 This essay will discuss altruism in the former sense, as behavior undertaken deliberately to help someone other than the agent for that other individual’s sake. There is a large and growing empirical literature on altruism, which asks whether there is an evolutionary or biological basis for human altruism, and whether non-human species exhibit it or something similar to it. These issues are addressed by the entries on  empirical approaches to altruism and  biological altruism. 