Until the end of the last Ice Age about 10,000 years ago, humans lived a hunter-gatherer lifestyle. The only species with which they developed a domestic relationship were those that shared such a nomadic existence. Most notably, it was the wolf that, in all probability, learned the advantages of scavenging around humans, while humans took advantage of the hunting skills of the wolf pack. The relationship produced the domestic dog, whose history traces back at least 15,000 years. Another ancient domesticate is the reindeer, a nomadic species that roamed with humans in northern climates, and whose unusual (for a cervid species) social behaviors allowed domestication to develop.

As the ice sheets retreated, new land areas opened up and were exploited and colonized by the weeds of the plant and animal kingdoms those species that were adaptable and hardy and could thrive in novel environments. Humans were part of this expansion and developed ever-closer relationships with those they hunted, especially sheep, goats, and gazelles. Sheep and goats progressed to full domestication around 9000 years ago, but gazelles, whose first response to alarm is to flee before halting to investigate the cause, did not prove capable of living closely with humans. Despite their great importance to humans for meat, they could never be fully domesticated.

Around 8000 years ago, somewhere in the Middle East, a domestication occurred that changed the face of the earth forever humans began to domesticate plants. The production and storage of small grains demanded that the hunter-gatherers take up a more settled existence. The cultivation of highly desirable foodstuffs in concentrated areas attracted opportunistic crop robber species, much as it still attracts wild elephants in Africa and Asia today. Humans had to learn how to live in close proximity with crop robbers like cattle and swine. The simplest solution was to kill the wildest and most aggressive for meat, while coming to an agreement with the rest. As human digestive systems are not designed to utilize the roughage portion of grain crops, sharing with other species was feasible. Natural selection of social, adaptable species of relatively phlegmatic temperament thus brought humans and these species into close contact; primitive artificial selection by humans emphasized the docility that allowed full domestication to take place. Cattle and pigs were domesticated soon after settled agriculture began.

As settled agriculture progressed, so did domestication. Between 4000 and 6000 years ago, large species such as llamas in South America, horses in Central Asia, and water buffalo in South Asia were domesticated. They not only provided food, fiber, hides, and bone for human use, but were sources of power to cultivate the land and transport goods, and of manure to fertilize the soil. Animal domestication enhanced the productivity of plant domestication.

The storage of grain attracted rodents, which in turn attracted cats. The mutual benefits of easy prey for the cats and pest control for humans led to cat domestication in North Africa around 4000 years ago. The relationship between humans and cats has always been an unusual domestication as cats retained a single major function (hunting) that did not depend on a hierarchical social structure for its success.

Domestications of other small mammals such as rabbits and cavies all occurred in the last 2000 years. Those species originally had important functions as food animals, but modern domestications have focused primarily on the pet trade. Domestication is not limited to mammals, however. Around 5000 years ago, silk moths were domesticated in East Asia and honeybees in North Africa. Chickens were domesticated about 8000 years ago, birds such as geese and ducks around 3000 years later. The earliest fish domestication was that of the carp, domesticated in Asia around 3000 years ago. A rare example of a recent domestication of a nonpet species is the ostrich. Domestication for feathers and meat began in the 19th century in Africa, and this species is now kept in many parts of the world. Full discussion of a wide range of species domestications can be found.[2] Most domestication occurred in Eurasia and North Africa, but the Americas produced domestic turkeys around 1000 years ago, in addition to mammals (e.g., llamas) domesticated earlier. In general, the Eurasian landmass, because of its size, harbored more domesticable species, and its east west axis allowed their widespread distribution as humans migrated.[3]

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