Eusociality is an advanced form of social organization in which labor is divided among castes. Here, young are raised communally, overlapping generations are observed, and the division of labor often results in reproducing and non-reproducing castes.
Altruism is a type of behavior when one individual, despite survival or reproductive costs, chooses to help another individual.
Altruism is advantageous when a pair’s relatedness and the benefit to the recipient is greater than the cost to the altruist. This is defined by the equation r (relatedness) × B (benefit to the recipient) > C (cost to the altruist)
The first is the haplo-diploidy hypothesis, which is seen in bees and ants. The second is the ecological hypothesis, which suggests that group protection from predators, cross-group competition, and a common nest site can lead to eusociality.
In a haplo-diploid species, 75% of genes are shared among sisters. In a diploid species, 50% are shared.