In 1960, anthropologist Louis Leakey sent a 26-year-old English secretary named Jane Goodall — who had no university degree and no scientific training — to a stretch of forest called Gombe to study wild chimpanzees. Within months she had observed a chimpanzee stripping leaves off a stalk to fish termites from a mound, overturning the long-held belief that only humans made and used tools

For most of the twentieth century, science had a simple test for what made us human: we made tools, and no other animal did. In 1949, the British Museum published a handbook that drew that exact line. Its author, the physical anthropologist Kenneth Oakley, opened the handbook by arguing that the employment of tools “appears to be his chief biological characteristic”. For a generation of researchers, toolmaking was the trait that set us apart.

Eleven years later, that line started to move. The person who moved it had no university degree, no scientific training, and had been working as a secretary.

The world Goodall walked into

In 1960, the idea that only humans made tools was close to settled. As Scientific American notes, Oakley had stressed toolmaking as a uniquely human trait because, unlike language, it left traces you could dig up and study. 

Into this walked Louis Leakey, the paleoanthropologist who would become Goodall’s mentor. Leakey wanted someone to watch wild chimpanzees over a long stretch. So in 1960 he sent 26-year-old Jane Goodall to Gombe, a game reserve on the shore of Lake Tanganyika in what is now Tanzania. According to National Geographic, she arrived on 14 July 1960 with no degree, and no training to observe. 

What she actually saw

The moment came that November. Goodall watched a male chimpanzee she had named David Greybeard working at a termite mound, and what he did did not fit the theory. Her field notebook recorded it plainly: “By the termite hill were two chimps, both male. I could see a little better the use of the piece of straw. It was held in the left hand, poked onto the ground, and then removed coated with termites.” Soon after, she saw chimpanzees strip the leaves off twigs to make the probes work better. That detail mattered. The animals were not just using an object. They were modifying one to do a job.

Goodall understood what she was seeing. Years later she described the shock: “Man, the tool maker, is how we were defined. And here was David Greybeard using a tool. It was hard for me to believe what I’d seen.” One animal at one mound had walked straight through the definition.

When word reached Nairobi, Leakey grasped the size of it. He is reported to have replied that “now we must redefine tools, redefine man, or accept chimpanzees as human.” 

Why Leakey’s gamble on an outsider mattered

The observation came from someone the science of the day would probably never have hired for the job. Leakey’s bet was that a trained eye would also be a filtered eye, primed to see chimpanzees as animals that did not make tools, because that is what the textbooks said. Goodall carried no such filter. She named individual chimpanzees rather than numbering them, and she recorded what she saw rather than what she expected.

Whether training would really have blinded a careful observer is debatable. Plenty of credentialed scientists have overturned their own field’s assumptions. But the pattern Goodall named is hard to ignore. She later reflected that her work would meet resistance: “My observations at Gombe would challenge human uniqueness, and whenever that happens, there is always a violent uproar.” Findings that blur the line between people and other animals often draw strong pushback, and an outsider had less standing to lose in delivering one.

The establishment came around. Goodall earned a PhD in animal behaviour from Cambridge in 1966, one of only a handful ever admitted without a first degree. She never framed the discovery as hers alone. “Without Louis getting me that first money to go,” she has said, “there would be no Jane studying the chimpanzees.”

The boundary that kept moving

The redefinition Leakey demanded did happen, and it did not stop with chimpanzees. In the early 1980s, Hedwige Boesch-Achermann and Christophe Boesch documented chimpanzees in Taï National Park in Ivory Coast cracking nuts with stone and wooden hammers.

Since then the list has grown well beyond apes. New Caledonian crows make hooked tools from twigs and cut leaves into shapes for prying insects out of cracks. In Shark Bay, off Western Australia, some bottlenose dolphins carry sea sponges on their beaks to shield them while foraging on the sea floor, a behaviour that appears to pass down within a single family line.

Toolmaking, once the sharp edge of the human category, turned out to be scattered across the animal world.