W.D. Hamilton’s description of kin selection and inclusive fitness in 1964 led to a major remake of ethology and behavioral biology. He pointed out, for example that since full sibs share half their genomes, anything one does for the other also propagates his own genome, discounted by one half in this case.
In general the discount is given by the coefficient of relationship between the actors: one half between full sibs or between parent and offspring, one quarter between actor and grandchild, and so on.
In the subsequent development and application of the theory, attention remained focused on such genealogical kinship. A kind of shared consensus dominated, especially when thinking about humans: more remote relationship was too small to be of any significance. In particular: ethnic tension, bigotry, and racism were acknowledged to be divorced from mechanisms of inclusive fitness.
Part of this consensus reflected another consensus in anthropology: pots moved in the past but people did not. The dominant model was of an earth carpeted with sessile yet relatively open communities doing limited mate exchange with their neighbors, all facing a common Malthusian limit.
The kind of eruptions familiar from history and recent prehistory, like the expanions of the Bantu or the Han or the Indo-Europeans or the Turks were dismissed as relatively recent consequences of agriculture. We did, after all, spend 99% or our evolution as foragers, just like Kalahari Bushmen, or so the reasoning went.
It is easy to toss out the 99% since people unambiguously like ourselves show up about 45,000 years ago, and agriculture took hold and spread 10,000 years ago. The 99% has to come down to 35/45 or 80%, but even so why would anyone think that Aurignacian invaders of Europe could be modeled by Kalahari Bushmen?
In this imagined homogeneous landscape (this is the crucial point) no one ever encountered anyone very different from himself so there could be nothing in our past to favor evolution of ethnic or racial discrimination and enmity.
Perhaps it is time to give bigotry another chance. With large sets of SNP typings on individuals we can bypass the whole genealogy issue and look directly at DNA differences over the whole genome.
I have been looking at populations in the HGDP (Human Genome Diversity Project) database, which can be gotten at http://www.hgdp.org. I am speaking here about what is called the coefficient of kinship, usually half the coefficient of relationship, because with kinship the algebra makes much more sense.
This figure shows, in the top panel, kinship measured between all possible pairs of 29 French in the French HGDP sample.
No one knows, by the way, how sampling was carried out for this nor for any of the HGDP populations.
The mass at f~0.5 represents kinship with self, more or less that 0.5 according to whether the individual was relatively inbred or outbred. The bottom panel shows, for each person in the sample, the kinship with his closest “relative” (who is probably not a known genealogical relative).
The second figure shows the same statistics for 29 Japanese. Again, the bottom panel shows that, from the viewpoint of kinship, one person is not very different from another person. In other words, with respect to inclusive fitness, there is almost nothing here nor in France to let it work.
Now imagine that these were two communities near each other living in quiet harmony. Then Washington hears about the situation and sends a social improvement team to furnish each community with more diversity by merging them into a single community. Here is the new distribution of kinship in the top panel and, in the bottom panel, the distribution of closest kin for each of the 58 members of the new merged community.
In the new diverse community the average person can find someone related as f~0.06, corresponding roughly to a great-grandchild at f=1/16. Suddenly there is a fitness payoff to discrimination.
Anything I do for my nearest cryptic kinsman is equivalent to doing .06/.5 12.5% of the same thing for myself, or rather for my Darwinian fitness. Suddenly there would be not-insignificant selection for kin and ethnic discrimination, even bigotry or racism.
The above two examples, French and Japanese, are large populations with deep gene genealogies. The HGDP also has several small ethnic populations in their sample, and the distribution of kinship within these populations is quite different.
This figure shows the data from the Druze, a community in the Middle East that has endured episodes of very small effective size.
Here opportunities for discord and clannishness are high as individuals able to discriminate kin would ally against the “others.”
In this kind of social/genetic environment one would predict very different patterns of family and clan and group loyalty and cooperation. One is reminded for example of the discord and acrimony that is often reported about reservation politics in North America.
Anoyone who writes academic or research papers knows that one writes a draft, puts it in the drawer to stew for a week or more, goes over it carefully, usually rethinks a number of points and sees new ones, and repeats the process until it is ripe.
The above isn’t like that. It has had a whole day and a half in the drawer during which it received perhaps two hours total of thoughtful revision. I am putting it out here because I think it must be interesting but I don’t have it all very clear in my head. If I can crowd source some of it it will be a big help.