Friday, March 21, 2008


It's certainly appropriate – as well as hilarious – to draw the analogy between humans and slime molds. Kurt Vonnegut, Samuel Clemens, and H. L. Mencken would approve. But there's serious truth in it:

Some cheaters can keep it in their genes
A new study examining social behaviour suggests certain individuals are genetically programmed to cheat and often will do- providing they can get away with it.

The researchers looked at slime moulds - microscopic single-cell organisms or amoebae that are forced to cooperate with one another when food is in short supply. Studying slime moulds at the cellular level provides the scientists with a unique insight into the genes that may also influence human behaviour.

The international team, including biologists from The University of Manchester, found that some amoebae have the ability to use cheating tactics to give them a better chance of survival. The research - published in the journal Nature - not only demonstrates that cheating is a natural phenomenon governed by our genes but that it may be widespread among social creatures.

This is familiar territory. I wrote about it here, where the subject (among other things) was the evolutionary origins of altruism and cooperation. One needs to read that (or be familiar with the viewpoint of evolutionary psychology on the origins of morality and ethics) in order to see how the following speculations fit in.

Apparently, in many social species, there is a tendency for populations to evolve with an equilibrium mixture of cheaters and non-cheaters ("altruists"). Although cooperation increases the probability of group survival, some individuals in any group can gain an advantage by cheating, so they will tend to persist in groups as time goes on. But they can't become too numerous without harming the group's survival. So eventually some equilibrium is reached.

In the simulation of intergroup warfare I discussed in my earlier post, it was the warfare which worked against survival, so that under such conditions, there were pressures against a large equilibrium fraction of cheaters. These pressures were manifested in such things as religion and moral/ethical codes of behavior, together with formalized punishment of cheaters.

But warfare isn't the only factor that can put pressure on group survival. Simply living in a hostile or marginal environment can do it. This seems to be what happens with slime molds. Individuals can be, well, individualists until there is an existential threat.

One wonders whether this isn't what happened to the Neanderthals. Their environment was harsh. They must have migrated to that environment during favorable conditions (otherwise, why stay?), but eventually conditions got worse. If they were not able to evolve (biologically and/or socially) fast enough to reduce the percentage of cheaters, it's reasonable to suppose all would die. Modern humans living around the same time in similar environments – and who survived – perhaps were able to evolve faster. Or else they had already better capabilities for intragroup cooperation to deter cheating. Things like abilities in their brains for cheater detection, a "theory of mind", and ethical reasoning.

Other considerations suggest that worsening environmental conditions leads to more intergroup warfare (if population density is high enough, so that there is competition for resources, not merely strugle to survive, as on an island without competing groups). Such warfare would also promote cooperation and intragroup altruism over cheating.

What kind of cooperation is helpful in the non-warfare scenario? Sharing of resources (food, shelter, tools, clothing, etc.) Also communal support for raising orphaned children. Groups that had such customs and low proportions of cheaters would be more likely to survive at all.

Incidentally, one of the principal investigators (Chris Thompson) in the slime mold study, seems to know his subject pretty well. Here's another item about his slime mold research.

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