Humans have used wild animal and plant products for numerous purposes since prehistoric times. Clothing was made from animal skins, and tools from bones. In many societies, products from rare species symbolized wealth and success. For example, flashy feathers from South American birds were given as a tribute to Inca chiefs by their subjects, and women in nineteenth-century Europe sported ostrich feathers in their hats. In East Asia, animal parts have been used to prepare medicines and aphrodisiacs. Exotic species have also been kept as pets—cheetahs and falcons, for example, were kept for hunting. In addition, species such as dogs, cats, apes, monkeys, frogs, guinea pigs, rats, and mice are used in scientific research.
Sadly, overexploitation of wild species for commercial gain is the second most important cause of animal extinction, after habitat loss. According to the World Conservation Union's 2000 IUCN Red List of Threatened Species, hunting, collection, and trade affect 37 percent of all bird species, 34 percent of mammals, and 8 percent of surveyed plant species. Once non-domesticated animal species are considered commodities, they have an extremely high likelihood of becoming endangered. A small subset of endangered species currently affected by trade include whales hunted for meat and blubber; exotic birds captured for the illegal pet trade; rhinos poached for their horns; minks killed for their pelts; snakes, alligators, and lizards hunted for their skins; and elephants slaughtered for their ivory tusks. The argalis (see Figure 10.1) is a species of wild sheep endangered because trophy hunters seek its massive horns.