Revisiting the consequences of cooperative breeding

Thornton & McAuliffe (2015) recently questioned the hypothesis that cooperative breeding has a variety of socio‐cognitive consequences, invoking both logical and empirical arguments. The cooperative breeding hypothesis (CBH) posits that the immediate tasks associated with extensive allomaternal care require motivational proximate mechanisms, such as increased social tolerance or proactive prosociality which, as a side‐effect, also can facilitate performance in socio‐cognitive tasks. Eventually, over evolutionary time this constellation may also, under specific conditions, facilitate increases in brain size. Thus, the CBH is not merely a modified version of the social brain hypothesis, as suggested by Thornton & McAuliffe, which would posit that a species has to be particularly smart to engage in cooperative breeding. In this reply, we first clarify these conceptual issues and then systematically address their criticism of the empirical evidence. We conclude that the empirical evidence for the CBH is strong in primates, but that future work on lineages other than primates is required to assess its generality.