Psychology Today Blogs - The Scientific Fundamentalist

Exotic Culture that Never Was: Part 1

Satoshi Kanazawa — Thu, 15 May 2008 15:33:56 -0700

Margaret Mead and the Samoa:

In a previous post, I explained that, at the most abstract level, all human cultures are the same and there is only one human culture. Nothing illustrates this point better than the recent (and somewhat shameful) history of the social sciences. It shows that every time there was news of a discovery of a new, exotic culture in a remote region of the world, completely different from the Western European culture, it turns out that the discovery was a hoax. Every time, it turns out that there are no human cultures that are radically and completely different from other cultures. The first such example is Margaret Mead’s research on the Samoa.

In 1923, Margaret Mead (1901-1978), one of the most celebrated anthropologists of all time, was an anthropology graduate student of Franz Boas (1858-1942) at Columbia University. Boas was a Jewish refugee from Nazi Germany, and was therefore politically and personally motivated to prove wrong the Nazi policy of eugenics. While this is an admirable goal in and of itself, Boas unfortunately chose the wrong tactics to achieve it. He wanted to show that biology had nothing to do with how humans behave, and that environment -- culture and socialization -- determines human behavior completely. He was a strong proponent of cultural determinism.

In order to demonstrate that culture and socialization determine human behavior in its entirety, Boas gave his graduate students (including Mead) the impossible task of finding a human culture radically different from the Western culture, where people behave completely differently from Americans and Europeans. Margaret Mead was sent to Samoa with this mandate from Boas.

On August 31, 1925, Mead arrived in American Samoa to conduct her research. She was to spend six months doing her fieldwork. Unbeknownst to Boas, however, Mead was involved in another, secret research project, and spent almost all of her time in Samoa doing this other work. She was to leave Samoa in a month, and she had not done any of the fieldwork for Boas on the topic of cultural and behavioral variability to find evidence that Samoan behavior was completely different from American behavior. She decided to finish this work quickly by interviewing two young local women about the sexual behavior of adolescents in Samoa on March 13, 1926.

Mead knew that in the United States and the rest of the Western world, boys were sexually aggressive and actively pursued girls, while girls were sexually coy and waited to be asked out on dates by boys. “How different are things in Samoa? How are Samoan boys and girls when it comes to sex?” Mead asked her two young female informants, Fa’apua’a Fa’amu and Fofoa Poumele.

Fa’apua’a and Fofoa, just like young women everywhere, were quite embarrassed to talk about sex to a total stranger. So they decided to make a big joke about it out of sheer embarrassment. They told Mead the opposite of how things were in Samoa. They told her that boys were quite shy, and girls actively pursued boys sexually. It was a hoax, but in the minds of Fa’apua’a and Fofoa, the story that they were telling Mead was so outrageous and so obviously untrue that they couldn’t believe that anyone in her right mind would believe them.

Except that Mead did, for this was exactly the type of “evidence” that Boas had sent her to Samoa to gather. Here now was evidence that sexual behavior of adolescents could be completely different from (nay, the opposite of) how it is in the United States. So culture does completely determine human behavior after all! Mead was ecstatic. She left Samoa in April 1926 and published her “findings” in Samoa in a book called Coming of Age in Samoa in 1928. The book immediately became an international bestseller and later a classic in cultural anthropology, and, among other things, formed the foundation of modern feminism. Feminists pointed to the “evidence” in the book to support their claim that, given different “gender socialization,” Western boys and girls could be completely different. Boys could be more like girls, and girls could be more like boys. So, in a sense, modern feminism was founded on the basis of a hoax.

More than sixty years later, on May 2, 1988, Fa’apua’a, who was then 86 years old, told a Samoan government official (who happened to be the son of Fofoa, who passed away in 1936) that everything she and her friend told Margaret Mead about the sexual behavior of Samoan boys and girls on that fateful night of March 13, 1926, was untrue. It was a hoax. As it turns out, overwhelming ethnographic evidence by now shows that Samoan adolescents are no different from adolescents anywhere else in the world. Boys are sexually aggressive and active, and girls are sexually coy and shy.

There is only one human culture

Satoshi Kanazawa — Sun, 11 May 2008 18:00:18 -0700

People often speak of culture in the plural (“cultures”) because they believe that there are many different cultures in the world. At one level, this is of course true; the American culture is different from the Chinese culture, both of which are different from the Egyptian culture, and so on. However, all the cultural differences are on the surface; deep down, at the most fundamental level, all human cultures are essentially the same.

Yes, culture and socialization do matter for human behavior, to a certain extent. But the grave error of traditional sociologists and others under the influence of the Standard Social Science Model (a term attributable to the co-founders of evolutionary psychology, Leda Cosmides and John Tooby) is to believe that human behavior is infinitely malleable, capable of being molded and shaped limitlessly in any way by cultural practices and socialization. Available evidence shows that this view is false. Human behavior, while malleable, is not infinitely malleable by culture, because culture is not infinitely variable. In fact, despite all the surface and minor differences, evolutionary psychologists have shown that all human cultures are essentially the same.

To use a famous metaphor, coined by the cultural anthropologist Marvin Harris, it is true that, at the surface level, people in some societies consume beef as food and worship pigs as sacred religious objects, while those in others consume pork as food and worship cows as sacred religious objects. So there is cultural variety at this concrete level. However, both beef and pork are animal proteins (as are dogs, whales, and monkeys), and both pigs and cows are animate entities (as are Buddha, Allah, and Jesus). And people in every human society consume animal proteins and worship animate entities (as I explained in an earlier post). At this abstract level, there are no exceptions, and all human cultures are the same. There is no infinite variability in human culture, in the sense that there are no cultures in which people do not consume animal protein or worship animate entities.

To use another example, it is true that languages spoken in different cultures appear completely different, as anyone who ever tried to learn a foreign language knows. English is completely different from Chinese, neither of which is anything like Arabic. Despite these surface differences, however, all natural human languages share what the linguist Noam Chomsky calls the “deep structure” of grammar. In this sense, English and Chinese are essentially the same, in the sense that beef and pork are essentially the same.

Any developmentally normal child can grow up to speak any natural human language. Regardless of what language their genetic parents spoke, all developmentally normal children are capable of growing up to be native speakers of English, Chinese, Arabic, or any other natural human language. In fact, when a group of children grow up together with no adults to teach them a language, they will invent their own natural human language complete with grammar. This does not mean, however, that the human capacity for language is infinitely malleable. Human children cannot grow up to speak non-natural language like FORTRAN or symbolic logic, despite the fact that these are far more logical and easier to learn than any natural language (no irregular verbs, no exceptions to rules). Yes, a developmentally normal child can grow up to speak any language, as long as the language is a product of human evolution, not a recent invention of computer scientists or logicians.

Pierre van den Berghe, a pioneer sociobiologist at the University of Washington, puts it best when he says

Certainly we are unique, but we are not unique in being unique. Every species is unique and evolved its uniqueness in adaptation to its environment. Culture is the uniquely human way of adapting, but culture too evolved biologically.

Despite all the surface differences, there is only one culture, because culture, like our body, is an adaptive product of human evolution. The human culture is a product of our genes, just like our hands and pancreas are.

Biologically, human beings are very weak and fragile; we do not have fangs to fight predators and catch prey or fur to protect us from extreme cold. Culture is the defense mechanism with which evolution equipped us to protect ourselves, so that we can inherit and then pass on our knowledge of manufacturing weapons (to fight predators and catch prey) or clothing and shelter (to protect us from extreme cold). We don’t need fangs or fur, because we have culture. And just like -- despite some minor individual differences -- all tigers have more or less the same fangs and all polar bears have more or less the same fur, all human societies have more or less the same culture. Fangs are a universal trait of all tigers; fur is a universal trait of all polar bears. So culture is a universal trait of all human societies. Yes, culture is a cultural universal.

All stereotypes are true, except...V: "All extremely handsome men are gay"

Satoshi Kanazawa — Thu, 08 May 2008 18:27:30 -0700

Another common stereotype about physical appearance is that extremely handsome men are likely to be homosexual. In one experiment, women rate pictures of men as more attractive if they thought that the men were homosexual than if they thought that they were heterosexual, while men do not exhibit the same tendency in judging the attractiveness of women. Extremely handsome celebrities, such as Tom Cruise, have long been dogged with rumors of being gay all their careers. Are extremely handsome men really more likely to be gay?

From an evolutionary psychological perspective, it does not make sense for extremely handsome men to be gay. As I note in a previous post, such men receive disproportionate opportunities for extra-pair copulations (“affairs”) and short-term mating because women typically seek them out for their high-quality genes. (Remember, beauty is not only skin deep, and beautiful people do have better genes.) High-quality genes of extremely handsome men will therefore be “wasted” if their carriers are exclusively or predominantly homosexual.

Consistent with the evolutionary psychological logic, it turns out that extremely handsome men are not more likely to be gay. In fact, there is some evidence for the exact opposite. Compared to other men, extremely handsome men are often least homosexual, and homosexual men are least physically attractive. While this may go against the common stereotype, it makes perfect evolutionary sense.

In contrast, there are some heritable physical traits that it makes evolutionary sense to be associated with homosexuality. For example, women universally seek mates who are taller than them, and as a result, taller men attain greater reproductive success than shorter men. So short men have relatively less to lose, reproductively speaking, by being exclusively or predominantly homosexual. While exclusive homosexuality can never have any reproductive payoff, relative loss in fitness terms (what the economists call the opportunity costs) is less if the men are expected to be less successful in heterosexual reproduction. Further, by refraining from direct reproduction themselves, men who have dimmer reproductive prospect (by being short, for example) can help and aid the reproductive success of their siblings with more promising prospect.

Conversely, for the same reason that taller men are reproductively more successful than shorter men, shorter women attain greater reproductive success than taller women. (As a footnote, this discovery was made by Daniel Nettle of the University of Newcastle, whom we’ve encountered before.) The evolutionary psychological logic thus suggests that taller women have relatively less to lose, reproductively speaking, by becoming exclusively or predominantly homosexual.

Once again, consistent with the evolutionary psychological logic, it turns out that shorter men are more likely to be homosexual than taller men, and homosexual men are shorter than heterosexual men. Similarly, taller women are more likely to be homosexual than shorter women, and homosexual women are taller than heterosexual women. Such is the power of the evolutionary psychological imagination: It can predict who’s more likely to be gay even in the absence of a stereotype.

None of this assumes that sexual orientation is a deliberate conscious choice. We know that at least male homosexuality is strongly genetically influenced. But a strong genetic influence on sexual orientation is not inconsistent with the findings that those who are less likely to be reproductively successful (ugly men, short men, and tall women) are more likely to be homosexual, because the genes for homosexuality can come to be associated with genes for physical appearance or for height. More research is necessary to explore the potential proximate mechanism by which the genes for male homosexuality have come to be associated with genes for height and physical attractiveness.

All stereotypes are true, except... IV: “You can’t judge a book by its cover”

Satoshi Kanazawa — Sun, 04 May 2008 20:35:58 -0700

Both Tom Hanks and Ray Liotta are handsome white Hollywood actors roughly the same age. But I am willing to bet that these two actors have never auditioned for the same part in their careers. (Imagine Ray Liotta sitting on a park bench, uttering the line “My name is Forrest Gump. People call me Forrest Gump.”) Why is this? Why are actors typecast?

Tom Hanks usually plays the good guy in movies, whereas Ray Liotta usually plays the bad guy. This is because Tom Hanks looks like a good guy, whereas Ray Liotta looks like a bad guy. If you show pictures of these two men to people in Papua New Guinea, who have never seen any movies in their lives, let alone movies starring Hanks or Liotta, they can probably tell which is the good guy and which is the bad guy. This suggests that the third stereotype or aphorism about physical appearance “You can’t judge a book by its cover,” meaning that you cannot judge people’s characters by their physical appearance, may be false.

There is some experimental evidence to support this suspicion. When people view pictures of others who have been shown to be either a cooperator or a defector, there is some tendency for people to remember the faces of defectors better than the faces of cooperators, even when they don’t know who is a cooperator and who is a defector. Similarly, people appear to be able to distinguish between honest people and dishonest people simply by looking at their pictures.

If you think about it, this makes perfect evolutionary sense. It is important for our ancestors (and for us as well) to guard against the possibility of deception, because being deceived can only have negative consequences for our survival and reproductive success. As a result, the human brain consists of many evolved psychological mechanisms that protect us from being deceived in our social exchange and interpersonal relationships. The ability to tell potential defectors (bad guys) from potential cooperators (good guys) by their appearance would be tremendously helpful for our ancestors (and us) in guarding against possible fraud.

Of course, the nature of evolutionary arms race is such that defectors and other dishonest people will be selected not to betray their deceptive nature by looking honest and trustworthy, so that people won’t be able to tell that they are bad guys. At any rate, evidence against the third stereotype “You can’t judge a book by its cover” is not yet as convincing as the evidence against the first two stereotypes “Beauty is in the eye of the beholder” and “Beauty is only skin deep.” More research is necessary to make sure that the third stereotype is definitely false.

The only exception, in which we already have solid evidence, is where the judgment involves physical attractiveness. The evidence is overwhelming that people judge beautiful people to possess all kinds of positive attributes, from intelligence, to competence, to good character, to social skills, captured in another aphorism “What is beautiful is good.” And the evidence shows that this perception is largely true. For example, beautiful people are slightly though significantly more intelligent than ugly people. Nobody said life was fair.

All stereotypes are true, except... III: “Beauty is only skin deep”

Satoshi Kanazawa — Thu, 01 May 2008 22:17:49 -0700

They say beauty is only skin deep, which means that beautiful people are no different from ugly people except for their appearance. This is the second stereotype or aphorism that evolutionary psychology has overturned. It turns out that beautiful people are genuinely different from ugly people, because they are genetically and developmentally healthier.

In my last post, I explained that the standards of beauty are culturally universal and innate. There are three main features that characterize beautiful faces: the geometric feature of bilateral symmetry, the mathematical feature of averageness, and the biological feature of secondary sexual characteristics. They all indicate genetic and developmental health of beautiful people.

Bilateral symmetry. Attractive faces are more symmetrical than unattractive faces. Bilateral symmetry (the extent to which the facial features on the left and the right sides are identical) decreases with exposure to parasites, pathogens, and toxins during development, and with genetic disruptions such as mutations and inbreeding. Developmentally and genetically healthier individuals have greater symmetry in their facial and bodily features, and are thus more attractive.
For this reason, across societies, there is a positive correlation between parasites and pathogen prevalence in the environment and the importance placed on physical attractiveness in mate selection; people place more importance on physical attractiveness when there are more pathogens and parasites in their local environment. This is because in societies where there are a lot of pathogens and parasites in the environment, it is especially important to avoid individuals who have been afflicted with them when selecting mates.

Averageness. Facial averageness is another feature that increases physical attractiveness; faces with features closer to the population average are more attractive than those with extreme features. In the memorable words of Judith H. Langlois of the University of Texas, who originally discovered that the standards of beauty might be innate, “attractive faces are only average.” Evolutionary psychological reasons for why average faces in the population are more attractive than extreme faces are not as clear as the reasons for why bilateral symmetry is attractive. Current speculation is that facial averageness results from the heterogeneity rather than the homogeneity of genes. Individuals who have two different copies (or alleles) of a gene are more resistant to a larger number of parasites, less likely to have two copies of deleterious genes, and at the same time more likely to have statistically more average faces with less extreme features. If this speculation is correct, it means that, just like bilateral symmetry, facial averageness is an indicator of genetic health and parasite resistance.

Secondary sexual characteristics. Unlike the geometric concept of bilateral symmetry and the mathematical concept of averageness, the biological concept of secondary sexual characteristics differ for the sexes. For men, features that are considered to be attractive are indicators of high levels testosterone (such as large jaws and prominent brow ridges). For women, features that are considered to be attractive are indicators of high levels of estrogen (such as large eyes, fuller lips, larger foreheads, and smaller chins). This is probably why women instinctively tilt their head forward and look up (making their eyes and forehead look larger than they are and their chin smaller than it is) when they want to appear attractive. (Think of the way Princess Diana was typically photographed). Similarly, men instinctively tilt their head back (making their jaw appear larger than it is and their brow ridge more prominent than it is) when they want to look attractive. For both sexes, faces that typify higher levels of sex-typical hormones are considered to be attractive.

Far from being only skin deep, beauty appears to be an indicators of genetic and developmental health, and therefore of mate quality; beauty is a “health certification.” More attractive people are healthier, have greater physical fitness, live longer, and have fewer lower back pain problems (although some scientists dispute these findings). Bilateral symmetry measures beauty so accurately that there is now a computer program that can calculate someone’s facial symmetry from a scanned photograph of a face (by measuring the sizes of and distances between various facial parts) and assign a single score for physical attractiveness, which correlates highly with scores assigned by human judges. A computer program can also digitally average human faces. Beauty therefore is an objective and quantifiable attribute of individuals, like height or weight, both of which were more or less “in the eye of the beholder” before the invention of the yardstick and the scale.

All stereotypes are true, except... II: “Beauty is in the eye of the beholder”

Satoshi Kanazawa — Sun, 27 Apr 2008 19:33:58 -0700

They say beauty is in the eye of the beholder, which means that different people possess different standards of beauty and that not everyone agrees on who is beautiful and who is not. This is the first stereotype or aphorism that evolutionary psychology has overturned. It turns out that the standards of beauty are not only the same across individuals and cultures, they are also innate. We are born with the notion of who’s beautiful and who’s not.

On the surface, the aphorism “beauty is in the eye of the beholder” appears quite reasonable. Many introductory college textbooks in sociology and anthropology include pictures of people who are considered to be beautiful in different cultures, and some of them look quite bizarre to the contemporary western eye. However, evolutionary psychological research has overturned this common assumption and widespread belief.

Within the United States, both East Asians and whites, and whites and blacks agree on which faces are more or less beautiful. Cross-culturally, there is considerable agreement in the judgment of beauty among East Asians, Hispanics, and Americans; Brazilians, Americans, Russians, the Aché of Paraguay, and the Hiwi of Venezuela; Cruzans and Americans in Saint Croix; white South Africans and Americans; and the Chinese, Indians, and the English. In none of these studies does the degree of exposure to the western media have any influence on people’s perception of beauty. How is it possible for people from such diverse cultures to agree broadly on who is beautiful and who is not?

It appears that people from different cultures share the same standards of beauty because they are innate; we are born with the knowledge of who’s beautiful and who’s not. Two studies conducted in the mid-1980s independently demonstrate that infants as young as two and three months old gaze longer at a face that adults judge to be more attractive than at a face that adults judge to be less attractive. Babies are wonderfully hedonistic and have no manners, so they stare at objects that they consider to be pleasing. When babies stare at some faces longer than others, it indicates that they prefer to look at them and find them attractive.

In the most recent version of this experiment, newborn babies less than one week old show significantly greater preference for faces that adults judge to be attractive. Another study shows that 12-month-old infants exhibit more observable pleasure, more play involvement, less distress, and less withdrawal when interacting with strangers wearing attractive masks than when interacting with strangers wearing unattractive masks. They also play significantly longer with facially attractive dolls than with facially unattractive dolls. The findings of these studies are consistent with the personal experiences and observations of many parents of small children, who find that their children are much better behaved when their babysitters are physically attractive than when they are not.

Even the most ardent proponents of the traditional view that “beauty is in the eye of the beholder” must admit that one week (or even a few months) is not nearly enough time for infants to have learned and internalized the (supposedly arbitrary) cultural standards of beauty through socialization and media exposure. These studies instead strongly suggest that the broad standards of beauty might be innate, not learned or acquired through socialization. The balance of evidence indicates that beauty is decidedly not in the eye of the beholder, but might instead be part of universal human nature.

But what are the culturally universal and innate standards of beauty? What common features characterize beautiful faces? How are beautiful faces different from ugly faces? These questions lead us to the next stereotype to be overturned by evolutionary psychology: “Beauty is only skin deep.” I will talk about it in my next post.

All stereotypes are true, except... I: What are stereotypes?

Satoshi Kanazawa — Thu, 24 Apr 2008 18:40:09 -0700

“Stereotypes” have a bad name, and everybody hates stereotypes. But what exactly is a stereotype?

What people call “stereotypes” are what scientists call “empirical generalizations,” and they are the foundation of scientific theory. That’s what scientists do; they make generalizations. Many stereotypes are empirical generalizations with a statistical basis and thus on average tend to be true. If they are not true, they wouldn’t be stereotypes. The only problem with stereotypes and empirical generalizations is that they are not always true for all individual cases. They are generalizations, not invariant laws. There are always individual exceptions to stereotypes and empirical generalizations. The danger lies in applying the empirical generalizations to individual cases, which may or may not be exceptions. But these individual exceptions do not invalidate the generalizations.

An observation, if true, becomes an empirical generalization until someone objects to it, and then it becomes a stereotype. For example, the statement “Men are taller than women” is an empirical generalization. It is in general true, but there are individual exceptions. There are many men who are shorter than the average woman, and there are many women who are taller than the average man, but these exceptions do not make the generalization untrue. Men on average are taller than women in every human society (and, by the way, there are evolutionary psychological explanations for this phenomenon, known as the sexual dimorphism in size, but that’s perhaps for a future post). Everybody knows this, but nobody calls it a stereotype because it is not unkind to anybody. Men in general like being taller than women, and women in general like being shorter than men.

However, as soon as one turns this around and makes a slightly different, yet equally true, observation that “Women are fatter than men,” it becomes a stereotype because nobody, least of all women, wants to be considered fat. But it is true nonetheless; women have a higher percentage of body fat than men throughout the life course (and there are evolutionary reasons for this as well). Once again, there are numerous individual exceptions, but the generalization still holds true at the population level.

Stereotypes and empirical generalizations are neither good nor bad, desirable nor undesirable, moral nor immoral. They just are. Stereotypes do not tell us how to behave or treat other people (or groups of people). Stereotypes are observations about the empirical world, not behavioral prescriptions. One may not infer how to treat people from empirical observations about them. Stereotypes tell us what groups of people tend to be or do in general; they do not tell us how we ought to treat them. Once again, there is no place for “ought” in science.

As empirical generalizations borne of the observations and experiences of millions of individuals, most stereotypes are on the whole true. If they are not true, they cannot survive long as stereotypes. Nonetheless, theory and research in evolutionary psychology have overturned a few stereotypes and shown them to be false. For some reason that I cannot quite fathom, all the stereotypes that have been shown to be false so far have to do with people’s physical appearances. In the next few posts, I will discuss each of these stereotypes which evolutionary psychological theory and research have shown to be false.

Why boys have cooties (but brothers don’t)

Satoshi Kanazawa — Sun, 20 Apr 2008 22:26:43 -0700

When little boys and girls reach a certain age, they start accusing each other of having “cooties.” They regard each other as yucky and dirty because they have cooties, and avoid any contact with them for fear of contracting cooties themselves. That is, until they suddenly “discover” each other when they hit puberty, then they become crazy about each other and no longer fear cooties. Why does this predictable developmental trajectory happen? Why do little boys and girls believe in cooties?

The key to the mystery of cooties is the Finnish anthropologist Edvard Alexander Westermarck (1862-1939). Westermarck taught at LSE, where I now teach, from 1904 until his retirement in 1930. On a very personal note, he is also my intellectual great-great-great-grandfather, by which I mean he was my mentor’s mentor’s mentor’s mentor’s mentor.

Westermarck is best known for discovering a phenomenon which is named after him: the Westermarck effect. It refers to the fact that when little boys and girls spend a lot of time together as they are growing up, they will later as adolescents find each other sexually repulsive. It is a mechanism designed for incest avoidance. Since individuals with whom small children come in regular and frequent contact as they grow up are almost always their genetic kin (their parents, siblings and other close family members), it will not be in the genetic interest of the children to be sexually attracted to them. So nature has selected individuals to possess a psychological mechanism that aids in avoiding their close genetic relatives as their suitable sexual mates.

As with all other evolved psychological mechanisms, however, the Westermarck effect sometimes backfires, when it finds itself in an evolutionarily novel environment that evolution could not have anticipated. (Evolution is always backward-looking and can only respond to situations that reliably and consistently existed in the past. Evolution can never anticipate the future, especially in a fast-moving environment like ours in the last 10,000 years.) One example where the Westermarck effect backfires is the Israeli kibbutz. In kibbutzim, all small children, from different families, are raised together communally. As a result of the (mis)operation of the Westermarck effect, Israelis who grew up in kibbutzim do not usually find each other sexually attractive as adults, and thus seldom marry each other, even though they are not genetically related.

Another example is a peculiar custom of adoption and child betrothal among traditional Chinese families. Under this practice, a wealthy Chinese family adopts a girl from a poor family which cannot raise her, and raises her with their own son, who is then betrothed to her. Alternatively, an heirless family adopts a boy so that he could later marry their daughter and carry on their family name. When they later marry as planned, however, the couple usually remains childless, because they find each other sexually repulsive as a result of having grown up together. Despite these exceptions, the Westermarck effect works fine as designed most of the time, because most other humans with whom most children regularly associate as they grow up in most societies under most circumstances are indeed genetic kin who should be avoided as mates.

From the perspective of the Westermarck effect, cooties (and their equivalents throughout the world) are a culturally specific device that reflects the operation of an underlying universal evolved psychological mechanism. Boys and girls in every society are evolutionarily designed to employ such a device (unconsciously) to make sure that they will not spend too much time with each other. Children’s play groups in all human societies are sex-segregated; boys play with boys, and girls play with girls. This will guarantee that boys and girls will later find each other sexually attractive when the time is right, which in the context of the ancestral environment was right at puberty.

This line of reasoning leads me to suggest an interesting new prediction, although it would be difficult to test it empirically. I have not seen any systematic scientific data on children’s alleged affliction with cooties and doubt that such data exist. Scientists tend not to take cooties seriously. Nevertheless, if cooties are a device for children to avoid spending too much time with each other so that they could later select them as sexual mates, then they should not employ the device against their own brothers and sisters, whom they will not be selecting as mates anyway and with whom they should be spending a lot of time. In other words, little girls should allege that little boys have cooties, but not their brothers, and little boys should allege that little girls have cooties, but not their sisters. Brothers and sisters may resent, fight, and even hate each other, but they should not allege cootiesitus against each other. A boy might tell his friends that his sister has cooties, in an attempt to keep them away from her, but he should not use the same affliction as an excuse to stay away from her himself. I would love to hear from parents who have both boys and girls for anecdotal evidence for or against my prediction.

Why do boys and girls prefer different toys?

Satoshi Kanazawa — Thu, 17 Apr 2008 21:59:36 -0700

Throughout the world, boys and girls prefer to play with different types of toys. Boys typically like to play with cars and trucks, while girls typically choose to play with dolls. Why is this? A traditional sociological explanation is that boys and girls are socialized and encouraged to play with different types of toys by their parents, peers, and the “society.” Growing scientific evidence suggests, however, that boys’ and girls’ toy preferences may have a biological origin.

In 2002, Gerianne M. Alexander of Texas A&M University and Melissa Hines of City University in London stunned the scientific world by showing that vervet monkeys showed the same sex-typical toy preferences as humans. In an incredibly ingenious study, published in Evolution and Human Behavior, Alexander and Hines gave two stereotypically masculine toys (a ball and a police car), two stereotypically feminine toys (a soft doll and a cooking pot), and two neutral toys (a picture book and a stuffed dog) to 44 male and 44 female vervet monkeys. They then assessed the monkeys’ preference for each toy by measuring how much time they spent with each. Their data demonstrated that male vervet monkeys showed significantly greater interest in the masculine toys, and the female vervet monkeys showed significantly greater interest in the feminine toys. The two sexes did not differ in their preference for the neutral toys.

Alexander and Hines’s article contains a wonderful picture (reproduced here in full living color, courtesy of Gerianne M. Alexander) of a female vervet monkey conducting an anogenital inspection (examining the genital area of the doll in an attempt to determine whether it is male or female), as a girl might, and a male vervet monkey pushing the police car back and forth, as a boy might. If children’s toy preferences were largely formed by gender socialization, as traditional sociologists claim, in which their parents give “gender-appropriate” toys to boys and girls, how can these male and female vervet monkeys have the same preferences as boys and girls? They were never socialized by humans, and they had never seen these toys before in their lives. Yet, not only did male and female vervet monkeys show the identical sex preference for toys, but how they played with these toys was also identical to how boys and girls might.

As stunningly ingenious and spectacular Alexander and Hines's initial study was, it stood alone in the scientific literature for a while. All new scientific discoveries must be replicated to make sure that the findings are both genuine and generalizable. Well, it took the field six years, but the original findings have now been replicated.

In a forthcoming article in Hormones and Behavior, Janice M. Hassett, Erin R. Siebert, and Kim Wallen, of Emory University, replicate the sex preferences in toys among members of another primate species (rhesus monkeys). Their study shows that, when given a choice between stereotypically male “wheeled toys” (such as a wagon, a truck, and a car) and stereotypically female “plush toys” (such as Winnie the Pooh, Raggedy Ann, and a koala bear hand puppet), male rhesus monkeys show strong and significant preference for the masculine toys. Female rhesus monkeys show preference for the feminine toys, but the difference in their preference is not statistically significant.

We do not yet know exactly why males of different primate species prefer wheeled toys and other vehicles, or why females of different primate species prefer plush toys and other dolls (except for their vague resemblance to babies, for which females are evolutionarily designed to care). However, it is becoming less and less likely that “gender socialization” is the reason why boys and girls prefer different toys, and more and more likely that there are some genetic, hormonal, and other biological reasons for the observed sex differences in toy preference.

Why do some battered women stay in their abusive relationships?

Satoshi Kanazawa — Sun, 13 Apr 2008 20:00:26 -0700

Carlin Flora has in her earlier post written about the puzzle of domestic violence. Given the enormous health and somatic costs of spousal abuse, the question of why many battered women stay with their abusive husbands or boyfriends is a puzzling one. While most battered women eventually leave their abusers, a substantial minority (estimates range from a quarter to a third) remain in their abusive relationships. The problem is doubly puzzling from an evolutionary psychological perspective, because it emphasizes the importance of life, survival, and individual welfare. Why do so many battered women stay in their abusive relationships?

What adds to the mystery is that most of the women are themselves mystified by their own choice. When pressed, however, many respond by saying “Because I love him”; emotional attachment to the abuser is one of the primary reasons battered women give for why they choose to stay. From an evolutionary psychological perspective, love and other emotions are proximate mechanisms that compel organisms to engage in behavior that, in the context of the ancestral environment, would have increased their inclusive fitness. The fact that women themselves are mystified by their own choice when they follow their emotions and stay with their violent partners seems to suggest the possible operation of evolutionary logic to which the women do not have complete conscious access. But what possible reproductive benefits can staying with violent mates have, when such women are often severely injured, sometimes killed?

From the Dawkinsian (or, more properly, Hamiltonian) gene-centric view of life, there is one thing more important than life itself, and that is reproductive success. Life is important, survival is important, only because you can’t get laid if you are dead. Life is merely a means to reproduction. Organisms (like humans) are only vehicles for their genes, and it is the genes, not the organisms, that are in the driver’s seat. It would therefore underscore the power of the gene-centric view of life, if staying with an abusive partner has some benefit to the victims’ genes, while it incurs tremendous costs to the victims themselves.

One possible such benefit is that, both in the United States and the United Kingdom, women mated to abusive partners have more sons. In the British sample, women who are mated to abusive husbands on average have one-eleventh more son than those who aren’t (.7912 vs. .7007). The difference increases to one-eighth of a son (.1324) in a multiple regression analysis which includes proper statistical controls for potential confounds. However, abused women have no more daughters than nonabused women (.6787 vs. .6836). And the tendency toward violence, which is largely a function of men’s baseline testosterone levels, is highly heritable. In other words, violent fathers tend to beget violent sons.

Violent men tend not to do well in civilized postindustrial societies like ours; they tend to be overrepresented in prison populations. However, our brain doesn’t know that. The human brain, including all of its evolved psychological mechanisms, are designed for and adapted to the conditions of our ancestral environment. In our ancestral environment, violent men probably did very well in their intrasexual competition for status, and thus for mating opportunities. The most prolific father in recorded history, Moulay Ismail the Bloodthirsty, who had at least 1,042 (but probably closer to 1,400) children in his lifetime, was also reputed to have killed 30,000 people by his own hands. Aggressive, violent, and ruthless men often made the best warriors and political leaders throughout human evolutionary history, until very recently.

In species characterized by high male parental investment (such as humans), males in higher dominance ranks on average make better fathers because of their greater ability to protect and invest in their offspring than men in lower dominance ranks. Children of such men of higher dominance ranks are therefore better off than those of men of lower dominance ranks. Further, if the battered woman already has children with the batterer, she may not be able to find a superior alternative mate and father for her children, because stepfathers represent probably the greatest physical danger to children. Infants and children who do not live with two biological parents face 40 to 100 times as great a chance of being injured or killed within the family as those who live with both biological parents. Thus, as terrible as living with a batterer might be for the physical welfare of the mother, the alternative (leaving him and living with another man who is not the genetic father of her children) might even be worse for the physical and reproductive welfare of her children (and thus her genes). It is therefore not entirely unreasonable to posit that women may have been selected to tolerate a certain level of nonlethal violence in their mates in order simultaneously to protect her children and to produce intrasexually competitive (if also wife-beating) sons.

I am emphatically not suggesting that women have a preference to mate with violent abusers instead of gentle, kind, and resourceful millionaires. Given the choice, any sane woman would prefer the latter to the former. However, the process of mating is far from random or unrestricted; no woman (or man) has an entire range of potential mates to choose from. Due to the highly socially structured and constrained nature of meeting people, which results in assortative (nonrandom) mating, the choice that some women unfortunately face is often between unemployed, uneducated, unintelligent, unmotivated, alcoholic men who are violent, and unemployed, uneducated, unintelligent, unmotivated, alcoholic men who are not. My suggestion is merely that, under some circumstances, women may have been selected to prefer the former to the latter. Some (present-day) losers may be better than others, especially in the context of the ancestral environment. There is even some evidence from field experiments from four American cities that employed men are more likely to batter their wives than unemployed men.

The difference in the mean number of sons between abused and nonabused wives (about one-eleventh to one-eighth of a son) is admittedly very small. However, evolutionary biological models show that even a 1% advantage in reproductive success is sufficient for the trait to spread in the population within a relatively short period of time. So even a small advantage of having a fraction of a son carrying his father’s violent genes and thus outcompeting his male rivals in intrasexual competition for status and mates might be sufficient for the tendency for women to stay with their abusive husbands to evolve.

The tendency for battered women to have more sons than other women do can potentially explain the otherwise puzzling phenomenon of why some battered women stay in their abusive relationships. This explanation, if at least partially true, underscores the power of evolutionary psychology and its gene-centric view of life. Sometimes organisms sacrifice their welfare and life in order to increase their reproductive success.