The notion of orangutan culture is provocative, as it suggests that human culture evolved in the context of immense environmental complexity. Yet such complexity obscures the potential effect of environmental variation on the origin of innovative foraging behaviors. The objective of this study is to understand the mechanisms that contribute to geographic variation in orangutan diet, and to establish the degree to which food choice in orangutans has a cultural basis. The question to be answered may be phrased, "To what extent does geographic variation in the abundance and quality of food resources affect orangutan foraging behavior and diet selection?" Three main hypotheses are tested. The first and second hypotheses will determine if orangutans select food items based on nutritional quality and availability in the habitat. If food selection cannot be explained by ecological principles, a further analysis will examine if these foods are harder to process and require longer periods of social learning during the juvenile dependency period, which can last up to nine years in orangutans. The third hypothesis will determine if orangutans develop innovative foraging behaviors in response to variations in food availability. Are innovative foraging behaviors more likely to evolve out of necessity when food is scarce or due to increases in leisure time when food is abundant?
The basic methodology to be used is geographical. A series of protocols integrate standardized observations of behavior, food nutritional analyses, and food mechanical properties across five field sites in Indonesia: four study populations in Borneo, and one in Sumatra. This project involves close collaboration between scientists from the United States, England, Switzerland, and Indonesia. Technological and intellectual exchange between foreign and Indonesian scientists is critical to the establishment and conservation of research partnerships and their associated habitats.
Based on population models and the current rate of deforestation, orangutans across Sumatra and Borneo may disappear within the next 25-100 years. Detailed investigations on orangutans and documenting the types of resources that promote innovative behaviors in this close human relative are critical because we may not have the opportunity in the future. Understanding the importance of culture in feeding behavior is also important for orangutan conservation. If socially-transmitted feeding skills are important for the maintenance of energy budgets in an area, then a decline in orangutan density, due to anthropogenic disturbances, may result in fewer opportunities for transmission of essential skills. Potentially, this could lead to these skills being lost from the population. The results will inform documentaries aimed at public education and conservation, which is critical for the persistence of this highly endangered species. The research will increase knowledge regarding which kinds of foods prompt cultural innovation and will help model the environmental milieu in which ape culture originated. The results will be critical for assessing the size of the culture gap between apes and humans and for evaluating why humans evolved such cultural complexity.
