Since then, at least five books with the same title have been published. Richard Overy, a British historian of the second world war, has now written a sixth, which skilfully draws together nearly 100 years of scientific and historical scholarship. His goal is to understand the mechanisms that have embedded warfare throughout human history. Although the answers, he finds, have remained “contested, fractured and frustratingly elusive”, there is one undeniable constant: that human groups from the earliest times to the present have resorted to collective, lethal violence against other groups when prompted by ambition, fear, need or prejudice.

To bring some shape to the debate, Mr Overy has split his critique of the academic literature into two sections. The first covers science: anthropology, biology, ecology and psychology. War can be explained as hard-wired into people through evolution (a Darwinian struggle for survival), determined by cultural norms or triggered by ecological pressures. Accordingly, people can be the prisoner of their genes or try to create societies in which warfare is no longer seen as desirable or inevitable.

The second section, which historians and many readers will favour, puts greater emphasis on human agency and mankind as the creator of cultures that sustain or even exalt warfare. Mr Overy describes “four broad motivational categories”: belief (religion), power, resources and security. These were the forces behind modern wars and also, Mr Overy argues, much earlier conflicts between pre-state groups.

From Neolithic times, across Europe and North America, sites of mass burials show unmistakable signs of violence: skulls with stone-axe injuries, arrowheads lodged in vertebrae and decapitations. Weapons for killing other humans rather than just for hunting were common; cave paintings show men skirmishing. Early warfare was clearly different in scale from that waged by modern states. But Mr Overy shows that the causes and aims of early conflicts were frequently not dissimilar to those of later periods.

A different question is whether—as Steven Pinker, a Canadian cognitive psychologist, argued in 2011—people are actually becoming less violent than their ancestors and less inclined to wage war. Although there has been no war between great powers since 1945, Mr Overy remains sceptical. The idea that modern men have developed an aversion to killing others is contradicted by the experience of the second world war when, after only brief spells of training, 100m ordinary men were persuaded “to bomb, shell, shoot and bayonet millions of their fellow species”.

The prospect of a wider war in the Middle East, Russia’s willingness to slaughter Ukrainians over territory, increasing tensions between America and China over Taiwan and the contest for supremacy, combined with the renewed relevance of nuclear weapons, suggests that the stage is set for “the kinds of war for which there is a long historical pedigree”. Mr Overy ends with a conclusion that would surely have depressed Einstein and buttressed Freud: “If war has a very long human history, it also has a future.”

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