Accordingto Hamilton’s(1964a, b) rule,a cost lyaction will be undertaken if its fitness cost to the actor falls short of the discounted benefit to the recipient,where the discount factor is Wright’s index of relatedness between the two. We propose a generalization of this rule,and show that...

We analyze how family ties affect incentives, with focus on the strategic interaction between two mutually altruistic siblings. The siblings exert effort to produce output under uncertainty, and they may transfer output to each other. With equally altruistic siblings, their equilibrium effort is...

Abstract A principal needs a worker for the production of a good. The worker can be hired as an internal agent, or an external agent under a contract. These two organizational modes correspond to in-house production and outsourcing, respectively. In each case, the agent earns experience...

What can evolutionary biology tell us about male-female differences in preferences concerning family matters? Might mothers be more solicitous toward offspring than fathers, for example? The economics literature has documented gender differences—children benefit more from money put in the...

How can a desire to cooperate in one-shot interactions survive, even though it gives a material disadvantage to its carrier? I analyze this issue using a one-shot public goods game between two altruistic individuals. Within a pair, the least altruistic individual is better off materially....