It is not the genes that make a person to go for blood donation or enrol for the army, for researchers have now attributed such self-sacrificing attitude to socially learned behaviour rather than an inherent trait.
Led by Adrian V. Bell, researchers from the University of California Davis used a mathematical equation, called the Price equation, which describes the conditions for altruism to evolve.
The equation motivated the researchers to compare the genetic and the cultural differentiation between neighbouring social groups.
The researchers used previously calculated estimates of genetic differences, and the World Values Survey (whose questions are likely to be heavily influenced by culture in a large number of countries) as a source of data to compute the cultural differentiation between the same neighbouring groups.
When compared, it was found that the role of culture had a much greater scope for explaining our pro-social behaviour than genetics.
In applying their results to ancestral populations, the World Values Survey was less useful.
But ancient cultural practices, such as exclusion from the marriage market, denial of the fruits of cooperative activities, banishment and execution happen now as they did then.
Such activities would have exerted strong selection against genes tending toward antisocial behaviour, and presumably in favour of genes that predisposed individuals toward being pro-social rather than anti-social.
This would result in the gene-culture coevolution of human prosocial propensities.
The study has been published in the latest edition of Proceedings of the National Academy of Sciences.