The Rational Optimist by Matt Ridley Page B

seek out different kinds of food from their menfolk. In the Alyawarre aborigines of Australia, while young women care for children, older women go out looking for goanna lizards, not for the kangaroos and emus that their menfolk hunt. A sexual division of labour would exist even without childcare constraints.
    When did this specialisation begin? There is a neat economic explanation for the sexual division of labour in hunter-gatherers. In terms of nutrition, women generally collect dependable, staple carbohydrates whereas men fetch precious protein. Combine the two – predictable calories from women and occasional protein from men – and you get the best of both worlds. At the cost of some extra work, women get to eat some good protein without having to chase it; men get to know where the next meal is coming from if they fail to kill a deer. That very fact makes it easier for them to spend more time chasing deer and so makes it more likely they will catch one. Everybody gains – gains from trade. It is as if the species now has two brains and two stores of knowledge instead of one – a brain that learns about hunting and a brain that learns about gathering.
    Neat, as I say. There are untidy complications to the story, including that men seem to strive to catch big game to feed the whole band – in exchange for both status and the occasional seduction – while women feed the family. This can lead to men being economically less productive than they might be. Hadza men spend weeks trying to catch a huge eland antelope when they could be snaring a spring-hare each day instead; men on the island of Mer in the Torres Strait stand with spears at the fringe of the reef hoping to harpoon giant trevally while their women gather twice as much food by collecting shellfish. Yet even allowing for such conspicuous generosity or social parasitism – depends on how you view it – the economic benefits of food sharing and specialised sex roles are real. They are also unique to human beings. There are a few birds in which the sexes have slightly different feeding habits – in the extinct Huia of New Zealand male and female even had different beak shapes – but collecting different foods and sharing them is something no other species does. It is a habit that put an end to self-sufficiency long ago and that got our ancestors into the habit of exchange.
    When was the sexual division of labour invented? The cooking theory points to half a million years ago or much more, but two archaeologists argue otherwise. Steven Kuhn and Mary Stiner think that modern, African-origin Homo sapiens had a sexual division of labour and Neanderthals did not, and that this was the former’s crucial ecological advantage over the latter when they came head-to-head in Eurasia 40,000 years ago. In advancing this notion they are contradicting a long-held tenet of their science, first advocated by Glyn Isaac in 1978 – that different sex roles started with food sharing millions of years ago. They point out that there is just no sign of the kind of food normally brought by gatherer women in Neanderthal debris, nor of the elaborate clothing and shelters that Inuit women make while their men are hunting. There are occasional shellfish, tortoises, eggshells and the like – foods easily picked up while hunting – but no grindstones and no sign of nuts and roots. This is not to deny that Neanderthals cooperated, and cooked. But it is to challenge the notion that the sexes had different foraging strategies and swapped the results. Either the Neanderthal women sat around doing nothing, or, since they were as butch as most modern men, they went out hunting with the men. That seems more likely.
    This is a startling shift of view. Instead of talking about ‘hunter-gathering’ as the natural state of humanity effectively since forever, as they are apt to do, scientists must begin to consider the possibility that it is a comparatively recent phase, an innovation of the