Final answer:
Reciprocal altruism is observed in many monkey species where unrelated monkeys groom each other to remove parasites from their fur. This behavior is based on the expectation of future reciprocity and the punishment of cheaters.
Step-by-step explanation:
Reciprocal altruism is the concept of unrelated individuals acting altruistically towards each other in nature. An example of this behavior can be observed in many monkey species where monkeys groom each other to remove parasites from their fur. The behavior is reciprocal, as both monkeys take turns grooming each other. This behavior is based on the expectation of future reciprocity, and individuals repeatedly encountering each other in the same social group. Punishment for cheaters who do not reciprocate is also necessary for reciprocal altruism to work.