In need-based sharing, sharing is more important than need

Cooperative resource sharing is widespread across cultures, and it was likely critical during much of human evolutionary history for pooling risk. Need-based specifically pools risk by following two cooperative rules: help others when asked, only request in need. In a two-part study, we first expanded an agent-based model need-based partnerships, adding types defection varying partnership sizes. We show that refusing to always has long-term cost, which increases with larger partnerships. contrast, “greedy” requests are not based on survival carry little-to-no cost. then conducted experimental vignette study osotua, tradition, Tanzanian Maasai pastoralists. found participants generally complied osotua requests, but shared amounts were conclude proposing framework models involving need fitness interdependence, where the cost asymmetry among favors decision heuristic individuals prefer those need, err side generosity uncertain.