226 Catherine Wilson
individual constituents would fare poorly in other-things-being equal competition
with rival genes.
It has nevertheless been doubted that group-living organisms actually behave
in ways that satisfy the exigent Sober-Wilson definition, and it is not clear that
behaviour involving a fitness cost as opposed to “vernacular” altruism is in need of
explanation. Many theorists have pointed out that helping behaviour and a dispo-
sition to fairness and co-operation can benefit the donor as well as the recipient to
a sufficient extent that the donor’s type is not eliminated from the population and
permitting the evolution of polymorphisms — a range of behavioural tendencies
ranging from extreme generosity to free-riding and advantage-taking. Egoism is
not an evolutionary stable strategy (ESS), defined as a strategy that does well
when it meets itself [Maynard Smith, 1982; Skyrms, 1996]. Further, a gene for
altruism would increase its representation in a small breeding community in which
most members are close relatives [Rosenberg, 1991] who help each other. Altru-
ism and fairness can be considered as forms of behaviour that make the social
environment more conducive to living and breeding for an entire population, and
emotion-based mechanisms that punish egoism with exaggerated retaliation might
be expected to evolve in tandem with egoism, thereby limiting its effects [Trivers,
1971; Frank, 1989]. Finally, sporadic self-sacrificing behaviour that seems evolu-
tionarily senseless, such as throwing oneself onto a hand grenade to save a comrade,
or jumping into an icy river when one cannot swim to rescue a child, may represent
an inadvertent overreaction of the human nervous system to an irresistible stimu-
lus. The propensity to perform such actions in rare cases need not receive a direct
evolutionary explanation. In some cases, especially where the reaction is instan-
taneous, it might be observed to resemble the immune system overreactions that
sometimes kill the organism the system is adapted to preserving. In other cases,
such as the devotion to a life of service by monks in a monastery or by a Mother
Teresa or an Albert Schweitzer, the behaviour in question is clearly motivated by
abstract ideals transmitted in revered texts and documents and unavailable to our
nonliterate ancestors, who can be ascribed at best a latent disposition, present in
at least some of them, to have self-sacrificing behaviour elicited by the appropriate
ideational stimuli.
Given the range of behaviour possible for us, the provision of a satisfactory
explanation for the evolution of some degree of altruism in group-living animals
including humans does not settle the question how benevolent, co-operative, and
fair we ought to be in the various situations that face us — how much to give
to charity for example, whether to co-operate on some occasion or opt out of an
existing co-operative arrangement, or whether to capitalize on a rival’s weakness
or ignorance. Yet the discussion of the evolution of altruism has had a remark-
able effect on the construction of the image of human nature that furnishes the
cultural background to contemporary moral debate. The error in taking the indi-
vidual organism to be the privileged and unique unit of selection, the assumption
that this individual was by nature selfish, and that the chief difference between
man and animal in this respect was that man was motivated by considerations of