Cooperative breeding (CB) can be defined as a reproductive system in which individuals other than the mother (allomothers) deliver routine care. Among primates, the strongest reliance on allomaternal care is found in callitrichids and humans. The cooperative breeding system requires the support of special motivational and cognitive processes, including increased social tolerance or attentional bias toward monitoring motivations and behaviors of others. Allomaternal care can explain the spectacular increase in brain size in the hominin lineage (the expensive brain hypothesis). This phenomenon can also account for both the emergence of menopause long before women’s death and the longevity gender gap. Moreover, the theory in question can account for impressive cognitive abilities of our species. Some issues in the field of developmental psychology have been discussed from the perspective of the CB theory
