Around the corner from my office in New York stands a string of sushi restaurants. At lunchtime most days they are packed with professionals, gobbling down cold lumps of toro (tuna belly), hamachi (yellowfin tuna) or ebi (prawn). So far, so unremarkable. But reflect, for a minute, on all that raw fish. A generation ago, the idea of American office workers munching cheerfully on uncooked tuna would have been almost laughable. After all, the USA was the land of (cooked) steak and fries; sandwiches and hamburgers were the norm for lunch. Many Americans had only the haziest idea of what the Japanese actually ate; and there were few sushi restaurants to be found, even in cities such as New York.

Yet in just a few years, sushi has colonised urban centres with startling speed. The first wave of sushi restaurants cropped up in California in the 1970s, partly to service the estimated one million Americans of Japanese descent. But now they are ubiquitous, serving Caucasians too: teenagers take sushi to school; prisons have introduced it; in California, it is served at trucker stops. Meanwhile the National Sushi Association reports that there are now more than 5,000 sushi bars in American supermarkets, with the number continuing to rise fast.

“When I first started teaching in the mid-1980s, if I asked a class of my students if anyone had eaten sushi, a few hands might go up,” observes Theodore Bestor, professor of anthropology at Harvard University, who did his academic research in Tsukiji fish market in Tokyo, and now studies food cultures. “But now all my students have eaten sushi; the attitude is: “How do you think I got to Harvard without being able to eat sushi?” Raw fish has become a symbol of modernity and sophistication; conversely, squealing “yuck” to cold tuna is profoundly uncool.