Do Chimpanzees Have a Stone Age?

In October 1960 a young researcher named Jane Goodall watched a male chimpanzee she had named David Greybeard strip the leaves from a twig, push it into a termite mound and pull it out covered in insects. When she reported it, her mentor Louis Leakey is said to have replied that science would now have to redefine “tool”, redefine “man”, or accept chimpanzees as human.

Six decades on, the question has shifted from whether apes make tools to how old their tool traditions are — and whether they left anything an archaeologist could dig up. The answer, to the surprise of many, is yes.

Chimpanzee cultures

In 1999 Andrew Whiten and eight colleagues pooled records from seven long-term chimpanzee field sites, some 150 years of combined observation, in Nature. They found 39 behaviour patterns that were customary in some communities and absent in others, with no ecological explanation. Termite fishing here, leaf sponges for drinking water there, different styles of grooming and different nut-cracking habits. The most reasonable explanation was learned tradition — culture, in the sense of behaviour passed from generation to generation by social learning.

The 4,300-year-old chimpanzee tool site

Chimpanzees in the Taï forest of Côte d’Ivoire crack hard-shelled nuts using a hammerstone on an anvil of rock or root. They have done this for as long as researchers have watched them, and Christophe Boesch has studied the behaviour since the 1970s.

In 2002 Julio Mercader, Melissa Panger and Boesch published an excavation of a chimpanzee nut-cracking site in Science. Digging beneath the forest floor, they found quartzite hammerstone fragments with the sharp edges and battered surfaces characteristic of percussion, mixed with nutshell. A follow-up study published in 2007 dated the oldest layers to at least 4,300 years ago — long before farming in the region and older than any contact with Europeans. It is the first archaeological record of a non-human ape tool tradition.

Some other populations seem not to have taken up nut-cracking at all, even where nuts and stones are available. That suggests it is a cultural invention, not an inevitable behaviour of chimpanzees.

Chimpanzee hunters

At Fongoli in Senegal, in dry savanna woodland, Jill Pruetz and Paco Bertolani documented in 2007 that chimpanzees sharpen sticks with their teeth and jab them into hollows in trees to kill sleeping bushbabies. Most of the tool-makers were females and juveniles. The finding was startling, partly because it was the first regular hunting with tools by a non-human primate, and partly because it showed females leading a technological innovation.

Monkeys are in the game too

Stone-using is not confined to apes.

• Capuchin monkeys. Bearded capuchins in Serra da Capivara National Park, Brazil, pound rocks to crack cashew nuts and dig for roots. In 2019 Tiago Falótico and colleagues excavated their tool sites and showed that capuchins have been doing so for at least 3,000 years, in a tradition that has been passed on across many monkey generations.
• Accidental flakes. In 2016 Tomos Proffitt and colleagues reported that when these capuchins smash quartzite cobbles against each other, they produce flakes that look like archaeological flakes made by hominins. But the monkeys do not use them; the flakes are a by-product of pounding. It is a warning that flakes alone do not prove a hominin made them.
• Long-tailed macaques. Macaques on islands off Thailand use stones to open oysters, snails and crabs, and researchers are beginning to study their tool use in the same way.

Could an ape learn to make Oldowan tools?

In the 1990s Nick Toth, Kathy Schick and Sue Savage-Rumbaugh taught the bonobo Kanzi to strike stone flakes and use them to cut a cord and open a box. Kanzi learned that sharp flakes were useful, and he did produce some. But he never mastered the skills that make Oldowan toolmaking work: selecting a good angle on the core, striking near the edge, and planning a sequence of blows. His method was crude, often throwing stones onto a hard floor to shatter them.

That gap is the important one. Oldowan makers were doing something ape-tool users are not: deliberately shaping a core to produce sharp edges, striking again and again in a controlled way. It takes precise aim, an understanding of how stone fractures, and a fair amount of manual dexterity.

How old is the human toolkit?

The oldest deliberately flaked stone tools currently known are the Lomekwian tools from West Turkana, Kenya, dated to about 3.3 million years ago, made by a hominin older than our genus. The best-documented early Oldowan sites, like Gona in Ethiopia and Ledi-Geraru, are about 2.6 million years old. In 2023 Thomas Plummer and colleagues reported Oldowan tools from Nyayanga in Kenya, about 2.9 million years old, associated with hippo butchery and with teeth of Paranthropus, showing that the earliest toolmakers may not all have been Homo.

What did the common ancestor of chimpanzees and humans, living some six to seven million years ago, do with stones? We do not know. But the fact that chimpanzees, and independently monkeys, use stone hammers suggests that the raw ability to use stones as tools is old, widespread and easily invented. It was the next step — flaking — that our lineage took.

Why it matters

Primate archaeology has changed how researchers think about the first human tools. It gives a baseline for what an ape-level toolkit looks like, and it tells archaeologists to be careful about naming a maker from a single flake. It also shows that a technology can persist for thousands of years without becoming more complex, which makes the long, slow stability of early hominin tools, followed by sudden bursts of innovation, seem less mysterious.

Chimpanzees do not have a Stone Age in the human sense. But they do have an archaeology — and it is teaching us where our own began.