Call Cultures in Orang-Utans?

Abstract

BackgroundSeveral studies suggested great ape cultures, arguing that human cumulative culture presumably evolved from such a foundation. These focused on conspicuous behaviours, and showed rich geographic variation, which could not be attributed to known ecological or genetic differences. Although geographic variation within call types (accents) has previously been reported for orang-utans and other primate species, we examine geographic variation in the presence/absence of discrete call types (dialects). Because orang-utans have been shown to have geographic variation that is not completely explicable by genetic or ecological factors we hypothesized that this will be similar in the call domain and predict that discrete call type variation between populations will be found.Methodology/Principal FindingsWe examined long-term behavioural data from five orang-utan populations and collected fecal samples for genetic analyses. We show that there is geographic variation in the presence of discrete types of calls. In exactly the same behavioural context (nest building and infant retrieval), individuals in different wild populations customarily emit either qualitatively different calls or calls in some but not in others. By comparing patterns in call-type and genetic similarity, we suggest that the observed variation is not likely to be explained by genetic or ecological differences.Conclusion/SignificanceThese results are consistent with the potential presence of ‘call cultures’ and suggest that wild orang-utans possess the ability to invent arbitrary calls, which spread through social learning. These findings differ substantially from those that have been reported for primates before. First, the results reported here are on dialect and not on accent. Second, this study presents cases of production learning whereas most primate studies on vocal learning were cases of contextual learning. We conclude with speculating on how these findings might assist in bridging the gap between vocal communication in non-human primates and human speech.

Population-Specific Use of the Same Tool-Assisted Alarm Call between Two Wild Orangutan Populations (Pongopygmaeus wurmbii) Indicates Functional Arbitrariness

“…Indeed, the geographic patterning of presence or absence of leaf kiss-squeaks is neither sufficiently explained by genetic differentiation between populations nor environmental differences [3]. This observed variation concurs with evidence demonstrating that genetic differentiation does not sufficiently explain the geographic pattern of other orangutan calls [15]. Conversely, orangutans have been empirically shown capable of observational learning [38].…”

“…First, a signal (with its respective function) may be present in one population but absent in another population (birds [5]:, bats [6]:, pinnipeds [7,8]:, cetaceans [9,10]:, nonhuman primates [11,12]:). Second, acoustically distinct signals with a similar function may be present in different populations (birds [13]:, cetaceans [14]:, nonhuman primates [4,15]:); such examples further imply that the signal’s acoustic structure is arbitrary. In other words, there is no particular relationship between the signal’s internal/external determinants (i.e.…”

From Grasping to Grooming to Gossip: Innovative Use of Chimpanzee Signals in Novel Environments Supports Both Vocal and Gestural Theories of Language Origins

“…Among orangutans, for example, van Schaik, Wich and their colleagues have demonstrated that three calls, raspberries, kiss squeak with hands, and kiss squeak with leaves, are patchily distributed among disparate study populations (van Schaik et al 2003;Wich et al 2012). For example, raspberries, which are bilabial fricatives associated in this species with nest-building, are reportedly absent from four of six sites studied, but present in two sites, one on the island of Sumatra the other on Borneo (van Schaik et al 2003).…”

Habitat Suitability Modeling of Bornean Orangutan (Pongo pygmaeus pygmaeus) in Betung Kerihun National Park, Danau Sentarum and Corridor, West Kalimantan

“…Nests were determined through purposive sampling method based on the information of community and staff of national parks. Nests are relatively easy to find since orangutans make nests every day (Wich et al 2012a). The research site was determined by considering the condition of location that can represent the area of the research site.…”

“…This area has also been designated as a strategic area district (kawasan strategis kabupaten) which is very important in terms of environmental concerns. One of the important fauna that exists in this region and national park is the bornean orangutan (Pongo pygmaeus), which also has become a global conservation icon (Wich et al 2012a).…”