Hunting and gathering peoples developed a successful adaptation that promoted generosity, altruism, and sharing while resisting upstarts, aggression and egoism. This is referred to as:

Egalitarianism

Explanation:

Egalitarianism: In anthropology, the concept of egalitarianism was first introduced by Karl Marks while creating the Marxist philosophy.

The term egalitarianism is referred to as the phenomenon that explains a social organization consisting of different people who has been observed while practicing a cultural ethos that encourages or uplift peaceful cooperation, sharing, and equality whereby discourages the conflict, property accumulation, authoritarianism, and status-seeking. It held a position to equal justice.

In the question above, the given statement referred to as egalitarianism.