Deviation from the mean

http://www.economist.com/science/displayStory.cfm?story_id=1045223



Human behaviour
Deviations from the mean
Mar 21st 2002
From The Economist print edition
AP

Biologists are helping economists to explain why humans are not always selfish

AT SOME point during their education, biology students are told about a
conversation in a pub that took place over 50 years ago. J.B.S. Haldane, a
British geneticist, was asked whether he would lay down his life for his
country. After doing a quick calculation on the back of a napkin, he said
he would do so for two brothers or eight cousins. In other words, he would
die to protect the equivalent of his genetic contribution to the next
generation.

The theory of kin selection-the idea that animals can pass on their genes
by helping their close relatives-is biology's explanation for seemingly
altruistic acts. An individual carrying genes that promote altruism might
be expected to die younger than one with "selfish" genes, and thus to have
a reduced contribution to the next generation's genetic pool. But if the
same individual acts altruistically to protect its relatives, genes for
altruistic behaviour might nevertheless propagate.

Acts of apparent altruism to non-relatives can also be explained away, in
what has become a cottage industry within biology. An animal might care for
the offspring of another that it is unrelated to because it hopes to obtain
the same benefits for itself later on (a phenomenon known as reciprocal
altruism). The hunter who generously shares his spoils with others may be
doing so in order to signal his superior status to females, and ultimately
boost his breeding success. These apparently selfless acts are therefore
disguised acts of self-interest.

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