The world looks increasingly similar even as each world resident experiences an increase in variety

From Apple Diversity has Grown by Alex Tabarrok. An excellent piece.

Mother Jones has a fun piece on apple hunters, people who track down long-forgotten apple varieties, sometimes to a single, ancient tree which they then clone in order to resurrect its unique apples. It’s a fun, human-interest story but Mother Jones also repeats a number of errors about apple diversity. Most notably:

In the mid-1800s, there were thousands of unique varieties of apples in the United States, some of the most astounding diversity ever developed in a food crop. Then industrial agriculture crushed that world. The apple industry settled on a handful of varieties to promote worldwide, and the rest were forgotten. They became commercially extinct—but not quite biologically extinct.

Mother Jones is tame compared to The New Internationalist which really ramps up the imagery:

Lincoln was assassinated. So were Washington and Jefferson. In fact all three Lincolns were wiped out. In the end it wasn’t so much an assassination as a massacre, with 6,121 of the 7,098 American apple varieties that blossomed last century now extinct….In less than a century, market pressures for uniformity have slaughtered crop diversity.

All of this is highly misleading at best. The innovative Paul Heald and co-author Sussanah Chapman show that the diversity of the commercial apple has increased over time not decreased (pdf). It is true, that in 1905 W.H. Ragan published a catalog of apples with some 7000 varieties. Varieties of apples come and go, however, like rose varieties or fashions and Ragan’s catalog listed any apple that had ever been grown during the entire 19th century. (Moreover, most varieties are neither especially good nor especially unique). At the time Ragan wrote, Heald and Chapman estimate that the commercially available stock was not 7000 but around 420 varieties. What about today?

The Fruit, Berry and Nut Inventory for 2000 lists 1469 different varieties of apples, a massive gain in terms of what growers can easily find for sale. The Plant Genetic Resources Unit of the USDA, in Geneva, New York, maintains orchards containing an additional 980 apple varieties that are not currently being offered in commercial catalogs. Scions from these trees are typically available to anyone who wishes to propagate their variety. The USDA numbers bring the total varieties of apples available to 2450.

In fact, there are more than 500 varieties of apples from the 19th century commercially available today–thus there are more 19th century apples available today than probably at any time in the 19th century!

But he doesn't stop there. He gets into some quite interesting aspects of variety and some of the paradoxes arising from globalization.

Increasing variety for individuals even as world variety declines is a fundamental fact of globalization. In the context of culture, Tyler explains this very well in his book, Creative Destruction; when people in Beijing can eat at McDonald’s and people in America can eat at great Chinese restaurants the world looks increasingly similar even as each world resident experiences an increase in variety.

Thus it may well be the case that more apples varieties were grown in large quantities in the 19th century but there are both more varieties commercially available today (our stock of genetic diversity is higher) and individual consumers have low-cost access to more apple varieties than ever before.