What is domestication?
Domestication is a process by which certain species of wild animals have been brought into close relationship with humans and thereby significantly changed the animals' ways of life. The process of domestication has been long and complicated, with unforeseeable consequences for both concerned sides. The consequences resulted in significant economic, social, cultural, and political changes.
The process of domestication is similar to that of evolution, except that the natural choice was made with artificial selection. Humans violently separated the ancestors of domestic animals from their wild relatives and step by step, generation after generation, also changed their appearence and features. This selection probably proceeded at first only accidentally. Only later, when humans noticed certain connections, did they start to use purposeful selection for different economic, cultural, or aesthetic reasons.
Which species were domesticated?
One of the main questions is why only a few species were domesticated from such a huge number of wild animal species. For example, only 14 species were domesticated from the large group of terrestrial mammalian herbivores and omnivores. The horse and the donkey were domesticated, but four zebra species and the Asiatic ass were not. There are many existing testimonies that people almost 20,000 years ago were keeping bears in captivity. The ancient Egyptians (in the Old Kingdom 2500 B.C.) were keeping tamed addax antelope, hartebeest, oryx, gazelle, and cheetahs (for hunting). The ancient Romans kept and bred dormice (for meat). None of these animals, however, was domesticated.
The answer is as follows. Wild animals must match several important conditions to be domesticated. If one of the conditions is not met, domestication will not occur. A candidate for domestication must not be a narrow food specialist (e.g., the anteater or panda) because nourishment must be easy to supply. It should also have a strong herd or pack instinct, which secures authority recognition and therefore simplifies comunication with a human. A social carnivore like a wolf is much easier to tame than a solitary hunter like a leopard. Likewise, sheep and goats, which have a social system based on a single dominant leader, are much easier to tame than deer and most antelopes, which live in herds without dominance hierarchies. And the candidate animal should be "in the right place at the right moment."
A distinctive barrier to successful domestication is food competition (one of the reasons why the bear was not domesticated was that humans were not able to feed both themselves and the bear). Other obstacles are nasty disposition, reluctance to reproduce in captivity (cheetah), and the tendency to panic in enclosures or when faced with predators (antelopes, deer), or a long reproductive cycle and slow growth rate (which obviously has prevented real elephant domestication). The reason why zebras were not domesticated, even though the colonists tried it in South Africa from the seventeenth century onwards, was due to their biting habits and dangerous behavior (they kick a rival until it is killed).
When and where?
The beginnings and the progress of domestication of most "classical" domestic animals are not known in detail because they depend on archaeological discoveries of human settlements, for example, bone fragments from waste holes, cave paintings, or statuettes of animals. In the latest periods, it is possible to obtain domestication information using genetic comparative analysis. According to archaeologists, the beginnings of domestication were at a period when human gatherers and hunters became sedentary farmers, a period in which the domestication of wheat, barley, and peas also occurred. This change occured at the turning point of the Stone Age (Paleolithic and Neolithic) and it was so radical that it is referred to as the "Neolithic revolution." It is a temporal border that occurred more than 12,000 years ago. In archaeological findings from western Asia, which are 11,000 and 9,000 years old, it is possible to clearly follow changes in the way of life according to the structure of food, which changed very distinctively during that interval. While the remains of wild animal species including cattle, pigs, gazelle, deer, foxes, rodents, fish, and birds predominate in the older findings, there is a distinct predominance of sheep and goats in the more recent findings. It is very difficult to determine if the bone remains come from already domesticated animals or wild ones because at the beginnings of domestication the skeletal changes were very small. If there are predominatly male bones in the findings (females were left for the production of offspring) or if the bones are markedly smaller than those of wild animals, archaeologists assume that they belonged to domestic animals.
The domestication of the majority of the traditional domestic animals usually occurred in areas where the human populations had reached a certain level of cultural development and where there was a suitable wild ancestor. These areas are designated as a "center of domestication." The oldest (10,000 to 6000 B.C.) domestic centers were located in western Asia and in the Middle East (the area of the "Fertile Crescent") and were related to the beginnings of sedentary settlements and the first successful experiments with breeding grain. In that area, goats and sheep were domesticated for the first time, followed by cattle and pigs. Nevertheless, a very narrow relationship was created a few thousand years earlier between tamed wolves and humans, so that the first domestic animal was a dog. This period became a sort of "start" and "instruction" period for the next domestication processes. The next significant domestic centers occurred in the Indian continent (zebu), in China (goose, duck, pig, silkworm moth), in Central Asia (horse, camel), and in Southeast Asia (domestic fowl, pig, buffalo). In these areas the common domestic animals of today were domesticated. A small percentage of domestic animals were bred on the American continents, in Middle America, the turkey and musky duck, and in the western part of South America, the llama and guinea pig. From these centers domestic animals spread to other areas. Some species expanded all over the world (dog, cat, cattle, horse, sheep, goat, domestic fowl) while others remained only in the original area of domestication (yak, Bali cattle, llama).
Why and how?
We have to appreciate that the first breeders of domestic animals did not have any instructions and they were not able to imagine where domestication would lead. It is assumed that the initial reasons motivating domestication were frequently different from the animals' subsequent use. However, the main reason was very simply to access a supply of food. Exceptions are cats and dogs, which became partners to people, and later assumed many other roles, such as dogs becoming guardians. Even though of various origins, the domestication scenarios of most animals were analogous and evolved in three main steps. First came capturing and holding a wild animal in captivity (mostly young animals, when their mothers were killed in the hunt), followed by gradual taming and herding. The third phase was breeding, where humans started to generate animals according to their needs or beliefs that they were improving certain desirable qualities (intensive livestock husbandry). Sometimes it was a spontaneous process when the animal connected to a human on a voluntary basis (dog, cat, pigeon), or when the human connected to the animal (reindeer).
Other species were barely tamed (wild ox, horse, ass). Domestication was a lengthy process; it is generally believed that the shorter the developmental cycle of an animal, the quicker the change of generations and, therefore, the shorter the domestication process.
What is a domestic animal?
A domestic animal can be defined as one that has been bred for a long time in captivity for economic profit in a human community that maintains total control over its territorial organization, food supply, and breeding, which is the most important issue. Because domestic animals did not develop in a process of natural evolution, they are not considered distinct animal species, and in the zoological terminology they are catergorized as forms.
Humans breed and use many other animals that have not passed through the domestication process. A typical example is the elephant. The working elephant has been used for some 5,000 years and is still an important part of the work force in Southeast Asia, even though they were never domesticated. Every individual is caught in the wild, violently tamed, and educated to perform specific work. It almost never reproduces in captivity. The Indian elephant (Elephas maximus) is used mostly for work, but the ancient martial elephants, for example those in Hanibal's army, were African elephants (Loxodonta africana). Other nondomesticated animals humans have employed include birds of prey used for hunting (falconry), cormorants used for fishing, macaques used to pick cocoa nuts on the beaches, and dolphins and pinnipeds used by some militaries.
Laboratory animals used for investigative and experimental purposes are also a special group. Even though they have a shorter history of coexistence with humans than the more common domestic animals, these other species are also considered domestic. Almost all domestic animals have been used as laboratory animals, but not all laboratory animals are domesticated. In the last decades, the spectrum of animals used for laboratory purposes has expanded to include wild animals.
A special group of domesticated animals is pets. People have been breeding them in their surroundings for several centuries or millennia, for example, the peacock or the dancing mouse.
Species that humans breed and change also include semi-domesticated animals, such as the fallow deer kept in enclosures. They reproduce with no problems and have several color forms. Animals used for fur also belong to this group (mink, fox, coypu, chinchilla), as do ostriches, which are bred in farms.
Another group of animals called "commensal," live with humans. Commensalism is defined as the reciprocal coexistence of two or more organisms. One of them benefits from this relationship and the other is neither harmed nor benefits ("no harm parasitism"). This relationship is very free, close to symbiosis. Humans provide many opportunities for commensalism. For example the house mouse (Musmusculus) exploits human hospitality, and obtains food profit from human coexistence as well as a safe hiding place. Rats, rooks, seagulls, and many other animal species benefit from rich food allocation in human wastedumps. Another example of commensalism is the pariah dogs in Asia and Africa. These live by scavenging around human towns, settlements, and roads. They are tolerated because they contribute to tidiness.
Domestic changes
When a given species of animal is bred in isolation from its wild habitat and at the same time protected against unfavorable conditions, specific traits start to appear that disadvantage the animal in a natural environment and would keep it out of the reproductive process in the wild—either because markedly different individuals are easier victims for predators or because no partner will accept them. These different traits are not kept in the wild populations or are very rare. Conversely, these individuals were of interest to humans because of their different appearance or their submissive nature. After some time, the changes in the nature, behavior, and in the reproduction cycle become distinctive in domestic animals. They also become stratified in their genetic make-up.
Resources
Books:Budianski, S. The Covenant of the Wild: Why Animals Chose Domestication. New York: William Morrow, 1992.
Clutton-Brock, J. A Natural History of Domesticated Mammals. Cambridge: Cambridge University Press, 1999.
Harris, D., ed. The Origin and Spread of Agriculture and Pastoralism in Eurasia. London: UCL Press, 1996.
Hemmer, H. Domestication: The Decline of Environmental Appreciation. Cambridge: Cambridge University Press, 1990.
Serpell, J., ed. The Domestic Dog: Its Evolution, Behaviour and Interaction with People. Cambridge: Cambridge University Press, 1995.
Periodicals:Bradley, D. G. "Genetic Hoofprints." Natural History (February 2003): 36–41.
Diamond, J. "Evolution, Consequences and Future of Plant and Animal Domestication."Nature 418 (2002): 700–707.
Grikson, C. "An African Origin of African Cattle? Some Archaeological Evidence." The African Archaeological Review 9 (1992): 119–144.
[Article by: Alena Cervená, PhD]
