Why Did We Start Drinking Milk? On the Ancient Rise of Dairy Consumption

When the last ice sheet had finished riding roughshod over large tracts of the Northern Hemisphere and melted back to the Arctic Circle, animals and plants beyond number began moving into available ecological niches like so many Noah’s Flood survivors climbing out of the ark and looking for anchoring spots. Many life forms found the homes that suited their needs in or close to an immense east-west stretch of open ground running from Manchuria to the Danube, or about 5,000 miles. Geographers call this vast sky-canopied expanse the Great Steppe of Eurasia.

The Eurasian steppe resembles our New World counterpart, the North American Great Plains, in being windswept and for the most part semiarid, with fiercely cold winters and hot summers. But it is far larger and has figured more dramatically in the global history of food.

In places the Great Steppe is only about 200 miles wide from north to south, in others more than 500 miles. To the north, it merges into mixed forest-steppe terrain followed by tremendous boreal forests. To the south, it borders some of the world’s most forbidding deserts. Despite a few mountain barriers, it has always functioned as a natural highway, or biological—and cultural—pipeline through which the eastern and western edges of Asia have exchanged influences in more dynamic and diverse ways than might seem possible to an observer unexpectedly set down in these grass-clad wilds.

Grasses, or Poaceae to botanists, were the family of plants that most dramatically seized the ecological initiative throughout the steppe as the planet began warming up after the last glacial epoch. Along its main body, river valleys and lake borders are almost the only places with enough water to support tree growth. But grasses, with their tough and many-branched roots, can make efficient use of limited rainfall, the chief factor that always kept many other kinds of plants from colonizing the sweeping corridor.

Grasses were the making of several complicated relationships between people and their food along the Great Steppe and in some mountainous areas abutting it. They may be the most important reason that nonhuman milk ever entered human diets—starting with the fact that these regions are, or until modern times were, ideal environments for wandering herds of grass-eating animals. The herbivores in turn attracted an array of predators unequipped to digest grass themselves but able to profit from it in the flesh of nearby herbivores. The most effective of all predators would be Homo sapiens.

The first stages on the path to the milking revolution emerged long before milking as an actual practice. They started when Neolithic peoples found that by usefully meddling in the reproductive cycles of certain wild grasses and animals, they could create a cushion against seasonal food shortages. The setting for these discoveries was a well-watered swathe of West Asian terrain some 500 miles south of the steppe, encompassing what is often dubbed the Fertile Crescent.

Researchers who study the beginnings of farming now map its earliest centers not only in the originally identified Fertile Crescent—a curving belt lying between the Zagros Mountains of modern Iran on the east and the Taurus Mountains of Turkey on the west—but also in several other sites of human activity farther west and south, on the Anatolian Plateau and close to the Levantine coast of the Mediterranean. These areas had their own scattered pieces of grassy terrain that would figure lastingly in global foodways.

At some point close to 10,000 BC, local hunter-gatherers took note of an important fact: not only would grasses that escaped being eaten by animals eventually bear seeds, but some of the seeds in question were worth searching out and collecting as food for humans.

Over an unknown number of centuries, people began encouraging likely specimens to reseed themselves in one spot and ripen on a fairly systematic schedule for easier gathering. At the same time, they learned to single out individual plants with unusual qualities like especially large seeds, or whole seed-heads that tended not to shatter when ripe and (inconveniently, from a human viewpoint) spill the contents on the ground before they could be efficiently harvested. By degrees, a focus on such traits shaded into planned cultivation, which in turn shaded into actual domestication.

There are various definitions of domestication, but all agree that it replaces natural selection with artificial selection for qualities desired by human custodians, eventually creating strains of true-breeding descendants that can rarely survive in their altered form without being planted, harvested, and maintained by people. The earliest resulting plants in the greater Fertile Crescent were what are now labeled cereal grasses or grain crops, ancestors of today’s wheat and barley. The last centuries before 10,000 BC appear to have seen the emergence of truly domesticated strains.

Meanwhile, the hunting sector of the Near Eastern hunter-gatherer economy had long depended on the vast populations of hoofed and horned grass-eaters that roamed the Great Steppe and the foothills of neighboring mountain regions. Swift and agile enough to usually outrun predators, they traveled in herds to avoid being picked off singly. Such itinerant groups were superbly equipped to rove across dozens or hundreds of miles throughout a year, cropping one range before moving on to another. Since wild grasses can grow back quickly and feed migrating herds more than once in the course of a year, the animals and their food supply were usually able to exist in stable ecological balance.

The West Asian ungulates (as zoologists call hoofed mammals) included Old World bison, assorted gazelles and antelopes, and four other great lineages that in time would beget the first domesticated milk-givers: goats, sheep, cattle, and horses. Horses, the outlier in the quartet, were domesticated long after the others and would not cross their paths for several thousand years—though they would then become a game-changing factor in human relationships with the other three.

Students of Neolithic civilizations believe that as with plants, the domestication of wild goats, sheep, and cattle occurred in stages over centuries or millennia rather than being the result of one bright idea. As the anthropologist David W. Anthony has observed, “Animal domestication, like marriage, is the culmination of a long prior relationship”—undoubtedly one that had begun with hunting and killing these creatures for their meat, along with gazelles and the rest. Successful hunters knew how to track a herd’s movements and corner it at some vulnerable point.

As people learned to coordinate group efforts and reliably steer herds into massive ambushes, they began to deplete some wild populations. Eventually somebody would have tried capturing and penning up a few young members of a herd, to be raised to maturity before slaughter. This approach had some success with individual captives, which often allowed themselves to be tamed. But real domestication required something far more difficult: getting the captives to reproduce so as to keep renewing the supply. Even today, no one fully understands why some creatures resist breeding in confinement much more stubbornly than others—one of the chief factors that hinder zoos from replenishing the numbers of many species now endangered in the wild.

For whatever reason, the first grazing animals of suitable size—that is, small enough for one or two strong men to tangle with them—that were finally persuaded to mate under permanent human custody were local wild goats and sheep. In them, late Neolithic peoples of the Fertile Crescent and its mountainous fringes had managed to find two of the very few hoofed mammals that can be chaperoned down the path to domestication.

Over many generations, probably starting at or before about 10,000 BC, selected groups of goats and sheep not only accepted human control in preference to freedom but began to deviate from their ancestral morphology (structure and outward appearance). Zooarchaeologists are not always sure whether bones recovered from the early transitional period belonged to wild or domesticated goats and sheep, but the final differences are so unmistakable that the animals are now classified in their own species, Capra hircus and Ovis aries. The coat of curly, crimped hairs—“wool”—that domesticated sheep acquired while losing an ancestral outer coat of longer hairs is only one example of morphological change.

A third target of Neolithic hunters was a much more terrifying candidate for domestication: Bos primigenius, the huge wild ox or aurochs (plural “aurochsen,” as in “oxen”). This ancestor of all domesticated cattle breeds was among the largest and fiercest creatures of the Old World grasslands. For sheer bulk, aurochsen would have presented greater challenges than wild goats or sheep. Almost no modern breeds suggest the size of full-grown aurochs bulls. The towering Italian Chianina, which is often six feet high at the shoulder and can weigh as much as 3,500 pounds, gives an idea of how unanswerably an aurochs must have stacked up against any human. The bulls were at least as aggressive as Spanish fighting bulls, though these are deliberately bred for less fearsome size and rarely reach five feet or 1,500 pounds.

Nevertheless, this powerful creature turned out to be one of the few herbivores that people finally managed to mold into a domesticated species, Bos bovis. The first domesticated cattle—selected for undersized dimensions—were considerably smaller than aurochsen, an obvious advantage for handlers. Nobody ever managed to completely breed the original ferocity out of bulls. But cows became habituated to conceiving and giving birth in captivity, if human helpers could introduce them to a sire without being mowed down in the process. Few domestic mammals show more striking male-female differences than today’s cattle, in either physique or behavior.

It is impossible to pinpoint a place or date where some inquisitive person first tried to milk one of the animals being kept for meat. The idea must have occurred to people in more than one corner of the general region, though adopting it as standard practice may have taken many centuries. Two things are certain: the subjects of early experiments did not have the large, capacious udders of today’s dairy animals, and did not share their compliant attitude toward being milked. Not only is shoving oneself between a nursing mother and her young a good way to get attacked, but simply yanking on a teat will do nothing but agitate her more.

Like human mothers, lactating goats, sheep, and cows have an instinctive need to see, touch, and smell the nurslings who depend on their milk. These sensory cues reinforce the particular combination of suction and pressure that the infant’s mouth exerts in suckling, helping to stimulate production of the hormone oxytocin, which governs the “letdown reflex.” The first humans who managed to trick the mother into letting down her milk had to allow the little one an initial few moments of nursing and then keep it as close to her as possible, usually by tethering it to her front leg or neck, while cleverly mimicking the suckling rhythm with their fingers wrapped around a teat in a particular grasp. (A later refinement in prompting the hormonal trigger was to have a helper blow air through a pipe inserted into the animal’s vagina or anus.) Another certainty is that by comparison with modern norms, these efforts would have yielded much smaller amounts of milk—though milk more naturally concentrated than anything one can buy today.

We do not know in what forms prehistoric peoples consumed milk, except that they could not have easily digested it fresh from the udder. Nonetheless, milking skills seem to have become well advanced by late Neolithic times (possibly about 6,500 BC) in the greater Fertile Crescent.

As living with the results of both plant and animal domestication became second nature to people, some intractable conflicts arose between the demands of the two enterprises. The old hunter-gatherer life allowed bands of humans to move around synchronously with both the annual migrations of animals and the seasons of wild fruits, vegetables, and anything else that can be reaped with two hands. Tending crops meant a break with this mobility and either rapidly or by slow degrees imposed a sedentary life on the tenders.

Sedentism, however, was an abnormal condition for herbivores used to eating their way from range to range. For them, survival had always been contingent on grazing one patch of grass, then moving on to the next. Where grass was plentiful, they could linger a while; where it was scarce, they had to cover wider areas. Goats were somewhat flexible in their needs, since they could readily browse on shrub or tree leaves. Sheep and to some extent cattle depended more heavily on grass. And as people soon found, any restricted pasturage on which a herd is kept grazing without letup is soon depleted, often with serious damage to the ground itself.

The dilemma for two-legged keepers moving on foot was how to either provide these instinctive wanderers with everything they needed (including protection against animal predators and human thieves) in an artificially confined space or travel as far and fast as they did. Sedentism-versus-mobility choices were an early example of a quandary that has never gone away: how to use land resources to balance a community’s food demands against the environmental costs that come with raising animals—or, to state the issue another way, mismatches between food consumption and sustainable food production. Complex modern economies have not so much solved these problems as displaced them beyond the everyday view of the consuming public, especially since the growth of cities began shunting the people who consumed perishable products into living spaces far distant from the site of production.

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Excerpted from Spoiled: The Myth of Milk as Superfood by Anne Mendelson. Copyright © 2023 Anne Mendelson. Used by arrangement with the Publisher. All rights reserved.