Mammals and Humans: Domestication and Commensals
Mammals and Humans: Domestication and Commensals
Mammals and humans: Domestication and commensals
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.
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.
One of the first signs of domestication is variability of color. The individuals all have white spots or all white or all black. It is interesting that white coloring is usually connected with lower performance (there are few white racing horses and even fewer winners) or with different defects (white noble cats have a high incidence of deafness).
Changes in hair and feathers
The quality of hair also markedly changes with domestication—the difference between guard hair and undergrowth vanishes. Long, wavy, or curly hair appears (sheep, donkey, horse, rabbit, cat, pig, goat, dog) or conversely the individuals lose hair (dog, cat). In horses, the hair of the tail and mane became visibly longer—wild horses have a short standing mane, and domestic horses have a mane that falls down to the neck.
Changes in the size and proportions of the body
Dwarf and giant forms have developed as a result of domestication. In the early phases of domestication the overall size of the body decreased (cattle, goat, sheep). This change is attributed to premeditated selection (easier control and housing of smaller individuals) combined with inadequate food. Extra long ears also appeared (dog, sheep, pig, cattle, cat, rabbit), curled tails (dog, pig), or very short tails (dog, cat, sheep). Horns also became variable in size and curvature, totally disappearing in some species (cattle, sheep, goat).
Changes in the skeleton and internal organs
Striking changes occurred in the skull; for example, there was a shortening of the snout and jaws and at the same time a reduction of the number of teeth (dog, cat, cattle, pig). The shortened snout and accentuated rounded eyes induced the juvenile appearance of the "eternal cub." It also resulted in lower brainpower and smaller brain volume. The skeleton became less resistant than that of wild animals as a consequence of the "comfortable life" with its lack of movement. For the same reasons, the size of some of the physical organs decreased, for example, the heart (35% lower by weight in the domestic rabbit when compared to its wild ancestor). Of course there are exceptions. The English thoroughbred, trained for several centuries for racing, has a heart about one fifth heavier than that of other horses of the same size. The fat storage mechanism has also been modified by domestication. In wild animals, fat is stored in the surroundings of the internal organs and under the skin, while in domestic animals it is stored among muscle filaments and around the tail, especially by pigs or sheep.
There have been changes in the reproduction cycle, prolonged lactation (cattle, sheep, goats), and more numerous litters or eggs. Domestic animals reproduce themselves practically throughout the whole year, and sexual adolescence starts earlier that it does in wild animals.
Domesticated animals lost shyness and many of them lost totally the ability to survive in the wilderness (sheep). Some instincts have changed or totally vanished and the rhythm of given activities has completely changed. For example, some dusk animals and night animals have become strictly day animals (pig) while some changed from monogamous to polygamous (goose). Many domestic offspring are not taught behavior because they are quickly weaned from their parents,
if they come in contact with them at all. They are denied the learning that parents teach their offspring in the wild.
What is the breed?
The basic category of domestic animals is the species, as is the case with wild animals. The species of domestic animals are differentiated into breeds, while that of wild animals are differentiated into subspecies. A breed is defined as a group of animals that has been selected by humans to possess a uniform appearance that is inheritable and distinguishes it from other groups of animals within the same species. Domestication and selective breeding have changed some species of domestic animals (camel, reindeer) very little. But in others, including the oldest and the most important species of domestic animals, tens and hundreds of breeds have been developed; compare for example the pocket-sized Chihuahua with the huge mastiff or Saint Bernard dog. Some specialized breeds are not able to carry out an independent existence. Others become wild without any problem and are able to set up feral populations under suitable conditions. People used artificial selection from the early days of breeding even though they did not know the rules of heredity and the selection of features was varied. For example, European cattle were bred to increase milk and meat production and working capacity, while African pastoralists preferred to increase the size of horns.
Enormous numbers of different breeds have developed during many millenia, most very well acclimatized to local conditions. It is estimated that 5,000–6,000 breeds exist today. Four thousand belong to the so-called "big nine" (cattle, horse, donkey, pig, sheep, goat, buffalo, domestic fowl, duck). However, the trend has moved to renewed selection efforts during the latest decades, for example, the present specialized daily milk production capacity of a Holstein Friesian averages 10.6 gal (40 l) of milk compared to the African N'Dama, produces 1.1 gal (4 l). These highly productive but very vulnerable breeds are now found all over the world, and in many places they have totally replaced the original breeds or have been crossbred with them. In this way, the original breeds disappear, and with them go extremly important genetic variations. In 1993, the Food and Agriculture Organization (FAO), started a project called Global Strategy for the Management of Farm Animal Genetic Resources, which is responsible for the preservation of livestock of no economic value. The categories "extinct" or "critically threatened breed" have been introduced, as has been done for wild animals.
Disadvantages of domestication
The number of domestic animals greatly exceed the number of wild or related species. In some cases, their wild ancestors have been completely exterminated. The breeding of domestic animals has provided people with many indisputable advantages, but it has its downside. The grazing of large livestock herds diminishes food and water resources of local wild
animals in Africa and leads to the total devastation of the landscape. Bison almost became extinct because pasture lands were required for domestic cattle in North America. Large areas of rainforest in South America are being converted to pasture for cattle today, presenting conservation difficulties. Herds of sheep and goats completely devastated large areas of Mediterranean and central Asia. The infestation by domestic rabbits nearly devastated the breeding of sheep, another domesticated animal, in more than half of the Australian continent. Enormous ecological damage was committed by wild populations of goats and pigs that were abandoned by sailors in many Mediterranean islands. Together with feral dogs and cats they liquidated enormous amounts of local fauna and flora. They are responsible for more than a quarter of extinct species and subspecies of vertebrates. Feral goats present a similar problem on a number of the Galápagos Islands, threatening the wildlife there.
Domestic horse (Equus caballus f. caballus)
The horse was the last of the five most common livestock animals to be domesticated. After a short period when it was used only as a source of meat, it became established as a perfect means of transport until the recent past.
The history of the wild horse in Europe and Asia from the end of the Pleistocene until its domestication in perhaps 4000 to 3000 b.c. is poorly understood. According to prevailing opinion, wild horses during the domestication belonged to two species. These were the Przewalski horse (E. przewalskii) from semidesertic central Asia and the tarpan horse (E. caballus, syn. E. ferus) with two subspecies, the forest tarpan (E. c. silvestris) and the steppe tarpan (E. c. ferus), which lived in an area ranging from western Europe to the Ukrainian steppes. The two species are the only ancestors of all recent breeds of domestic horse. The last tarpan was exterminated in 1879 in the Ukraine and the Przewalski horse was no longer found in the wild as of 1960, surviving only in zoos. However, its breeding is so successful now that the process of its reintroduction has started in Mongolia.
It is assumed that the area of steppes between the Dnieper and the Volga Rivers is the oldest domesticating center for horses. The region was populated by a culture called the Sredni Stog in the years 4000 to 3400 b.c. The horses were bred doubtless not only for meat but also for riding. It is also assumed that, in the same period, horses were domesticated by other people who lived in the steppe corridor of Eurasia from southeast Europe to Mongolia. From the second millenium b.c., the combative tribes of nomadic Skyt, Kimmer, Hun, and Mongol started out from Asian steppes in regular intervals on the backs of their hardy and tough ponies to the west, east, and south and, until the fifteenth century, propagated not only terror and dread but also the fame and genes of their horses. In ancient civilizations, horses were first considered "luxury goods." However, they spread very quickly and at the turning point of the second and first millenium b.c. they we're a common phenomenon. During the first millenium b.c., horses were also commonly used for farming, transportation, and sport.
After almost 6,000 years of human service, the appearance and many features of the horse have changed, though less than that of other domestic animals. The first primitive horse breeds developed naturally with the influence of different climate, food, and prevailing working usage. Today there are more than 200 breeds of horses, in a range of different sizes. The smallest horse is the Falabella, at 28 in. (71 cm) high and with a weight of 44 lb (20 kg), and the largest is the Percheron, which is 6 ft (1.8 m) and 2,600 lb (1,180 kg). All the breeds have unique performance, working abilities, and stamina. In the sixteenth century, horses went back to the American continent, where they had lived more than 10,000 years ago. Most of them ran wild and constituted large feral populations of mustangs (North America) and cimmarons (South America). Correspondingly, the same situation occurred later in Australia, where feral brumbies live today.
Domestic donkey (Equus africanus f. asinus)
It is said that the donkey is the horse of the "poor people" and undeservingly it remains in the shadow of its more famous relatives. It is not actually headstrong, dumb, and lazy. It has only a more evolved instinct of self-preservation, which allows it to preserve itself from human service. The donkey does not as a rule bond emotionally to humans as horses do. If it has good treatment and a warm stable, it is a priceless helper, especially in stony terrain. It does not mind hot weather or miserable food, it hates only dirty water and rainy weather.
The domestic donkey is the descendant of two subspecies of the African ass. The Nubian wild ass (E. a. africanus) was domesticated in 5000 b.c. in the Nile Valley and in the area of Libya, today it is assumed extinct. The second subspecies is the Somali wild ass (E. a. somaliensis). It was also domesticated in the area around the Persian Gulf, and is today nearly extinct. The descendants of both subspecies crossbred and quickly spread, thanks to military expeditions and lively mercantile bustle, through Palestine to western Asia and farther to the east through Morroco to the Pyrenean Peninsula, where they arrived in the second millenium b.c. It is known that during the first millenium, the Celts were breeding donkeys. The Asiatic ass (Equus hemionus) was for some time an object of interest but domestication did not succeed due to its uncontrollable nature.
Donkey breeds have never reached the number of varieties that horse breeds have. They differ in height (from 2 to 5 ft[0.6–1.5 m]), in weight (175 lb–990 lb [80–450 kg]), in color, and in the quality of hair. The donkey is still a common component of country life in the Mediterranean, the Balkans, south Asia, South America, and other subtropical and tropical areas. Feral donkey populations live for many generations in the southwest United States and in Australia.
Humans have used horses and donkeys to breed hybrid species. The most famous is the mule, the offspring of a female horse (mare) and a male donkey (jackass). A second hybrid is less known, the dunce hinny, whose parents are a female donkey (jenny) and a male horse (stallion). Hybrids inherit more traits from the mother. Another interesting interspecies hybrid is the zebroid. It is the offspring of some zebra species and a horse, or rarely a donkey.
Cattle (Bos primigenius f. taurus)
Cattle are the oldest domestic animals. Their importance lies in giving meat, milk, and working power. Leather, fat, hooves, and horns are also valuable, and dried excrements are used as fuel, building material, and fertilizer. Cattle were first used as draft and riding animals, allowing people to drastically change their way of life. Some African people, for example the Hottentots, use them for riding even today. Cattle are the main source of meat and milk and the second most numerous domestic animal in the world, after domestic fowl. Under the cattle category, we can include the descendants of the aurochs, and those of other domestic cattle such as the yak, gayal, Bali cattle, and buffalo. They come from areas with extreme climatic conditions (high in the mountains or from the tropics), where they are used as domestic cattle. The kouprey (Bos sauveli) from the forests of Cambodia occupies a special place among cattle, for it may be the last surviving form of the wild ox, which went through an early form of domestication and then ran wild again.
The aurochs (Bos primigenius) was a progenitor of domestic cattle. It occupied the forests of the whole temperate zone of the Old World from Europe to north Africa and west Asia to the China Sea at the end of the last glacial period. In this large area, it developed more subspecies. The wild ox had survived almost until the end of that glacial period in Asia and north Africa, and in the middle and west European forests, until the end of the Middle Ages. The last individual became extinct in Poland in 1627. The domestication of the wild ox
began in 7000 b.c. and it is assumed that it started almost at the same time in several places—Greece, Macedonia, the Fertile Crescent (Mesopotamia, Egypt, Persia), and later (5000 b.c.) in the Indus Valley. It is possible (according to new genetic research) that an independent domestic center existed also in north Africa and could even be the oldest.
Why did people try to domesticate such massive and dangerous animals? They already bred sheep and goats at that time, which were sufficient as a source of food. It is possible that at first there were religious reasons. Wild cattle symbolized fertility and power for many cultures and they were significant sacrificial animals. Cattle derived from aurochs include some 450 breeds today and are divided into two basic groups. One is humpless cattle, which are the European descendants of the aurochs (B. p. primigenius, syn. Bos taurus). The second group includes cattle with a hump (zebu) whose progenitor is assumed to be the Indian subspecies of the aurochs (B. p. namadicus, syn. B. indicus).
The oldest known bone findings, which confirm the existence of humped zebu (thorny projections of neck vertebrae distinctly bifurcated) are almost 6,000 years old and come from Iraq. However, the domestication of the zebu probably occurred in the Indus Valley. The zebu adapted to subtropical and tropical climates and became resistant to tropical diseases. After domestication, it spread quickly to Malaysia, Indonesia, and China and to the west to Africa. Today it is one of the most plentiful cattle in the African tropics and subtropics and in the Indian subcontinent.
Domestic yak (Bos mutus f. grunniens)
The yak was domesticated in Tibet from 3000 to 1000 b.c., and its progenitor is the wild yak (Bos mutus). It is almost one
third smaller than its wild progenitor and it has markedly weaker horns or no horns. It moves without any problems at altitudes of 9,800–19,500 ft (2,990–5,940 m). It is an indispensible helper for the mountain inhabitants and the basic source of livelihood. The yak provides milk, meat, and wool. Dried excrement is used as fuel. The yak is a great working animal. It bears around 330 lb (150 kg) very easily, it serves as a riding and draft animal, and is used for plowing. Twelve million yaks live in the mountains areas of Tibet, China, Nepal, Mongolia, and southern Siberia. It is bred to a small extent in North America and in the Swiss Alps.
Gayal (Bos gaurus f. frontalis)
The gayal or mithan is the domesticated form of the wild gaur (B. gaurus). For a long time, it was not clear if the gayal and gaur were the same separated species or if the gayal had developed by crossbreeding of a gaur with bantengs or zebu. The gayal is noticeably smaller than the gaur, it has shorter conical horns, a markedly shorter skull, and a wider and flatter forehead. It has a large double dewlap on the chin and neck. It is most commonly brown and black but can also be spotted or white. The gayal is not a typical domestic animal; it usually lives in small groups in the jungle at the periphery of a village and comes back to the village only towards evening, lured by salt. The economic use of the gayal is insignificant. Sometimes is it used for field work or for its meat; its milk is not drinkable. The gayal was used by many people as a sacrificial animal or as currency. Sometimes the animals escape and run wild, but the domestication influence is still seen in their calm temperament. Feral populations live in northern India.
Bali cattle (Bos javanicus f. domestica)
Bali cattle is the domestic form of wild banteng (B. javanicus), which lives in the forests of Java, Borneo, Malaysia, and Thailand today. Its domestication took place in Java around 1000 b.c. Wild bantengs were caught and tamed in the Middle Ages, in Bali, Sumatra, and Java until the eighteenth century. Bali cattle are smaller than banteng, the horns lack the characteristic curvature, and the skull is smaller. The external sexual signs are weaker than in the wild species. The domestic species grows more rapidly and matures earlier. Elegant Bali cattle have adapted to life in tropics better than the zebu. It was never bred for a specific purpose and because of that it has no major economic value. Approximately1.5 million individuals are bred today. It is used as other domestic cattle for field work and riding. Milk utility is low but meat has excellent quality and taste. Bali cattle are crossbred with the taurine cattle, and with the zebu, but male descendants are infertile. Bali cattle often run wild, and feral populations live in savanna in the south of Sulawesi and in Australia.
Sheep (Ovis ammon f. aries)
Sheep and goats are assumed to be the oldest domestic livestock. Sheep are bred in different areas around the world from lowlands to mountains and from tropics to cold north moorlands. They are exceptionally acclimatized to extreme conditions. They are also very useful, providing meat, milk, tallow, wool, fur, leather, horn, lanolin, dung, and they carry loads in Tibet. No culture or religion forbids killing sheep or eating sheep meat.
The exact origin of the domestic sheep is not clear because all wild sheep in the genus Ovis are fertile when bred together and zoologists still do not agree about their taxonomy. Two groups of wild sheep are considered as having first undergone domestication. They differ in the size of the body and in their habitats. The arkhar or argali sheep (O. ammon) is the representative of the "mountain" group. It has six subspecies and it lives in central Asia in altitudes ranging from 16,500 to 19,500 ft (5,030–5,940 m). The Asiatic mouflon (O. orientalis) and the urial sheep (O. vignei) are members of the "steppe" group of wild sheep. They also have several subspecies and live in lower regions from west Asia to northwest India. The European mouflon (O. musimon syn. O. ammon musimon) is a special case. It comes from Corsica and Sardinia and it was assumed to be the progenitor of domestic sheep for a long time. However it is itself a feral form of the early Neolithic domestic sheep, which came with humans to Corsica 9,000 years ago. The question of domestic sheep progenitors is still debated. With certainty we can eliminate only the species that were not domesticated. These are the American bighorn sheep (O. canadensis), Dall's sheep (O. dalli), and the Siberian snow sheep (O. nivicola), which were not "in the right place at the right time." All other species are good candidates.
Almost 14,000-year-old paintings from the La Pileta cave in Spain show sheep and goats in a corral. It takes a long time for wild sheep, which were kept in simple corrals, to become truly domestic animals. The oldest findings of domestic sheep come from the north Iran mountains (Zawi Chemi Shanidar) and date from 9000 b.c. However, there were certainly more areas of domestication in western Asia at that time. In 4000 b.c., domestic sheep were bred throughout the civilized world. At first they gave only meat, milk, and leather, and only later did wool sheep appear, though only with short and rough wool (in Mesopotamia around 3000 b.c.). In the first millenium, sheep spread all over Europe, Africa (except in primeval forest areas), and Asia (to Sulawesi). At that time sheep with white, longer wool were common, with four horns or without horns (known from ancient Egyptian frescos). Sheep from antique Greece and Rome resembled modern breeds. The number of sheep breeds today ranges between 550 to 630. They are categorized according to wool type, tail length, fat deposits, or utility. There are no existing feral sheep populations except that of the European mouflon and the Soay sheep.
Goat (Capra aegagrus f. hircus)
Goats live throughout the world but they flourish in humid tropical forest areas. Their number is still increasing, especially in the desert and the semi-desert areas where it is not possible to keep other domestic animals. Goats give meat, milk, leather, hair, wool, horn, and dung and have very low food requirements.
The domestic goat progenitor is the bezoar goat (C. aegagrus), which lived in western and central Asia. According to radiocarbon dating, the sheep was domesticated first but goats were more numerous than sheep in the early domestic period. The oldest domestic center of both species was Sierra Zagros at the border of Iraq and Iran. Determination of whether remains belong to wild or domestic goats is possible according to horn shape. Archaeologic findings show that the originally scimitar horns of wild goats changed during several hundred years (8000 to 7000 b.c.) to the twisted horns of domestic goats. We do not know why people preferred these animals with twisted horns or if the horn shape related to the behavior of goats, or their productivity.
The domestic goat quickly spread to all inhabited areas of Europe, Asia (to Sulawesi), and Africa. It preserved its animation, shrewdness, and obstinacy from its progenitors, which passes for happy malevolence. There are many feral domestic goat populations, for example, in New Zealand, in Australia, and unfortunately in the Galápagos and other islands where they cause severe ecological problems. There are now some 200 to 350 goat breeds.
Pig (Sus scrofa f. domestica)
The domestic pig was likely domesticated after cattle. It is omnivorous (as humans are), and is exceedingly intelligent. The number of domestic pigs is estimated at nearly 913 million worldwide. The only places they are not bred are in unsuitable climate areas (tropics, polar areas) and in Israel and Islamic countries, where eating pork is forbidden by religion. The pig is bred only for its meat and fat, although leather is a secondary product.
The progenitor of the domestic animal is the wild boar (Sus scrofa), which lived in a large area from western Europe and north Africa to Southeast Asia. A range of subspecies evolved, of which two were domesticated, the European wild boar (S. s. scrofa) and the Asian banded boar (S. s. vittatus). The next two species domesticated in Southeast Asia were the Sulawesi wild boar (S. celebensis) and the Philippine warty pig (S. phiilippensis).
Wild boar domestication dates from 7000 to 6000 b.c. One of the important preconditions of this process was sedentary civilization because, unlike sheep, goats, and cattle, pigs are not able to live a nomadic life. Pig domestication occurred independently in two or maybe more places, partly because of how relatively easy pigs are to tame. The first domestic centers (6500 b.c.) were in western Asia, India, and some islands. From there, domesticated pigs were moved into China, Egypt, and farther into Africa. The second center of domestication from 5000 b.c. lies in northern Europe by the Baltic Sea. The third important area was the Mediterranean.
Domestic pigs came to the New world with European settlers. Sailors also left them on islands. Other feral populations developed in South and Central America, Australia, and New Zealand. As feral goats do, the pigs destroy specialized island fauna and flora.
Camels and llamas
The camel was and is an excellent transport vehicle in desert areas where horses and donkeys cannot survive. In deserts, camels can survive ten times longer than humans and four times longer than donkeys. They provide meat, milk, blood, leather, and hair, and excrements are used as fuel. The wild Bactrian camel (Camelus ferus) is the ancestor of the Bactrian or two-humped camel (C. ferus f. bactrianus). It comes from east and central Asia. The remaining populations live in the periphery of the Gobi Desert. It was domesticated by nomadic tribes, probably in the second or first millenium b.c. in Iran or in the Gobi Desert.
There is no known evidence about the wild progenitor of the dromdary or one-humped camel (Camelus dromedarius). It was proposed that the progenitor could be the extinct Camelus thomasi, which lived in the interface of the Tertiary and Quaternary periods in north Africa and in adjoining areas of Asia. The one-humped camel was probably domesticated in 3000 b.c. in the Arabian Peninsula or in the steppe areas of western Asia. The oldest testimonies of domestic camels come from Egypt and the Sinai, 5,000 years ago. Almost 19 million domestic camels are bred worldwide, of which almost 90% are one-humped camels. They live in desert areas from the western Sahara to India and as feral populations in Australia, where they were introduced one hundred years ago. The twohumped camel is bred in Mongolia, China, Afghanistan, Iran, and Turkey.
Two species of camelids live in South America: the guanaco (Lama guanicoe) from semidesert mountain areas, and the vicuña (Vicugna vicugna) from high mountain areas. Only the guanaco was domesticated, perhaps in 3000 b.c. Its descendants are the llama (Lama guanicoe f. glama) and the alpaca (L. guanicoe f. pacos). The llama has been used as a transport animal, and for meat and wool, and the alpaca primarily for wool.
Reindeer (Rangifer tarandus)
Not much is known about the domestication of the reindeer. It is assumed that it was domesticated at only one place in the Sayan mountains from 3000 to 1000 b.c. Chinese sources from the sixth century describe the reindeer as a domestic animal. The reindeer may have become used to humans when it came to human settlements to lick salt from human urine. It served in place of cattle and horses in harsh northern conditions. Domestic reindeer live in northern Eurasia and Canada. The Canadian caribou (R. tarandus caribou) was never domesticated. Domestic reindeer do not differ from wild reindeer, except that they may vary in size and coloring. Those who keep reindeer must live the nomadic way of life because the reindeer still migrate along ancient paths. The domestic reindeer serves as a riding and draft animal, and provides milk, meat, leather, hair, and antlers.
Dog (Canis lupus f. familiaris)
The dog was the first domestic animal; however, the beginning of its coexistence with humans is still unclear. The wolf (Canis lupus) is the progenitor of all domestic dog breeds and feral populations. Fifteen thousand years ago, the wolf lived in all of Eurasia, in north Africa, and in North and Central America. It evolved into many subspecies, which differ in size and color. The small Indian wolf (C. l. pallipes) and the larger Eurasian wolf (C. l. lupus) are the most likely dog ancestors.
Humans were interacting with wolves in the end of Pleistocene. They were hunting the same type of prey and in the areas where they coexisted, both species got used to each other over thousands of years. Food lured the wolves to human settlements and humans counted on the watchfulness of wolves. Taming an adult wolf is almost impossible, but small cubs are easier to tame. The problem of feeding the cubs was solved very simply: women nursed them. If the cubs were too aggressive, the humans killed them for food. Only submissive individuals were allowed to reach adulthood and reproduce. The ease of this domestication process was confirmed by recent experiments with foxes. Individuals were selected according to their level of aggressiveness. The behavior changed during a mere twenty generations and the white spots and curled tail present in domestic dogs appeared in that time as well.
The skeletal remains of the first domestic dogs come from different places around the world, from Israel, Turkey, Iran, Japan, England, Denmark, Germany, and North America. The oldest findings verifying the existence of the domestic dog is an 11,000-year-old grave, found in northern Israel in the Ein Mallaha settlement. Feral populations of dogs developed in places where wild populations of wolves never lived. The dingo (C. l. dingo) spread in Australia at least 4,000 years ago. The forest dingo (C. l. halstromi) spread over New Guinea and Timor. Feral dog populations exist in many other places all over the world. Around 420 domestic dog breeds are registered but that number may still change.
Domestic cat (Felis silvestris f. catus)
The cat is one of the most recent domestic animals. In spite of its coexistence with humans, it still has an independent nature and the perfect hunting instincts of a solitary hunter. It is highly individualistic and should not have undergone successful domestication at all.
The progenitor of the domestic cat is the African subspecies of wild cat (Felis silvestris lybica). Domestication of the cat occurred in Egypt from 4000 to 2000 b.c. Preserved cat mummies provide dometication evidence. The oldest are of tamed cats from the 4000 b.c. period while mummies from the end of the Middle Kingdom period are of domesticated cats. The domesticated cats have shortened skulls and often irregular denture. The cat likely started its coexistence with humans voluntarily and to the benefit of both sides. Wild cats were drawn together into the Nile Valley because of the number of rodents that accompany human settlements. They quickly became common domesctic animals and they achieved the status of sacred animal of the goddess Bastet. The domestic cat has spread from Egypt throughout the Mediterranean and reached southern Europe in 500 b.c. The cat came to the east with merchants to Turkey, Persia, and along the silk road to China and Southeast Asia. It penetrated Central Europe at the beginning of the Middle Ages. Benedictine monks were the first true cat breeders (they also bred the first rabbits and pigeons in Europe). Feral cat populations exist on many islands and threaten the populations of local insular animals.
Rabbit (Oryctolagus cuniculus f. domesticus)
The rabbit is the "youngest" domestic animal. The wild rabbit (Oryctolagus cuniculus) is the only progenitor of the domestic rabbit. The monks in Benedictine monasteries started its domestication at the beginning of the Middle Ages in the south of France. Rabbit meat was eaten during Lent and so the monks kept the rabbits in closed tiled monastery yards. Rabbit breeding spread from France to England, Belgium, and Holland in the seventeenth and eighteenth centuries and the biggest boom in rabbit breeding began in the nineteenth century. Rabbits were already the source of cheap and readily available meat for a large number of people in Europe. Several hundred breeds exist today because of the rabbit's popularity as a pet, as well as a source of food and other material.
Guinea pig (Cavia aperea f. porcellus)
The guinea pig is one of the few animals domesticated in the New World. It was a sacrificial animal and a pet for the local inhabitants. The wild guinea pig (C. aperea) may be the progenitor but some zoologists think the montane guinea pig (C. tschudii), which lives only in the mountainous areas of Peru, southern Bolivia, northwestern Argentina, and northern China, is the progenitor. The period of its domestication has not been determined exactly, but the remains of domestic guinea pig were discovered in deposits dating back to 3000 b.c. in the Peruvian Andes. The guinea pig became the most popular and the most often bred rodent. It is very easily tamed, almost never bites, and it is able to communicate very well.
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Alena Cervená, PhD