Cooperation is widespread in nature, occurring in every taxa on Earth. Nevertheless, the
contexts in which cooperation occurs—and the forms it takes—vary widely. In this Review …

The social decisions that individuals make—who to interact with and how frequently—give
rise to social structure. The resulting social structure then determines how individuals …

Abstract In Shark Bay, Western Australia, male bottlenose dolphins form a complex nested
alliance hierarchy. At the first level, pairs or trios of unrelated males cooperate to herd …

Some nonhuman animals form adaptive long-term cooperative relationships with nonkin that
seem analogous in form and function to human friendship [1–4]. However, it remains unclear …

The social intelligence hypothesis (SIH) posits that within-group interactions drive cognitive
evolution, but it has received equivocal support. We argue the SIH overlooks a major …

Humans care about having a positive reputation, which may prompt them to help in
scenarios where the return benefits are not obvious. Various game-theoretical models …

A central premise of the science of comparative affect is that we can best learn about the
causes and consequences of affect by comparing affective phenomena across a variety of …

Social instability frequently arises in group-living species, but the potential costs have rarely
been investigated in free-living cooperative breeders, especially across different timeframes …

Quantification of activity budgets is pivotal for understanding how animals respond to
changes in their environment. Social grooming is a key activity that underpins various social …

Reciprocity and pseudo‐reciprocity are two important models for the evolution of
cooperation and often considered alternative hypotheses. Reciprocity is typically defined as …