Inclusive fitness is a concept in evolutionary biology that explains how an organism's genetic success is influenced not just by its own reproduction, but also by the reproductive success of its relatives. This means that helping family members can increase the chances of shared genes being passed on to future generations. For example, a squirrel might warn its relatives of a predator, sacrificing its own safety to protect its family. This idea was popularized by the biologist W.D. Hamilton, who introduced the concept in the 1960s. Inclusive fitness helps explain behaviors like altruism, where individuals act in ways that benefit others, especially those who share their genes.