Saturday, 3 September 2011

Whither evolutionary psychology?


Is groupthink genetically determined? Twin studies suggest that people are prewired to identify and comply with social rules.

Where to from here? Will evolutionary psychology ossify and disappear? Or will it redefine itself and move on?

In a sense it doesn’t matter. A name is just a name, and the field of evolution and human behavior has had other names. The main issue is whether the current name is a help or a hindrance. Will it allow change from within?

Bolhuis et al. (2011) think so. In their call for a new evolutionary psychology, they have made several recommendations. One is to accept the reality of gene-culture co-evolution. In short, we should pick up where research petered out some two decades ago.

Amongst the overrepresented categories in genome-wide scans of recent selection are numerous alleles expressed in the human nervous system and brain. This raises the possibility that complex cognition on which culture is reliant (social intelligence, language, and challenges associated with constructing and adapting to new environmental conditions) have driven human brain evolution. Mathematical models exploring how genetic and cultural processes interact provide strong support for the role of gene-culture coevolution in human evolution.

Evolutionary psychologists should reconsider their assumption of a universal human nature. “For example, sex differences in mate preferences constitute a large proportion of EP research and are generally assumed to exhibit universal patterns.” Yet sex roles assume different forms in different human populations.

Another recommendation is to bridge the gap between postulated “psychological mechanisms” and actual neurons. We now have tools, notably MRI, that can locate where a specific mental activity occurs in the brain. Again, such research should take variation within and between human populations into account and not be confined to the usual participant pool of North American university students.

Finally, evolutionary psychologists should stop assuming that the human mind consists mainly of domain-specific programs. Much of our thinking is, in fact, domain-general.

Uh, what is ‘domain-general’? Think of a computer program that has plenty of sections or variables left blank. The blanks can be filled in with information, thus enabling the same kind of program to do a wide range of tasks. We call this in-filling process ‘learning.’

Learning thus takes place via programs that have already been partly hardwired. This is why we can learn some things better than others. There are also constraints on how fast we can learn, how much we can learn, and on how easily we can integrate learned information. Learning is not the opposite of genetic determinism. The two concepts are complementary.

By minimizing the role of learning, evolutionary psychologists not only lose the high ground of credibility but also give a free hand to those who say that humans can learn to think anything. A good example is the debate over social rules:

EP has engaged in a longstanding debate with advocates of cultural evolution over whether human social learning is governed by evolved content biases (e.g., choose the sugar-rich food) or by domain-general context biases (e.g., conform to the local norm). There is sufficient empirical evidence for the deployment of context biases, such as conformity or prestige bias, to render the casual dismissal of transmitted culture counterproductive. (Bolhuis et al., 2011)

Groupthink is a reality, and its persistence in modern societies should make it ideal for EP research. One puzzle of twin studies is the relatively high heritability of religious fundamentalism. Among twins reared apart, 40-46% of the variance seems to be genetic in origin (DiLalla et al., 1996). Perhaps there has been natural selection for humans who can more easily identify and comply with social rules, thus sparing themselves the pain of learning them the hard way.

This point is worth investigating because willingness to comply with rules varies from one individual to another, and from one population to the next. Some people have an unusually high level of rule compliance. Why? Is it learned or innate? Or a bit of both?

Some evolutionary psychologists have actually been moving in this direction. Denise Cummins (1998, p. 37) describes mental evolution as “a strategic arms race in which the weaponry is ever-increasing mental capacity to represent and manipulate internal representations of the minds of others.” In addition to ‘indicative reasoning’ (what is true or false), humans have a capacity for ‘deontic reasoning’ (what is permitted, obligated, or forbidden). For deontic rules, people look for examples of violations. For indicative rules, people look for examples of proof.

In short, indicative rules are subject to change, as people learn more about their environment. Deontic rules are not so easily changed. The latter generally change with a new class of higher-status individuals, who not only are the preferred source of deontic rules but are also seen as being above the rules. Thus, people more easily remember cheaters than non-cheaters, but this memory is weaker when the cheaters are high-status individuals (Mealey, Daood, & Krage, 1996).

All of this raises a problem for the Pleistocene EEA. Hunter-gatherer societies have little if any social stratification. The same is largely true for simple agricultural societies. The ‘big man’ is not a force for social stability and rule making. His dominance is transient, lasting as long as his strength, charisma, and ability to intimidate.

Societies became stratified only during the last 10,000 years. This time also saw the beginnings of lawmaking, codified morality, and organized religion. Of course, there is no reason why these phenomena could not have influenced human nature via gene-culture co-evolution. The last 10,000 years have seen more genetic evolution than the previous 100,000 … or even the previous million.

But to say so is anathema to those who still believe that the human mind stopped evolving over a million years ago.

References

Bolhuis, J.J., G.R. Brown, R.C. Richardson, and K.N. Laland. (2011). Darwin in mind: New opportunities for evolutionary psychology, PLoS Biol 9(7): e1001109. doi:10.1371/journal.pbio.1001109
http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001109

Cummins, D.D. (1998). Social norms and other minds: The evolutionary roots of higher cognition. In D.D. Cummins & C. Allen (eds.) The Evolution of Mind (pp. 30-50). New York: Oxford University Press.

DiLalla, D.L., G. Carey, I.I. Gottesman, and T.J. Bouchard Jr. (1996). Heritability of MMPI personality indicators of psychopathology in twins reared apart, Journal of Abnormal Psychology, 105, 491-499.

Mealey, L., C. Daood, & M. Krage. (1996). Enhanced memory for faces of cheaters, Ethology and Sociobiology, 17, 119-128.


25 comments:

Chris Crawford said...

I find myself nodding my head in understanding and agreement with almost everything in the post, but two sentences leap out at me:

1. "Evolutionary psychologists should reconsider their assumption of a universal human nature."

I always thought of it as a matter of various cultural attributes being more or less common, with an undoubtedly large group (200, according to Human Universals being universal, and another undoubtedly large group being strictly cultural in nature. "Human nature" is one of those dangerously vague terms that serves only to get us into pointless arguments. Better, I think, to talk about behavioral attributes or groups of behavioral attributes.

Is this consistent with your meaning? Am I just nitpicking?

2. "The last 10,000 years have seen more genetic evolution than the previous 100,000 … or even the previous million."

Wow! That's a really strong statement! Do you really mean to say that the human gene pool is changing 10 to 100 times faster than it was, say, 100,000 years ago? I could understand that if we were down to a population bottleneck with just a few people left; gene pools can change rapidly under such circumstances. But with 7 billion of us, it takes a long time for any genetic modification to work its way through the population. And a few thousand years ago, human mobility was so limited that it's hard to imagine how Roman genes could end up in Japanese babies, much less Mayan babies.

The rapid expansion of human population would suggest to me that selection effects are less powerful now, in turn suggesting that changes in the gene pool are taking place more slowly. I certainly agree that selection is still at work, and that the gene pool is changing. But it seems to me that the biggest changes would come from gene pool mixing. If I were to predict future changes in the overall gene pool, I'd expect the most salient development to be a spreading of the great diversity of the African human genome into the world population. But I'm just guessing.

Anonymous said...


I certainly agree that selection is still at work, and that the gene pool is changing. But it seems to me that the biggest changes would come from gene pool mixing.


Where are the genes for dyslexia these days? That is, up until perhaps 100 years ago, dyslexia, which is genetic, did not really matter, and such individuals in the Western world could pass those genes on. I would suggest that they have pretty much been flushed from the Western gene pool now.

If I were to predict future changes in the overall gene pool, I'd expect the most salient development to be a spreading of the great diversity of the African human genome into the world population.


What use is that diversity in the West or in an advanced civilization? Can you cite specific cases where it would be useful? Maybe you hope to get more whites into the elite sprinting crew?

Chris Crawford said...

"What use is that diversity in the West or in an advanced civilization? Can you cite specific cases where it would be useful?"

No, I can't cite specific cases. I am instead relying on a general principle about sex, parasites, and disease: the more diverse the gene pool, the more robust a species' response to a new pathogen. On a broader level, it is thought that a highly diverse gene pool gives a species a large library of responses to any environmental change.

Anonymous said...


No, I can't cite specific cases. I am instead relying on a general principle about sex, parasites, and disease: the more diverse the gene pool, the more robust a species' response to a new pathogen. On a broader level, it is thought that a highly diverse gene pool gives a species a large library of responses to any environmental change.


Humans use behavior to reduce the effect of some parasites (fleas, mosquitoes--eg, poisons etc), and for others, the MHC is very diverse, even among whites.

Given that we are a highly social species, and that some of us, eg Europeans and East Asians, have lived in highly complex societies for the last several thousand years (4-5 possibly for east asians) we do not need diversity in the areas, I would suggest, that Africans can provide, but need it in genes related to cognition and complex systems. We have less need for fast-twitch muscle fiber.

Of course, at the end of the day, if we, with our complex societies destroy ourselves, the Africans might well have the last laugh.

Reader said...

My problem with Evolutionary Psychology is that it's a predominantly male field. As such, it's a mostly male, logical view of the world which is largely unsupported by female experience.

Other than Sarah Hrdy I struggle to think of any females who agree with EP. There was a particularly negative article about it written by a woman who is a Newsweek columnist: Link

Worth reading, although it's 5 pages long. I used to be really into EP in the past, but have backed off in recent times.

She disputes many of the typically male ideas about courtship and mating, for example, that were put forth by the male EP commentariat, such as that women care a lot about men's resources, that women go for older men, that beauty standards are universal and innate, etc.

All of these have on many occasions been proven false in my own experience, as well. I find a lot of examples in daily life that contradict the tenets of EP, although I used to be a strong believer in the past.

Until I come across a book written by a female EP author, I'll continue to be a little skeptical. I think we have to face the fact that all of us posting on this site are men (I don't know if Peter has had any female readers), and there's a whole world hidden from us. Just a thought.

Chris Crawford said...

First off, I'd like to retract (with much embarrassment) my comments regarding the increase of genetic change in the last ~30K years. I went back and re-read a few papers on the subject and realized that the DNA evidence unquestionably supports that representation. I need some time to do some mental re-adjustments.

Anonymous, you state that the rest of humanity does not need the genetic diversity of the African gene pool. Our knowledge of the African gene pool is still limited in details; we know that it's more diverse than the Eurasian gene pool, but we do not know what the actual genetic traits being varied might be, nor how they might affect the rest of humanity. I cannot see how your point is justified when we don't have the knowledge to justify it.

Reader, your post is shamefully sexist! I don't care who writes the material. I don't care if the author is black, white, Christian, Muslim, Chinese, Uzbeki, Republican, Democrat, rich, poor, or male or female -- and you shouldn't either. The only consideration should be the verity of the material, as determined through research and informed discussion.

If you really must know, Leda Cosmides -- a woman -- is one of the founders of evolutionary psychology. And that shouldn't matter one way or the other.

chris said...

@Reader

"My problem with Evolutionary Psychology is that it's a predominantly male field. As such, it's a mostly male, logical view of the world which is largely unsupported by female experience.

Other than Sarah Hrdy I struggle to think of any females who agree with EP. There was a particularly negative article about it written by a woman who is a Newsweek columnist: Link

Worth reading, although it's 5 pages long. I used to be really into EP in the past, but have backed off in recent times.

She disputes many of the typically male ideas about courtship and mating, for example, that were put forth by the male EP commentariat, such as that women care a lot about men's resources, that women go for older men, that beauty standards are universal and innate, etc. "

see http://www.psychologytoday.com/blog/homo-consumericus/201105/evolutionary-psychologists-are-largely-composed-sexist-men-except

"All of these have on many occasions been proven false in my own experience, as well. I find a lot of examples in daily life that contradict the tenets of EP, although I used to be a strong believer in the past."

scientific study > anecdotal experience

individual case != average rule

Reader said...

I knew someone was going to mention "facts" and "verity of the material."

The thing is that there are several verities. The tendency to systemize, analyze, and reduce the world to observable facts and logic is a distinctly male, linear way of thinking. There is nothing wrong with it, I have the same mindset because I'm male. That's why there are so many male atheists, for example, and hardly any female ones.

The problem is when males begin to ascribe certain beliefs or behaviors to the other half of the population, namely females, who have never confirmed those beliefs or behaviors.

Have you ever spoken with women regarding their assumed preference for older men, or about their assumed interest in securing commitment from men and pair-bonding, as EP would have us believe? I have, and their reaction was vociferously negative. Nearly all of them rejected these findings.

I just have trouble dealing with the implication that the female gender is dumb, since they disagree with our male "facts" (generally speaking). Certainly, women are not dumb. But then why do they not sign on to the tenets of EP?

Anonymous said...


I just have trouble dealing with the implication that the female gender is dumb, since they disagree with our male "facts" (generally speaking). Certainly, women are not dumb. But then why do they not sign on to the tenets of EP?


Real psychology 101. It is not in someone's interests to agree that they behave the way good theory suggests that they are likely to behave. They lose considerable behavior flexibility that way, and especially, lose the ability to maximize their value in the sexual marketplace.

Thus, for example, males are likely to deny that they are philanderers because that way they are more likely to get into a woman's pants.

Anonymous said...


Anonymous, you state that the rest of humanity does not need the genetic diversity of the African gene pool. Our knowledge of the African gene pool is still limited in details; we know that it's more diverse than the Eurasian gene pool, but we do not know what the actual genetic traits being varied might be, nor how they might affect the rest of humanity. I cannot see how your point is justified when we don't have the knowledge to justify it.


The experiment of introgressing African diversity into the European gene pool has already already been tried. It has been a dismal failure, as Diversity is Chaos shows.

Proof that we don't need that diversity.

Chris Crawford said...

Reader, I think you're struggling with some serious misunderstandings about a) males; b) females; and c) EP. First, the research on cognitive skills shows no gender-based differences in such things as "logical thinking". There ARE some differences in spatial reasoning and social reasoning, and a few other things, but there's nothing in EP claiming that men are smarter or more logical than women.

I'd also suggest that you be very careful about anecdotal evidence, because your personal experience is a microscopic subset of the universe of human behavior.

Lastly, I urge you to be careful about your interpretation of what EP actually says. People who have only a passing acquaintance with EP seem to have this fixation with the notion that EP is deterministic: that your genes dictate your personality. This is a hoary old argument ("nature versus nurture") and it's a complete waste of time. The relationship between genes and culture is extremely complex and many issues are still being hammered out. I myself like to think of personality as a layered structure: the genes provide the foundation, culture is built on top of that foundation, and individual experience lies on top of that. We all share the same basic foundation, but it's hard to see that foundation because it's buried underneath the other two. Hence, genetic heritage influences behavior only in an abstract, generalized way. Culture operates at a more visible level, and individual experience is the final icing on the cake that differentiates one person from another.

Here's another way of putting it: all vertebrates share the same basic skeletal layout: spine, head, arms, legs, and tail. Thus, I have the same skeletal organization as lizards, birds, fish, and horses. That skeletal organization is analogous to the genetic foundations of our behavior. Despite the many differences between humans and these other species, there are a lot of commonalities: movement usually involves some twisting of the spine; we generally move in the direction we're looking, which is also the direction we're facing; we ingest food in our heads/fronts and expel waste towards our rear; and so on. These are very general statements, and there remain plenty of interesting exceptions. But they're still useful generalizations that help us understand some things.

If we want to understand more, then we look more specifically at different classes or even families. And the closer we drill down to a species, the more precise we can be in describing behavior.

Chris Crawford said...

The experiment of introgressing African diversity into the European gene pool has already already been tried. It has been a dismal failure, as Diversity is Chaos shows.

Proof that we don't need that diversity.


Whoa! This sure smells like gross racism. PLEASE disabuse me of such an ugly suspicion.

gcochran said...

Sharon Begley, that Newsweek columnist, is a complete idiot. That hardly proves that folk like Tooby and Cosmides are correct, but it is worth knowing.

Peter Frost said...

Chris,

By "human nature" I mean hardware not software, i.e., genetic influences on human behavior.

Human genetic evolution has not been linear. It's more like an exponential curve, with most of the changes taking place on the right-hand side of the chart.

Hawks et al. found that the pace of genetic change rose over a hundredfold when hunting and gathering gave way to agriculture beginning 10,000 years ago. So, yes, the past 10,000 years have been more important than the previous million.

J. Hawks, E.T. Wang, G.M. Cochran, H.C. Harpending, R.K. Moyzis, Recent acceleration of human adaptive evolution, P Natl Acad Sci USA. 104 (2007) 20753-20758.

I don't share your belief that diversity is a good thing in and of itself. There have been a number of studies on this point, and they generally show a negative correlation between the adaptiveness of a trait and its variability. In short, excess genetic variability is like excess weight. You're better off without it.

Reader,

There are a lot of women in evolutionary psychology, and not just Sarah Hrdy. Linda Mealey, Helen Fisher, Michele Surbey and, of course, Leda Cosmides come to mind. Women are especially well represented among the youngest generation of evolutionary psychologists.

Are women well represented in other branches of psychology?

Anonymous said...

Chris Crawford starts throwing around the racism word and says:


Whoa! This sure smells like gross racism. PLEASE disabuse me of such an ugly suspicion.


That doesn't work. Please disabuse me of the thought that you are a wanker.

The first article currently at that site points out that those with African ancestry have a higher propensity for food sensitization and allergies.

Another useful fact for you. I work in Silicon Valley. The percentage of tech workers with black ancestry is much lower than their percentage in the general population or even their percentage in CA, however, Chinese make up a very large percentage of tech workers as do Indians.

Chris Crawford said...

Peter, what do we know about the "ideal size" of a gene pool? I know about the rule of thumb for 500 individuals as a minimum for species viability -- presumably that minimum reflects something about inbreeding. Inasmuch as genetic diversity (and sex) are a species' first line of defense against pathogens, we'd expect the genetic diversity of a species to somehow reflect the average pathogen load for members of that species. I admit, most people in the developed world have a low pathogen load, and certainly the high genetic diversity in Africa is related to the high pathogen load from all those lovely tropical diseases. I suppose that we could argue that, in the absence of tropical diseases, we don't need that much genetic diversity. I think I'll look into this issue more carefully.

Anonymous, I don't think I want to have any further interactions with you.

M said...

Anonymous, you state that the rest of humanity does not need the genetic diversity of the African gene pool. Our knowledge of the African gene pool is still limited in details; we know that it's more diverse than the Eurasian gene pool, but we do not know what the actual genetic traits being varied might be, nor how they might affect the rest of humanity.

In the long term, African variants seem certain to be useful, provided the appropriate selective context, but in the short term, most traits we find desirable and enriched in Eurasian populations are I believe mostly additive (IQ is mostly additive, apparently), without hybrid vigour dominance effects, so greater percentage of African ancestry is in general not going to be anything other than worse from our perspective (and possibly "evolution's perspective" - although Africans seem to reproduce in relatively great numbers, and that is "fitness").

Although if we go by standard theory that they most African specific variants built up pre-Holocene, either as picked up from archaic Homo in Africa or due to large population size in Africa and bottlenecks, it would seem comparatively unlikely that they are particularly useful in post-Holocene contexts, rather than selectively neutral (although I'm sure even, e.g. chimpanzees would have *something* useful we could extract from them - just that most things would be not).

Peter Frost said...

Chris,

The mating network of modern hunter-gatherers is between 175 and 475 individuals.

Sub-Saharan Africans have more genetic diversity largely because they have stayed put in the same place and accumulated more "junk variabilty." Please see my previous comment: the more variable a gene is, the lower its adaptive value. There are exceptions (balanced polymorphisms and the like), but this rule of thumb generally holds up.

Ancestral Eurasians were a much smaller 'founder group' who took only a small part of this variability with them.

Anonymous said...


(and possibly "evolution's perspective" - although Africans seem to reproduce in relatively great numbers, and that is "fitness").


K vs R.

When you hit the Malthusian limit, or exceed it (which at times you can do) the crash causes problems.

Chris Crawford said...

Now I'm really confused! I was under the impression that density of pathogens was a major factor in genetic variability, because of the arms race between pathogens and their victims. I suppose that the deciding data would be a comparison of genetic diversity of tropical Amerindians with temperate Amerindians.

Obviously, I have much more reading to do.

Anonymous said...


Ancestral Eurasians were a much smaller 'founder group' who took only a small part of this variability with them.


Dienekes has this to say: Admixture confounds effective population stuff

He also suggests that selection must have been intense for those out of Africa which makes sense. I suspect that admixture allowed them to help themselves to well adapted alleles from already established out-of-Africa populations.

This also relates to whether or not that diversity back in Africa is useful, given that lots of it would appear to be random junk and other parts of it has been selected against during (some of our) sojourns out of Africa.

Peter Frost said...

Chris,

A major factor? No. There are a number of balanced polymorphisms that provide some protection from different pathogens (e.g., malaria), but they do not explain the high genetic variability in sub-Saharan Africa. We see the same accumulation of junk variability in nonhuman primates, e.g., bonobos. If a population stays put in one place and doesn't get squeezed through bottlenecks or founder events, it will accumulate a lot of variability that isn't phenotypically expressed.

Anon,

You're referring to the Cochran-Hawkes theory of gene "cherry-picking." One example was supposed to be the latest microcephalin variant. That turned out to be ... untrue.

Cherry-picking assumes that archaic humans had a lot to offer modern humans. I don't think so. Even when they were adapting to similar environments, moderns and archaics resorted to very different adaptive strategies.

But I could be wrong. All I ask is to be proven wrong.

Anonymous said...


Cherry-picking assumes that archaic humans had a lot to offer modern humans. I don't think so. Even when they were adapting to similar environments, moderns and archaics resorted to very different adaptive strategies.


Since many of us are unfamiliar with those different strategies, perhaps you could explore them in a later posting.

However, before the advent of Quinine, those who had picked up some sickle-cell anemia (including some in the Mediterranean) would be at an advantage over whites in much of sS-Africa.

Anonymous said...

"Evolutionary psychologists should reconsider their assumption of a universal human nature."

I think it's more a question of layers. I think it's quite possible there's a *base* universal human nature but that base has been modified among different groups in different places in different ways.

If so then i think a bigger question is if the base nature has been *over-written* in part by later changes or whether it has been *over-ruled* by later changes. If it's the second option then there will be a permanent conflict between the various layers and that will be an important factor in human behavior.

I think the most likely option is that the base is something like

1.1.1.1.1

and different groups have developed different overlays so European might be

-.2.2.-.-

giving a result of 1.2.2.1.1

whereas East Asians might have an ovelay -.-.-.2.2

giving a result of 1.1.1.2.2

with Japanese maybe having a third overlay

-.-.3.-.-

giving 1.1.3.2.2

etc

Layers.

If so then a clear and full understanding of the base is a good first step.

Drive-By Poster said...

Reader, the first thing you need to learn is to to judge by actions rather than words. Second, systematized thinking isn't "linear", because complex systems aren't linear! Third, if women are not too good at it, then that's too bad for them. It's impossible to think scientifically without thinking systematically.