Pets.

• Position: LIFE-CYCLE STUDIES

Overview

Human domestication of animals probably began with dogs about 17,000 years ago, although some experts believe the association is much older. Dogs got an assured supply of food and shelter, and in return they offered ingrained tracking, hunting, and guarding skills. It's been argued that dogs selected humans, not the other way around, but one way or another a symbiotic relationship developed.

Other species were tamed later during the Neolithic period, which saw the spread of farming and the domestication of goats, sheep, pigs, and cows. Chickens have been "kept" creatures for at least 8,000 years. The cat was domesticated 9,500 years ago in Cyprus, when wild cats came in from the cold to eat the rodents infesting the grain stores of early farmers. It took a couple of millennia more before donkeys and horses were harnessed for transport. Some animals, despite apparent potential, can't be domesticated; the zebra is a notorious case of one that can't be drafted. But almost any creature can, and has been, kept as a pet, including rats, scorpions, and cockroaches. Low expectations widen the range of possibilities.

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Pets Today

Pets (companion animals) are a huge industry, worth about US$40 billion per year in the United States and $10 billion per year in Japan, where a rare dog like a teacup poodle can cost $10,000. The allure of even more-exotic pets plays a big part in the global trade in illegal wildlife, worth $6 billion a year.

People clearly love pets, and studies suggest that pets confer health benefits such as lower blood pressure. There is a tragic side to this phenomenon, however. Trade in illegal animals has led to species extinctions and to disruption of natural ecosystems. Many pets suffer and/or die of neglect, abuse, or simple carelessness; in the United Kingdom, for example, 50 percent of domestic pets are clinically obese. The pursuit of exotic traits by breeders has...