Cooperation in an Uncertain World: For the Maasai of East Africa, Need-Based Transfers Outperform Account-Keeping in Volatile Environments.

Using an agent-based model to study risk-pooling in herder dyads using rules derived from Maasai osotua ("umbilical cord") relationships, Aktipis et al. (2011) found that osotua transfers led to more risk-pooling and better herd survival than both no transfers and transfers that occurred at frequencies tied to those seen in the osotua simulations. Here we expand this approach by comparing osotua-style transfers to another type of livestock transfer among Maasai known as esile ("debt"). In osotua, one asks if in need, and one gives in response to such requests if doing so will not threaten one's own survival. In esile relationships, accounts are kept and debts must be repaid. We refer to these as "need-based" and "account-keeping" systems, respectively. Need-based transfers lead to more risk pooling and higher survival than account keeping. Need-based transfers also lead to greater wealth equality and are game theoretically dominant to account-keeping rules.