Reciprocal altruism is a behavior observed in some species where individuals help others with the expectation of receiving help in return. This concept suggests that acts of kindness can enhance survival and reproductive success, as forming cooperative relationships can lead to mutual benefits over time. The idea was popularized by the biologist Robert Trivers in the 1970s. It is often seen in social animals, such as vampire bats, which share food with others in their group. By helping each other, these animals increase their chances of survival, demonstrating the importance of cooperation in nature.