What Chimps and Bonobos Reveal About Being Human

In the forests of Gombe in Tanzania, a young researcher named Jane Goodall watched a chimpanzee she had named David Greybeard do something that, in 1960, was supposed to be impossible. He stripped the leaves from a twig, poked it into a termite mound, waited, and pulled it out covered in insects, which he then ate. He was making and using a tool. When Goodall sent word back to her mentor, the paleontologist Louis Leakey, he replied with a line that has been quoted ever since: "Now we must redefine tool, redefine Man, or accept chimpanzees as humans."

That moment captures why anthropologists are so fascinated by our closest living relatives. Chimpanzees and bonobos share roughly 98 to 99 percent of our DNA, depending on how you count, and the human lineage split from theirs only around six to seven million years ago, a blink in evolutionary time. By watching them, we get something close to a living mirror. The behaviors we share with them are probably old, inherited from a common ancestor. The ones we do not share may be the genuinely human inventions. The trick, and the hard part, is telling the two apart.

Two cousins, two very different personalities

It is tempting to treat "the chimpanzee" as a single window onto our past, but nature gave us two windows, and they look out on strikingly different scenes. Chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are separate species, divided by the Congo River, and they are equally related to us. Yet their societies could hardly be more different.

Chimpanzee society is built around tense, status-driven male coalitions. Males stay in the group they are born into, compete fiercely for rank, and a dominant alpha can hold his position through a mix of strength, intimidation, and political alliances. Aggression is a routine tool of social life.

Bonobo society, by contrast, is generally led by females who form strong bonds with one another, even though they were not born together. Tensions that would trigger a fight among chimps are often defused among bonobos through social and sexual contact rather than violence. Researchers sometimes summarize the contrast as "chimps resolve sex with power, bonobos resolve power with sex," which is a tidy line, though real behavior is messier than any slogan.

The lesson for anthropology is humbling. We cannot simply look at one ape and declare, "this is the ancestor we came from." We descend from a creature that was neither chimp nor bonobo, and humans have ended up with a behavioral repertoire that includes pieces of both, plus a great deal that is our own.

Tools, culture, and the long shadow of a termite twig

Goodall's termite-fishing observation was the first crack in the wall separating humans from the rest of the animal kingdom. In the decades since, the catalogue of ape tool use has grown impressively. Chimpanzees in West Africa use stones as hammers and anvils to crack open hard nuts, a skill that young chimps take years to master and that varies by region. Some populations sharpen sticks to jab at small prey; others use leaves as sponges to soak up drinking water.

What makes this more than a collection of clever tricks is that these behaviors are socially learned and locally variable, which is the hallmark of culture. A chimpanzee community in one forest may crack nuts while a community a few hundred kilometers away, with access to the very same nuts and stones, never does. The difference is not in their genes or their environment but in their traditions, passed from mother to infant by watching and copying. Anthropologists now speak comfortably of "chimpanzee cultures," a phrase that would have sounded absurd before Gombe.

So is technology uniquely human? Clearly not in its simplest form. What does appear distinctive is the ratchet effect, the way human technology accumulates and builds on itself across generations. A chimp's nut-cracking technique today is roughly what it was a thousand years ago. Human tools, by contrast, compound: the stone flake leads to the hafted axe, which leads, eventually, to the machine shop. We do not just invent; we inherit, improve, and rarely lose ground. That cumulative quality, sometimes called cumulative culture, may be one of our species' real signatures.

Politics, fairness, and the roots of morality

If you want to see the deep roots of human social life, watch a chimpanzee community manage power. The primatologist Frans de Waal spent decades documenting what he openly called chimpanzee politics: alliances, betrayals, and reconciliations conducted with a sophistication that anyone who has worked in an office will recognize. After a fight, rival chimps often groom and embrace, repairing the relationship rather than letting it fester. De Waal argued that the building blocks of morality, empathy, a sense of fairness, and the impulse to reconcile, did not appear from nowhere with humans but were inherited from ancestors who needed to live together to survive.

There is some experimental support for this view, though it should be read carefully. In studies where two monkeys perform the same task and one receives a tastier reward, the short-changed animal may refuse to continue or throw the lesser food back, behavior often interpreted as a basic sense of unfairness. Scientists still debate exactly what such reactions mean and how far they extend, so it is wise to treat these results as suggestive rather than settled.

What seems more clearly human is the scale and abstraction of our moral life. A chimp can reconcile with a specific individual it knows. Humans build moral systems, laws, religions, and ideals of justice, that apply to strangers we will never meet and bind millions of people we have never seen. The raw materials are ancient; the cathedral we built from them appears to be ours.

The darker mirror: violence and warfare

Anthropology has to be honest about the uncomfortable parts of the mirror, and chimpanzees provide one. For years, researchers assumed that lethal violence between groups was a human aberration. Then, at Gombe in the 1970s, Goodall's team documented something disturbing: a community split in two, and over several years the larger faction systematically attacked and killed the members of the smaller one, in what became known as the "Gombe war." It was not a single brawl but a sustained, fatal conflict between groups of the same species.

Later research confirmed that lethal intergroup aggression occurs across many chimpanzee populations. Males will patrol the edges of their territory in silent groups and, when they catch a lone neighbor, attack with deadly intent. This has fueled a long and still unresolved debate. Some scientists argue it reveals deep evolutionary roots for human warfare; others caution that the comparison is loose, that human conflict is driven by culture, weapons, and ideology in ways no ape behavior can fully explain. Importantly, bonobos, equally related to us, show no comparable pattern of lethal raiding, which is a strong reminder that violence is not an inescapable destiny written into our shared ancestry. The honest scientific position is that the capacity for organized aggression has old roots, but how, when, and whether it expresses itself is anything but fixed.

What looks genuinely human

After all the parallels, what is left that seems to set us apart? A few candidates hold up reasonably well under scrutiny.

Full language stands near the top. Apes communicate richly through gestures, calls, and facial expressions, and captive apes have been taught to use symbols. But no animal shows anything close to human grammar, with its open-ended ability to combine a finite set of words into an infinite number of new meanings, including statements about the past, the future, and things that do not exist.

Cumulative, ratcheting culture, discussed earlier, is another. We are the species that builds libraries.

Theory of mind, the ability to model in detail what another individual knows, believes, or falsely believes, appears far more developed in humans, especially the capacity to reason about beliefs that are mistaken. Large-scale cooperation among strangers is a third: humans routinely trust, trade with, and coordinate alongside people they have never met, knitting together societies of millions. And our control of fire and cooking, which changed our diet, our biology, and even the size of our guts and brains, has no parallel among living apes.

None of these traits arrived fully formed. Each grew from something older, visible in flickers among our cousins. That is precisely the point. The boundary between human and ape is not a wall but a slope, and studying primates helps us see exactly where the ground begins to rise.

Key Takeaways

Chimpanzees and bonobos are not our ancestors but our cousins, equally distant from a shared forebear who lived six to seven million years ago, and that makes them an irreplaceable tool for understanding ourselves. By comparing the warlike, status-obsessed chimpanzee with the peaceable, female-bonded bonobo, anthropologists can see that traits we once thought uniquely human, tool use, culture, politics, empathy, reconciliation, and even organized violence, have ancient roots that long predate our species. At the same time, the comparison sharpens what does seem distinctive about us: full grammatical language, technology that compounds across generations, cooperation among total strangers, a detailed reading of other minds, and the taming of fire. We are, in the end, a particular kind of ape, built from very old parts arranged in a strikingly new way, and the more closely we study our relatives in the forest, the more clearly we see both how much we inherited and how much we made ourselves.