Social animals show elaborate cognitive skills to deal with others, but there are few reports of animals physically using social agents & their respective responses as means to an end—social tool use; origins of Machiavellian intelligence

Schweinfurth, M. K., DeTroy, S. E., van Leeuwen, E. J. C., Call, J., & Haun, D. B. M. (2018). Spontaneous social tool use in chimpanzees (Pan troglodytes). Journal of Comparative Psychology, 132(4), 455-463. http://dx.doi.org/10.1037/com0000127

Abstract: Although there is good evidence that social animals show elaborate cognitive skills to deal with others, there are few reports of animals physically using social agents and their respective responses as means to an end—social tool use. In this case study, we investigated spontaneous and repeated social tool use behavior in chimpanzees (Pan troglodytes). We presented a group of chimpanzees with an apparatus, in which pushing two buttons would release juice from a distantly located fountain. Consequently, any one individual could only either push the buttons or drink from the fountain but never push and drink simultaneously. In this scenario, an adult male attempted to retrieve three other individuals and push them toward the buttons that, if pressed, released juice from the fountain. With this strategy, the social tool user increased his juice intake 10-fold. Interestingly, the strategy was stable over time, which was possibly enabled by playing with the social tools. With over 100 instances, we provide the biggest data set on social tool use recorded among nonhuman animals so far. The repeated use of other individuals as social tools may represent a complex social skill linked to Machiavellian intelligence.

Sharing food from a single plate increased perceived coordination among diners, which in turn led them to behave more cooperatively & less competitively toward each other; the effect on cooperation occurred among strangers also

Shared Plates, Shared Minds: Consuming  from a Shared Plate Promotes Cooperation. Kaitlin Woolley & Ayelet Fishbach. In press, Psychological Science, https://kaitlinwoolleycom.files.wordpress.com/2018/11/shared_plates-in-press.pdf

Abstract: A meal naturally brings people together, but does the way a meal is served and consumed further matter for cooperation between people? This research (n=1476) yielded evidence that it does. People eating from shared plates (i.e., Chinese style meal) cooperated more in social dilemmas and negotiations than those eating from separate plates. Specifically, sharing food from a single plate increased perceived coordination among diners, which in turn led them to behave more cooperatively and less competitively toward each other compared with individuals eating the same food from separate plates. The effect of sharing a plate on cooperation occurred among strangers, which suggests that sharing plates can bring together not only allies, but strangers as well.

Keywords: food consumption, cooperation, coordination, social dilemma, negotiation
The raw data and supplemental material for all studies are available at OSF: bit.ly/2nxqNXu