The proposal that altruism can benefit the altruist because it will be reciprocated by other members of the group. For example, meerkats spend part of their time above ground foraging and part standing upright watching for predators; if a sentinel sees a predator it gives an alarm call that sends the others running for safety. If the sentinel is exposed to greater risk than other members of the group, the time it spends on watch will be worth it if the amount of time it can spend foraging safely while others are on watch exceeds that risk. Observation suggests this is not what happens, however, and that sentinels spend as much time as they can in a safe lookout position close to a burrow, even if they live alone. Some authorities have suggested that food sharing is a form of reciprocity, but this may involve little or no cost to the giver, in which case it is not altruistic.
Subjects: Ecology and Conservation.