Extraterrestrial Altruism examines a basic assumption of the Search for Extraterrestrial Intelligence (SETI): that extraterrestrials will be transmitting messages to us for our benefit. This question of whether extraterrestrials will be altruistic has become increasingly important in recent years as SETI scientists have begun contemplating transmissions from Earth to make contact.

Technological civilizations that transmit signals for the benefit of others, but with no immediate gain for themselves, certainly seem to be altruistic. But does this make biological sense? Should we...