We offer a game-theoretic proof of Hamilton’s rule for the spread of altruism. For a simple case of siblings, we show that the rule can be derived as the outcome of a one-shot prisoner’s dilemma game between siblings. Copyright Springer-Verlag Berlin/Heidelberg 2004

Neo-Darwinian concepts such as van den Berghe's ethnic nepotism infer that the origin of inter-group conflict resides primarily in ethnocentrism, defined as the extension of inclusive fitness to extra-familial interactions. Silverman, however, has proposed an alternative view, based on the...

We investigated the role of kinship in intraspecific nest parasitism of wood ducks (Aix sponsa). Among waterfowl, female philopatry creates the potential for female relatives to nest in proximity. Costs of intraspecific nest parasitism to host females may be reduced if parasites lay eggs with...

Understanding the reasons behind stable group formations has received considerable theoretical and empirical attention. Stable groups displaying homing behavior have been suggested to form as a result of, for instance, benefits from knowledge of the social or physical environment or through kin...

Helpers at the nest in the cooperative breeding system of long-tailed tits Aegithalos caudatus exhibit kin preference in their helping behavior. The aim of this study was to use multivariate analyses to investigate whether helpers accrue indirect fitness benefits through their cooperation by...

Reproductive skew models attempt to predict the fraction of reproduction contributed by each individual that participates in a communal brood. One potential limitation of these models is that individuals make a single, fixed decision about group membership and reproductive allocation at the...

Successful Polistes dominulus nests can be started by one or more nest founding queens (foundresses). Consequently, there is much interest in the specific benefits that induce cooperation among foundresses. Here, we experimentally demonstrate one major benefit of cooperation, namely that...

In cooperatively breeding species, helpers typically provide food to offspring, and distribute food throughout the brood or litter. However, in the communal breeding banded mongoose (Mungos mungo), some group members escort individual pups during their period of dependence, and escorts...

Previous studies of coastal river otters (Lontra canadensis) in Prince William Sound, Alaska, USA, documented atypical social organization for mammals. Social groups were composed largely of males, but some males remained solitary year-round and most females were asocial. Because, in carnivores,...