The Easter Island tragedy has become an allegory for ecological
catastrophe and a warning for the future. In the economic
literature the collapse is usually attributed to irrational or
myopic behavior in the context of a fragile ecosystem. In this
paper we propose an alternative story involving non-cooperative
bargaining between clans to share the crop. Each clan's bargaining
power depends on its threat level when fighting a war. The biggest
group has the highest probability of winning. A clan's fertility is
determined ex ante by each group. In the quest for greater
bargaining power, each clan's optimal size depends on that of the
other clan, and a population race follows. This race may exhaust
the natural resources and lead to the ultimate collapse of the
society. In addition to well-known natural factors, the likelihood
of a collapse turns out to be greater when the cost of war is low,
the probability of succeeding in war is highly responsive to the
number of fighters, and the marginal return to labor is high. We
analyze whether these factors can account for the difference
between Easter and Tikopia Islands. The paper also makes a
methodological contribution in that it is the first fertility model
to include strategic complementarities between groups' fertility
decisions.