The Guadalupe River that flows through Texas used to be known as The River of Nuts, a fact that Wikipedia does not confirm. The nut in question is the pecan, Carya illinoinensis, and the pecan tree is the state tree of Texas. The groves of wild pecans that lined the rivers of Texas are, however, threatened by the very popularity of the nuts they bear, and in particular by the fickle global nut market. The Chinese, you see, have gone nuts for pecans, increasing their purchase of American pecans from 3–4% in 2006 to 30–40% today. And if they abandon the pecan as quickly as they took it up, the wild pecan groves might be abandoned too. All this, and much more, I learned from James McWilliams, professor of history at Texas State University. His new book is one of those delights that looks at the global sweep of human endeavour through a little lens, in this case the pecan.

Why it was the Chinese, rather than the French, the English or some other country, that chose to absorb the pecan surplus, I guess we’ll never know. McWilliams told me that Chinese people he spoke to believe the nuts prolong life; irrational as that may seem, no American grower is going to say they don’t. And while the high prices are good news for growers, they’re not so good for people who want pecan-containing industrial food.