p235
The Origin of Values (edited by M. Hechter, L. Nadle and R. E. Michod; Aldine de Gruyter, New York, 1993) という魅力的タイトルの本があるが，この本では社会学者も生物学者も社会的コンテクストでの価値の発生しか論じていない．
人間の利他行動はグループ間紛争の結果か
そうであるのがかなりにもっともらしい．
Lethal intergroup competition promoted human altruism (?)
S Bowles Group Competition, Reproductive Leveling, and the Evolution of Human Altruism
(BG) Group selection has long been judged untenable on empirical grounds for most species. But there have been no empirical tests of this explanation for humans.
上の話を裏書きする次のような論文が出た．
Oxytocin drives parochial altruism
De Dreu et al., The Neuropeptide Oxytocin Regulates Parochial Altruism in Intergroup Conflict Among Humans
Science 328 1408 (2010)
Oxytocin promotes in-group trust and cooperation, and defensive, but not offensive, aggression toward competing out-groups.
Intergroup conflict is strong enough to promote costly altruism in humans
S Bowles Did Warfare Among Ancestral Hunter-Gatherers Affect the Evolution of Human Social Behaviors?
Science 324 1293 (2009)
*I ask a more precise question: If more cooperative groups were more likely to prevail in conflicts with other groups, was the level of intergroup violence sufficient to influence the evolution of human social behavior?
‘Love thy neighbor’ didn’t mean what we now think it means. It meant only ‘Love another Jew.’ The point is devastatingly made by the American physician and evolutionary anthropologist John Hartung (he has written a remarkable paper on the evolution and biblical history of in- group morality, laying stress, too, on the flip side ― out-group hostility).
＊45 year domestication experiment of red fox selected for fearless and nonaggressive appraoch to humans.
＊Resultant fox kits are not only as skillful as dog puppies in using human gestures but are also more skilled than fox kits from control popuation.
Sciece 314 1569 (2006)
＊The author's empirical estimates (see table 4 for hunte-gatherers) show that genetic differences between early human groups are likely to have been great enough so that lethal intergroup competition could account for the evolution of altruism.
＊The mechanism seems to presuppose advanced cognitive and linguistic capacities, possibly accounting for the distinctive forms of altruism found in our species.
Altruism and Parochialism evolve hand in hand
Choi et al., The Coevolution of Parochial Altruism and War
Science 318 636 (2007)
Parochial altruism could have evolved if parochialism promoted intergroup hostilities and the combination of altruism and parochialism contributed to success in these conflicts. Under conditions likely to have been experienced by late Pleistocene and early Holocene humans,
neither parochialism nor altruism would have been viable singly, but by promoting group conflict, they could have evolved jointly.
*The estimated level of mortality in intergroup conflicts would have had substantial effects, allowing the proliferation of group-beneficial behaviors that were quite costly to the individual altruist.
汝の隣人を愛せよ，というのはまさに隣人を愛することであって，別の集団の人間を愛することではないのだ．R. Dawkins, The God Delusion (Houghton Mifflin Company 2006)のp253のあたりにはつぎのようにある:
そしてこれは，結果として，人口密度を環境収容能力のはるかに下に保ち，集団すべての安定な存続を可能にしたメカニズムかもしれないのである．斥力コアあるいはパウリの排他原理が粒子系を安定化しうるように，生きものの攻撃性は生態系を安定化しうるのである．家畜化はこの攻撃衝動を弱めることで高密度の飼育を可能にする．そのため，野生化した家畜は容易に環境を破壊するのである．
攻撃性が選択的に除かれるとどういうことが起こるかに関してキツネの長年にわたる撰択実験はいろいろ興味深いことを教える．
Hare et al., ``Social Cognitive Evolution in Captive Foxes Is a Correlated By-Product of Experimental Domestication,’’
Curr Biol 15 , 22 (2005)
＊It is likely the oberved social cognitive evolution did not require direct selection for improved social cognitive ability.