible evidence on modern sex differences from psychology or biology, but I guess that the topic is taboo enough that most researchers steer clear of it. Which might explain part of ev psych's poor reputation--more willingness to pursue taboo areas of research.

I think there are two more categories of not knowing enough: thinking that something is universal when one has limited samples of different human societies, and not knowing how an organism will respond to unusual circumstances, thus assuming that some behavior is more hard-wired than it actually is.

The latter is a truly wicked problem: we can't find out how things operate under novel circumstances until those novel circumstances are realized. (When you have something like physics where the rules are so well-grounded, you can speculate more confidently than you can with something fuzzy like human society and nature.) It's no sin of a theory to not tell us these things for sure, unless it's rhetorically marshalled for that ("women won't become great scientists because on the savannah...") Although it could count as Bayesian evidence. With things like sex and racial differences you can happily say (if your values swing that way) "okay, maybe it's that way and maybe it's not, but the best way to put egalitarianism to an empirical test is to realize as complete a social equality as possible and see what happens. Purely in the name of science, of course." What makes the problem really wicked is that some counterfactuals would be very undesirable to implement. We just have to hope it's knowledge we'll never get to obtain.
Indeed! And one can't even say "racial and sex discrimination is illegal in some countries, so we can assume that the remaining differences are biological", because stereotype threat is present in even the most liberal modern cultures. I'm having a hard time imagining how a good social scientist a hundred years ago would go about measuring the effect of race and sex on, say, math skills, and not be surprised by the progress we've made nowadays.

Occasionally, the studies purporting to show cross-cultural sex differences actually show that the differences are smaller in the more egalitarian countries.

On some measures they show the opposite - differences being smaller in less egalitarian cultures - although the relevant point there is that they have both sexes trending in the same direction (typically the traditionally "male" one.) The two most obvious explanations I can think of for this are that the relative distance is an artifact of survey estimates (we can say for some constructed ... (read more)


One example I found was an experiment to test the variations in resource expenditure for different grandparents. Dekay (1995). The evolutionary model they used precisely predicted the pattern of resource expenditure. Maternal grandmothers contributed most, followed by maternal grandfathers, followed by paternal grandmothers followed by paternal grandfathers.

You make it seem like this is an exception to the rule. Reading through an ev. psych textbook, I am constantly surprised by the clever experiments I never would have thought of to test evolutionarily b... (read more)

I think this is an excellent example to serve as a focus of arguments for and against evolutionary psychology. The idea here is not to praise or critique this particular piece of research, but rather to discuss what kinds of things good scientific researchers might do with this subject matter vs the things that sloppy researchers might do. The cited paper is not available online, but a later survey paper by the same author gives the rough outline. As I understand it, DeKay is suggesting that differential care for grandchildren is a (genetic?) fact of human nature. And that the explanation for this differential can be found in the fact that some "fathers" are actually cuckolds, together with the standard evolutionary theory of inclusive fitness (aka kin selection). The empirical part of the research examines a sample of grandparents and finds that the predicted differential grandchild-care behavior is actually observed. knb finds this research to be "clever", "surprising", and "impressive". I, on the other hand, am more skeptical. Since we don't have the actual research paper, we can't criticise the actual research, but we can ask the kinds of questions that an evolutionary biologist might ask if it had been submitted for peer review to a biology journal. First a scientist would want to know what other hypotheses had been considered and then empirically rejected. For example, might the results tell us something about culture (social norms) rather than about human nature. The scientist would want to make sure that the empirical sample of grandparents was taken from a broad diversity of human cultures and hence that a "human nature" label is not mistakenly being attached to a parochial cultural trait. Besides culture and genetics, another possible explanatory factor for human behavior is rational self interest. I would want to know whether any of the sampled grandparents had any reason to rationally suspect that they were not true ancestors. Another alternate hypo
This doesn't relate to the grandparents thing, but I think most research has shown that parental investment is highest for adopted children, followed by biological children, followed by stepchildren.
I quickly googled this, because I was suspicious whether these results did properly control for socioeconomic factors. Apparently, they did. But the first google hit suggested another huge complication. This paper suggests that adopted children get more parental investment because they require more parental investment. That is, because they are often problem kids. Differential parental investment in families with both adopted and genetic children Kyle Gibson Abstract Stepchildren are abused, neglected and murdered at higher rates than those who live with two genetically related parents. Daly and Wilson used kin selection theory to explain this finding and labeled the phenomenon “discriminative parental solicitude.” I examined discriminative parental solicitude in American households composed of both genetic and unrelated adopted children. In these families, kin selection predicts parents should favor their genetic children over adoptees. Rather than looking at cases of abuse, neglect, homicide and other antisocial behavior, I focused on the positive investments parents made in their children as well as the outcomes of each child. The results show that parents invested more in adopted children than in genetically related ones, especially in educational and personal areas. At the same time, adoptees experienced more negative outcomes. They were more likely to have been arrested, to have been on public assistance and to require treatment for drug, alcohol or mental health issues. They also completed fewer years of schooling and were more likely to divorce. In adoptive families, it appears that “the squeaky wheel gets the grease.” Parents invest more in adoptees not because they favor them, but because they are more likely than genetic children to need the help. I conclude that discriminative parental solicitude differs in adoptive and step households because adoptive families generally result from prolonged parenting effort, not mating effort like stepfamilies.
I don't have journal access - does it discriminate between from-infancy adoptees and adoptees from foster homes?
Very good question, but I don't have journal access either.
There are quite a few studies relating to this - I posted some as children of the mother-comment.
Some starting points "Grandparental investment as a function of relational uncertainty and emotional closeness with parents" * "Differential Investment Behavior between Grandparents and Grandchildren: The Role of Paternity Uncertainty" * "An Evolutionary Perspective on Parental and Grandparental Investment (2010)" * "LINEAGE BASED DIFFERENCES IN GRANDPARENTAL INVESTMENT: EVIDENCE FROM A LARGE BRITISH COHORT STUDY" *

Thank you for posting this, Kaj. It's exactly what the community needs at this time. Far too many transhumanists accept the claims coming out of evolutionary psychology uncritically. Bravo!

What? Another branch of psychological research found to lack an ordinate degree of evidence, reason and application of scientific method? Say it is not so!

It is almost as if people practicing in certain "sciences" need to make up good stories to continue getting funded. I wonder if this is a problem though. The general public (through their tax donations) mostly pay scientists of all stripes to come up with good stories.

[one objection to E. P. is:] Memetic pressures shaping cultures.

Probably the single biggest problem for E. P. is that its practitioners typically don't "get" menetics. Pinker is a good example of this.

The issue has been explained in detail in these papers:

The good news is the... (read more)


Sorry for the multiple comments, but I have separate points to make, and I think this makes it easier to make them clear.

There are basically two kinds of ev-psych explanations: one proposing an evolutionary origin for a present-day trait (an explanation) and one proposing a previously unknown trait based on evolutionary considerations (a prediction).

I think this is confused. Ev. psych explanations also generally make predictions which (if empirically validated) provide evidence that the ev. Psych explanation is the correct one.

One example of this is t... (read more)

This can be misleading. More women than men attempt suicide, but male deaths outstrip female due to method lethality - men are more likely to go out with a gun, women more likely to sign out with twin bottles of vodka and vikoden. This could be because more men Really Do Want To Kill Themselves For Real, as opposed to a cry for help, or it could just be that men are far more likely to own a gun and women more likely to have a painkiller addiction. What is true is that, if diagnosed rates of depression are accurate, a depressed man is more likely to commit suicide than a depressed woman, because more women than men are diagnosed with depression. This might be due to differential rates of hormone production (I wouldn't be able to tell you what, and since any social factors leading to depression are going to end up using hormonal mechanisms as well, the cause of it would be difficult to ascertain), but whether or not that's there men are almost certainly underdiagnosed, since they're less likely to seek out help for mood disorders. It's a very thorny question.
Other factors-- I've heard that women are apt to prefer poison over gunshot because of strong socialization to not leave a mess. I don't have substantiation for this, but it doesn't sound crazy. I've also heard that depression manifests differently in men (more likely to appear as violence and/or alcoholism) and not get diagnosed.
What's Denys deCatananzaro's explanation?
De Catanzaro (sorry, my misspelling) developed a theory that suicide occurs in people who have low estimates of their ability to contribute to their own genetic fitness. So he looked at various factors that specifically contribute to lower genetic fitness, such as believing you are a burden to family, being homosexual (that surprised me), being a virgin, not having had sex in a year, and not having had sex in a month. The survey questions he created had very high correlations with suicidal ideation and suicidal action. At least some of his predictions were apparently novel. Separately, this evolutionary explanation for suicide also offers a possible explanation for why men commit suicide so much more often--they are much more likely to fail at heterosexual mating. Once you account for the mating difference, the difference almost disappears.
This is a nice example of the slipperiness I sometimes notice when I think about how one could test an ev. psych hypothesis. My first thought after reading your comment was 'but won't all those factors be just as correlated with unhappiness and depression as with genetic fitness? Surely there's a less complex explanation here: unhappy people don't like living as much, so they try killing themselves more.' Then I thought a little more and realized that could also have an ev. psych basis: maybe we evolved to kill ourselves more when we're unhappy with life. But that's a different ev. psych argument than 'we evolved to kill ourselves more when we have low genetic fitness.' Or is it? Maybe we evolved to kill ourselves more when we're unhappy because unhappiness correlates with low genetic fitness? What would it even mean in concrete terms for all of these possible evolutionary explanations to be false?
I've noticed that psychological descriptions of suicidal depression involve not just crushing unhappiness in general, but also isolation. Is it possible that suicide evolved as a society-level equivalent to the cellular mechanism of apoptosis? A tribe whose least productive, least connected members voluntarily wander away to self-terminate might have a significant competitive advantage in terms of food production per member, without the runaway perverse-incentive stuff Enron got caught in. This isn't just a group-selection thing, either. Given that you're going to be providing preferential treatment to your close relatives anyway, having a genetic predisposition for suicide means that such intrafamilial charity is less likely to be wasted on hopeless causes, since the hopeless ones don't stick around.
Having a family member who commits suicide increases the risk of suicide. Assuming that this sort of study is accurate, it backs the idea that people get emotionally entangled with each other. A General Theory of Love builds on the observation that human babies can die of loneliness to observe that many animal species and humans in particular need social contact for metabolic regulation. (Is this a Far line of thought, or what?) In other words, even a not-very-promising member of a tribe may still be supplying non-obvious metabolic regulation services. I'm guessing that people who live in tribes just don't get nearly as isolated as can happen in civilization. Anyone have actual knowledge about this? Stats on suicide among hunter-gatherers?
I don't know anything about hunter-gatherers, but suicide rates among industrialized nations correlate very highly with rates of single-person households. There aren't many social indicators on which Sweden does worse than Italy, but suicide is one of them.
Also, are we evolved to abuse people with possibly low genetic fitness? To create low genetic fitness if it gives us a genetic fitness advantage?
Interesting. The problem with the corelation with homosexuality is that homosexuals are frequently up against violent prejudice, though less so in recent years. Being bullied can cause longterm psychological damage. I know someone who endured really bad depression for a long time [1], and it's plausible that the major reason she didn't commit suicide was that she had a child. Did deCatanzaro [2] look at whether whether people actually have children? Whether abandoning children has a high correlation with suicidality? Admittedly, it would be hard to tease out the causality in the latter. [1] She was being treated for depression. What she actually has is Bipolar 2 (bipolar with so little mania that it's hard to notice), which is metabolically quite different from straight depression-- the right meds made a huge difference. [2] That's how it's spelled on his website [3]-- there's no space between the e and the C. [3] I think of the web + google as the larger part of my brain.
Suicide rates for gay teens have been dropping like a rock for the past two decades (though they remain above the heterosexual rate.) Homophobia is still awful but it's one of the most obvious ways in which the world is getting better.
If the rates are changing dramatically wouldn't this imply they are not mainly caused by genetic components?
DeCatanzaro did look at the effect of not having children, which was significantly correlated with suicide.

Yes, we're all tired of hearing cousin Joe's transparent attempts to rationalize his personal prejudices by convincing himself that 'it's evolution'. And yes, as a general rule, in propositions of the form 'humans exhibit behavior X due to evolutionary explanation Y' the 'explanation Y' part provides very little evidence. But I can't help but notice that this makes a very convenient excuse to dismiss any observation you happen to be uncomfortable with, just because it comes packaged with an evolutionary explanation.

Since the whole topic of human behavior i... (read more)

Hardly. If I take an offered explanation for an observation with a grain of salt, that doesn't mean I can dismiss the observation itself. At most I can dismiss the explanation. Yes, that's what I was saying. Evolutionary psychology is likely to also help with this, yes, though we need to be careful with it and remember what we don't know.

Have we had an article that compared/contrasted evolutionary psychology with explaining the blue tentacle?

I don't think the two have much in common. To wake up one morning with a functional blue tentacle in place of my arm is an event of extremely low a priori probability. Hence we should expect that the explanation, should we find one, will be detailed enough to explain every aspect of the event. That is, we will immediately know we have found the right explanation when we encounter it. The typical thing explained by evolutionary psychology, on the other hand, has a rather high a priori probability. For example, it might explain why one sex is generally better at some task than the other sex. The a priori probability is something like 50%. And plausible explanations are easy to come up with. The difficulty here is in choosing among all of the plausible candidate explanations.

This may be a case in which I'm telling everyone something they already know, but I will continue because I'm not seeing any evidence for or against.

In a sexual relationship there are obviously two parties, the X component and the Y component.

The next factors are the gestational period for each.

Say the X component has a gestational period of every 50 days and the Y component has a gestational period of every day.

Both X and Y components live for 100 days.

The next factor is that there is only ever a maximum population of breeding pairs, say 50 of each for a ... (read more)

I'm being voted down, still without seeing any evidence for or against.... I know it's due to a popular vote, but does anyone have any argument, or are we just taking advantage of the voting mechanism? I'm starting to feel like the availability of stating ones opinion is counteracting the way things actually work...
I've downvoted. As for reasons, the comment is difficult to understand. At least you should tell what do you exactly mean by But the main reason for my downvote was If it is easy, then do it. It can make your point more comprehensible.
prase, Thanks. Maybe I should have made clear that X can only reproduce with Y and Y only with X; the definition of sexual reproduction. I think I should simplify it... If X can reproduce 2 times in its life and Y can reproduce 100 times in its life the natural assumption would be that Y will reproduce more. BUT Remember that the population consists of equally half of each sex and that X will be in gestation for most of theirs. This means that X will participate in reproduction only twice in their life time, for any given period. Considering that there are 50 total X in that amount of time, that is 100 possible gestations. For Y there are 50 times 100 days of possible gestation total, or five thousand possible days of creating gestation. Y has to choose among X and X has to choose among Y. Does X or Y have more to chose from? I hope this clarifies, I will continue if needed, again, thanks.
Thanks for clarification, upvoted. So if I understand correctly: Let's assume a total population of 100, from which 50 X and 50 Y. At each day, there is one X available, so all Ys have to compete for that given X, while the one X in question can choose among 50 Ys. Seems consistent, and even true for some animals whose males carry sexual ornaments, while the females' look is rather mundane. However, in some species, like deers or wolves, males compete directly against each other and females don't seem to have much choice either. Nevertheless, since you have written it, I suppose you have infered some interesting consequences...
Yes, there is a very large and very interesting variety found in this process. If we take the all of the variables into consideration, all of the possible ways X and Y can work: We have (n1)X and (n2)Y for a population of ((n1)X + (n2)Y), the ratio of (n1)X to (n2)Y, the population can increase or decrease, a gestation variable of (g)X that cooperates with breeding potential of (b)Y... I could go on, but since this is not an attempt at a full research paper, I think my point in this respect is clear, that the potential for variation in reproductive method is huge. The question I ask myself is just how important is this to humans? Look at the basic survival methods of the sexes, X and Y; we eat the same foods, breath the same air, and our physiology is the same for these purposes. The only difference between X and Y is due to the nature of sexual reproduction. I think that it is of such importance, and so basic, that when examining human culture and society it should be one of the main focal points, of any line of examination.
What you wrote about X and Y seems true enough. I haven't followed the context so didn't engage.

That sort of information [i.e. facts about "human nature"] can only be found by ordinary empirical research, and ordinary empirical research doesn't need evolutionary psychology for anything else than suggesting interesting hypotheses.

Amen. Evolutionary psychology is generally considered to be pseudo-science by most evolutionary biologists. It amazes me how readily laymen are fooled by this nonsense. Of course we evolved, and of course our adaptations are a result of natural selection. But that doesn't help us to know about ourselves unless... (read more)

I disagree with this comment, but I think the score of -5 is far too harsh. That's spam/nonsense/troll territory. While I would not put this above 0, on account of sentences like nor would I put it below -2, since after all it also contains this:
Thx. I'm up to -4 now. :) Yeah, I guess I deserve that.
Citation needed.
The opposition of Gould, Lewontin, and the Roses needs no citation - you can easily find it by Googling. Jerry Coyne is an outspoken critic - . Larry Moran even more so. This is a fairly gentle explanation of what is wrong with evolutionary psych from the viewpoint of evolutionary biology. But even more telling was my total inability to Google up any citations at all in which more prominent evolutionary biologists (Dawkins, Doug Futuyma, the late John Maynard Smith, etc) say anything nice about evolutionary psychology. In case you didn't notice, that is a counter-challenge. Please provide a citation showing that any eminent biologist considers evolutionary psychology to be good science.
Dawkins on Pinker:
Yes, Dawkins doesn't mention evolutionary psychology at all, but he praises three books by an author, only one of which is generally considered a work of evolutionary psychology. Of course H. Allen Orr's review of The Blank Slate was quite critical, for all of the same reasons being discussed here. My challenge stands: cite a biologist praising (or even defending) evolutionary psychology as science.
Pinker is an evolutionary psychologist; it's his métier. I don't know on what grounds you say that "only one" of the three books mentioned is considered a work of evolutionary psychology (I don't even know which one of the three you mean! -- I'm guessing How The Mind Works?); but in any case, given Pinker's reputation for advocating evolutionary psychology, it is extraordinarily unlikely that Dawkins would have praised Pinker in those terms if he (Dawkins) shared your view that the subject is pseudoscience. The quote strongly implies that Dawkins holds a view of evolutionary psychology that is drastically different from yours, which I don't think you anticipated. Update!
No, I meant Blank Slate as the one of three which is ev.psych. I haven't read How the Mind Works but assumed from the title that it is into the mechanism of mind rather than its evolutionary origin. I read most of The Language Instinct and formed the impression that it too was mostly about mechanism rather than origins. But I will take your word for it (and Tim's word) that I was wrong. Updated.
Back cover blurb from "How the Mind Works": "In this extraordinary book, Steven Pinker, one of the world's leading cognitive scientists, does for the rest of the mind what he did for language in his 1994 bestseller The Language Instinct. He explains what the mind is, how it evolved, and how it allows us to see, think, feel, laugh, interact, enjoy the arts, and ponder the mysteries of life. And he does it with the wit, clarity, and verve that earned The Language Instinct, worldwide critical acclaim and awards from major scientific societies." Similar blurb from "The Language Instinct": "With wit, erudition, and deft use of everyday examples of humor and wordplay, Pinker weaves our vast knowledge of language into a compelling theory: that language is a human instinct, wired into our brains by evolution like web-spinning in spiders or sonar in bats. The theory not only challenges convention wisdom about language itself (especially from the self-appointed "experts" who claim to be safeguarding the language but who understand it less well than a typical teenager). It is part of a whole new vision of the human mind: not a general-purpose computer, but a collection of instincts adapted to solving evolutionarily significant problems - the mind as a Swiss Army knife."
I agree that evolutionary psychology is not well-regarded by biologists in general, but Dawkins is an exception to this trend. He's even praised one of the most obviously sloppy practitioners (Satoshi Kanazawa.) Dennet, as a fellow adaptationist (though no biologist per se), is in a similar camp.
Chapter 5 ("The roots of religion") of the God Delusion is largely a work of evolutionary psychology.
I don't have a copy to check, but from what I can remember Dawkins was careful to say that what he was doing is not real science but merely a counter to a hypothetical theist argument along the lines of "If God doesn't exist, then where do our ideas of God and morality come from?" That is, his claims were no stronger than "It is plausible that it might have happened this way." In any case, I have admitted I was wrong about Dawkins. He now seems to me to be a moderate supporter of the ev.psych enterprise, rather than, as I had believed, someone who cringed but kept his mouth shut rather than alienate fellow "Darwinists".
I was pretty amazed at how Dawkins pussy-footed around his opponents in "The God Delusion". His claims seemed pretty mild - along the lines of "it is OK to be an atheist". He discusses "the important and developing field of evolutionary psychology" directly - on page 208: "The idea of psychological by-products grows naturally out of the important and developing field of evolutionary psychology. Evolutionary psychologists suggest that, just as the eye is an evolved organ for seeing, and the wing an evolved organ for flying, so the brain is a collection of organs (or 'modules') for dealing with a set of specialist data-processing needs. There is a module for dealing with kinship, a module for dealing with reciprocal exchanges, a module for dealing with empathy, and so on. Religion can be seen as a by-product of the misfiring of several of these modules, for example the modules for forming theories of other minds, for forming coalitions, and for discriminating in favour of in-group members and against strangers. Any of these could serve as the human equivalent of the moths' celestial navigation, vulnerable to misfiring in the same kind of way as I suggested for childhood gullibility."
Surely all those works are heavily laced with evolutionary psychology.
Exhibit 1 is surely - father of sociobiology.
Yes, but what does this have to do with evolutionary psychology? The wiki article on Wilson never mentions evolutionary psychology. When I Google for "Wilson evolutionary psychology", I find this complaint that Wilson doesn't like "evolutionary psychology" even though the author wants to claim Wilson as the founder of the discipline. So lets have Exhibit 2. [Edit: minor typo]
The quote seems to be: "Today, my only complaint is that Wilson has never really embraced the word usage of "evolutionary psychology" and prefers that we consider it nothing more than "human sociobiology"." Sociobiology came first - evolutionary psychology is a more modern offshoot that only deals with human universals and mostly ignores human culture.
Buller's Adapting Minds I read this a while back but have been putting off writing about it while I thought about it (and until I reread at least parts of it). Some parts I think are mistaken and some need more work, but it is mostly an interesting critique of Evolutionary Psychology. The hardest to follow, and where I think the most potential benefit lies, is in Chapter 4 on modularity of minds. One big problem for evolutionary psychology is its claim for "massive modularity" versus the well established plasticity of minds at the neural level, and that all memory and mental function relies completely on the neural plasticity.
It's a good book, but see also Debunking Adapting Minds.
I read that, and many other criticisms, before I bought the book. Some of the criticisms are accurate, others miss, and most there is no real way to decide rationally either way. As for most of the criticisms from the EvoPsych direction, they are of the 3 chapters on specific adaptation claims that I haven't read, I am more interested in the basis, and especially as I pointed out above the conflict between evo-psyc and neural plasticity which I don't think even this paper addresses adequately (and the others mostly or entirely ignore). I'm not going to respond any more right now, like I wrote above I need to think through it a bit more.
I haven't read Adapting Minds, but I've seen responses to it by evolutionary psychologists. You can find a bunch of them on Cosmides' and Tooby's website See this one by Delton, Robertson, and Kenrick for instance: ... Another negative review from Machery and Barrett concluded: The arguments of Buller's critics seem well-reasoned and well-cited, though someone who has read his book would have to confirm that they are fair to him.
Has anyone from evolutionary biology proper weighed in with a critique of Buller? Even Buller's critics admit that the book was well received generally in the academic press.
Amazon's summary has: * IMO, that does an excellent job of making the author sound clueless.
I personally have nothing against the term "Human Nature". But I think it is easy to reconstruct Buller's meaning here. Our "nature" has clearly evolved; evolution takes place (in part) as a result of variation in a population; evolution of our "nature" is still taking place; hence there is still variation in the "nature" of the human population; hence the whole concept that the species has an essential "Human Nature" is flawed. We are diverse. I'm not sure I would want to call that kind of word chopping "clueless". But I would point out that the diversity in human nature is the result of the last 150,000 years or so of our evolution, whereas our shared evolutionary history (creating an "essence" of human nature) spans a period roughly 40 times as long.
It reminds me of those who argue against: ...on the grounds that intelligence is composed of many diverse abilities. Someone making such a complaint about the term "Human Nature" simply hasn't bothered to understand what the term is intended to refer to.
That is simply untrue. Ev. Biologists often make use of ev. psych reasoning. Dawkins does this all the time.
Could you give an example? Perhaps you and I understand different things by evolutionary psychology.
I'm guessing that most laypeople here identify Ev Psych with the sort of explanations offered in Pinker's How the Mind Works and The Blank Slate. Are those the kinds of explanations that you consider to be pseudoscience?
I haven't read Blank Slate. What little I remember of the fraction I read of How the Mind Works made the case for a materialistic and reductionist account of the Mind, and pointed out that the Human Mind evolved by natural selection. I am in complete agreement on both points - those viewpoints did not originate with Evolutionary Psychology, and EP does not have the sole responsibility for defending them. So, since I don't know the explanations you are talking about, I can't say for sure they are pseudo-science. But I do know of a demarcation criterion. Did Pinker suggest how his explanations could be tested by experiment? Did he report the results of experiments? If not, then he was either doing pseudo-science or philosophy. Sorry, I don't have a demarcation criterion to distinguish those two. But, if someone says they are doing philosophy, I usually give them the benefit of the doubt.
Hang on: we can't understand adaptations - unless there are fossils?!? What about molecular residues? What about current utility? What about current variation? There is a considerable quantity of evidence relating to these issues lying around - even without fossils.
Re: "Evolutionary psychology is generally considered to be pseudo-science by most evolutionary biologists." It's a real science - just one where we would like more data - and most science is like that. Neanderthal resurrection should provide another data point someday.
Ah, yes. And that is why, every summer, when teaching duties are completed, the practitioners of evolutionary psych and their graduate students head out into the field to collect more data! And Neanderthal resurrection will tell us next to nothing, since we still will have no idea what selective pressures our ancestors faced or what pressures Neanderthal ancestors faced. To say nothing of the difficulty in assessing the differences between Neanderthal psychology and H. sapiens psychology. And even if this weren't a problem, we would still have only two data points to work with.
There's chimps and bonobos - and other primates. That is quite a few "data points" - considering the mountain of information that can be obtained from each of them.