artiodactyl

Abundance and distribution

Artiodactyls were once the dominant herbivores (plant-eating mammals) of almost every continent. They are an important link in the chain by which the sun’s energy, having been used by green plants, is made available to other forms of life. They tend to be medium-size or large animals. If they were any smaller, they would compete with rabbits and the larger rodents. And if they were larger, they would compete with elephants and rhinoceroses, the largest of terrestrial herbivores. The success of artiodactyls has depended on skeletal adaptations for running and on the development of digestive mechanisms capable of dealing with plant foods; none is adapted to flying, burrowing, or swimming. The individual species tend to be fairly narrowly adapted, in comparison with other mammals, but many of them nonetheless have broad distributions.

Native artiodactyls are absent only from the polar regions and from Australasia, but many have been introduced into Australia and New Zealand. In Australia the position of medium and large herbivores is occupied by kangaroos. Through most of its evolutionary history, the order was absent from South America; only within the last few million years have some groups entered that continent. The occurrence of the majority of living artiodactyls in the Old World is a recent phenomenon; a considerable variety once inhabited North America.

The order Artiodactyla contains nine families of living mammals, of which the Bovidae (antelopes, cattle, sheep, and goats) is by far the largest, containing nearly 100 species. There are five Eurasian and four African species of pigs (family Suidae) and two Central and South American species of piglike peccaries (Tayassuidae). The two hippopotamus species (Hippopotamidae) are African. The more familiar large species were until recently widespread throughout Africa south of the Sahara and in the Nile Valley; the pygmy hippopotamus has a restricted distribution in West Africa. The camel group (Camelidae) was formerly abundant in North America, the now extinct North American stocks having produced the camelids of South America (wild guanaco and vicuña, domestic llama and alpaca) and the Old World dromedary and Bactrian camel.

The remaining artiodactyls (i.e., the suborder Ruminantia) are all ruminants (cud chewers), the most primitive of which are the chevrotains (Tragulidae), with nine species in Asia and one, the water chevrotain, in West Africa. The chevrotains are clearly remnants of a group that was once more numerous and widespread. Deer (Cervidae) are basically Eurasian and have not spread into sub-Saharan Africa, although they have reached the Americas. There are about 30 species, the greatest number being concentrated in South America and tropical Asia. The giraffe and the okapi (Giraffidae), two distinctive African species, are closely related to deer. The pronghorn (Antilocapridae), although sometimes called pronghorn antelope, is not a true antelope; it is the only survivor of a stock of ruminants that was very successful in the Neogene Period in North America (about 23 million to 2.6 million years ago). The family Bovidae is primarily African and Eurasian, with a few members in North America. Bovids are advanced artiodactyls, many of which live in open grassland and semi-arid areas.

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Importance to humans

Artiodactyls have long been exploited by humans for economic purposes. At Olduvai Gorge in East Africa there is clear evidence of the use of antelopes for food almost 2 million years ago. In Europe during Paleolithic times (about 30,000 years ago) Cro-Magnon man depended heavily on the reindeer. By this time the use of animals other than as food had become established; skins were used as clothing and footwear, and bones were used as tools, weapons, and accessories.

The domestication of animals was a major advance in human history. Domestication of herd animals probably arose gradually, perhaps before agriculture. Domesticated goats and sheep are first known from the Near East at some date close to 7000 bce. Cattle and pigs were domesticated at some subsequent date but certainly before 3000 bce. In South America the llama, now used for transport, and the alpaca, which provides a source of wool, were developed from guanacos by the Incas or their predecessors. The dromedary (Camelus dromedarius), domesticated in Arabia, was introduced into the Southwestern United States, southwestern Africa, and inland Australia in the 19th century. A large feral population now exists in Australia.

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In addition to providing meat, milk, hides, and wool, artiodactyls have served man in a number of other ways. In Kashmir, the underfleece, or pashm, of the Siberian ibex (Capra ibex) and of local domesticated goats has been used as the basis for the manufacture of cashmere shawls. In southwestern France, pigs have been used to locate underground truffles (the fruiting bodies of certain edible fungi).

No group of mammals is more extensively hunted than the artiodactyls. Sport hunting of various deer supports a multimillion-dollar industry in North America and Europe. In many cultures hunting has been reserved for monarchs or the aristocracy. In the centuries after the Norman Conquest of England, the forest law provided severe punishment for the slaughter of deer and boars. Père David’s deer (Elaphurus davidianus) of China now survives only because it was preserved first in the hunting park of the emperors of China and later by the Duke of Bedford after the slaughter of the Chinese herds at the end of the 19th century.

Wild ungulates were the primary source of meat for human populations long before the appearance of modern man. Prehistoric man hunted the large mammals of his environment with an ever increasing effectiveness that was certainly instrumental in his survival. The extent to which man was involved in the extinction of some of the larger Pleistocene animals (i.e., those that were abundant 2.6 million to 11,700 years ago) is still being investigated. There is now known to have been a wave of late Pleistocene extinction of large mammals, including artiodactyls; in North America this wave reached its zenith about 9000 bce. Many animals also became extinct in Africa, where long-horned buffalo and large relatives of hartebeests survived until very recently. More of the large mammals have survived in Africa than elsewhere, but the reason for their survival is not known. A second, probably final, wave of extermination of the larger mammals has taken place with the spread of European culture and firearms in the past 300 years. It has been marked by wanton slaughter and has ultimately produced an interest in conservation. It now seems, however, that the unprecedented demands on the environment being made by rapidly expanding human populations will result in a nearly complete extinction of large wild mammals.