Final answer:
Eusociality, observed in social insects, involves nonreproductive individuals contributing to the inclusive fitness of the colony through cooperation and kin selection, ensuring shared genes are passed on.
Step-by-step explanation:
The social system involving overlap in generations, cooperative care of young, and nonreproductive individuals performing altruistic acts is known as eusociality. This system is often observed in social insects like bees, wasps, ants, and termites. Sterile workers in these societies take care of the offspring of reproductive members, most notably the queen, because they are genetically closely related. By doing so, these workers contribute to the passage of their shared genes through the success of the queen's progeny, a concept called kin selection. This type of social structure ensures that even nonreproductive individuals can contribute to the inclusive fitness of the colony by supporting relatives that carry similar genes.