Looking for unity in diversity: human cooperative childcare in comparative perspective

Abstract

Humans engage in cooperative childcare, which includes some elements not found in other animals, such as the presence of post-reproductive helpers, extensive food sharing among adults and a pervasive sexual division of labour. In animals, cooperative offspring care has typically been studied in two different contexts. The first mainly involves helpers contributing care in cooperatively breeding family groups; the second context is allomaternal care in species usually not categorized as cooperative breeders (e.g. plural and communal breeders, often without male care). Comparative analyses suggest that cooperative breeding and allomaternal care in plural and communal breeders have distinct evolutionary origins, with humans fitting neither pathway entirely. Nevertheless, some critical proximate mechanisms of helping, including hormonal regulators, are likely to be shared across species. Other mechanisms may vary among species, such as social tolerance, proactive prosociality or conditional mother–infant bonding. These are presumably associated with specific details of the care system, such as whether all group members contribute, or whether mothers can potentially raise offspring alone. Thus, cooperative offspring care is seen in different contexts across animal lineages, but may nonetheless share several important psychological characteristics. We end by discussing how work on humans may play a unifying role in studying cooperative offspring care.

No sex differences in the economy of load‐carriage

“…Although we have not evaluated possible differential energetic returns obtained from distinct transport strategies among sexes, it could be possible that, differential benefits could be also behind these behavioral distinctions on carrying activities. However, from an alternative perspective, these differenced sex activities also have direct consequences on the fitness of the entire group, as occur with other collaborative behaviors that affect human life history (Burkart, van Schaik, & Griesser, ; Gurven & Walker, ; Kramer, ; Kramer & Otárola‐Castillo, ). In this framework, as part of a cooperative population (Kramer, ), females also receive benefits from the complementary strategies performed by other individuals in the group (Nakahashi & Feldman, ).…”

Humans as model organisms

“…We might then use experimental and observational information to (for example) assess whether chimps do in general recognize agents from their voices, or whether they can remember in the afternoon what another saw in the morning. In some respects, Burkart et al's paper on cooperative breeding converges with this strategy: they point out that cooperative breeding in humans is a synthesis of three cooperative strategies, two of which are usually found in separate lineages: biparental care, care from older to younger siblings and alloparental care from plural breeding [39]. So they see human cooperative breeding as a mosaic of associated elements, in both its behavioural organization (where the help comes from, and what are the costs and benefits for the helpers and the helped) and in its proximate underpinnings (these include both hormonal mechanisms for much elevated social tolerance and hormonal mechanisms that drive positive prosociality).…”

Humans as a model for understanding biological fundamentals

“…endocrine mechanisms). Similarly, Burkart et al [30] consider prosocial behaviour and its relationship to cooperative breeding, concluding that while there are unique aspects to human cooperation, they are strongly underpinned by shared endocrine mechanisms across the animal kingdom and, at least among primates, some shared psychological mechanisms as well. In his synthesis of all contributions to this special feature, it is the latter perspective that Sterelny [14] agrees most closely with.…”