Chimpanzees return favors at a personal cost

Abstract

Humans regularly provide others with resources at a personal cost to themselves. Chimpanzees engage in some cooperative behaviors in the wild as well, but their motivational underpinnings are unclear. In three experiments, chimpanzees (Pan troglodytes) always chose between an option delivering food both to themselves and a partner and one delivering food only to themselves. In one condition, a conspecific partner had just previously taken a personal risk to make this choice available. In another condition, no assistance from the partner preceded the subject’s decision. Chimpanzees made significantly more prosocial choices after receiving their partner’s assistance than when no assistance was given (experiment 1) and, crucially, this was the case even when choosing the prosocial option was materially costly for the subject (experiment 2). Moreover, subjects appeared sensitive to the risk of their partner’s assistance and chose prosocially more often when their partner risked losing food by helping (experiment 3). These findings demonstrate experimentally that chimpanzees are willing to incur a material cost to deliver rewards to a conspecific, but only if that conspecific previously assisted them, and particularly when this assistance was risky. Some key motivations involved in human cooperation thus may have deeper phylogenetic roots than previously suspected

The evolutionary roots of prosociality: the case of instrumental helping

“…However, in several studies the target objects could not be manipulated at all by the recipient since they were out of her reach [3,25,27,28]. This stimulus-enhancement hypothesis can also not explain why chimpanzees would help those A c c e p t e d M a n u s c r i p t individuals, who have helped them previously, more [38,39,40]. And lastly, the bonobo results also pose a problem for this explanation, since they help proactively, so either one believes in that a different alternative explanation would be needed for them.…”

Chimpanzees help others with what they want; children help them with what they need

“…One interesting avenue for future research is to identify the conditions under which chimpanzees are paternalistic and do correct others. Previous work has shown that chimpanzee helping behavior does increase towards conspecifics who have benefitted the individual in the past (Schmelz, Grueneisen, Kabalak, Jost, & Tomasello, ). In such scenarios of dependence chimpanzees may correct others’ dysfunctional requests for help because they themselves want to be helped by having their need rather than their request being fulfilled.…”

A receptor for herbivore-associated molecular patterns mediates plant immunity

“…3C), while INR associated more strongly with AtSERK co-receptors after peptide treatment (Fig. 3D, 3E) Dynamic plant defense responses to herbivory have been examined for nearly 50 years (22)(23)(24) and are induced by numerous insect associated elicitors or HAMPs (3,4). Tables S1-S2…”

“…Herbivores defoliate and often devastate plants, making effective inducible defense responses critical for plant resilience (1,2). To combat insect herbivores, plants respond to specific molecular patterns present in oral secretions (OS) and frass by amplifying wound-induced defenses and activating resistance (3,4). Analogous immune responses to microbes and other 50 pests are mediated by ligand-receptor interactions mediated by receptor kinases (RKs) or receptor-like proteins (RLPs) (5).…”

“…Among defense-eliciting HAMPs, inceptins are a potent bioactive series of proteolytic 55 fragments derived from the chloroplastic ATP synthase γ-subunit (cATPC) found in Lepidopteran larvae OS (4,8). An abundant inceptin present during caterpillar herbivory on cowpea (Vigna unguiculata) is an 11 amino acid (AA) peptide, termed Vu-In ( + ICDINGVCVDA -).…”