What was Known?
What was known about chimpanzees when Jane Goodall stepped off that boat to begin her study of the wild chimp communities living in Tanzanian forest around one of the world's longest, largest and deepest freshwater lakes, (Lake Tanganyika)?
Very little. As far as we know to this day, only one man had ever tried to make a serious study of chimpanzee behavior -- Henry W. Nissen. He spent 2 1/2 months in the field in western Guinea. Though he had difficulty getting close to the chimpanzees, he did report new observations, including that chimpanzees sleep at night in arboreal nests and spend much of their day ranging in search of food such as fruits and nuts.
Others had studied chimpanzees in captivity. According to Jane Goodall biographer Dale Peterson in Jane Goodall: The Woman Who Redefined Man: "In 1912 the Prussian Academy of Sciences established a primate research station at Tenerife, in the Canary Islands, where Wolfgang Kohler experimentally documented creative problem-solving among chimpanzees: moments of apparent insight and the spontaneous fashioning of useful tools and makeshift ladders to retrieve remotely dangled bananas. A different study placed a baby chimpanzee in a household to be raised alongside a human baby. The human parents believed the chimpanzee, Gua, came to understand about 100 words. Peterson writes: "[T]he experiment was prematurely terminated, rumor has it, when the human baby began making chimp noises."
The right incentive: In this famous photo, the chimpanzees in Kohler's study used a "step-ladder" to reach the dangling bananas.