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220px-Great_Lizard-cuckoo_(Coccyzus_merlini),_cropped As I have stated before one of the strangest things to me is the ‘urban myth’ among many biologists that 10% of children exhibit misattributed paternity. In plain English, one out of ten fathers of any given child are not their biological fathers, though that is the social understanding. So this excludes children who were adopted and such. In general these are explicitly cases where the putative father is unaware that he’s been cuckolded. The 10% figure is a nice round number, and I regularly hear it in the public arena, but it is also surprisingly pervasive among academic scientists. A few years ago I was in a seminar where a behavioral ecologist alluded to the figure in passing, and being who I am I had to raise my hand and object that it just wasn’t the true. The researcher, who did not work with humans, was genuinely surprised at my objection, and didn’t seem to be particularly invested in the figure he gave, and was quite open to updating his beliefs about this issue. I experienced this again on Twitter recently, where a biologist casually referred to the 10% value, and I pointed to my 2010 post which leans heavily a on 2006 meta-analysis, which suggests values closer to 1-3%. Instead of being defensive, he simply acceded to the new information.

More recent work seems to have confirmed this finding: Low historical rates of cuckoldry in a Western European human population traced by Y-chromosome and genealogical data. It seems obvious that a 10% rate of confused paternity is going to show up in a discordance between genetic and genealogical paternal lines. The authors of the above paper use two methods:

…based on an unbiased population-wide sample, the Y chromosomes of presumed patrilineally related males were compared with each other. Subsequently, EPP rates were estimated based on the discrepancy between the legal genealogy and the actual genetic relatedness. Second, the historical EPP rate within Flanders was estimated based on the genetic traces of a substantial past migration event from northern France to Flanders.

For the Flemish in Belgium the rates were 1-3%. Perhaps the Flemish in Belgium are unique, but that seems unlikely. There have been a reasonable amount of studies in Western Europe on this topic, and this is in line with other results. There may be cross-cultural differences though. But my bet is that in parts of Asia where there are long-term patrilineages, such as China or Mongolia, you’ll come up with a similar figure. The situation might be different in “small-scale societies,” and in particular those where women are primary economic producers, and not particularly dependent on male resources (these tend to be matrifocal societies, where agricultural labor depends on the hoe and not the plough).

But going back to the 10% figure, consider what it would mean if it was correct. In a random family of two children in about one out of five cases there’d be misattributed paternity in at least one of the families*. Most people have at least five close friends, so misattributed paternity wouldn’t be an abstract issue, it would be something you’d confront in your day to day life. Additionally, it seems unlikely to me that the chance of conception from affairs is going to be higher than within marriages, because many would take precautions in illicit relationships. So the proportion of sexual activity that is “extra-pair” is going to have to be rather high. Is that plausible? The major caveat here is that there are differences between population segments, not just across cultures. The rates for high status individuals seems very low. The rates for low status individuals seem rather higher. The 10% figure is actually not that implausible from samples which are skewed toward the underclass, which is often the case when you are looking at laboratory data uncorrected for background variables (i.e., the men who avail themselves of paternity testing services are not an unbiased sample of the population; they usually have something to worry about at a much higher rate).

The final conclusion is that we should be rather happy that the rates are likely far lower than 10%. A lot of work on extra-pair paternity has been done on birds, and here’s a paper from 2013, Faithful females receive more help: the extent of male parental care during incubation in relation to extra-pair paternity in songbirds:

Parental care provided by males occurs in a diverse array of animals and there are large differences among species in its extent compared with female care. However, social and ecological factors responsible for interspecific differences in male’s share of parental duties remain unclear. Genetic fidelity of females has been long considered important. Theory predicts that females should receive more help from their mates in raising the offspring in species with high genetic fidelity. Using avian incubation behaviour as a model system, we confirmed this prediction. The extent of male’s help during incubation increased with decreasing rate of extra-pair paternity across species (22 species of socially monogamous songbirds from 13 families; male’s share of incubation ranged from 6% to 58%), even after accounting for covariates, biases in species selection and intraspecific variability. Moreover, this result was not sensitive to two different phylogenies and branch length estimates. We suggest that our findings support the notion, backed by theory, that genetic fidelity is an important factor in the evolution of male parental care. We offer several behavioural scenarios for the coevolution between male’s share of parental duties and the genetic mating system.

The basic theoretical logic is pretty obvious. If cheating “pays,” then it will become ubiquitous until everyone becomes a cheater, and the social system will converge upon a new equilibrium. You can have low female fidelity and low male investment in family life, or you can have high female fidelity and high male investment in family life (assuming that the child-mother relationship is the core of a family), but exchanging the traits is probably not a viable long term proposition (see: Hippy communes, which tend to have short half-lives, or societies such as in the highlands of Papua, where males don’t invest much in offspring, but paternity is not a major social issue where sanction is ferocious as in other societies). High fidelity from females toward males who do not provide any resources or care of offspring seems irrational. And conversely, high male investment in offspring that are highly possible to be another male’s seems irrational.**

* Obviously it is unlikely that the events are independent probabilities, so there are more likely to be cases that both children being misattributed than one would expect from assuming that each child has a 10% chance of being from a different biological father.

** From an evolutionary perspective.

• Category: Science • Tags: Evolutionary Psychology 
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Someone named Dan Slater recently wrote a book, Love in the Time of Algorithms, and has an op-ed out titled Darwin Was Wrong About Dating. The piece is littered with generally unpersuasive refutations of the relevance of a Darwinian framework in understanding the evolutionary origins of human behavior. I say this while granting that I have come to find much evolutionary theorizing somewhat shoddy. But that’s true for much of science, and scholarship more generally. It just so happens that evolutionary psychology has social and political relevance, while other fields do not. Wrong science does not negate the importance of an evolutionary framework.

The ultimate question is whether you believe that human behavior has a significant biological basis (or more frankly, does any behavior have a biological basis aside from homosexuality?). This does not imply that human behavior has an exclusive biological basis. Nor does it specify the precise nature of that basis. Gorillas, chimpanzees, and bonobos all exhibit different behavioral patterns in socialization and mating which likely have some biological basis, but they are all rather varied. And if you accept the additional proposition that “Nothing in Biology Makes Sense Except in the Light of Evolution”, then you need to start considering an evolutionary context for the emergence of human cultural forms.

To me the power of evolutionary thinking should not be seen to be equally relevant as a prior in all circumstances. What raised my eyebrows is that Slater suggests that “But the fact that some gender differences can be manipulated, if not eliminated, by controlling for cultural norms suggests that the explanatory power of evolution can’t sustain itself when applied to mating behavior.” First, if you haven’t bothered to read the piece, it presupposes a classic straw man of essentialism. The reality is that evolutionary analysis demands some level of ‘population thinking.’

More importantly, when it comes to mating behavior in particular evolutionary considerations are likely much more powerful and should be given more weight. That is because mating behavior, or lack thereof, has such a strong impact on reproductive fitness. Natural selection works through correlations between variable fitness and phenotypes, where the latter exhibits heritable variation. Imagine that James Deen’s preference for non-procreative intercourse was strongly heritable (perhaps due to a major loss of function mutation). Obviously natural selection would operate against it. A persistence of ‘maladaptive’ behaviors in a first order sense shouldn’t make us reject the logic of natural selection, but probe the further structure of the phenomenon (e.g., the handicap principle).

Ultimately for me the issue isn’t whether evolution has power to shape our behavior. Rather, consider what the world would be like over the course of human natural history if evolution did not constrain our behavioral patterns. Would we see be able to predict the world around us, both in the present and the recent past? Charles’ Darwin’s descent with modification and natural selection framework actually is extremely persuasive to many because it explains the patterns one perceives in molecular phylogenetics, a field which came to fruition over a century after Darwin’s death. Does the behavior of humankind over the past 100,000 years make more, or less, sense in an evolutionary framework? I would say more, but there is much that is clouded or unclear, and so will be the purview of social scientists. It isn’t that Darwin was wrong, it is that Darwin is not all. Nor do many make such a claim.

• Category: Science • Tags: Evolutionary Psychology 
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Greta Scacchi, cousin-lover

There has been some discussion in the comments why the posts on inbreeding are getting so much attention. I think this is a milder form of the same sort of curiosity about why young males have a fascination with pornography: we are obsessed with sex. This is not an arbitrary fascination, nor is it a loss of innocence which may have been avoided. Sex is our raison d’etre as sexual organisms. Evolutionary psychology gets a bad reputation for positing adaptive explanations for everything under the sun, from dancing to migraines. But, if there is anything which is the target of adaptive constraint and selective pressures, it is the suite of traits which relate to sex and mating in a direction fashion. It is sometimes stated that sex is about power, but the bigger reality is that power is about sex.

But reducing human behavior purely to one explanatory framework is too reductive even for me. An individualist framework where singular males and females operate as evolutionary versions of rational H. economicus, always optimizing fitness through subterfuge and inducement, leaves something to be desired in characterizing the true rich tapestry of human behavior. And this tapestry is not arbitrary; rather, its general shape and topography is anchored by particular innate parameters.

For example, the story of Tristan and Iseult seems clearly to be rooted in a common human archetype, an evoked aspect of human complex societies where cultural necessities can work at cross-purposes with individual biological dispositions. Humans evolved as a species in relatively small-scale groups. Though I am skeptical of the idea that pre-Neolithic societies were atomized down to the level of only small bands, I do think that the rise of agriculture resulted in the emergence of new cultural forms and complexities. Hunter-gatherers clearly have their own taboos and social constrictions, but civilizations have transformed this segment of the cultural toolkit into massive and baroque scaffolds which constrict our impulses. For thousands of years it seems likely that young women such as Deirdre have been “given” to older men of power such as Conchobar. There is benefit in this arrangement for all. Men of power can breed with nubile young women, transforming their status into reproductive value. And, as Chinese history and the life of Anne Boleyn tells us there is much gain for these women and the families of these women who subordinate natural impulse to rational calculation. Yet still, impulses do quite often break free and negate rational calculation (see: Catherine Howard).

I have stated before that the customs and traditions which many Westerners perceive to be “conservative,” a fixation on female honor, elaborated patriarchal lineages, complex familial and social hierarchy, etc., are in fact innovations of the age of agriculture. They were cultural inventions designed to manage and control humanity in an organized fashion, as a scattering of souls congealed into vast rivers of people. The past few centuries, and in particular the past few decades, have seen a collapse of much of the old institutional order. But hunter-gatherers did not live by impulse alone, as is clear in the results of the communes of the 1960s and 1970s. Love is never free, there are always consequences, both biological and psychological. Not only did hunter-gatherers have their own cultural mores, but we do not live in the world of hunter-gatherers. It may be that particular norms and customs at tension with our evolved intuitions are still necessary to bind us together as societies, where the many may cooperate to facilitate the flourishing of all.

Where does incest come into all of this? As I have noted earlier the Westermarck effect illustrates that extremely close first order incestuous relationships (father-daughter, sister-brother) are not favored in a deep evolutionary sense. And yet such incest can be favored and propagated by culture! The incest between near relations among ancient Egypt’s elite is well known, but apparently the practice also spread to the peasantry via emulation. I am willing to bet that sex with your brother or sister is not as satisfying as sex with someone with whom you are not related (though I would appreciate no anecdata in this domain!), but clearly cultural forces can even favor this arrangement.

The major issue comes to relations between relatives at some remove. I do not think there is nearly a strong case for aversion to relations with first cousins beyond what might be covered by the Westermarck effect due to extended family cohabitation. And unlike first order incestuous relationships the biological abnormalities of the offspring of first cousins are sharply mitigated. They are at worst comparable to the risks which older parents may be foisting upon their children by conceiving them later.

But, I think that cousin marriage as a norm should still be discouraged, just as polygamy as a norm should be discouraged. From the perspective of an elite male polygamy is arguably the more natural arrangement! But man does not live on an island. While individual instances of cousin marriage and polygamy can allow for flourishing, as a whole societies where these practices are normative and ubiquitous suck. When I say they suck, I mean that they suck from the Western liberal perspective where a level of egalitarian individual access to self-actualization and flourishing is prized.

When considering social arrangements I believe it is critical to focus less on individual first principles, and look to a more holistic set of metrics which value the organic community, from which individuals often derive such explicit and implicit psychic gratification. I suspect that one can argue that the cognitive toolkit we have today is very well equipped for life in small bands. Perhaps the closest analog to this are the cliques and circle of friends which young people develop. There is no need for institutional formality or a detailed set of prescriptions of behavior. Natural disposition and impulse can operate nearly perfectly on this scale. But we do not live merely in our own small social bubbles, we are embedded in a larger society. And for that there may need to be a cultivation of traits, tendencies, and dispositions, which are at cross-purposes which our selfish natures.

To have a real discussion about what the proper balance between our moral intuitions and the necessary social engineering of a complex post-industrial society is we need to reinsert communal values into the discussion. Not just what are the aims of you as an individual maximizing your own happiness. Not just what rights and responsibilities you as an individual have. But what is the vision for the society as a whole, and what are its goals, and what equilibrium would perpetuate the greatest good for the greatest number.

Image credit: Georges Biard

• Category: Science • Tags: Anthropology, Evolutionary Psychology, Sociology 
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A reader reminded me of an amusing paper, Who Likes Evolution? Dissociation Of Human Evolution Versus Evolutionary Psychology. The gist of the results are below (I added some clarification):

The propositions to gauge acceptance of evolutionary psychology revolve around sex differences. One can argue whether this is an appropriate measure, but to a first approximation I think it gets to the heart of the matter. There are deep evolutionary genetic (number and size of gametes) and anatomical reasons to assume that sex differences in behavior are not exclusively a function of cultural variation. One can argue about the details of the inferences that evolutionary psychology makes (I think it is subject to the problems rife in psychology as a whole), but I don’t think its ultimate underpinning in sociobiology is crazy.

Nevertheless, I do think there are some empirical results which are robust enough across a range of studies and observations that we move from theoretical likelihood to concrete assessment of the probability of a particular sex difference. For example, the idea that males on average all things equal tend to exhibit more aggression than females. To me this seems to be very low hanging fruit among the range of hypotheses. And yet many people are not willing to admit this. This is where I throw my hands up in the air. The fact is that my friends’ protests to the contrary the problems with evolutionary psychology as it is today tend to engender sneering, more than attempts to rectify the situation and produce a real inter-disciplinary science of humanity.

Which brings me to H. Allen Orr. Within evolution Orr is probably most well known for a body of work which culminated in his book co-authored with Jerry Coyne, Speciation. But for those outside of evolution Orr is probably more well known for his writings in The Boston Review and The New York Review of Books. In these venues he has engaged in broadsides against Intelligent Design, the “New Atheism,” and, evolutionary psychology. I assume from the results above that those who accept evolution but reject evolutionary psychology do so because they have read H. Allen Orr, a practitioner of the evolutionary arts himself, and understand on intellectual grounds biology can not tell us much about human affairs.

Note: For a core cadre of literal readers: the title is sarcasm.

• Category: Science • Tags: Evolutionary Psychology 
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Last night I listened to a very long discussion between Robert Wright, author of The Moral Animal, and Jonathan Haidt, author of The Righteous Mind: Why Good People Are Divided by Politics and Religion. If you have been reading my weblog for years there may not be much new, but if you haven’t, then you’ll encounter a lot of novel information, in particular from Jonathan Haidt. I was intrigued by Haidt’s references to evolutionary and anthropology, and I immediately noticed on Twitter that of the 17 people he follows, two are John Hawks and Paul Bloom. John is a friend, and Paul Bloom has been highly influential in my own thinking about cognitive psychology (see Descarte’s Baby). Additionally, many of the other “shout outs” which Haidt makes are familiar to me as well (e.g., Scott Atran, the neo-functionalism of David Sloan Wilson, etc.).

In lieu of a conventional blog post here a list of comments, reacting mostly to Haidt’s various assertions.

– The biggest “bombshell” that Haidt drops is his empirical finding that when people of a given political ideology, going from very liberal to very conservative, are asked to model the opinions of other people when it comes to their “moral foundations”, only one group mischaracterizes the others. That group consists of those who are “very liberal”. Haidt reports that very liberal respondents tend to incorrectly predict the rationales given by conservatives for their positions, whereas moderates and conservatives characterize the rationales given by liberals accurately. Why?

Haidt’s explanation is that liberals tend to emphasize only a subset of moral foundations, while non-liberals emphasize a more diverse palette. By analogy then it is difficult for someone who can not taste “sweetness” to understand why anyone would crave sugary foods. In contrast, non-liberals can appreciate some of the flavors which liberals appreciate, and so can properly identify that the liberal position consists in large part of amplifying the importance of those dimensions, to the neglect of others.

This is a finding which will require a great deal of digestion. Though I identify for various reasons on the political Right, my own “moral foundations” tend toward liberalism. My shift away from this position as a conscious choice had to do with rational reflection on the nature of human flourishing more generally. So I find Haidt’s argument appealing and plausible, insofar as I still tend to have difficultly in a deep reflexive sense understanding many of the impulses of a more standard issue human.

One prediction here is that in your personal life you might observe that while liberals mischaracterize conservatives, conservatives caricature liberals. Caricatures might be misleading, but they consist more of exaggerating salient tendencies beyond normality, rather than constructing new features. Another aspect of this result which bears rumination is that liberals in particular are ill-served by living in a cultural “bubble,” because they lack an intuitive grasp on the moral cognition of non-liberals. This might explain the constant liberal gripe that people “vote against their interests,” as liberals define “interests” in a manner which does not conform to the full range of values which other groups hold (or, liberals view those values as fundamentally irrelevant or illegitimate).

As a younger person I spent most of my time around religious conservatives. Today almost all of my time is spent around secular liberals. As a right-wing atheist I’m not subject to a “bubble” of like-minded people (I am not a libertarian). As an observation after the fact I would suggest that religious conservatives had a tendency of reducing liberals to pure hedonic calculators. This is a caricature, and does not capture the fullness of the liberal moral imagination. But, it does grasp upon the reality that the liberal disposition emphasizes hedonic needs (i.e., material conditions) to a greater degree than non-liberal dispositions (i.e., spiritual conditions).

– I’m not sure about the particular utility of Haidt’s moral foundations. I believe they capture some element of reality, but like a lot of social science conceptual frameworks they strike me as always subject to post hoc “fine-tuning,” to the point where you have to question their usefulness. For example, there are plenty of liberals of environmentalist bent who are quite post-materialist. These are the same set who would oppose genetically modified foods, and “playing God.” Who are these people in this framework? Note how Haidt gets a little confused about libertarians. I think he handles them appropriately, but there are limitations to the model he is pushing forward (though it is probably an advancement over some of the stuff that George Lakoff was selling about 10 years ago; Lakoff in fact struck me as one of those very liberal people who didn’t understand non-liberal cognition except through his own presuppositions).

– Haidt is familiar with a lot of evolutionary and anthropological literature. The main problem I have here is that his arguments seem inordinately to rest upon tendentious areas of contemporary science. He accepts the existence of multi-level selection in humans, and recent adaptive acceleration in humans during the Holocene. I’m probably moderately skeptical of the former and moderately convinced of the latter, but the point is that there is still debate going on about these topics. The more disputed areas his argument necessarily rests upon, the more likely it’s likely to collapse because the probability of Haidt picking “winners” in all these case is not high (in part because he’s not a specialist in those domains).

– He also references the issue of “missing heritability” (though not by name) and the fact that quantitative traits have not been well served by modern genomics. I think he’s spot on here, but he does overreach on occasion. For example, statistical geneticists are getting a sense of the genes which are responsible for north vs. south European height differences. He also reports some older literature on dopamine receptor genes. This goes to show that always relying on the latest science can be problematic, insofar as you rapidly become outdated if you don’t keep a hawk’s eye on the literature. It seems he’d have been better served relying on a few moderately old paradigms, limiting his downside risk, and also setting as background parameters tried & true models.

– Then Haidt touches upon the fact that many Left-liberals are generally are hostile to research which conflicts with thir normative presuppositions. Here I have somewhat mixed feelings. For example, he points out that many cultural Left-liberals have been wary of critiquing the rising rates of illegitimacy for fear of offending groups which they label as victims (e.g., single mothers, blacks, etc.). These trends have had negative social effects, and there’s a robust social science on this. Children of “broken homes” have more difficult life outcomes. But the problem here is that these studies almost never correct for family genetic correlations. By this, I mean that if a person is a child abuser, and their parents’ were child abusers, the presupposition is often that the individual modeled child abuse from their parents. This neglects the reality that these individuals share genetic correlations, and there may be biological dispositions toward high aggression and low empathy being transmitted across the generations. In fact the behavior genetic literature which Haidt references finds that there is often only a minimal parental environmental influence on long term life outcomes.

Does this mean that we shouldn’t care about the illegitimacy rate? No. Rather, instead of focusing on individual variation and outcomes, we need to focus on the effect of changes on the broader social environment because of the importance of norm of reaction. By this, I mean that genetics is good at predicting variation in the context of a given background environment. To paraphrase Hillary Clinton, “it takes a village.” The impact of illegitimacy may be less upon a given individual, and more upon broader social dynamics, such as anomie, which percolate back to the individual. By analogy, consider someone who has a disposition toward alcoholism. If they were raised in Provo, Utah, the disposition would remain. Their odds of becoming alcoholic would be far higher than someone who did not have the genetic disposition. But their chance of becoming an alcoholic may also be far lower than someone without the disposition who was raised in Denmark! Why? Because the social norms differ so greatly. In fact, Provo’s social norms may be more powerful than the norms of the family the individual was raised in.

The reason I want to focus on the collective is that Jonathan Haidt is pointing out liberal concern about ostracism and exclusion of groups and individuals, but the key is to move the scale of social action and reform the collective whole. I believe this would obviate Left-liberal discomfort about picking on victim groups (to be clear, I think this sort of position would be mildly disingenuous, but if the only way to get everyone on board is a little shading of the details to make them more comfortable that would seem prudent; see theistic evolutionism for another example!). Left-liberals seem wary of overdue emphasis on individual responsibility, but more willing to ascribe individual outcomes to broader social phenomena out of the individual’s control. If illegitimacy was framed in such a fashion, concerns over the dynamic might gain some Left-liberal support. If the key is to transcend material causes, it might be possible as is made clear when it comes to environmentalism (yes, I understand many environmental arguments are materialist, but many clearly are not)

Staying on taboos, near the end of the diavlog Wright and Haidt have a long discussion about moral sensibilities and race. Haidt reprises his comment in Edge (I can’t find it in Edge’s ghetto website) that different populations may have different moral sensibilities due to recent human evolution. Imagine if conformity was a quantitative trait, and you select upon that trait, shifting the trait distribution. It’s not too hard to imagine different selection regimes resulting in different distributions. Haidt argues that because of liberal concern for racism such questions can never be addressed on prima facie grounds; in other words, liberals ignore science when it does not suit their sensibilities. Wright is skeptical, and clearly he is holding to the older evolutionary psychological model which implies that cognitive competencies are fixed and universal. Haidt does not elucidate well in my opinion that he’s talking about quantitative traits, and the theoretical paradigm is as simple here as animal breeding. Finally, because Haidt brought up race Wright has a difficult time comprehending that Haidt is not talking about race as (East) Asian, white and black, but as subpopulations differentiated by ecology and history.

In general I think Haidt is correct about the issue at hand. Haidt must know this from personal experience. But I think the important point here is that from what I can tell many Left-liberals have long ago moved on from rejecting bio-behavioral differences between populations as a possibility, to being highly skeptical of such differences between the sexes in practice if not in principle. While the former is relatively tendentious, the latter is far less so in scholarly circles. There are important evolutionary and behavioral ecological rationales for why there should be behavioral dimorphism between the sexes. In the general public of course, as well as disciplines inflected by behavioral ecology or evolutionary psychology, sex differences in behavior are not much to get concerned about. And in principle most people with objections to the current research findings for whatever reason also can accept the possibility of such a program in the abstract. But the reality is operationally a particular set of cultural guardians in Left-liberal social sets apply gale force skepticism to any bio-behavioral explanation in a highly aggressive manner, so the whole domain remains relatively fallow. Who wants to generate hypotheses and report results if such acts will result in critique of motives and moral character? I doubt that anyone would have anticipated this 20 years ago, as this seems so 1970s, but that’s my own assessment (to get a sense of what I’m talking about, I believe Amanda Marcotte would in principle accept that scientists could study sex differences without being sexist, but I doubt many scholars would survive her audit).

The one caveat that I would put on all these taboos and shibboleths is that what people are will to say, or more accurately not say, in public is very different from what they may entertain in private as at a minimum as a thought experiment or hypothesis. I can attest to this because many of the bright lines that Jonathan Haidt outlines are rather easy to transgress if one’s interlocutor is sufficiently versed in the biological science. I’m speaking from personal experience. People need to know your motives are pure, and, they need to not be stupid and ignorant (the latter is a problem). Once those preconditions are met then it is not impossible to work through difficult topics, whatever they may be.

– Finally there’s the point about human flourishing, and Haidt’s contention that conservative political and social philosophy has a lot of insight in fostering human happiness. I agree with Haidt broadly on this. That’s why I’m a conservative. But a key point I want to inject here is that I personally am not the type of person who flourishes in a conservative society. I’m too individualistic, egotistic, and lacking in the depth of moral sentiments which are the human norm (I am a natural libertarian). This is why another important insight is that societies need internal structure and genuine diversity of niche, so that people with different lifestyles can flourish. There does need to be a Castro district in San Francisco, but there also needs to be conservative small towns which are relatively homogeneous in population and values.

Many liberals and atheists will object to Haidt’s contention that conservatives and religious people are happier. There’s a lot of ways you could approach this issue to argue with it, but I think it is important not to deny its truth to a first approximation. The result does seem robust and replicated. Note that when I report that social liberals are smarter than social conservatives many social conservatives automatically assume that I’m a social liberal, while I.Q. skeptical social liberals become temporarily enamored of psychometrics. The results I report are first approximations, and there are details which need to be fleshed out. Skepticism is warranted, but it needs to be measured. One must be careful not to modulate one’s skepticism because of normative preferences; skepticism must be cherished and doled out evenly to get a better sense of reality. In the end I think the biggest point I would like to make is that measuring happiness is probably overrated; ironically, I think in Haidt’s framework that’s a conservative position!

Note: Just a shout out to regular readers, if your comment on this post is stupid I might delete it without warning. But I won’t ban you as I normally would upon deletion.

• Category: Science • Tags: Evolutionary Psychology, Jonathan Haidt 
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John Horgan has a long review of Robert Trivers’ long overdue book, The Folly of Fools: The Logic of Deceit and Self-Deception in Human Life. I really don’t care how well Trivers analyzed the topic, this is such a rich and important issue that I can’t help but think he must have hit some important mines of insight. I haven’t read The Folly of Fools, but I can recommend Natural Selection and Social Theory: Selected Papers of Robert Trivers. It’s not just a compilation of papers, there are biographical chapters which flesh out the context behind a particular idea at a given time. Trivers also shows up prominently in Defenders of the Truth: The Sociobiology Debate and Mother Nature: Maternal Instincts and How They Shape the Human Species.

• Category: Science • Tags: Evolutionary Psychology, Sociobiology 
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The New York Times has a short piece on Steven Pinker up. Nothing too new to long time followers of the man and his work. I would like to point readers to the fact that Steven Pinker has a F.A.Q. up for The Better Angels of Our Nature: Why Violence Has Declined. He links to my post, Relative angels and absolute demons, as supporting his dismissal of Elizabeth Kolbert’s review in The New Yorker. I have to admit that I find much, though not all, of the coverage of science in The New Yorker to exhibit some of the more annoying stereotypical caricatures of humanists when confronting the specter of natural philosophy.

I should also mention I started reading The Better Angels of Our Nature over Thanksgiving. I’m only ~20% through it, and probably won’t finish until Christmas season gets into high gear, but so far it’s a huge mess. In both a good way, and a bad way. The good way is that it’s incredibly rich in its bibliography, with fascinating facts strewn about the path of the narrative. The bad way is that so far it lacks the tightness of The Blank Slate or The Language Instinct in terms of argument. This may change. Finally, I think I should mention that Pinker has already addressed some of the criticisms of his methodologies brought up in the comments sections of my posts. Those who have specific critiques probably should read the book, because he seems to try sincerely to address those. Or at least they should address those critiques to people who have bothered to read the book.

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A new paper in PLoS Biology is rather like the last person to leave turning the light off. Evolutionary psychology as we understood it in the 1980s and 1990s is over. Darwin in Mind: New Opportunities for Evolutionary Psychology:

None of the aforementioned scientific developments render evolutionary psychology unfeasible; they merely require that EP should change its daily practice. The key concepts of EP have led to a series of widely held assumptions (e.g., that human behaviour is unlikely to be adaptive in modern environments, that cognition is domain-specific, that there is a universal human nature), which with the benefit of hindsight we now know to be questionable. A modern EP would embrace a broader, more open, and multi-disciplinary theoretical framework, drawing on, rather than being isolated from, the full repertoire of knowledge and tools available in adjacent disciplines. Such a field would embrace the challenge of exploring empirically, for instance, to what extent human cognition is domain-general or domain specific, under what circumstances human behaviour is adaptive, how best to explain variation in human behaviour and cognition. The evidence from adjacent disciplines suggests that, if EP can reconsider its basic tenets, it will flourish as a scientific discipline.

By “evolutionary psychology” the authors are not addressing a field just at the intersection of evolutionary biology and psychology. Rather, they’re speaking to the group of scholars who came to the fore in the 1990s under the leadership of Leda Cosmides and John Toobey as UCSB. These thinkers adhered to a specific set of parameters outlined above in regards to the basic theoretical framework of evolution and cognition through which their empirical research was framed. I can not speak to the cognitive psychology, the presumed massive modularity for example, but it does seem that their assumptions about human evolutionary history are a touch antiquated. Sometimes I wonder if this might be a feature and not a bug. I’ve been told personally by two people who knew the goings on at the UT Austin evolutionary psychology program that there wasn’t much emphasis on keeping up to date on the most recent work in evolutionary or genetic science (or at least there wasn’t in the mid-2000s, which is when my sources were familiar with the state of the research being done). The impression I received is that that would just muddy the waters and weaken the theoretical basis of the research program.

But sometimes the bedrock needs to be shaken up. It seems that time is upon us. From what I can gather evolutionary psychology was very much a response to the sociobiology controversies of the 1970s. On the one hand there was a real scientific distinction. Many of the sociobiologists were fundamentally biologists dabbling in social theory, while evolutionary psychology was more often dominated by social scientists who took biology seriously. But the reality is that sociobiology by 1980 had a major public relations problem, especially in the social sciences, which was dominated by what Toobey and Cosmides termed the Standard Social Science Research Model. The evolutionary psychology paradigm was more constrained and tightly focused, and its emphasis on human universals helped it mollify somewhat the charges of ‘genetic determinism.’ After all, genetic determinism is a lot less threatening when it is proposing theses which one finds appealing and praiseworthy. A few of the sociobiologists, such as Sarah Blaffer Hrdy, were not always keen on discarding the older term, but I think most understood that it was a small price to pay for continuing the program of synthesizing human behavior and biology.

Today there’s no need for half-measures or the erection of a hardy citadel robust and rigid in theory against the hordes of the SSRM. E. O. Wilson’s vision of consilience is coming to fruition not through a top-down project, but via the bottom-up reality of the emergence of a disparate array of scientific fields whose tentacles reach into varied domains, and bind them together. Nature is one after all, it is just our perception and cognition which is fragmented. The realization of a comprehensive and near total understanding of human genetic variation at the sequence level is within reach as more and more human genomes get cataloged. At this point talking about the “Paleolithic Mind” and the “environment of evolutionary adaptedness” seems quaint. One must be cautious, knowing that a genomic region may have been the target of powerful selective forces within the last ~10,000 years does not usually transparently tell us exactly the functional fitness rationale for that adaptive event. But it’s early days yet.

The letter of Toobey and Cosmide’s paradigm will be brutally violated in the coming decades. That’s science, the smasher of idols. But the spirit of their enterprise will live on. After all, despite some of the over enthusiasms of their acolytes they were never believers that biology dictated all. Rather, they were pushing back against the tendency to see ‘culture’ as a plastic and omnipotent deus ex machina in the mental furniture of social scientists. I place culture itself in quotes because the same spirit which scientists working with cold and positivist aims also animates those anthropologists who operate within the small ‘naturalistic paradigm’ of that discipline, who aim to reduce culture down to its constituent parts, rather than leave it to be a protean mystery.

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In an interesting piece in The Guardian on possible proto-gorilla/proto-human hybridization, the journalist lobs this grenade:

But now that the once popular “single-origin model” of the evolution of Homo sapiens has been disproved, and the previously controversial “multiregional hypothesis” has been proven by DNA evidence, perhaps we need a rethink. According to the multiregional hypothesis all modern people, including modern Africans, are the descendents of breeding and hybridising between separate ancestral groups, all at various stages of evolutionary development.

Evolutionary lice research has helped palaeoanthropologists, including Stringer, to embrace the multi-regional hypothesis. “I’m sure there is plenty more to come from the lice research,” he told me. We know that it took 4m years, 5-9m years ago, for our ancestors to completely split from archaic chimps. During that time hybrids would have been born that mated both with our ancestors and ancestral chimps.

The issue here is semantics. I think regular readers of this weblog will know to be more cautious than to contend that the “single-origin model” of our species has been “disproved,” while its inverse has been “proven.” Those are strong words in science. Additionally, I seriously doubt that Chris Stringer would identify as a multi-regionalist. Some wires got crossed here, to the point where I somewhat feel this article is a case of science communication malpractice. Its main purpose was probably to conjure up the image of man-gorilla sex, but by way of that it totally garbled and misled on the basic state of knowledge in relation to human evolution.

I’m not much into credentialing, as an undereducated fellow myself, but I was curious as to the author’s background:

Carole Jahme has a master’s degree in evolutionary psychology and is the author of Beauty and the Beast: Woman, Ape and Evolution. In 2004 she won the Wellcome Trust’s Award for Communication of Science to the Public

There is simply no excuse that someone with this much background in human evolution should make such a hash of the basic details of what we currently know. Yes, times are a changing, but if you are going to label Chris Stringer a multi-regionalist, you better ask him if he defines himself as such when most of his professional career has been as the primary counter-point to multi-regionalist thinking!

A possible explanation may be the need for journalism to be “punchier” and simplify a bit on the margins. So blame the editor. But if you have to do so much modification that you distort the science then that defeats the original purpose.

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In the wake of yesterday’s review of a paper on heritable variance in trait preferences realized in romantic partners I couldn’t help but be intrigued by this new study out of PLoS ONE, Evolutionary History of Hunter-Gatherer Marriage Practices. It’s actually a pretty thin piece of work in all honesty from what I can tell. They wanted to query ancestral ranges of marriage patterns by mapping the cultural variation in customs onto a phylogenetic tree. To generate that tree they took mtDNA sequences, which to me seems kind of old school. Using the cultural patterns present in living hunter-gatherer groups they presumed they could infer the ancestral state.

So combining these two sources of data they generated this:

They conclude:

Arranged marriages are inferred to go back at least to first modern human migrations out of Africa. Reconstructions are equivocal on whether or not earlier human marriages were arranged because several African hunter-gatherers have courtship marriages. Phylogenetic reconstructions suggest that marriages in early ancestral human societies probably had low levels of polygyny (low reproductive skew) and reciprocal exchanges between the families of marital partners (i.e., brideservice or brideprice).

There’s an immediate problem in that “binning” or categorizing these customs as “arranged” vs. “courtship” is somewhat artificial to my mind. That’s a perennial issue in anthropology, so setting that aside this is actually an interesting question if you could adduce the ancestral state in a clear and distinct manner. A book like The Mating Mind argues that sexual selection driven by free choice is the major driver of human evolution. But if marriage is arranged by one’s family then that significantly weakens the selective effect. Yes, theoretically the parents and offspring could have perfectly aligned preferences, but I doubt that’s what’s going on.

As it is I probably do lean toward the model of mate-choice outlined by Geoffrey Miller in The Mating Mind. I’ve long held that the rise of powerful extended patrilineages eliminated the relatively level playing field between men and women which may have existed in “small-scale” societies. This does not mean that hunter-gatherers were and are gender egalitarian in a way we’d understand them, but I doubt that you’d ever see the transformation of women into de facto property of powerful groups of men which occurred with upper class Athenian women or modern Saudi women. I think that sort of mobilization of collective power to control other humans and bind social institutions with marriage ties is a feature of mass society and agricultural civilization. In particular, of higher status lineages strongly associated with the distinctive institutions of a given society. By this, I mean that a medieval or early modern European aristocrat may have had to marry for family considerations, but the peasant was often constrained by more prosaic practicalities. He or she had relative free choice once the variables of distance and social class were accounted for. If one does not have property at stake marriage can be much more of an individual affair.

Ultimately the plausibility of the range of answers to this sort of question comes down to one thing for me: why crazy love? I don’t think romantic love is a cultural invention. It’s a neurological phenomenon which is easily evoked given the right conditions. The software comes pre-installed on the hardware, you don’t need to download it. My own opinion emerges partly out of personal experience. My family comes from a society where arranged marriage is normal, especially among elite lineages. But love happens, and people have strong individual preferences. If they are compliant they will suppress these individual urges for what they know to be good, prudent, and respectable. Oftentimes they may not have a practical choice. The parents and older siblings who make the decisions which go against the instinctive and romantic preferences of the subordinate parties themselves are not lacking in feeling, and understand what they’re doing, and they may have gone through the same process. In many societies individual action is marginalized in favor of the interests and preferences of the family, which is ultimately dominated by older individuals within the kinship network. The interests of the firm and the employee do not always perfectly align!

Don’t hate the player!

But this sort of social water running up the psychological hill, that is, the suppression of individual preference in the interests of collective rationality, needs some fuel to drive the process. You need something forcing individuals to cede their own range of options and accept that others will make the right decisions. In a pre-modern world I think that the fuel for that force consists of the rents stolen from the populace by elites. The rational for Augustus’ marriage to Scribonia was clearly different from that of his marriage to Livia. As a young man Augustus needed the money and connections which marriage with the older Scribonia would provide. Money and connections which ultimately emerged from the protection racket that was the late Republican aristocracy. As an older man Augustus’ was powerful enough to follow is hearts’ desire by expending the accumulated capital he’d built up, in part by operating within the system so long (instead of fighting his rival Marc Antony he allied with him until the triumvirate was not feasible).

The historical example above shows that the dichotomy between courtship and arranged marriage can manifest within an individual’s lifetime based on their context. I believe that if arranged marriages where individuals had marginal choice were overwhelmingly dominant across human history and prehistory than the psychological tension imposed by the preference for personal choice should slowly be eliminated by natural selection. From what I know that does not seem to be so. I infer from that that a mix of social customs was always operating, but that arranged marriage tended to become dominant only in more complex societies with enough inequality and monopolization of marginal surplus by some lineages to “fuel” the decisions of firms at cross and counter-purposes to individuals.

As for our ancestral hominin bands, I believe their bias toward courtship and arrangement was the same as our own. In a situation of material surplus there is more to fight over, and inequality may arise in the power hierarchy. When things matter, people become pawns. In flatter social contexts free choice would be given more room to operate, as there would be less to fight over.

🔊 Listen RSS Judging by some of the amusing search queries I find every Friday people have a wide range of tastes and fetishes when it comes to pornography. From what I can tell the realized phenotypic interval in mate choice is less varied and eye-opening, but exists nonetheless. Why? Is there a rhyme or reason, or is it simply random chance and the necessity of the biological clock ticking? These are not issues which aren’t discussed or mooted thoroughly regularly. The popular science literature is littered with hypotheses from social and evolutionary psychology. How else could you have a books such as The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature and Survival of the Prettiest: The Science of Beauty. This is sexy science by definition. Not Physics Letters.

There are three broad issues which have interested me in the domain of attraction and evolution. First, what is the character of cultural universals of beauty rooted in biological preferences? Second, what is the character of cultural variation in beauty rooted in contingencies or local conditions? And third, what are the genetic and non-genetic factors in individual mate preference? In this post I’ll focus on the last. Not to put a fine point on it: are you born with a “type,” or is your “type” a matter of chance and necessity after you are born? An interesting twist on the second issue is that one phenomenon which falls into the “not born” but biological category is the process of sexual imprinting. For example, you may exhibit attraction to individuals who resemble your opposite sex parent.* The clear connection to the presumed “Oedipus complex” of this probably explains it prominence.

A new paper in The American Naturalist aims to examine the question of realized variation individual preferences with a huge sample of twins, monozygotic and dizygotic. By realized, I mean that they focus on the people with whom you actually pair up, not your ideal avowed preference. Variation in human mate choice: simultaneously investigating heritability, parental influence, sexual imprinting, and assortative mating:

Human mate choice is central to individuals’ lives and to the evolution of the species, but the basis of variation in mate choice is not well understood. Here we looked at a large community-based sample of twins and their partners and parents…to test for genetic and family environmental influences on mate choice, while controlling for and not controlling for the effects of assortative mating. Key traits were analyzed, including height, body mass index, age, education, income, personality, social attitudes, and religiosity. This revealed near-zero genetic influences on male and female mate choice over all traits and no significant genetic influences on mate choice for any specific trait. A significant family environmental influence was found for the age and income of females’ mate choices, possibly reflecting parental influence over mating decisions. We also tested for evidence of sexual imprinting, where individuals acquire mate-choice criteria during development by using their opposite-sex parent as the template of a desirable mate; there was no such effect for any trait. The main discernible pattern of mate choice was assortative mating; we found that partner similarity was due to initial choice rather than convergence and also at least in part to phenotypic matching.

Much of the paper is given over to a review of previous research. Some of these did find heritable preferences (e.g., some women might have a stronger preference for tall men than other women, and this can be explained by genetic differences across the range of women). And you’ve probably encountered the stuff on MHC, opposite sex imprinting, etc., in the mainstream press. The MHC results are usually of the form “women prefer the smell of t-shirts of men with different MHC profiles.” Sometimes the results are really strange and counterintuitive. One study was of the form “women prefer the smell of t-shirts of men with the MHC profiles similar to their fathers.” And from this a lot of reasoning about how genomic imprinting manifested ensued. Though I hadn’t encountered John Ioannidis’ work on the prevalence of false positives in the research literature yet, I started wondering how so much strange, often contradictory, results were getting through peer review. Who is an honest individual to trust? In this paper the authors basically seem to be contending that in previous studies with smaller sample sizes the random noise ended up meeting the statistical significance threshold. You do enough studies, that will happen, and you’ll find that those false positives are the ones that will be published, especially in a sexy field like social or evolutionary psychology.

So what did they find? Basically they had a total sample size of over 20,000 Australian twins and their parents consisting of pair bonds of various lengths. They didn’t have values for all of the individuals for the traits of interest, so the real sample size for a given trait may be considerably smaller. But, they’re still at least an order of magnitude larger than the N of the range of studies which reported positive findings and which they reviewed in their introduction.

This is a paper with tables, not charts. So let’s start with table 3. On the left you have the mean value for a given trait. Some of these are transformed from categorical to numerical. For example, religiosity is a number which corresponds to a rank order in the frequency of church attendance. The second pair of columns has the correlation between partners. Age is a very impressive correlation. I’ve seen the same value for educational attainment in the General Social Survey, in that I actually ran that specific correlation and came out with that result. The attitudes trait is really a composite which measures social liberalism/conservatism. It is relatively high along with religiosity. The low values for personality variables really make me just wonder how good the measures of personality which psychologists have at their disposal are. Height and income are surprisingly low correlations. Finally, in the last column they look at the heritability of the trait itself. For example, within the Australian population nearly 70% of the variation in body mass index in the population is controlled by variation in genes in the population. Many psychological traits are around 25-50% heritability. Notice the high value for height. This is in keeping with what you find in other developed nations where nutritional inputs are saturated.

A major issue that they wanted to test was whether partners become more similar over time, or whether their similarity was a function of assortative mating. For example, do their body mass indices converge over the duration of their relationship? Overall they found that no, there was no convergence. The correlations just didn’t vary as a function of relationship length. The similarity on a trait like religiosity is apparently mostly a function of initial matching.

But what about family background? Assortative mating can be viewed simply as a matter of individuals expressing their preference, but obviously choices aren’t made in a vacuum by H. economicus. And yet this is a very interesting question for any given trait that can’t be taken for granted in terms of the answer. In The Nurture Assumption Judith Rich Harris pointed out on many personality traits there was actually only marginal evidence for the effect of family socialization. Rather, there was about equal effect of genetics and “non-family environment,” which is really just an unaccounted for grab-bag. Harris’ thesis was, and is, that peer effects account for much of this residual. So what’s going on with mate choice specifically?

Below you see a list of correlations for traits. The abbreviations are straightforward. MZ = monozygotic, DZ = dizygotic, F = female, M = male, and OS = opposite sex. So there isn’t an MZOS because monozygotic twins are the same sex, by definition. The correlation differences between MZ and DZ twins are pretty comprehensible. MZ twins share 100% of their genes. DZ twins share an expected value of 50% (in reality, there’s a standard deviation of 3%). But notice the last six rows. There’s really not much difference between MZ and DZ pairs here. That’s strongly indicative of marginal additive genetic variance effecting mate choice. In this table it is clear that twins’ partners were not more similar in any trait to the twins’ opposite-sex parent than to the twins’ same-sex parent. That’s a strike against the imprinting thesis.

Finally, there is some evidence of family effects. In particular, there was statistically significant results for female MZ and DZ twins in terms of correlations in their choice of mates for income & age. What does this mean? The authors imply that this is suggestive of family socializing effects. In other words, parents have particular expectations of the type of man that a daughter is supposed to bring home, and the daughter complies with those expectations on many occasions. Notice that there’s not a difference between MZ and DZ females for income. In fact, there’s a slight tendency for there to be more correlation between DZ twins! (I wouldn’t make much of this, look at the standard errors in the parentheses). The individual preference difference here seems to be marginal. Most of the correlation is due to family background and the individual’s own trait (e.g., high earning females pair up with high earning males not because they have genes which predispose attraction to high earning males, but because they have a tendency to pair up with men who resemble them).

Where does this leave us? First, there are obvious limitations to this study. Heritability estimates are sensitive to environmental background effects. In India the correlation between twins and siblings in terms of the religious identity of their partners is going to be very high. That’s because of cultural norms. If the offspring have particular preferences, they’re going to be tightly scaffolded by the parameters set by the extended family. The authors themselves admit that they were focusing pair bonds. Studies of “speed dating” and such might give different results because humans may facultatively engage in different strategies in different circumstances. In a non-developed nation the class effect will probably be stronger, bosting the “family effect” of income correlation, because the range is going to be so much higher in terms of the realized impact of income and household maintenance (i.e., poor people in developed nations live well enough to get fat).

I think the big picture is to be very cautious of sexy positive results from sample sizes in the hundreds. Especially if you double check the literature and see results pointing in different directions!

Citation: Zietsch BP, Verweij KJ, Heath AC, & Martin NG (2011). Variation in human mate choice: simultaneously investigating heritability, parental influence, sexual imprinting, and assortative mating. The American naturalist, 177 (5), 605-16 PMID: 21508607

* We’re talking purely of heterosexuals here and in the study below.

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Today in Slate there’s an argument for why society should discourage first-degree incest. The main thrust of the piece seems to be broadly utilitarian, in that incest is destructive to the family unit and society has a rational motive in discouraging the practice. The reason that the argument is even made is because of analogies that some social conservatives make between incest and gay marriage. I’m not too interested in the argument against first-degree incest, because I think this is a practice which is aberrant because there are biological dispositions most humans have which make it unthinkable.* Though the genetic reasons are broadly well known, Steven Pinker reports on the psychological mechanisms which enforce the taboos in The Blank Slate.

Of course there are exceptions to the rule. The first-degree incest taboos can be violated in the case of royal families which wish to preserve and accentuate their divine genealogical essence. This was famously well known in ancient Egypt down to the Roman conquest, but one also found the practice in Hawaii. In rural Egypt apparently brother-sister marriage continued among commoners (who presumably emulated the elites) down to the Roman period. Human nature has dispositions in many cases which are not “hard-wired.” But the disposition in this case is so strong that I believe arguing about the legality of consensual adult incest is an academic matter. The discussion is only surfacing because of its possible relevance to another issue, gay marriage.

Polygamy though is a different case. Here the ethnography seems to be clear that though the majority of men in the majority of societies did not practice polygamy, in most cultures polygamy was acceptable, and commonly practiced by high status males. In many cases polygamy was the preferred ideal, which was not attainable for the typical male due to economic constraints. Only with the spread of Western-normative mongamous customs, inherited from the Greeks and Romans, has polygamy been marginalized.

But we may be better for it. Polygamy’s many wives don’t capture ‘market value’:

Economist Shoshana Grossbard admits she was naive when she did her doctoral thesis on polygamy more than 30 years ago at the University of Chicago.

Then, she believed that a simple supply-and-demand analysis would explain the economics of polygamous societies.

Besides, she says, “I thought it was cool to say that polygamy might be advantageous to women and repeat what Gary Becker (her thesis adviser and Nobel laureate) has said.”

Polygamous societies have a higher frequency of arranged marriages. It’s not surprising, says Grossbard. Young women aren’t likely to choose old men for husbands, plus men find young wives easier to control.

Of course, that increases the likelihood of early widowhood and financial hardship.

In societies where a bride price is paid, women don’t “capture their increased market value.” Instead, she says, potential husbands pay the fathers. No money goes to the bride.

Divorce tends to be easier in polygamous societies. The threat of it keeps women in line and it allows men to shed wives who are too old or noncompliant.

Child custody almost always is the right of the father.

Isolating women makes it more difficult for them to escape and makes them even more financially dependent on their husbands.

As beautiful as the harem in Grenada’s Alhambra is, Grossbard says, “The whole institution is typical of polygamous societies.”

There, eunuchs – castrated men – guard the wives.

There are variations in the nature of polygamy. My understanding is that in some African societies women in polygamous relationships have their own independent economic life, and the male is a transient between matrifocal households. The opposite extreme occurs in Muslim societies where women are secluded from men and denied from participation in public life.

In any case, unlike first-degree incest or gay marriage, polygamy does remain rather common, and legal, in much of the world:


One must note that in some nations, such as India, polygamy is only legal for minorities for which it is a traditional custom. That being said, in many nations where it is legal, it is not always common, nor is it socially acceptable in many circles.

But it is notable to me that gay marriage & incest, and polygamy, are very different cases. Polygamy is a practice which has broad appeal, and even in many societies where it is banned de facto polygamy is not uncommon. The integration of a ban on polygamy into the legal codes of societies such as India and China is interesting, because the practice was not unknown among pre-modern elites, and persisted down to the 20th century. The film Raise the Red Lantern is about a polygamous household in 1920s China. The historical roots of the turn against polygamy seems to be tied to the rise of Western hegemony within the last few hundred years, and that itself derives from the integration of Greco-Roman norms into the Christian religion. The Romans and Greeks were obligate monogamous peoples in the Classical period, and this obligate monogamy became a feature of Christianity (though not Judaism, which retained polygamy among Ashkenazim until the 10th century, and other Jewish groups which may still retain the practice, though no longer in Israel). The barbarian warlords of Northern Europe often had to make their accommodation with this “Roman” custom upon their conversion to Christianity (though the reality is that the Church often gave monarchs de facto exemption).

If the dominance of the ideal of monogamy is a contingent accident of history, will we see a shift toward greater pluralism in the near future, with the decline of the West? This is not an implausible contention. But, I also do wonder if legally sanctioned polygamy does not trigger a destabilizing “winner take all” dynamic in complex societies, producing a lack of social trust which means that such societies have limits in terms of the scale of their complexity. In other words, perhaps advanced economies necessarily need and foster a level of gender equality which formal polygamy is simply not consonant with?

Addendum: The existence of “super-male” lineages such as that of Genghis Khan is a testament to the power and presence of polygamy as a genetic phenomenon over the last 10,000 years. Even if most men in a given society can not practice polygamy because of economic and social constraints, it may be that the majority of future generations are descended from polygamists because of their fecundity, and that of their polygamous male offspring who would inherit their status.

* No comments about how you fantasized about your sister to refute my generalization!

• Category: Science • Tags: Culture, Evolutionary Psychology 
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The waist-to-hip ratio research has been done to death, but an interesting twist, Blind men prefer a low waist-to-hip ratio:

Previous studies suggest that men in Western societies are attracted to low female waist-to-hip ratios (WHR). Several explanations of this preference rely on the importance of visual input for the development of the preference, including explanations stressing the role of visual media. We report evidence showing that congenitally blind men, without previous visual experience, exhibit a preference for low female WHRs when assessing female body shapes through touch, as do their sighted counterparts. This finding shows that a preference for low WHR can develop in the complete absence of visual input and, hence, that such input is not necessary for the preference to develop. However, the strength of the preference was greater for the sighted than the blind men, suggesting that visual input might play a role in reinforcing the preference. These results have implications for debates concerning the evolutionary and developmental origins of human mate preferences, in particular, regarding the role of visual media in shaping such preferences.

Full description of the research here.

• Category: Science • Tags: Evolutionary Psychology 
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Gingival Transcriptome Patterns During Induction and Resolution of Experimental Gingivitis in Humans:

A relatively small subset (11.9%) of the immune response genes analyzed by array was transiently activated in response to biofilm overgrowth, suggesting a degree of specificity in the transcriptome-expression response. The fact that this same subset demonstrates a reversal in expression patterns during clinical resolution implicates these genes as being critical for maintaining tissue homeostasis at the biofilm–gingival interface. In addition to the immune response pathway as the dominant response theme, new candidate genes and pathways were identified as being selectively modulated in experimental gingivitis, including neural processes, epithelial defenses, angiogenesis, and wound healing.

ScienceDaily has a more awesome title, Nearly One Third of Human Genome Is Involved in Gingivitis, Study Shows:

Research conducted jointly by the University of North Carolina at Chapel Hill and Procter & Gamble (P&G) Oral Care has found that more than 9,000 genes — nearly 30 percent of the genes found in the human body — are expressed differently during the onset and healing process associated with gingivitis. Biological pathways associated with activation of the immune system were found to be the major pathways being activated and critical to controlling the body’s reaction to plaque build-up on the teeth. Additionally, other gene expression pathways activated during plaque overgrowth include those involved in wound healing, neural processes and skin turnover.

Perhaps then bad breath and poor oral hygiene are simply a fitness indicator, and kissing evolved as a method for humans to evaluate each other’s health as an “honest” signal?

• Category: Science • Tags: Evolutionary Psychology 
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How universal are human mate choices? Size doesn’t matter when Hadza foragers are choosing a mate:

It has been argued that size matters on the human mate market: both stated preferences and mate choices have been found to be non-random with respect to height and weight. But how universal are these patterns? Most of the literature on human mating patterns is based on post-industrial societies. Much less is known about mating behaviour in more traditional societies. Here we investigate mate choice by analysing whether there is any evidence for non-random mating with respect to size and strength in a forager community, the Hadza of Tanzania. We test whether couples assort for height, weight, BMI, percent fat and grip strength. We test whether there is a male-taller norm. Finally, we test for an association between anthropometric variables and number of marriages. Our results show no evidence for assortative mating for height, weight, BMI or percent fat; no evidence for a male-taller norm; and no evidence that number of marriages is associated with our size variables. Hadza couples may assort positively for grip strength, but grip strength does not affect the number of marriages. Overall we conclude that, in contrast to post-industrial societies, mating appears to be random with respect to size in the Hadza.

Here’s some stuff from the discussion:

Overall, however, our analysis suggests size and strength are not greatly important when Hadza are choosing a mate. This lack of size-related mating patterns might appear surprising, since size is usually assumed to be an indicator of health, productivity and overall quality. But health and productivity may be signalled in alternative ways in the Hadza, who are a small, relatively homogeneous population. An individual’s health history may be more important than size, for example, and this may be relatively well known in a small, mobile population. Additionally, there may be some disadvantages to large size in food-limited societies, where the costs of maintaining large size during periods of food shortage may be high. Such disadvantages will not be seen in food abundant societies, so that large size may be a better indicator of quality in postindustrial populations. Finally, research on another African forager population found that height is negatively correlated with hunting returns (Lee 1979), suggesting that tall height may not be an indicator of productivity in such economies.

Here’s a chart which shows the proportion of females-taller-than-male marriages by culture:

In a previous post I suggested that the shift from small-scale societies to agricultural societies witnessed a transition from an emphasis on innate individual level social intelligence toward rules and heuristics (in other words, wisdom embodied in the preferences of society and its institutions). External physical characteristics are correlated with “health,” so they’re useful. And those who are not physically attractive can signal their own status and abilities in other ways, ugly fat men can for example buy material signalers to show that they have something going on. It strikes me that the Wisdom of Seinfeld is most appropriate for large urban areas with some degree of anonymity. Quick & dirty signalers to filter and influence one’s choices are critical in the incredibly large number of human interactions possible in these urban agglomerations. By contrast, if George Costanza lived in a village one would know enough about his persona to dismiss a random “pairing” with an attractive woman as an aberration (or, one would know the back-story to this bizarre pairing).

As our modern post-industrial society shifts toward information transparency perhaps we’ll become less “shallow”? Remember the 1995 film Species, the attractive alien character met a handsome male at a night club. She assessed his fitness through his looks to make the initial choice. But later she killed him when she found that he was a diabetic. If she’d been able to access his health profile on her iPhone perhaps he would have been able to live for another day?

• Category: Science • Tags: Anthropology, Evolutionary Psychology 
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Seems to be the “take away” message from Bryan Caplan’s post, Monogamy and Heterogeneity. Interestingly, I’ve run into nature-based arguments in regards to human behavior and norms (e.g., “it’s the natural way” or “it’s against nature”) mostly from two sets, back-to-nature-hippies and social conservatives. As Caplan suggests there is a tendency in these cases for the two groups to generalize from their own likely innate preferences, though the defections and deviations from both groups over time suggest that there’s a lot of heterogeneity within them and some people are just conforming to the ideologies and leaders of their packs. Humans are supposed to have good Theory of Mind, but I think even that is a little outmatched by the enormous sample space of possible choices available in a post-industrial consumer society living well above the margins of subsistence. Minor innate behavioral dispositions which might have been marginal or buffered in a small-scale society may snowball due to the unending positive feedback loops which can be generated by the diversity of choices we can make today.

The pre-modern polyamorist was likely constrained in the number of individuals they might have sexual relations with because the number of people in their social world was small. Similarly, there wasn’t nearly as much temptation and opportunity (or perceived opportunity cost) for the pre-modern monogamist. The realized distribution of behavior may be much more stretched out in modern society than in the past. After all, how nerdy would most of the readers of this weblog be if they’d been peasants? How many ways are there to plant a seed? (I’m sure I’m going to get answers to that rhetorical question)

• Category: Science • Tags: Behavior Genetics, Evolutionary Psychology 
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Interacting with women can impair men’s cognitive functioning:

The present research tested the prediction that mixed-sex interactions may temporarily impair cognitive functioning. Two studies, in which participants interacted either with a same-sex or opposite-sex other, demonstrated that men’s (but not women’s) cognitive performance declined following a mixed-sex encounter. In line with our theoretical reasoning, this effect occurred more strongly to the extent that the opposite-sex other was perceived as more attractive (Study 1), and to the extent that participants reported higher levels of impression management motivation (Study 2). Implications for the general role of interpersonal processes in cognitive functioning, and some practical implications, are discussed.

Everything fits intuition, right?

H/T Sheril

• Category: Science • Tags: Evolutionary Psychology 
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Over at ScienceBlog:

I would like to invite discussion on my paper, On Fodor on Darwin On Evolution, which is a critique of Jerry Fodor’s Hugues Leblanc Lectures at UQAM on “What Darwin Got Wrong“….

Jerry Fodor argues that Darwin was wrong about “natural selection” because (1) it is only a tautology rather than a scientific law that can support counterfactuals (“If X had happened, Y would have happened”) and because (2) only minds can select. Hence Darwin’s analogy with “artificial selection” by animal breeders was misleading and evolutionary explanation is nothing but post-hoc historical narrative. I argue that Darwin was right on all counts. Until Darwin’s “tautology,” it had been believed that either (a) God had created all organisms as they are, or (b) organisms had always been as they are. Darwin revealed instead that (c) organisms have heritable traits that evolved across time through random variation, with survival and reproduction in (changing) environments determining (mindlessly) which variants were successfully transmitted to the next generation. This not only provided the (true) alternative (c), but also the methodology for investigating which traits had been adaptive, how and why; it also led to the discovery of the genetic mechanism of the encoding, variation and evolution of heritable traits….

No comments on the post yet, so GNXP readers should check out the paper.

• Category: Science • Tags: Evolutionary Psychology 
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When Young Men Are Scarce, They’re More Likely To Play The Field Than To Propose:

In places where young women outnumber young men, research shows the hemlines rise but the marriage rates don’t because the young men feel less pressure to settle down as more women compete for their affections.

But when those men reach their 30s, the reverse is true and proportionately more older men are married in areas where women outnumber men.

The original paper is here.

• Category: Science • Tags: Evolutionary Psychology 
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Life histories, blood revenge, and reproductive success among the Waorani of Ecuador:

The Waorani may have the highest rate of homicide of any society known to anthropology. We interviewed 121 Waorani elders of both sexes to obtain genealogical information and recollections of raids in which they and their relatives participated. We also obtained complete raiding histories of 95 warriors. An analysis of the raiding histories, marital trajectories, and reproductive histories of these men reveals that more aggressive warriors have lower indices of reproductive success than their milder brethren. This result contrasts the findings of Chagnon…for the Yanomamo. We suggest that the spacing of revenge raids may be involved in the explanation of why the consequences of aggressiveness differ between these 2 warlike lowland South American peoples.

Perhaps these data are wrong somehow. That being said, I think the “psychic unity of mankind” and an attempt to shoehorn everything into cultural universals led anthropologists, whatever their ideological preferences (or lack thereof) to over generalize about the ubiquity of one optimal reproductive strategy. The data from human ethology about fitness on “small scale societies” can be confusing, it is clear in many cases that the researchers were looking for a particular finding but couldn’t validate their expectations.

Rather than one model to rule them all it seems likely that a species with such a complex social system as ours does have various niches in which different morphs can optimize their fitness. Greg Clark implicitly assumes this in Farewell to Alms. The martial blood nobility had lower fitness than the relatively pacific gentry up until about 1800 in England because they were killed in war so often. But these patterns also vary over time, Peter Turchin has data sets from Europe which show wild swings in fitness of these martial elites over the past 1,000 years in Europe. When times were good, they were really good (e.g., the Victorian era when the nobility became breeders of the first order), and when they were bad they were really bad (e.g., the War of the Roses when the English nobility “thinned” itself out through conflict).

More crassly one has to ask oneself if history is a story of the ascent of the alpha what exactly are the pussies doing hanging around so thick on ground? In a Cartesian manner the very existence of these multitudes refutes the single strategy model.

• Category: Science • Tags: Evolutionary Psychology 
Razib Khan
About Razib Khan

"I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. If you want to know more, see the links at"