Is blood really thicker than water?

The outcome of a duel between mathematical models supports the reigning theory of the genetics of altruism. Called inclusive fitness, it says altruism is competitive if it benefits relatives carrying the same gene as the selfless individual. Attacked by a Nature article published in 2010, it is defended by Washington University evolutionary biologist David Queller.

Ignorance is sometimes bliss

Evolutionary biologist W.D. Hamilton predicted that organisms ought to evolve the ability to discriminate degrees of kinship so as to refine their ability to direct help to individuals with whom they shared the most genes. But two WUSTL biologists point out that there seem to be many cases where “a veil of ignorance” prevents organisms from gaining this kind of information, forcing them to consider a situation from the perspective of all members of their group instead of solely from their own perspective or that of their close kin.