Several hypotheses propose that cooperative breeding leads to increased cognitive performance, in both nonhuman and human primates, but systematic evidence for such a relationship is missing. A causal link might exist
because motivational and cognitive processes necessary for
the execution and coordination of helping behaviors could
also favor cognitive performance in contexts not directly
related to caregiving. In callitrichids, which among primates rely most strongly on cooperative breeding, these motivational and cognitive processes include attentional biases toward monitoring others, the ability to coordinate actions spatially and temporally, increased social tolerance, increased responsiveness to others’ signals, and spontaneous prosociality. These processes are likely to enhance performance particularly in socio-cognitive contexts.
Therefore, cooperatively breeding primates are expected to
outperform their independently breeding sister taxa in
socio-cognitive tasks. We evaluate this prediction by
reviewing the literature and comparing cognitive performance
in callitrichids with that of their sister taxa, i.e.
squirrel monkeys, which are independent breeders, and
capuchin monkeys, which show an intermediate breeding
system. Consistent with our prediction, this review reveals
that callitrichids systematically and signiWcantly outperform their sister taxa in the socio-cognitive, but not in the non-social domain. This comparison is complemented with more qualitative evaluations of prosociality and cognitive performance in non-primate cooperative breeders, which suggest that among mammals, cooperative breeding generally produces conditions conducive to socio-cognitive performance. In the hominid lineage, however, the adoption of extensive allomaternal care presumably resulted in more pervasive cognitive consequences, because the motivational consequences of cooperative breeding was added to an ape-level cognitive system already capable of understanding simple mental states, which enabled the emergence of shared