Although positive reciprocity (reciprocal altruism) has been a focus of interest in evolutionary
biology, negative reciprocity (retaliatory infliction of fitness reduction) has been largely …

Why do people take revenge? This question can be difficult to answer. Vengeance seems
interpersonally destructive and antithetical to many of the most basic human instincts …

Lifetime reproductive success of individuals in a natural population provides an estimate of
Darwinian fitness. We calculated lifetime reproductive success in a colony of female …

Coastal upwelling is responsible for thriving marine ecosystems and fisheries that are
disproportionately productive relative to their surface area, particularly in the world's major …

Page 1 The Pinnipeds Seals, Sea Lions, and Walruses Marianne Riedman Page 2 The
Pinnipeds SEALS, SEA LIONS, AND WALRUSES Marianne Riedman ALS" eals This lucid …

Parents will increase their fitness by varying the sex ratio of their progeny in response to
differences in the costs and benefits of producing sons and daughters. Sex differences in …

Extended bouts of fasting are ingrained in the ecology of many organisms, characterizing
aspects of reproduction, development, hibernation, estivation, migration, and infrequent …

Humans use punishment to promote cooperation in laboratory experiments but evidence
that punishment plays a similar role in non-human animals is comparatively rare. In this …

Over the past 30 years or so, research effort in behaviour and ecology has progressed from
simple documentation of the habits or habitats of differ ent species to asking more searching …

Evolutionary theories of morality, beginning with Darwin, have focused on explanations for
altruism. More generally, these accounts have concentrated on conscience (self-regulatory …