Domestication of sheep

Sheep were among the first animals domesticated, likely the second after dogs—and unlike cattle or pigs, sheep transformed not just food production but clothing. The woolly sheep we know today didn't exist in nature; it was created through millennia of selective breeding that turned a hair-covered wild animal into a walking textile factory.

The wild ancestor of domestic sheep was the mouflon (Ovis orientalis), still found in mountains from Turkey to Iran. Mouflons have hair, not wool—short, stiff fibers that shed seasonally. The fluffy fleece that defines modern sheep resulted from selecting for animals whose hair follicles produced longer, finer, continuously growing fibers. This was a complete reengineering of the animal's integumentary system, achieved without any understanding of genetics.

Sheep domestication began in the Fertile Crescent around 10,000 BCE, roughly simultaneous with goat domestication and slightly before cattle. The earliest domesticated sheep still had hair coats; wool sheep appear in the archaeological record only around 6000 BCE. For four thousand years, sheep were raised primarily for meat, milk, and skins. The wool revolution came later, transforming textiles and creating wealth measured in flocks.

The conditions favoring sheep domestication were geographic. Mouflons lived in upland areas where agriculture was emerging. They are gregarious, following leaders rather than scattering when threatened—a herding instinct that made management possible. Their size was manageable; unlike aurochs, mouflons could be handled by small groups. And sheep eat grass that humans cannot digest, converting marginal land into portable wealth.

The cascade from sheep domestication shaped civilizations. Wool became the primary textile of the ancient and medieval worlds; the English wool trade financed cathedrals. Shepherding enabled pastoral lifestyles across marginal lands from Scotland to Mongolia. The accounting systems that evolved to track sheep flocks—clay tokens in Mesopotamia—prefigured writing. The first clay tablets recorded sheep counts, not literature.

Genetic evidence reveals a bottleneck: all domestic sheep descend from a small founding population, probably fewer than 100 animals successfully domesticated and bred. This founder effect means modern sheep have lost much of the genetic diversity present in wild mouflons. The same bottleneck appears in other domesticated species—a signature of the rare event when capture, taming, and breeding all succeed.

By 2026, over 1 billion sheep graze six continents. The wool industry produces 2 million tons annually. The hair-covered mouflon that scrambled through Zagros Mountain passes 12,000 years ago has become a global commodity, its descendants producing meat, milk, wool, and leather in virtually every climate humans inhabit.