THAT orientals and occidentals think in different ways is not mere prejudice. Many psychological studies conducted over the past two decades suggest Westerners have a more individualistic, analytic and abstract mental life than do East Asians. Several hypotheses have been put forward to explain this.

One, that modernisation promotes individualism, falls at the first hurdle: Japan, an ultra-modern country whose people have retained a collective outlook. A second, that a higher prevalence of infectious disease in a place makes contact with strangers more dangerous, and causes groups to turn inward, is hardly better. Europe has had its share of plagues; probably more that either Japan or Korea. And though southern China is notoriously a source of infection (influenza pandemics often start there), this is not true of other parts of that enormous country.

That led Thomas Talhelm of the University of Virginia and his colleagues to look into a third suggestion: that the crucial difference is agricultural. The West’s staple is wheat; the East’s, rice (see article). Before the mechanisation of agriculture a farmer who grew rice had to expend twice as many hours doing so as one who grew wheat. To deploy labour efficiently, especially at times of planting and harvesting, rice-growing societies as far apart as India, Malaysia and Japan all developed co-operative labour exchanges which let neighbours stagger their farms’ schedules in order to assist each other during these crucial periods. Since, until recently, almost everyone alive was a farmer, it is a reasonable hypothesis that such a collective outlook would dominate a society’s culture and behaviour, and might prove so deep-rooted that even now, when most people earn their living in other ways, it helps to define their lives.

Mr Talhelm realised that this idea is testable. Large swathes of China, particularly in the north, depend not on rice, but on wheat. That, as he explains in a paper in Science, let him and his team put some flesh on this theory’s bones.

The team gathered almost 1,200 volunteers from all over China and asked them questions to assess their individualism or collectivism. The answers bore little relation to the wealth of a volunteer’s place of origin, which Mr Talhelm saw as a proxy for how modern it was, or to its level of public health. There was a striking correlation, though, with whether it was a rice-growing or a wheat-growing area. This difference was marked even between people from neighbouring counties with different agricultural traditions. His hypothesis that the different psychologies of East and West are, at least in part, a consequence of their agriculture thus looks worth further exploration. And such exploration is possible—for India, too, has rice-growing and wheat-growing regions.

How resilient Asia’s collectivist cultures will be as they lose their rural roots remains to be seen. But the message from Japan, and also from more recently modernised places such as Korea, Taiwan, Hong Kong and Singapore, seems to be “quite resilient”. For some, Asian values—with their tenets of solidarity and collective action—are cause for celebration. For others, they are stifling and a barrier to social progress. But whichever side you take, if Mr Talhelm is correct they are only “Asian” because, back in the neolithic, farmers in many parts of that continent found Oryza a more congenial crop to grow than Triticum.