IT HAS been dubbed the Samaritan paradox. Why have we evolved to do altruistic things like giving blood or caring for the sick without expecting them to do the same for us? Bizarrely, it could be because it makes us better at waging war.
Samuel Bowles, an economist at the Santa Fe Institute in New Mexico, studied modern hunter-gatherer groups along with archaeological evidence of early human conflicts and data on climate and other environmental variables from about 150,000 years ago. He concluded that the struggle for survival faced by early humans was so severe that war among groups and the wholesale destruction of localised populations was common (Science, vol 314, p 1569).
Bowles then constructed a mathematical model that pitted groups with genes for altruistic behaviour against groups without. Altruism protects the group against the costs of combat, he says. For example, one of the consequences of an inter-group conflict may be a broken leg - a potentially fatal injury for the person affected, as it would leave them unable to forage. Food sharing would mean they could survive, ultimately making it less risky for the group to go to war.
Biologists have long written off differences in survival between groups as an important driver of evolution, as natural selection works on genes, not groups. But Bowles's model incorporates gene differences, making his idea more plausible, says anthropologist Robert Boyd of the University of California, Los Angeles.
reposted from: NewScientist
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