It’s difficult to comprehend the uniqueness of the Acheulean handaxe and the breathtaking mystery of its persistence. 

For more than a million years, and across thousands of kilometres spanning much of Africa, Asia and Europe, the bifacial handaxe form was the only design template imposed upon stone artefacts. No other technology has ever enjoyed such an enduring monopoly.

Researchers have demonstrated that it was a practical design with a range of advantages. But those features hardly seem sufficient to explain its extraordinary persistence. Did some other force maintain it across its range in time and geography, preventing it from degrading or being replaced by new mutations in stone-shaping? Contemplating the Acheulean, I felt that a bold hypothesis was an appropriate response to its unique strangeness. If nothing else, its eye-catching character would reassert just how strange and mysterious the Acheulean was.

It seemed to me that sexual selection could explain features of the Acheulean phenomenon that were beyond the reach of functional accounts. The most striking ones were the signs of apparent detachment from practicality – handaxes with no marks indicating they had been used, handaxes too big for hands, and investment in form far beyond what would be needed to make an efficient tool. But the most fundamental one was the very limited evolution of stone artefact form over a span of time in which the makers of those artefacts must have evolved considerably. Something had to be maintaining that form, and constraining new forms from emerging. The evaluation of potential mates, in which the criterion was the ability to produce an artefact that could be assessed by reference to a fixed template, could be that something.

One of the key principles underlying the model was that such selective processes were specific to hominin populations that differed in their adaptive organisation from modern ones. In other words, what went on in the Acheulean was not a prequel to modern human behaviour, except in the banal sense that it happened first. Nor did the model imply anything about relations between modern humans. So I’d like to make it very clear that I have never, ever called it the ‘sexy handaxe theory’.

I have to admit that the label helped to get it talked about more than calling it the ‘handaxe sexual selection model’ did. But I’d have been a lot happier if it had generated more science. It’s a hypothesis I’d like to see tested, not just referenced. At minimum, I’d like the model to be recognised as an intellectually serious attempt to develop dialogue between prehistoric archaeology and evolutionary thinking. And I’d like to point out that the basic hypothesis was really quite down to earth. Steve Mithen and I simply proposed that a range of qualities – physical, cognitive, temperamental – were significant criteria for female Acheulean hominins in their choice of mates, and that making handaxes demonstrated those qualities. You might call that 'sexy', but I wouldn’t. Sensible, maybe.

As We Know It: Coming to Terms with an Evolved Mind, Granta 1999
Handaxes: Products of Sexual Selection? Marek Kohn and Steven Mithen, 1999, Antiquity 73, 518–26.