Jared Diamond's The Third Chimpanzee has enjoyed a long and comfortable life as one of the great evolutionary narratives of the late twentieth century. Its central claim — that humans are basically chimpanzees with better software — has seeped into everything from evolutionary psychology to popular journalism, from explanations of war and rape to theories of capitalism and climate collapse. We are, on this view, merely a third chimp species: cleverer, louder, more destructive, but fundamentally operating on the same biological firmware.

It is an elegant story. It is also, I want to suggest, mostly wrong.

Jonathan Leaf's recent book The Primate Myth offers a sustained challenge to the entire chimp-comparison framework, and while his tone is sometimes polemical, his core point is devastating: humans are not best understood as modified apes, and the attempt to read human social life off chimpanzee dominance hierarchies is less science than mythopoetic storytelling dressed in lab coats.

Diamond's book didn't merely popularise an idea; it entrenched a framework — what might be called primate reductionism — that now underwrites much of evolutionary psychology and anthropology. It is time, I think, to retire it.

Diamond's Thesis: Humans as Hairless Chimps

Diamond's argument is simple enough to state:

1.Humans and chimpanzees share roughly 98–99% of their DNA.

2.Therefore, the behavioural differences between us must be relatively small in evolutionary terms.

3.Therefore, chimpanzees are our best living model for understanding human nature — including violence, sexuality, territoriality, hierarchy, and warfare.

From this, Diamond constructs a sweeping narrative: humans fight wars because chimps fight territorial wars; humans engage in dominance politics because alpha chimps do; humans exhibit cruelty because chimps do; humans commit genocide because chimps massacre rival groups. Civilization, in this picture, is a thin veneer laid over primate savagery.

It is a grim story, and one that flatters modern pessimism. But it rests on a crucial inference that almost no one stops to interrogate:

Genetic similarity does not entail behavioural similarity — and certainly not explanatory adequacy.

Leaf's book dismantles precisely this inference.

The Category Error: Taxonomy ≠ Psychology

Leaf's central argument is not that humans aren't biologically primates. Of course they are, in the Linnaean sense. The error lies in assuming that taxonomic classification provides psychological or sociological explanation.

Bats and whales are both mammals. No one models bat navigation by studying whales. Yet somehow humans are endlessly modelled using chimpanzees — not because the analogy is powerful, but because it is rhetorically convenient.

Diamond treats evolutionary closeness as if it licensed behavioural projection. But this is a category mistake. Evolution produces radical novelty, not merely incremental adjustment. A few regulatory genetic changes can reorganise cognition, culture, language, and social structure beyond anything remotely comparable to the source species.

Leaf documents something Diamond ignores: human brains are not scaled-up chimp brains. They differ not only in size, but in connectivity, developmental plasticity, neurotransmitter dynamics, and cortical specialisation. Language alone introduces a representational architecture that has no primate analogue. Culture then compounds this by enabling cumulative, symbolic, normative systems that are not merely complex but self-modifying.

Chimp societies do not write constitutions. They do not invent science. They do not produce legal systems, religions, literature, or mathematics. They do not commit suicide, engage in mass ideological movements, or build global trade networks. They do not create art, sports, fashion, or philosophy. These are not peripheral embellishments to chimp psychology; they are structurally alien modes of organisation.

Diamond acknowledges these differences but treats them as quantitative upgrades. Leaf insists — correctly — that they are qualitative discontinuities.

The Violence Myth: From Gombe to Gaza

Diamond famously leaned on Jane Goodall's observations of chimpanzee intergroup violence to argue that human warfare is simply primate territorial aggression scaled up. This move has been endlessly cited as evolutionary validation of political pessimism: war is in our genes; peace is a cultural delusion.

But this inference collapses on inspection.

Chimpanzee raids are opportunistic ambushes, not institutionalised warfare. They lack command structures, symbolic coordination, ideological justification, or strategic planning. They are not wars; they are predation events among conspecifics. Human warfare, by contrast, is a deeply cultural phenomenon: structured by law, ideology, honour codes, national identity, logistics, industrial production, and abstract political objectives.

More importantly, humans routinely organise mass cooperation among unrelated strangers, including for peaceful, altruistic, and prosocial ends — something essentially absent in chimp societies. Humans form states, charities, hospitals, disaster-relief networks, international research collaborations, and humanitarian law systems. Chimps do not.

Diamond's story treats violence as the evolutionary default and cooperation as a fragile cultural overlay. Leaf flips this: human ultra-cooperation is the anomaly, not chimp aggression. And it is this cooperative architecture — not chimp dominance — that actually explains the success of our species.

Sexuality, Hierarchy, and the Alpha Ape Fantasy

Diamond and his evolutionary-psychology heirs have also been fond of explaining human sexuality through primate dominance hierarchies: male competition, female selection, mating strategies, and reproductive payoff optimisation.

But Leaf points out something obvious yet oddly ignored: human sexuality is saturated with symbolic meaning, norms, institutions, long-term pair bonding, romance narratives, kinship systems, and moral expectations — none of which exist in chimpanzee societies.

Humans marry. They divorce. They commit adultery. They fall in love. They write poetry. They experience sexual shame, jealousy, devotion, obsession, celibacy, repression, sublimation, and fetishisation — all phenomena that presuppose symbolic selfhood and cultural norms. Chimps copulate.

Similarly, the obsession with alpha hierarchies ignores the fact that human societies routinely punish dominance behaviour rather than reward it. In most functional human groups, bullies are ostracised, tyrants overthrown, and dominance checked by institutions. Humans are not dominance apes; they are rule-following, norm-enforcing, cooperation-optimising social engineers.

Chimp hierarchy is brute-force primacy. Human hierarchy is symbolic legitimacy. Conflating the two is not evolutionary insight; it is metaphor abuse.

The Deeper Problem: Evolutionary Storytelling as Secular Theology

Diamond's book belongs to a broader genre: evolutionary morality tales. These are not merely scientific explanations but cosmological narratives about what humans "really are" beneath civilisation's veneer. They function psychologically much like original sin doctrines — only now the Fall happened in the Pleistocene savannah rather than Eden.

Leaf's great insight is that these narratives are not neutral. They smuggle metaphysical assumptions about human nature under the guise of biology. They legitimise political pessimism, cultural cynicism, and moral fatalism. If humans are chimps in clothes, then brutality is natural, inequality inevitable, and civilisation a doomed cosmetic layer over animal instinct.

But this vision is not forced on us by science. It is chosen.

And it is oddly selective. Why do we model ourselves on chimps rather than bonobos — equally close genetic relatives, but notably more cooperative, female-dominated, sexually playful, and conflict-averse? Why not dolphins? Or elephants? Or wolves? The answer is sociological, not biological: chimpanzees conveniently confirm our darkest intuitions about ourselves.

Diamond didn't merely describe chimps; he curated a moral anthropology.

Human Uniqueness is Not Anti-Evolutionary

One of the rhetorical tricks of primate reductionism is to frame any claim about human uniqueness as covert creationism. But this is nonsense. Evolution produces novelty. It produces phase transitions. It produces new organisational regimes.

Language alone constitutes such a transition. With language comes recursive thought, counterfactual reasoning, normativity, narrative identity, institutional design, and cumulative culture. Once language appears, the relevant comparison class is no longer animals but symbolic systems — mathematics, law, religion, economics, politics. At that point, chimpanzees cease to be informative models.

Leaf's point is not that humans are metaphysically separate from animals, but that they are biologically discontinuous in cognitive architecture. This is no more anti-evolutionary than recognising that birds are discontinuous from reptiles in flight, or that whales are discontinuous from land mammals in ecological niche.

Evolution does not flatten difference; it generates it.

Why the Chimp Myth Persists

If the chimp analogy is so weak, why does it persist?

Three reasons:

1.Narrative simplicity. "We're chimps with iPhones" is a clean story. "We're a symbolic ultrasocial species with emergent institutional cognition" is not.

2.Ideological convenience. Chimp models naturalise violence, hierarchy, inequality, and pessimism about reform.

3.Scientific prestige laundering. Wrapping cultural theory in DNA statistics gives it an aura of inevitability.

But explanatory elegance is not explanatory truth. And biology is not destiny unless you turn it into theology.

Retiring the Third Chimp

The Third Chimpanzee was an engaging book. It was clever. It was provocative. It was also, in retrospect, a conceptual dead end.

Jonathan Leaf's The Primate Myth performs a necessary demolition: it exposes the chimp-comparison framework not merely as empirically weak but as structurally incoherent. Humans are not a clever primate species. They are a symbolic, norm-governed, ultrasocial cognitive anomaly — a species whose primary ecological niche is not forest or savannah, but institution, language, and abstraction.

We are not naked apes.

We are not hairless chimps.

We are not the third chimpanzee.

And the sooner evolutionary storytelling lets go of that myth, the sooner we can begin constructing a science of human nature that actually explains what humans do — rather than forcing our civilisation into a jungle diorama of primate reductionism.

https://www.amazon.com/Primate-Myth-Latest-Science-Theory/dp/B0F27ZZ9ZN