By Harold McGee
A handful of different wheats have been grown from prehistoric times to the present. Their evolution is fascinating and still somewhat mysterious, and is summarized in the box. The simplest wheat and one of the first to be cultivated was einkorn, which had the standard genetic endowment of most plants and animals: namely two sets of chromosomes (a “diploid” species). Somewhat less than a million years ago, a chance mating of a wild wheat with a wild goatgrass produced a wheat species with four sets of chromosomes, and this “tetraploid” species gave us the two most important wheats of the ancient Mediterranean world, emmer and durum. Then, just 8,000 years ago, another unusual mating between a tetraploid wheat species and a goatgrass gave an offspring with six sets of chromosomes: and this offspring gave us our modern bread wheats. The extra chromosomes are thought to contribute to the agricultural and culinary diversity found in modern wheats, most importantly the elasticity of the gluten proteins. Today 90% of the wheat grown in the world is hexaploid bread wheat. Most of the remaining 10% is durum wheat, whose main purpose is making pasta. The other wheats are still cultivated on a small scale.