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← A misguided attack on kin selection

Richard Dawkins's Avatar Jump to comment 12 by Richard Dawkins

Thank you s.k.graham for your explanation. My own exposition, as Electric Monk says, is in The Selfish Gene, and I apologise for assuming, in my Notes above, prior knowledge of that book or equivalent.

To expand on the point about haplodiploidy being incidental to Hamilton's classic double paper of 1964, out of 49 pages ( in the Narrow Roads of Gene Land reprint), the haplodiploidy hypothesis occupied a mere three and a half pages. This was followed by another three pages discussing the fact that Hymenopteran queens often have multiple mates -- precisely the point advanced by Nowak et al as a 'new' criticism! Hamilton then went on to discuss the case of the termites (which are not haplodiploid) thereby anticipating another of the 'new' criticisms. The termites, as Hamilton also pointed out, have a completely different tell-tale predisposition to eusociality under his theory, namely recurrent inbreeding, which raises the coefficient of relatedness in a way parallel to the 'haplodiploidy effect'.

Given that Nowak et al seem to think haplodiploidy is central to Hamilton's theory, I am astounded that they totally fail to mention the work of Robert Trivers and Hope Hare on sex ratio biases in Hymenoptera (see The Selfish Gene for a full discussion). Trivers and Hare calculated optimal sex ratios from the point of view of a queen, and from the point of view of a worker ant, given haplodiploidy. If the queen exerts power over the ratio of males to females, the stable ratio of colony investment in males versus reproductive females would be 1:1. If the workers have control over the sex ratio, there would be three times as much investment in females as in males. They went on to measure the actual ratios in 20 species of ants and found a female bias as per the haplodiploidy prediction. There was even an 'exception that proves the rule' in the form of slave-making species whose workers have no power because the work is all done by slaves. The Trivers/Hare study has been criticised on various grounds, but it is astonishing that Nowak et al ignore it completely.

In any case, the most important point is that Hamilton's theory does not -- and never did -- stand or fall by the enigmatic special case of haplodiploidy. On the contrary, by far the bulk of work using the theory has been done on ordinary diploid organisms, and the bulk of Hamilton's own thinking on the subject concerned diploid organisms. Hamilton's theory of Inclusive Fitness is not something set apart from 'Standard Natural Selection Theory'. It is Standard Natural Selection theory, made complete by filling in a logical implication that had previously been overlooked.


Tue, 31 Aug 2010 09:42:50 UTC | #508420