I haven’t read the paper (by Richard Akresh, Joyce Chen and Charity Moore) yet… so caveat emptor!
Altruism among family members can inhibit cooperation by increasing the utility players expect to receive in a non-cooperative equilibrium. To test this, we examine agricultural productivity in West African polygynous households. We find cooperation, as evidenced by more efficient production, is greater among co-wives than among husbands and wives. Using a game-theoretic model, we show this outcome arises because co-wives are less altruistic towards each other than towards their husbands. We present a variety of robustness checks, which suggest results are not driven by selection into polygyny, greater propensity for cooperation among women, or household heads enforcing others’ cooperative agreements.
the full paper is here: Akresh-Altruism-Efficiency.