More on Evolutionary Psychology
So I've been commenting recently on wanton_heat_jet's journal about evolutionary psychology after he left a series of comments on my RPG journal post "On Gender Disparity in RPGs" from last year. At around that time, I also had a post on my personal blog, "Evolutionary Psychology," more about the scientific side of this.

He started in with "ev psych and RPGs." and followed with a series of ten posts thus far on evolutionary psychology (see his June 2009 archive). This was also picked up by robin_d_laws in his post, "We Evolved On the Grasslands To Have This Debate."

A number of others have been dismissive of this. However, I ran into similar evolutionary arguments from multiple people at a panel at WisCon, so I am convinced that belief is widespread enough that it bears addressing.

The Short Form

From my observation, the field of evolutionary psychology is overwhelmingly filled with unscientific crap. It may be that there is some valid work within the cesspool, but I haven't seen it, and it would have to overcome a major hurdle to distance itself from the rest of it.

robin_d_laws admitted widespread problems in evolutionary psychology, but did recommend a few including Robert Wright, Jeffrey Schloss and Frans de Waal. I'm remain doubtful based on what I read, such as his recommended vlog entry, "Humanity's Primate Heritage." From what I've seen, their discussion is airy speculation -- it's trying to argue in favor of evolution over creationism, but there isn't any real content regarding psychology.



Use of Evolutionary Data

There is no doubt that humans are a product of evolution, and that our genetics are an important factor in our behavior. However, the details of are evolution are found in the fossil record, which have very limited cues telling us of behavior. We can observe the behavior of humans in the modern-day among the various surviving cultures, but that might not correspond to the norms of behavior thousands or millions of years ago.

Humans are exceptional in many ways from comparable mammals, not only in brain size. Our body hair (for land animals), our bipedal gait, our fertility cycle and mammaries, and more. We can conjecture about trends, but that must be taken with large handfuls of salt.

I suspect that modern-day gender dynamics reflect paleolithic gender dynamics in a similar way to how the average modern-day diet reflects the average paleolithic diet. On that basis, I think that evolutionary logic applies to game design in roughly the same way that it applies to cooking. One may in principle come up with a new idea for cooking based on evolutionary logic. However, given that we are cooking for modern-day humans, it is an absurd stretch.

Presuming Adaptations

A key issue with evolutionary psychology is its use of "just so stories." In short, suppose that a particular trait or behavior exists in modern humans. The evolutionary psychologist points out how this behavior might have had a functional benefit for early hominids. This behavior or psychological trait is then presumed to be genetically programmed.

Simply put, that is stupid. Just because a trait would be useful doesn't mean that it necessarily exists. There are endless hypothetical traits -- anatomical as well as psychological -- that could potentially have been useful to us. That they would have been useful doesn't mean that they exist. For example, humans and their ancestors made stone cutting tools for over a million years, for longer than they had hunted. However, that does not mean that the process of creating a stone axe is genetically programmed into our brains.

Human Evolution and Sexual Dimorphism

To the best of our knowledge, humans evolved from the extinct line of austrolopithecines (from 2-4 million years ago), and from earlier forms of the genus Homo. Species in the genus Homo include Homo Habilis (2.4 to 1.8 million years ago) and Homo Erectus (1.8 million to 70,000 years ago). The exact line of descent is not clear, however, and there may be other species or subspecies not yet found.

Homo Habilis apparently scavenged meat and used tools, but did not hunt. Homo Erectus hunted and made use of fire. Both of these species had greater sexual dimorphism than modern humans -- i.e. in modern humans, males are closer in size to females. (cf. "Analysis of Early Hominids")

Hunting became important for early humans once it was established. In the Upper Paleolithic Age, estimates vary that food from hunting amounted to from 20% to 70% of the caloric intake. Among modern humans of all cultures, hunting is usually considered an exclusively male task. The gender roles among earlier species is not known. It may be inferred from the example of modern humans that hunting was generally done by males, but this is not a given. For example, in lions the male is much larger and stronger, yet hunting is done primarily by the females.

I frequently hear the claim that men are larger and stronger because they are evolved to be hunters, which is patently false. Their larger size may have helped male hominids be the main hunters, but their size is not an evolutionary adaptation for that purpose. It was quite the opposite. Since hunting began, men have grown closer in size to women.

Genetic Gender Roles

There are most certainly going to be genetic differences, both in morphology and behavior, between men and women. Among mammals and birds, males tend to be larger and also tend to have more adornment and/or coloration. cf. "conspicuous males" In sexual selection, males tend to compete for the attention of females by various display behaviors.

The general tendencies may not hold true for humans, but if they were, they would suggest that men have a genetic predisposition to more competitive and performative behaviors. That is, men may genetically tend to be more interested in sports, dance, fashion, and make-up. However, the decrease in sexual dimorphism of humans compared to their ancestors suggests a lessening of male competition based on size.

Claims are also made regarding men's taste for violence, often based on male competitions to impress females common among primates and mammals in general. However, the logic is generally twisted. A common claim is that women don't like action movies or boxing matches because they are inherently less violent. Within evolution, watching male contests is a more characteristically female trait. Evolutionary logic would suggest that watching men fight is more enjoyed by women, since they can improve the fitness of their offspring by observing and selecting a more fit mate.

A rather amusing bit was Tweet's claims about sports. He originally stated regarding the predominance of men in D&D, "It's about a group assembling to undertake (imaginary) risks for glory and dominance. It's the same reason that team sports, such as basketball, are more male, whereas women compete to be judged beautiful and worthy (ice skating, gymnastics)." He attempted to defend this in his post, "ev psych, gymnastics, and ice skating." However, it was pointed out to him that ice skating and gymnastics were historically male sports, whereas basketball was adopted by women almost immediately for women since its invention in 1891. kynn also provided statistics showing how vastly more women participated in soccer, volleyball, and basketball than in gymnastics or figure skating. He attempted to recover this by claiming that he was talking about our "cultural footprint" rather than actual behaviors of men and women, but that makes no sense in an evolutionary perspective.

A similar point was made in the heritability of Big Five personality traits, that differ between sexes. An interesting study on this is "Gender differences in personality traits across cultures" (2001). This is sometimes claimed as showing cross-cultural universality, but that isn't what it shows. It compares gender differences in personality ratings among 26 countries, but most of those are relatively Westernized first-world nations. In other countries, though, the results were quite different. For example, Zimbabweans had the opposite gender difference in Neuroticism and Agreeableness to those seen in other countries (i.e. women were slightly less neurotic and less agreeable than men, whereas the first-world trend is the other direction). Other countries showed major differences as well, notably South Korea, Japan, and black South Africa. There is close agreement, say, between Yugoslavia and Portugal and the U.S. -- but I think that is indicating similarity of environment.

Many behaviors can arise from the environment, even if they are done for millions of years. Evolutionary psychologists like to say that because we have been hunting for a million years, therefore hunting is programmed into the DNA of men but not women. However, we have been creating stone cutting tools for longer than we have been hunting. I have yet to hear claims of how the processes of chipping a stone axe are genetically programmed.

I think that we will find that there are some adaptations for stone tools and hunting. However, I expect that our modern-day behaviors will be markedly different from our ancestors in a great many categories, and in ways that are not predictable by simple common sense.

Identifying Genetically Programmed Behaviors

In one post, Tweet suggests that behaviors that come "naturally" to us -- i.e. those that do not require special effort by parents or the community -- are those that are genetically programmed. However, I believe that is based on false logic.

Humans raised in modern society are in a vastly different environment than the ancestors of humanity were. Even if no special effort is made to train them, animals raised in conditions vastly different from their natural habitats (such as homes or zoos) often display behaviors that are quite different from their behavior in the wild. It can be extremely difficult or even impossible to train an animal to live in its natural habitat after being raised elsewhere. By the same token, trying to raise a child in today's society who could survive in the grasslands would take enormous effort.

One example would be human food. The modern foods that we enjoy most are likely to bear little resemblance to the Paleolithic diet that we evolved for. In fact, sticking to a Paleolithic diet can be as difficult as other diets.

Humans in particular are excellent learning machines. There are an enormous number of things that we learn from our environment without it being a great effort to learn. For example, in our society, children rapidly learn that long hair and dresses are markers for being a girl. However, that is not culturally universal.

It may be genetically encoded for us to learn spoken language, and for us to learn markers for sex. Even if that is so, however, the specifics may depend on environment -- i.e. the specific language that we learn, and the specific markers for sex (such as girl clothes vs boy clothes, or girl games vs. boy games).

Why this is important

It is important because people spread around fabricated claims as well as other biased quotes and bad science that try to prop up sexist stereotypes. wanton_heat_jet passed on some, like linking to an ABC News story that began with the claim, "For instance, a woman uses about 20,000 words a day while a man uses about 7,000."

I pointed out that this claim was fabricated, and linked to a review from the British science journal Nature that reported "The Female Brain disappointingly fails to meet even the most basic standards of scientific accuracy and balance." and "Misrepresentations of scientific details are legion." However, he continued to defend author Brizendine, claiming here that "She's a popular writer and her big ideas are good even if her details don't always measure up."

Besides fabrications, there are wildly misused claims. For example, Tweet claimed that women inherently tended towards imaginative social play -- citing as evidence that monkeys had such sex-biased instincts. As far as I can tell, that referred to a 2002 study, "Sex differences in response to children's toys in nonhuman primates." (This study was also mentioned in ozarque's journal here.) The researchers at UCLA gave a set of 48 vervet monkeys of each gender a set of six toys: two "masculine" (a toy car and a ball), two "feminine" (a pot and a doll), and two "neutral" (a book and a stuffed dog). Their conclusion noted, "We found differences between male and female vervet monkeys that resemble the well-established differences in the toy preferences of boys and girls, consistent with the proposed existence of innate object preferences. However, although female vervets preferred 'feminine' toys over 'masculine' toys, male vervets did not appear to prefer 'masculine' toys over 'feminine' toys. This difference between male vervets and boys may indicate that toy preferences in boys are directed by gender socialization to a larger degree than are toy preferences in girls." I think even casual consideration makes one doubt how much this study really gets at the nature versus nurture question in humans -- let alone the conclusion that girls favor imaginative social play in general.