Wednesday, September 19, 2007

Crazy Monkeys

In David Sloan Wilson's book Evolution for Everyone, he tells a story about crazy monkeys, and the evolutionist explanation for why this behavior, though seemingly contra-survival, can keep coming up in a rhesus monkey population.

Here are the basics (paraphrasing the book). Every generation, a small faction of males in a rhesus monkey colony active as if they are out of control. They take insane risks in jumping between branches. They bully and rebel, can't be controlled by their mothers or by their peers.

The first theory the researcher, Dr Stephen Suomi, was that perhaps this behavior conferred an advantage to the psycho males - they could enter a new group, take over with their bullying and crazy behavior, mate with the females whether they liked it or not, and thereby perpetuate their genes.

But experiments showed that this theory was wrong. Rejected by family and friends, the psycho males never learn to compete well with other males or to fit into a group. Rejected, they typically lead a miserable solitary existence until they die. So why doesn't this sort of maladaptive behavior die out?

The answer appears to be that the same gene that causes males to go crazy turns out to produce confident, capable females who achieve high status within their groups. These females breed more, and, just as important, due to their enhanced abilities are even able to raise sons with the "crazy gene" to be fine young monkeys. Mothers lacking the gene who gave birth to sons having the gene (thanks, Dad) weren't so effective, and the crazy gene expressed itself to produce crazy monkeys.

So the gene stays active in the population, and due to the statistical dynamics, about 10% of male rhesus monkeys get the crazy gene, with a smaller percentage of these not having the advantage of corresponding super mom who end up acting...crazy.

The basic story of the crazy monkey - adaptations that thrive work for the group (or species), not necessarily for an individual. Certainly, at an individual level they can't be too destructive or they would die out in a population. But they don't have to be individually helpful, and can sometimes be individually hurtful.

For the longest time I've wondered about religion, and how some of the craziest acts of humans seem to come from religious extremists.

Initially, I used simplistic explanations. In searching for better answers, I looked to neurobiology. Antonio Damasio has produced some great work on how emotions work (and are in fact necessary) in reasoning. Better yet was Pascal Boyer's Religion Explained, which went into some evolutionary origins concepts for religion, and did pretty good job of explaining what religion was (and wasn't), and how our brains dealt with it.

But this only got into the proximate reasons for religious tendencies (meaning that it helped explained why people act religious, but not why these brain structures and cultural structures developed in the first place). For the trait to become so widespread in our species, it must have some larger effect that helps species survival. (In evolutionist terms, proximate causes are the immediate biological or physical mechanisms that cause a behavior or outcome. Ultimate causes are the species level reasons why such a behavior or outcome propagates through the generations more effectively than others).

In Darwin's Cathedral, David Sloan Wilson gets into these proximate and ultimate causes of religion. In his theory, the ultimate cause of religion is that it is adaptive at a group level. In other words, religion is a mechanism that causes people to group together with common purpose. (Clearly there's more to it than that - otherwise he couldn't fill a whole book. But the gist is that religious tendency in the human brain is a proximate cause which supports an ultimate cause of forming groups that perform better than individuals, or even of other groups that aren't so cohesively knit).

Getting together into cooperating groups doesn't require religion. And certainly having religious feelings and irrational beliefs don't always result in forming a cohesive group. But individuals who initially developed the genetic variation producing the god module portions of the brain had powerful feelings, and connecting with other individuals with similar feelings (to the exclusion of those who didn't) made sense. And because these feelings evoke such powerful emotions, this mechanism provides a very strong social glue for like individuals. Groups who can collectively whip themselves into a religious fervor can feel more connected, and more cohesive, than those who group based on less emotional drivers.

This is finally a reason which makes sense to me, and which is consistent with known facts of religion. This is a group-supporting behavior, like altruistic punishment, that provides survival and propagation benefit to members of the group over members outside of it.

Personally, I may not like the fact that the mechanisms of religiosity periodically result in a crazy monkey. But I can understand the selection advantage to groups with strong binds and common purpose, which religion historically has provided.

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