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Q&A: Orangutan scientist talks with CNN

Harvard anthropologist Cheryl Knott
Harvard anthropologist Cheryl Knott

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Cheryl Knott is director of the Gunung Palung Orangutan Project in West Kalimantan on the island of Borneo in Indonesia. The Harvard University anthropologist talked to CNN about a report she co-authored in the January 2 edition of Science magazine.

CNN: What's the significance of determining that orangutans have culture, and have for 14 million years?

KNOTT: Biological anthropologists would argue that culture is an evolved human adaptation. Thus, the question is, when did this evolve? Is it unique to humans? Do we see behaviors in our closest living relatives, the apes, that have cultural aspects to them? If so, under what conditions do these cultural behaviors occur? How are they invented? How are they transmitted? Answering these questions helps us to understand how, when and why full-blown culture evolved in humans.

So, basically, the significance is that seeing incipient culture in orangutans helps us to understand how, when and why culture evolved in humans.

CNN: What was the most surprising label, signal or skill you observed for this study?

KNOTT: One of the most interesting behaviors at Gunung Palung is the kiss-squeak vocalization. This is a loud, drawn-out kissing sound. We've known that orangutans in all populations do this when they are alarmed. But, what we didn't know was how much the signal varied. In Gunung Palung, for example, almost all orangutans grab a handful of leaves and kiss into the leaving, presumably to help them amplify the sound, and then they drop them. Other interesting behaviors we've observed are using leaves as drinking scoops, and watching a pregnant female cradle a bunch of leaves, like a doll.

CNN: Does culture help in an evolutionary way, for example, the ability to use tools to gather otherwise unreachable food sources?

KNOTT: In some cases. For example, Carel van Schaik and I have a paper on Neesia eating in orangutans comparing our two sites. Neesia is a very high fat fruit -- with the seeds containing 70 percent fat. But, the seeds are also protected by highly irritant hairs. At Suaq (Carel's site), they use tools to extract these seeds whereas at Gunung Palung (my site) they do not. Tools may be helping them to eat these high fat seeds at a higher rate, and thus obtain a nutritional benefit that may help in survival.

CNN: What's next in your research?

KNOTT: This study examined behaviors that are observed during the course of examining other research questions. For me, these include understanding why orangutans have the longest inter-birth interval of any mammal, what is controlling the long period of juvenile development and what determines when an adult male orangutan develops secondary sexual characteristics.

CNN: What is it about orangutans that drew you to study them?

KNOTT: They are fascinating, little studied creatures that hold clues to understanding broader questions of ape and human evolution. My initial study examined the eight-year inter-birth intervals in orangutans, the longest of any mammal. The orangutan stands as one of the most unique of all primates. They are the largest arboreal mammal, have the longest inter-birth intervals, are the most solitary of all diurnal primates, and have the highest rates of forced copulations. Males seem to take two different developmental pathways, with some males not developing the typical adult male features, such as big cheek pads, for many years after attaining reproductive maturity.

CNN: How threatened is the habitat of orangutans ?

KNOTT: This study demonstrates the richness of orangutan behavior and how the study of orangutans is important for understanding human evolution. Sadly, though, time is running out. Our ability to study and learn from these fascinating creatures is vanishing as these forests rapidly disappear with the whirr of the chainsaw.

This is a comparative study from six orangutan study sites but two of them have already been shut down due to illegal logging and civil war. Orangutans are in dire threat of extinction. Help from the international community is desperately needed to save these amazing creatures.

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