The effects of sociability on exploratory tendency and innovation repertoires in wild Sumatran and Bornean orangutans

Abstract

It has been hypothesized that opportunities for social learning affect the size and complexity of the adult skill set of birds and mammals, their learning ability, and thus ultimately also their innovation frequency. To test these predictions we compared rates of social learning, rates of independent exploration (independent learning) and innovation repertoires between individuals of a highly sociable population of Pongo abelii at Suaq Balimbing and a less sociable population of Pongo pygmaeus wurmbii at Tuanan. Suaq immatures showed significantly higher rates of peering, even after controlling for differences in association time and diet complexity, implying that they make disproportionally greater use of their increased opportunities for social learning. As predicted, we found that immatures and adults at Suaq also showed significantly higher rates of exploratory behaviour. The difference between the individuals of the two popuations remained when controlling for association time, suggesting persistent developmental effects, intrinsic differences, or both. Accordingly, Suaq animals had a larger set of learned skills and a higher mean dietary complexity. Our findings show that population level sociability, individual rates of exploration and population-wide repertoires of innovations are positively linked, as predicted.Cultural effects on cognitive development in humans have been documented for a long time and have reached the status of common knowledge: social inputs during childhood have a strong effect on the development of the cognitive skill set 1 . Studies on institutionalized children have shown that children raised with limited social inputs show deficits in a variety of domains, including language, social-emotional development and intelligence 2,3 . These effects are also evident in structural and functional changes in the brain 4,5 . Recent studies have shown that later cognitive performance is also affected by more subtle differences in the frequency and quality of social inputs during critical periods of early childhood 6 : increased social interactions during day care 7 , a higher degree and consistency of parents' responsiveness during early childhood 8,9 and early education and care programs 10 were all found to have significant positive effects on cognitive development and later cognitive abilities in various domains including problem solving, inhibitory control, memory and language.Experiments on a variety of nonhuman species suggest that similar processes might also be at work in other animals, suggesting some degree of evolutionary continuity. On the one hand, extreme social deprivation during development has been shown to lead to smaller adult skill sets and reduced learning abilities in several mammal taxa [11][12][13][14] . At the other extreme, enculturation (treating infants as if they were human babies) is known to lead to a more rapid development of a broader set of skills as well as increased learning ability in primates, in particular apes 15,16 . Thus, as in humans, social inputs du...

Early sociability fosters later exploratory tendency in wild immature orangutans

“…Orangutans are ideal to test for social effects because levels of sociability vary not only across populations but also between individuals of the same population and within individuals over time. As for immediate social effects, on the basis of our previous findings (31) and findings in other species (33,34), we predict that (ii) during all stages of development, an individual's exploratory tendency will be positively correlated with current sociability. As for the developmental effects, patterns observed in humans lead us to predict that opportunities for social learning during development will affect orangutan exploratory tendency cumulatively and thus that (iii) an immature's exploratory tendency will be positively correlated with its overall past experienced sociability (as a measure of opportunities for social learning).…”

“…During the period in which immature orangutans acquire their skills, bouts of intensive, selective social attention immediately induce practice and exploration. Accordingly, infant orangutans show a high rate of socially induced exploration (30,31). Initial exploration rates are extremely low, steeply increase in age to a peak during mid-infancy, and then gradually drop to near-zero values around early adulthood (30,31).…”

Cofeeding tolerance in chimpanzees depends on group composition: A longitudinal study across four communities

“…Macaque species are organized in social grades according to their described level of social tolerance ( Thierry, 2007 ; Balasubramaniam et al., 2018 ), Sumatran orangutans are reported to be more tolerant than Bornean orangutans ( Forss et al., 2016 ), redfronted lemurs more tolerant than ringtailed lemurs ( Fichtel et al., 2018 ), and bonobos more tolerant than chimpanzees ( Clay and de Waal, 2013 ; Hare et al., 2012 ; Tan and Hare, 2013 ), but see ( Jaeggi et al., 2010 ; Cronin et al., 2015 ) for conflicting findings. These species-level assumptions have also been advanced to explain and predict interspecific variation in behaviors such as cooperation ( Petit et al., 1992 ; Hare et al., 2007 ; Cronin, 2017 ), prosociality ( Burkart and van Schaik, 2013 ; Burkart et al., 2014 ; Fruth and Hohmann, 2018 ; Cronin, 2012 ), and social learning ( van Schaik, 2003 ; Schuppli et al., 2017 ; van Schaik et al., 1999 ).…”

Grouping behavior of Sumatran orangutans (Pongo abelii) and Tapanuli orangutans (Pongo tapanuliensis) living in forest with low fruit abundance

“…These parties mainly seem to provide social benefits, such as opportunities to mate, socialize and play, or find protection from harassment (Delgado & van Schaik, 2000; van Schaik, 1999). Also, temporary party formation provides opportunities for social transmission and social learning (Schuppli et al, 2017; van Schaik & Knott, 2001). The observed variation in orangutan party size seems to reflect individual‐based fission–fusion dynamics (Aureli et al, 2008; van Schaik, 1999) and individuals are often solitary and form relatively small parties because of the high costs of feeding competition.…”