In a post over at Steve Sailer’s blog, kin selection is used explain nepotism. He sparks interest in the beginning of the post with this statement:
I’ve noticed that a lot of smart people like Richard Dawkins and Gregory Cochran assume that while Pierre L. van den Berghe’s theory of ethnic nepotism –which extends W.D. Hamilton’s kin selection theory to the more distant kin of one’s ethnic group (see “The Ethnic Phenomenon,” 1981) — may work as a mathematical theory, it can’t possibly work in reality.
Do I think that kin selection might help explain ethnocentrism/patriotism/etc? Possibly, but not very likely. (And I certainly don’t agree with steves general idea that racism/sexism or whatever-ism has support in biology)While I do agree with Dawkins about mispriming- yes- see the cuckoo example, kin selection operates on a different order of magnitude (or more) than that of nationalism. Steve and others are correct in pointing out the distant kin issue, but they forget that while they should be accounted for, their proportion of genes shared via common descent decreases rapidly and so too does their ability to exert strong selective pressure.
Think about the number of shared genes you might sacrifice by denying aid to a sibling- potentially many. Now think about the number of genes you might sacrifice in a 3rd cousin- many fewer. Use this idea to think about how strong selection might act on altruistic acts and brothers- versus more distant kin…
A minor criticism of the majority of his examples is that most of them are probably not altruistic- and therefore not pertinent. The definition of altruism requires that the act you perform must have both positive effect on the recipient and negative effect on the actor. Although it is nice to feed a hungry relative- nowadays there is not an appreciable fitness effect on the actor.
2 responses so far ↓
1 Steve Sailer // Jan 21, 2007 at 12:25 am
“but they forget that while they should be accounted for, their proportion of genes shared via common descent decreases rapidly”
Two points:
A. You’re forgetting about inbreeding. If you take your family tree back 1000 years, you’d have a trillion open slots who were your ancestors 40 generations ago. So, it turns out that you are related to your very distant relatives through many different paths, which accumulate to a fairly large degree of relatedness.
B. During periods of population growth, with fertility above the replacement rate, the number of shared genes in your third cousins, on average, is greater than in your second cousins, which is greater than in your cousins, which is greater than in your siblings.
B.
2 gcochran // Jan 22, 2007 at 11:10 am
It is not that I disbelieve the math: the math says it doesn’t work.
When rare, a gene pushing this kind of behavior would shrink, not grow. Imagine a gene, still rare, that makes the bearer willing to make some kind of sacrifice that helps Germans in general.
By the way, it is hard to find cases in which this is even _possible_ - you need a situation in which your sacrifice has a big payoff. Defebding a nest is a common case in which there really is such a possibility, rather like Horatius at the bridge, which is why most eusocial special (bees, ants, termites, mole rats) are cavity nesters.
Anyhow, suppose that he then died in a way that saves 100 random Germans - not particularly likely to be close relatives.
Since the gene is rare, the odds are that he didn’t save a single copy of the gene. The gene frequency has gone _down_, not up.
Now if he’d died to save three brothers - well, they each have a 50% chance of carrying the gene, _even_ when it the gene is rare -
so the gene frequency goes up, not down.
You have to help people who are more closely related than the average of your breeding population - significantly closer.
Ethnic nepotism as a real biological imperative, based on kin selection, simply does not work.
Now on the other hand a green-beard gene might work - because in that case, the effective relatedness of someone bearing the green-beard marker is always 1.0
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