What are the three criteria required for eusociality?

• A. Cooperative brood care, reproductive division of labor, and overlapping generations in a nest.
• B. Cooperative brood care only.
• C. Reproductive division of labor and overlapping generations only.
• D. Overlapping generations in a nest only.

Answer: (B)

Eusociality hinges on three traits: cooperative brood care, reproductive division of labor, and overlapping generations. In colonies exhibiting eusociality, individuals beyond the breeding pair help raise the young, creating a shared brood-care system. Reproductive division of labor means only a few individuals reproduce while others take on non-reproductive roles as workers or soldiers, handling tasks like foraging, defense, and care of the brood. Overlapping generations means individuals from multiple age groups live in the same nest and interact across generations, which supports division of labor and colony stability.

Having only cooperative brood care fits part of the picture, but without the other two components the full eusocial pattern isn’t present. The combinations that omit one or more of these criteria fail to capture the complete social structure seen in truly eusocial societies, such as honeybees, ants, and termites.