Whereas humans already prefer helpers by 3 months of age, bonobos favor hinderers, maybe from attraction to dominant individuals

Bonobos Prefer Individuals that Hinder Others over Those that Help. Christopher Krupenye, Brian Hare. Current Biology, https://doi.org/10.1016/j.cub.2017.11.061

Highlights
•    Bonobos discriminate between agents that either help or hinder others
•    Whereas humans already prefer helpers by 3 months of age, bonobos favor hinderers
•    Bonobos’ preference may stem from attraction to dominant individuals
•    This form of prosocial preference may be derived in humans

Summary: Humans closely monitor others’ cooperative relationships [1 ;  2]. Children and adults willingly incur costs to reward helpers and punish non-helpers—even as bystanders [3; 4 ;  5]. Already by 3 months, infants favor individuals that they observe helping others [6; 7 ;  8]. This early-emerging prosocial preference may be a derived motivation that accounts for many human forms of cooperation that occur beyond dyadic interactions and are not exhibited by other animals [9 ;  10]. As the most socially tolerant nonhuman ape [11; 12; 13; 14; 15; 16 ;  17] (but see [18]), bonobos (Pan paniscus) provide a powerful phylogenetic test of whether this trait is derived in humans. Bonobos are more tolerant than chimpanzees, can flexibly obtain food through cooperation, and voluntarily share food in captivity and the wild, even with strangers [ 11; 12; 13; 14; 15; 16 ;  17] (but see [18]). Their neural architecture exhibits a suite of characteristics associated with greater sensitivity to others [ 19 ;  20], and their sociality is hypothesized to have evolved due to selection against male aggression [ 21; 22 ;  23]. Here we show in four experiments that bonobos discriminated agents based on third-party interactions. However, they did not exhibit the human preference for helpers. Instead, they reliably favored a hinderer that obstructed another agent’s goal (experiments 1–3). In a final study (experiment 4), bonobos also chose a dominant individual over a subordinate. Bonobos’ interest in hinderers may reflect attraction to dominant individuals [24]. A preference for helpers over hinderers may therefore be derived in humans, supporting the hypothesis that prosocial preferences played a central role in the evolution of human development and cooperation.

Keywords: prosocial preference; prosocial motivation; social evaluation; third-party knowledge; cooperation; human evolution; human development; bonobo; great ape; reputation attribution