Testing the cultural intelligence hypothesis in orangutans: an evolutionary perspective (#508)
In order to explain human intelligence we need to understand its presence and causal mechanisms in animals. Here we present a study investigating the cultural intelligence hypothesis by using orangutans as a model taxon. Because intelligence is largely constrcuted developmentally, the cultural intelligence hypothesis focuses on the social inputs and opportunities for interacting with the physical environment during ontogeny. It predicts that the more of such inputs an individual experiences, the more learned skills it acquires, but also the better it gets at solving problems. This prediction can be tested at developmental and evolutionary time scales. First, the developmental perspective predicts differences between individuals depending on exposure to social learning experienced during a lifetime. Data from wild orangutans strongly support this idea in that more gregarious populations possess more enhanced skill sets and innovations. Moreover, is it supported by the difference we are observing between wild and captive orangutans, the latter exposed to artificially high social density as well as human social inputs. Second, from a evolutionary perspective species with systematically richer social environment may over time evolve to become more intelligent, reflected by larger brain size. We performed an across zoo study on two closely related species; Sumatran, Pongo abelii (N=19) and Bornean, Pongo pygmaeus (N=13). The homogenous and similar environmental conditions provided by zoos should allow us to detect any intrinsic differences between these two species. At nine European zoos mother-reared orangutans were examined on their novelty response as well as their cognitive performance, in the form of a set of tasks assessing problem solving ability. Results suggest an intrinsic difference in how the two pongo species apply their learning ability, with Sumatrans being more likely to show necessary problem solving skills. Thus Pongo abelii may have experienced higher selection on learning mechanisms.