Overbites and the History of Civilization

Human teeth are rather weakly attached to the jaw, and they can move around a great deal. This is, of course, how orthodontics works. But teeth also move in response to how you use them; eat a lot of a certain food that requires a lot of chewing, and your teeth can shift into a different position, especially during adolescence.

Contemporary parents contemplating their orthodontists' bills have often wondered why their kids have these problems, which don't seem to have troubled past generations nearly so much. Could it be the way we eat? Jane Kramer in the New Yorker, reviewing a book by food historian Bee Wilson:

By the late eighteenth century in Europe, people were slicing their food into bite-size morsels and carrying them to their mouths with forks—those formerly weird things, Wilson calls them. And they hardly needed to chew such tiny pieces, which in most cases were already softened by pounding, overcooking, or long, gentle braisings. At the same time, the modern overbite began to appear prominently in upper-class Western European jaws. Do not confuse this with the seriously inconvenient condition known to the world as buck teeth (without which we would have no orthodontists, and no mortified adolescents with mouthfuls of rubber bands and wire braces). Wilson’s modern overbite refers to “the way our top layer of incisors hangs over the bottom layer, like a lid on a box,” as she nicely puts it, and is “the ideal human occlusion” for the way we now eat. Why this happened and how long it took to happen is open to some debate, but it’s clear that until it happened most humans had the bite of other primates—“where the top incisors clash against the bottom ones, like a guillotine blade.”

Wilson’s favorite theory comes from the American physical anthropologist Charles Loring Brace, a specialist in the evolution of hominid teeth. In 1977, Brace published an article that put the age of the Western overbite at no more than two hundred and fifty years—which is to say that flatware and, with it, a significant change in how we chewed were all it took for the edge-to-edge occlusion that we inherited from the Neanderthals to be replaced by the bite we now call normal. Brace was haunted by overbites. He had long assumed them to be an incremental and selective evolutionary change that began with agriculture and the consumption of grains. But the jaws he studied, on his way to building a database on the evolution of hominid teeth—apparently the biggest in the world—changed his mind. The transformation he’d seen in those eighteenth-century-gentlemen jaws was too abrupt, and too radical, to qualify as evolution, especially given the rapidity with which it then followed the spread of flatware into the middle classes, in the nineteenth century. In 1914, in the run-up to war with Germany, a stainless-steel alloy—developed to prevent corrosion in gun barrels—went on sale in Sheffield, England. Once stainless appeared on the country’s dinner tables, the guillotine bite all but disappeared. 

And as with so many other civilized refinements, this one appeared first in China:

For Brace, the proof of his hypothesis as to the relation between jaws and cutlery came when, “on his eternal quest” for new teeth to study, he visited Shanghai’s natural-history museum, examined the pickled jaw of a graduate student, dating from the Song dynasty (960 to 1279 A.D.), and discovered the same incisor overbite that, by his reckoning, had first appeared in Europe eight hundred to a thousand years later.

Perhaps when the Undomesticated Men finally make their appearance in the mountains of Idaho, they will raise their children without forks and make them gnaw their meat off the bone, so their teeth don't go soft and over-civilized.