Thursday, May 16

Tell Truths, Not Stories

On either side of a recent conference in London, where participants discussed the possibility that "human ancestors were exposed to a period of semiaquatic evolution", a number of voices have taken aim at the so-called Aquatic Ape Hypothesis. The AAH attempts to grapple with some interesting ideas, like why fish protein and fat is so important to our health, notably brain development, or why infants have an instinctual ability to swim, which disappears between 4 and 6 months. According to the mainstream theories of recent human evolution, these facts don't make a whole lot of sense.

It has been pointed out by many journalists (see the infamous Space Ape Hypothesis) that the AAH is still kind of ridiculous. Henry Gee points out the most crucial of flaws in the AAH, and more importantly, faulty underlying reasoning. For instance, sinuses, proposed to aid the theoretical Aquatic Ape in maintaining buoyancy underwater, are found in all mammals.

The AAH debate has been warmed over by a million people, both qualified and unqualified, over the course of decades. We don't need another tiny voice in that mix; I don't have anything to add about the AAH. But, the AAH represents much of what is wrong with evolutionary psychology, and points to a core issue that I've argued and discussed with many of my peers over the past several years: How do you make any progress in evolutionary psychology without creating a bunch of baseless just-so stories?

The short answer is, Slowly, and with a lot of hesitance.

When a psychologist found that that individuals who worry the most about social rejection are most likely to act out in response to rejection cues, what she found was truth. This is a fact of human psychology. There aren't any such facts about ancient psychology because we have no prehistoric psyches to work with, only archaeology, non-human primates, and modern humans.

What can we then say? Still quite a bit. Example: incest avoidance. Animals avoid mating with siblings and other close relatives because of the dangers of incest. There are many mechanisms spread across the kingdom that work to prevent incest from happening; in baboons, males disperse to a new troop to avoid reproducing with their relatives. In humans, we come to recognize those who we grow up in close company with as family members. This frequently applies to childhood friends of the opposite sex, and was a major problem for the sustainability for the Israeli kibbutz system. This is a psychological mechanism, born from an evolutionary need. It is respected enough to have been named. It is called the Westermarck effect.

Ultimately, the validity of evolutionary psychology lies with the validity of all science. If your findings aren't logically sound, other scientists will see through them, and you won't get published. Modern science has an additional tool: statistics, which allows us to falsify theories with varying degrees of confidence. Like any other field, statistics isn't perfected, but it is a powerful tool.

Unless your argument against evolutionary psychology is that all evolutionary psychologists are deranged, there is no particular reason to target evolutionary psychology. Evolutionary psychology is like psychology which is like all of science. There is fraud, there are charlatans, and sometimes just honest people get things wrong. We do what we can about that, but we don't disavow the entire field. 

If you would like to read more about the AAH itself, esteemed professors and bloggers John Hawks and PZ Meyers recommend that you go here. The site is more than just a discussion of the AAH, it is an informative primer for any interested in the logic of evolutionary psychology.

1 comment:

  1. The aquatic ape stuff is also emblematic of another problem. Many evolutionary hypotheses that would be considered absurd if they were applied to other species are treated as respectable when human origins are involved. There seems to be a cognitive bias that favors outlandish stories about human development; we evidently want to feel that human evolution was special.