Once upon a time, it was thought that only human beings made and used tools. Today, as readers of Dragonfly magazine know, we are more humble. We now realize that many animals, including birds, make and use tools. Of all the other animals known to use tools, the chimpanzee is perhaps the most interesting. Jane Goodall and Wolfgang Kohler are two scientists who studied tool making and use among chimps. Here are their stories.
Wolfgang Kohler was a psychologist
who studied learning
and thinking among animals. In the 1920s, many
scientists thought that
animals could only learn through trial and error.
They thought that when
an animal faced a problem, such as finding food, it
would stumble around
until it hit upon the right answer by trying different
actions until it
got lucky. But Kohler believed that animals, especially
chimps, were much
smarter than most people imagined. He believed that
chimpanzees were capable
of intelligence, and even insight. To test his ideas
he did several experiments.
Kohler worked with four chimps named Chica, Grande, Konsul, and Sultan. Kohler's basic experiment was to place a chimp in an enclosed play area. Somewhere out of reach he placed a prize, such as a bunch of bananas.
To get the bananas, the chimp would have to use an object as a tool. The objects in the play area included sticks of different lengths and wooden boxes. He discovered that chimpanzees were very good at using tools. They used sticks as rakes to pull in bananas places out of reach. And they also used sticks as clubs to bring down fruit hung overhead. Sometimes they stood long sticks on end and quickly climbed up the 7 meters and grabbed the bananas before the stick fell over. The chimpanzees also learned to use boxes as step ladders, dragging them under the hung bananas and even stacking several boxes on top of one another.
Kohler's chimps were able to do more than use tools, he actually observed chimps building tools. For example, he observed chimps breaking off branches from a tree to make a "rake." One of the smartest chimps, Sultan, was given a very difficult problem. Kohler placed a bunch of bananas outside Sultan's cage and two bamboo sticks inside the cage. However, neither of the sticks was long enough to reach the bananas. Sultan pushed the thinner stick into the hollow of the thicker one, and created a stick long enough to pull in the bananas (see the picture of Sultan doing this at the top).
Other chimps have been observed using a short stick to bring in a long stick, and then using the long stick to bring in a bunch of bananas. Kohler believed that these chimps showed insight -- acting as if they "saw" the solution before carrying out the actions. However, not all scientists agree with this idea. What do you think?
Wolfgang Kohler observed chimps creating and using tools in captivity. Jane Goodall discovered that chimpanzees make and use tools "in the wilderness." Since she was a little girl, Jane Goodall dreamed of studying animals in Africa. Although her family did not have much money, she was encouraged by her family to follow her dreams. Her mother once told her, "Jane, if you really want something, and if you work hard, take advantage of opportunities, and never give up, you will somehow find a way." As a young woman, she was working as a secretary when a letter came inviting her to stay with a friend in Kenya, Africa. At first, she worked as a secretary in Kenya too. When she learned that a scientist named Louis Leakey was working at the natural history museum nearby, Goodall set off to meet him. Louis Leakey was famous for his studies of our human ancestors. Leakey took her around the museum and asked all sorts of questions. Because she had never given up her dream of Africa, and had continued to read books about the continent and its wildlife, she could answer many of them. Jane Goodall made quite a good impression on Leakey, and he gave her a job as his assistant. In that job, Jane Goodall made one of the most exciting scientific discoveries of all.
Louis Leakey decided she was the person he'd been looking for to go to Lake Tanganyika to study chimpanzee behavior. But she had to overcome a major problem. At that time, the country of Tanganyika (now called Tanzania) was under Britain's rule. The British authorities were horrified at the thought of a young, untrained girl going into the bush. In those days, people -- especially women -- did not go trekking off to work with wild animals. But finally the authorities agreed that she could go, provided she had a companion. It was her mother, who had always encouraged her, who served as her companion.
A few months after Jane Goodall began her study, she observed a chimp she called David Greybeard pick a blade of grass and carefully trim the edges. He stuck the grass into a termite mound, left it there for a moment, and pulled it out. Termites swarmed over the blade of grass. He then ate the termites clinging to the grass blade. David Greybeard had made a tool -- a "fishing rod" for termites. This was the first report of chimpanzees making and using tools in the wild. It shocked the scientific world! Until then, humans were thought to be the only animals to make tools in nature. In fact, tool-making was part of some scientists' definition of "human." If tool-making was only a human trait, then were chimps human? Jane Goodall's discovery opened a new debate about what it meant to be a human being. Do you still think that only people use tools? How would you investigate whether or not a pet is capable of using tools?
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Photos courtesy of the Jane Goodall Institute, Ken Regan, TE LeVere, and Wolfegang Kohler's (1927) The Mentality of Apes Routledge and Kegan Paul, LTD.: London.
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