Once again new data show that nonhumans can be kinder than we've previously thought and that patterns of behavior we thought were uniquely human are not. Duke University researchers Jingzhi Tan and Brian Hare have shown, in a series of experiments on captive bonobos (previously called pygmy chimpanzees) living at the Lola ya Bonobo Sanctuary in the Democratic Republic of Congo, that unlike chimpanzees, these great apes will share food with strangers. The original study called "Bonobos Share with Strangers" can be found here and a summary can be seen here.
In this novel set of experiments, bonobos were presented with a pile of food and then given the chance to release from other rooms a stranger, a group mate, or both individuals. Tan and Hare showed that bonobos will voluntarily donate food to strangers and give up a meal as long as there are social benefits that entail having the opportunity to interact with a stranger, but they also will help others get food even when there are no social perks. They conclude that prosociality ("voluntary behavior intended to benefit another") in bonobos "is in part driven by unselfish motivation, because bonobos will even help strangers acquire out-of-reach food when no desirable social interaction is possible."
"Other-regarding preferences toward strangers are not uniquely human"
These creative experiments support the argument that we must be very careful when making claims about human exceptionalism when writing about animal minds and the cognitive and social skills of other animals. They also show that we must continue to conduct comparative research on many different species because in this case chimpanzees do not show the same behavior patterns and we might have wrongly concluded that such food sharing and social tolerance are uniquely human or evolved later. Along these lines Tan notes, “If you only studied chimps you would think that humans evolved this trait of sharing with strangers later ... But now, given that bonobos do this, one scenario is that the common ancestor of chimps, humans and bonobos had this trait.” We also do not know if individuals of other species such as social carnivores (for example, wolves, coyotes, or jackals) or perhaps domesticated dogs display these patterns of behavior so we must keep that door open as well.
Social tolerance is an important evolved trait for expanding social networks
To sum up, Tan and Hare conclude, "Other-regarding preferences toward strangers are not uniquely human" ... and initially evolve "due to selection for social tolerance, allowing the expansion of individual social networks." They note that we don't "possess a unique proclivity to share with others – including strangers". However they do caution, following up on the work of Arizona State University's Kim Hill and his colleagues, that "it is likely that humans are unique for the ability to extend our ape-like prosociality even to the most costly of contexts. These extreme other-regarding preferences possibly rely on language and social norms making it unlikely that such preferences preceded the evolution of these socio-cognitive abilities."
Please stay tuned for more on the fascinating lives of the amazing animals with whom we share our planet.
The teaser image by Jingzhi Tan one of the authors of the original paper can be seen here.