Chimpanzees are able to learn how to use tools when shown how to operate the items by other chimps in the wild, according to a new study. This is the first time that social learning of this type has been seen in the animal's natural environment.
The Sonso chimpanzee community, which resides in the Budongo Forest of Uganda, was the subject of the new study. Researchers wanted to know how they developed a pair of unique tool-using techniques, unseen elsewhere in the wild.
"[R]esearchers have been fascinated for decades by the differences in behavior between chimpanzee communities; some use tools some don't, some use different tools for the same job. These behavioral variations have been described as 'cultural'... spread when one individual learns from another; but in most cases they're long established and it's hard to know how they originally spread within a group," Catherine Hobaiter, psychology lecturer at the University of St Andrews, said.
Some chimpanzees use leaf-sponges as a form of cup, from which they drink water. The Sonso population has developed a method of using moss along which leaves to carry water. They also learned how to re-use leaf-sponges left behind from earlier use. Each of these developments in the populations has never been seen before in the group or studied for more than 20 years.
Investigations of chimpanzees in the wild are faced with a number of challenges. Because of these difficulties, most psychological studies of the animals are carried out on captive populations. Some biologists have questioned the ability of such studies to determine behaviors in the wild. This new study was one of few to investigate the primates in their natural environment.
New tool use was discovered in the group when Nambi, a dominant female adult, spotted a 29-year-old male making a moss-sponge. In less than a week, seven additional members of the population were also constructing and utilizing similar tools. One 12-year-old male chimpanzee was observed picking up a discarded cup and using one of the simian-designed utensils. Soon, eight other chimps were also re-using the tools, yet only half of those individuals witnessed the behavior before adopting it themselves.
Discovery that behaviors can be learned socially by chimpanzees lends evidence to the theory that these skills developed in primate ancestors of humans. This also leads to the questions of how and why humans separated from other animals, becoming able to learn, and teach, much more complex behaviors than seen in the Sonso population.
Study of chimpanzee tool use and teaching methods which convey the necessary skills was detailed in the online journal Plos One.
Chimpanzees using tools were recorded on video, available on the Plos Media YouTube channel.