Walk down a dairy aisle and you may start to notice how little we've done with the whole concept. Worldwide, there are about 6,000 mammal species, each with its own unique milk, but Americans get at least 97 percent of all our dairy products from one animal. (That would be the cow.) Even at my local Whole Foods, purveyors of exotica like shad roe and that kombucha stuff, there was only a single brand of goat's milk. "EASY TO DIGEST!" reads the desperate carton.
Over at the cheese counter, the situation was a little better. Sheep's milk made a decent showing. But was that it?
"There's a buffalo-milk mozzarella over in the refrigerator section, but yeah," the cheesemonger told me. "I know a chef who's trying to make a pig's-milk cheese. I'm not sure how that's going."
Abroad, things are a little more diverse: Various foreigners drink the milk of the camel, the yak, the water buffalo, the reindeer, the elk and a few other animals. With the exception of the horse, whose milk is fermented and drunk in central Asia as the lightly alcoholic kumis, all dairy animals of any importance are ruminants, a class of mammal whose four-chambered stomachs allow the production of terrific amounts of milk from high-fiber, low-nutrient pasturage. Their large, graspable teats make milking easy. (Inspect the belly of your cat or dog and you'll get an idea why we don't milk our pets: lots of itty-bitty nipples.)
The three dairy animals familiar to Westerners were domesticated between 10,000 B.C. and 8000 B.C. in the Fertile Crescent. Goats and sheep were probably first, followed by cows. All three have since been bred to improve temperament and output, but cows have responded the most profoundly.