Orangutan Sociality, Tool Use, and Human CultureAmong Orangutans: Red Apes and the Rise of Human Culture. By Carel vanSchaik. Cambridge: Belknap Press of Harvard University Press, 2004.

Abstract

It has long been believed that culture is one of the critical characters which divide human from other animals, but decades of animal research have revealed that cultural differences maintained by social transmission are found in many nonhuman primates and in other animals. In particular, it is now well-documented that wild chimpanzees show cultural variations between local communities in many behavioural traits such as tool use, grooming, and courtship signals (Whiten et al 1999). In captivity, orangutans seem as intelligent as chimpanzees. They are excellent tool users and specialists in escaping from a cage. In contrast to the hyperactive chimpanzees, they are curious and patient enough to open a door if they happen to have substitutes for the key or a bar. However, few toolusing behaviours had been reported from wild orangutan populations. Carel van Schaik and colleagues have made a breakthrough discovery in this area. Van Schaik has been studying wild orangutans at Ketambe, North Sumatra, Indonesia, since 1976, but the story of this book begins with the discovery in 1993 of a population in a coastal swamp forest at Suaq Balimbing with one of the highest population densities of orangutans in the world. Their density is due in part to the inaccessibility of the swamp forest to humans and in part to the abundance of food in the forest. These orangutans are also more social (i.e., interact with other orangutans more frequently) than others; the stereotypical images of orangutans as solitary philosophers in the forest do not apply well to them. Finally, they are excellent tool users. Why do the orangutans at Suaq differ so much from others? In his attempt to answer this question van Schaik provides an excellent introduction to the latest primate socioecological theories. Socioecology deals with the relationship between social characteristics of species or populations and ecological conditions such as the distribution and abundance of food or predators. In plain words, van Schaik shows how the availability of food might affect the orangutans’ social characteristics, why orangutans grow and breed in slow motion, and how infanticide risk influences females’ social behaviour. On the basis of his findings van Schaik advances a new hypothesis about the evolution of intelligence and emergence of cultures (van Schaik and Pradhan 2003). He argues that the combination of individual learning (innovation) and social learning capabilities can be achieved through natural selection and that a tolerant or egalitarian nature towards group members, or “sociability,” plays an important role in the evolution of a high level of intelligence. His social learning hypothesis for the evolution of intelligence is different from the Machiavellian intelligence hypothesis (Byrne and Whiten 1988; Whiten and Byrne 1997), which regards the requirements of everyday social life as the most important factor: intelligence has evolved to cope with cooperative and/or competitive relationships with group members. These two hypotheses are not mutually exclusive and appear to operate at different stages of evolution. Finally, van Schaik attempts to draw some inferences about human nature from his findings. It is inevitable at this stage that this final chapter contains considerable speculation, but now we have good working hypotheses and can move on to a better understanding. In 1997–98, the most severe El Nino events of the century caused large-scale forest fires in Indonesia. Several million hectares of potential habitat for orangutans disappeared. At the same time, economic crisis hit the Southeast Asian countries, and Indonesia suffered the most severe damage from it. This caused political instability in both central and local governments and conflict among local peoples. Illegal logging, further forest fires, and poaching did immeasurable damage to wildlife. Van Schaik’s narrative never becomes emotional and accuses no one, but his deep sorrow is palpable. He is concerned about local extinctions and a possible loss of cultural diversity among orangutans. I strongly hope that this unique creature and its cultures will survive these difficult years.