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Domestication (from the Latin domesticus: "of the home") is the cultivating or taming[1] of a population of organisms in order to accentuate traits that are desirable to the cultivator or tamer. The traits that are sought may be for certain physical appearances, behavioral characteristics, individual sizes, litter sizes, hair/fur qualities or colors, rates of growth, or desired changes in fecundity, longevity, ability to use marginal grazing resources, production of by-products, and many others.[2] Domestication can result in dependency on human activity. The organism may lose their ability to survive in the wild.[3] This differs from taming in that a change in the phenotypical expression and genotype of the animal occurs, whereas taming is simply an environmental socialization/behavioral trait; the process by which animals become habituated to human presence.
Plants domesticated primarily for aesthetic enjoyment in and around the home are usually called house plants or ornamentals, while those domesticated for large-scale food production are generally called crops. A distinction can be made between those domesticated plants that have been deliberately altered or selected for special desirable characteristics (see cultigen) and those plants that are used for human benefit, but are essentially no different from the wild populations of the species. Animals domesticated for home companionship are usually called pets, while those domesticated for food or work are called livestock or farm animals. Domestication is the process of changing plants or animals to make them more useful to humans. Domestication of plants led to the development of agriculture. Domestication led to many things such as the use of fibers to make clothes, making food, and the need to stay in one place.
| This section possibly contains original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (December 2014) |
Charles Darwin was the first to describe the connection between domestication, selection and evolution.[4] Darwin described how the process of domestication can involve both unconscious and methodical elements. Routine human interactions with animals and plants create selection pressures that cause adaptation to human presence, use or cultivation. Deliberate selective breeding has also been used to create desired changes, often after initial domestication. These two forces, unconscious natural selection and methodical selective breeding, may have both played roles in the processes of domestication throughout history.[2] Both have been described from human perspective as processes of artificial selection.[citation needed]
The domestication of wheat provides an example. Wild wheat falls to the ground to reseed itself when ripe, but domesticated wheat stays on the stem for easier harvesting. There is evidence that this change was possible because of a random mutation that happened in the wild populations at the beginning of wheat's cultivation. Wheat with this mutation was harvested more frequently and became the seed for the next crop. Therefore, without realizing, early farmers selected for this mutation, which may otherwise have died out. The result is domesticated wheat, which relies on farmers for its own reproduction and dissemination.[5]
The domestication of dogs provides another example. It is speculated that tamer than average wolves, less wary of humans, selected themselves as dogs over many generations. These wolves were able to thrive by following humans to scavenge for food near camp fires and garbage dumps, which gave them an advantage over more shy individuals. Eventually a symbiotic relationship developed between people and these proto-dogs. The dogs fed on human food scraps, and humans found that dogs could warn them of approaching dangers, help with hunting, act as pets, provide warmth, or supplement their food supply. As this relationship progressed, humans eventually began to keep these self-tamed wolves and breed from them the types of dogs that we have today.
In recent times, selective breeding may best explain how continuing processes of domestication often work. Some of the best-known evidence of the power of selective breeding comes from the Farm-Fox Experiment by Russian scientist, Dmitri K. Belyaev, in the 1950s. His team spent many years breeding the domesticated silver fox (Vulpes vulpes) and selecting only those individuals that showed the least fear of humans. Eventually, Belyaev's team selected only those that showed the most positive response to humans. He ended up with a population of grey-coloured foxes whose behavior and appearance was significantly changed. They no longer showed any fear of humans and often wagged their tails and licked their human caretakers to show affection. These foxes had floppy ears, smaller skulls, rolled tails and other traits commonly found in dogs.[6]
Despite the success of this experiment, it appears that selective breeding cannot always achieve domestication. Attempts to domesticate many kinds of wild animals have been unsuccessful. The zebra is one example. Despite the fact that four species of zebra can interbreed with and are part of the same genus as the horse and the donkey, attempts at domestication have failed.[7] Factors such as temperament, social structure and ability to breed in captivity play a role in determining whether a species can be successfully domesticated.[2] In human history to date, only a few species of large animal have been domesticated. In approximate order of their earliest domestication these are: dog, sheep, goat, pig, ox, yak,[8] reindeer,[9] water buffalo, horse, donkey, llama, alpaca, Bactrian camel and Arabian camel.[10]
According to evolutionary biologist Jared Diamond, animal species must meet six criteria in order to be considered for domestication:[11]
However, this list is of limited use because it fails to take into account the profound changes that domestication has on a species. While it is true that some animals retain their wild instincts even if born in captivity, e.g. laying hens,[12] pigs[13] and laboratory mice,[14] some factors must be taken into consideration.
Number (5) may not be a prerequisite for domestication, but rather a natural consequence of a species' having been domesticated. In other words, wild animals are naturally timid and flighty because they are constantly faced by predators; domestic animals do not need such a nervous disposition, as they are protected by their human owners. The same holds true for number (4) – aggressive temperament is an adaptation to the danger from predators. A Cape buffalo can kill even an attacking lion, but most modern large domestic animals were descendants of aggressive ancestors. The wild boar, ancestor of the domestic pig, is certainly renowned for its ferocity; other examples include the aurochs (ancestor of modern cattle), horse, Bactrian camels and yaks, all of which are no less dangerous than their undomesticated wild relatives such as zebras and buffalos. Others have argued that the difference lies in the ease with which breeding can improve the disposition of wild animals, a view supported by the failure to domesticate the kiang and onager. On the other hand for thousands of years humans have managed to tame dangerous species like bears and cheetahs[citation needed] whose failed domestications had little to do with their aggressiveness.
Number (6), while it does apply to most domesticated species, also has exceptions, most notably in the domestic cat and ferret, which are both descended from strictly solitary wild ancestors but which tolerate and even seek out social interaction in their domestic forms. Feral domestic cats, for example, naturally form colonies around concentrated food sources and will even share prey and rear kittens communally, while wildcats remain solitary even in the presence of such food sources.[15] Zoologist Marston Bates devoted a chapter on domestication in his 1960 book The Forest and the Sea, in which he talks a great deal about how domestication alters a species: Dispersal mechanisms tend to disappear for the reason stated above, and also because people provide transportation for them. Chickens have practically lost their ability to fly. Similarly, domestic animals cease to have a definite mating season, and so the need to be territorial when mating loses its value; and if some of the males in a herd are castrated, the problem is reduced even further. What he says suggests that the process of domestication can itself make a creature domesticable. Besides, the first steps towards agriculture may have involved hunters keeping young animals, who are always more impressionable than the adults, after killing their mothers.
Another strong factor deciding whether a species will be considered for domestication is quite simply the availability of more suitable (or even better already domesticated) alternatives. For example a community that had been introduced to domestication by neighboring peoples will generally find it much more practical, economical and time saving to import already domesticated species than experiment with wild animals (even if they are of the same species). Generally speaking, the species of animals originally domesticated by early humans in the interconnected landmasses of Eurasia and Africa were far superior, both in working capacity and in food production, than the species found in the other continents, namely the Americas and Oceania.
The earliest human attempts at plant domestication occurred in South-Western Asia. There is early evidence for conscious cultivation and trait selection of plants by pre-Neolithic groups in Syria: grains of rye with domestic traits have been recovered from Epi-Palaeolithic (c. 11,050 BCE) contexts at Abu Hureyra in Syria,[16] but this appears to be a localised phenomenon resulting from cultivation of stands of wild rye, rather than a definitive step towards domestication.[citation needed]
By 10,000 BCE the bottle gourd (Lagenaria siceraria) plant, used as a container before the advent of ceramic technology, appears to have been domesticated. The domesticated bottle gourd reached the Americas from Asia by 8000 BCE, most likely due to the migration of peoples from Asia to America.[17]
Cereal crops were first domesticated around 9000 BCE in the Fertile Crescent in the Middle East. The first domesticated crops were generally annuals with large seeds or fruits. These included pulses such as peas and grains such as wheat.[citation needed]
The Middle East was especially suited to these species; the dry-summer climate was conducive to the evolution of large-seeded annual plants, and the variety of elevations led to a great variety of species. As domestication took place humans began to move from a hunter-gatherer society to a settled agricultural society. This change would eventually lead, some 4000 to 5000 years later, to the first city states and eventually the rise of civilization itself.[citation needed]
Continued domestication was gradual, a process of trial and error that occurred intermittently. Over time perennials and small trees began to be domesticated including apples and olives. Some plants were not domesticated until recently such as the macadamia nut and the pecan.[citation needed]
In other parts of the world very different species were domesticated. In the Americas squash, maize, beans, and perhaps manioc (also known as cassava) formed the core of the diet. In East Asia millet, rice, and soy were the most important crops. Some areas of the world such as Southern Africa, Australia, California and southern South America never saw local species domesticated.[citation needed]
Domesticated plants often differ from their wild relatives which they[18]
The boundaries between surviving wild populations and domestic clades can be vague. A classification system that can help solve this confusion surrounding animal populations might be set up on a spectrum of increasing domestication:[citation needed]
This classification system does not account for several complicating factors: genetically modified organisms, feral populations, and hybridization. Many species that are farmed or ranched are now being genetically modified. This creates a unique category because it alters the organisms as a group but in ways unlike traditional domestication. Feral organisms are members of a population that was once raised under human control, but is now living and multiplying outside of human control. Examples include mustangs. Hybrids can be wild, domesticated, or both: a liger is a hybrid of two wild animals, a mule is a hybrid of two domesticated animals, and a beefalo is a cross between a wild and a domestic animal.[citation needed]
A great difference exists between a tame animal and a domesticated animal. The term "domesticated" refers to an entire species or variety while the term "tame" can refer to just one individual within a species or variety. Humans have tamed many thousands of animals that have never been truly domesticated. These include the elephant, giraffes, and bears and cats. There is debate over whether some species have been domesticated or just tamed. Some state that the elephant has been domesticated, while others argue that the cat has never been domesticated. Dividing lines include whether a specimen born to wild parents would differ in appearance or behavior from one born to domesticated parents. For instance a dog is certainly domesticated because even a wolf (which genetically shares a common ancestor with all dogs) raised from a pup would be very different from a dog, in both appearance and behaviour.[19] Similar problems of definition arise when domesticated cats go feral.
Many other languages, such as Spanish, use the same word for both concepts.
Selection of animals for visible "desirable" traits may make them unfit in other, unseen, ways. The consequences for the captive and domesticated animals were reduction in size, piebald color, shorter faces with smaller and fewer teeth, diminished horns, weak muscle ridges, and less genetic variability. Poor joint definition, late fusion of the limb bone epiphyses with the diaphyses, hair changes, greater fat accumulation, smaller brains, simplified behavior patterns, extended immaturity, and more pathology are a few of the defects of domestic animals. All of these changes have been documented in direct observations of the rat in the 19th century, by archaeological evidence, and confirmed by animal breeders in the 20th century.[20] A 2014 commentary published in Genetics proposed that many of these features may arise due to mild neural crest deficits that also cause tameness; hence, selectively breeding tame animals also selects for these negative traits.[21]
One side effect of domestication has been zoonotic diseases. For example, cattle have given humanity various viral poxes, measles, and tuberculosis; pigs and ducks have given influenza; and horses have given the rhinoviruses. Humans share over sixty diseases with dogs[citation needed]. Many parasites also have their origins in domestic animals.[2] The advent of domestication resulted in denser human populations which provided ripe conditions for pathogens to reproduce, mutate, spread, and eventually find a new host in humans.[citation needed]
Other negative aspects of domestication have been explored. For example, Paul Shepherd writes "Man substitutes controlled breeding for natural selection; animals are selected for special traits like milk production of passivity, at the expense of overall fitness and naturewide relationships...Though domestication broadens the diversity of forms – that is, increases visible polymorphism – it undermines the crisp demarcations that separate wild species and cripples our recognition of the species as a group. Knowing only domestic animals dulls our understanding of the way in which unity and discontinuity occur as patterns in nature, and substitutes an attention to individuals and breeds. The wide variety of size, color, shape, and form of domestic horses, for example, blurs the distinction among different species of Equus that once were constant and meaningful."[22]
Going further, some anarcho-primitivist authors describe domestication as the process by which previously nomadic human populations shifted towards a sedentary or settled existence through agriculture and animal husbandry. They claim that this kind of domestication demands a totalitarian relationship with both the land and the plants and animals being domesticated. They say that whereas, in a state of wildness, all life shares and competes for resources, domestication destroys this balance. Domesticated landscape (e.g. pastoral lands/agricultural fields and, to a lesser degree, horticulture and gardening) ends the open sharing of resources; where "this was everyone's," it is now "mine." Anarcho-primitivists state that this notion of ownership laid the foundation for social hierarchy as property and power emerged. It also involved the destruction, enslavement, or assimilation of other groups of early people who did not make such a transition.[23]
To primitivists, domestication enslaves both the domesticated species as well as the domesticators. Advances in the fields of psychology, anthropology, and sociology allows humans to quantify and objectify themselves, until they too become commodities.[24]
Since the process of domestication inherently takes many generations over a long period of time, and the spread of breed and husbandry techniques is also slow, it is not meaningful to give a single "date of domestication". However, it is believed that the first attempt at domestication of both animals and plants were made in the Old World by peoples of the Mesolithic Period. The tribes that took part in hunting and gathering wild edible plants, started to make attempts to domesticate dogs, goats, and possibly sheep, which was as early as 9000 BC. However, it was not until the Neolithic Period that primitive agriculture appeared as a form of social activity, and domestication was well under way. The great majority of domesticated animals and plants that still serve humans were selected and developed during the Neolithic Period, a few other examples appeared later. The rabbit for example, was not domesticated until the Middle Ages, while the sugar beet came under cultivation as a sugar-yielding agricultural plant in the 19th century. As recently as the 20th century, mint became an object of agricultural production, and animal breeding programs to produce high-quality fur were started in the same time period.[25]
The methods available to estimate domestication dates introduce further uncertainty, especially when domestication has occurred in the distant past. So the dates given here should be treated with caution; in some cases evidence is scanty and future discoveries may alter the dating significantly.[citation needed]
Dates and places of domestication are mainly estimated by archaeological methods, more precisely archaeozoology. These methods consist of excavating or studying the results of excavation in human prehistorical occupation sites. Animal remains are dated with archaeological methods, the species they belong to is determined, the age at death is also estimated, and if possible the form they had, that is to say a possible domestic form. Various other clues are taken advantage of, such as slaughter or cutting marks. The aim is to determine if they are game or raised animal, and more globally the nature of their relationship with humans. For example the skeleton of a cat found buried close to humans is a clue that it may have been a pet cat. The age structure of animal remains can also be a clue of husbandry, in which animals were killed at the optimal age.[citation needed]
New technologies and especially mitochondrial DNA, which are simple DNA found in the mitochondria that determine its function in the cell provide an alternative angle of investigation, and make it possible to reestimate the dates of domestication based on research into the genealogical tree of modern domestic animals.[citation needed]
It is admitted for several species that domestication occurred in several places distinctly. For example, research on mitochondrial DNA of the modern cattle Bos taurus supports the archaeological assertions of separate domestication events in Asia and Africa. This research also shows that Bos taurus and Bos indicus haplotypes are all descendants of the extinct wild ox Bos primigenius.[26][27] However, this does not rule out later crossing inside a species; therefore it appears useless to look for a separate wild ancestor for each domestic breed.
The dog was the first domesticated animal dating 18,000-32,000 years ago, which supports the hypothesis that dog domestication preceded the emergence of agriculture and occurred in the context of European hunter-gatherer cultures.[28] This preceded the domestication of other species by several millennia. In the Neolithic a number of important species such as goats, sheep, pigs and cattle were domesticated, as part of the spread of farming which characterises this period. The goat, sheep and pig in particular were domesticated independently in the Levant and Asia.[citation needed]
There is early evidence of beekeeping, in the form of rock paintings, dating to 13,000 BC.[citation needed]
Recent archaeological evidence from Cyprus indicates domestication of a type of cat by perhaps 9500 BC.[29][30][31]
The earliest secure evidence of horse domestication, bit wear on horse molars at Dereivka in Ukraine, dates to around 4000 BC. The unequivocal date of domestication and use as a means of transport is at the Sintashta chariot burials in the southern Urals, c. 2000 BC. Local equivalents and smaller species were domesticated from the 26th century BC.[citation needed]
The availability of both domesticated vegetable and animal species increased suddenly following the voyages of Christopher Columbus and the contact between the Eastern and Western Hemispheres. This is part of what is referred to as the Columbian Exchange.[citation needed]
| Species | Date | Location |
|---|---|---|
| Dog (Canis lupus familiaris) | prior to 33000 BCE[28][32][33] | Western Europe |
| Sheep (Ovis orientalis aries) | between 11000 BCE and 9000 BCE[34][35] | Southwest Asia |
| Pig (Sus scrofa domestica) | 9000 BCE[36][unreliable source?][37] | Near East, China, Germany |
| Goat (Capra aegagrus hircus) | 8000 BCE[38][unreliable source?] | Iran |
| Cow (Bos primigenius taurus) | 8000 BCE[39][dead link] | India, Middle East, and North Africa |
| Cat (Felis catus) | 7500 BCE[29][30][31][40] | Cyprus and Near East |
| Chicken (Gallus gallus domesticus) | 6000 BCE[41][dead link] | India and Southeast Asia |
| Guinea pig (Cavia porcellus) | 5000 BCE[42] | Peru |
| Donkey (Equus africanus asinus) | 5000 BCE[43][44] | Egypt |
| Domesticated duck (Anas platyrhynchos domesticus) | 4000 BCE | China |
| Water buffalo (Bubalus bubalis) | 4000 BCE | India, China |
| Horse (Equus ferus caballus) | 4000 BCE[45][dead link] | Eurasian Steppes |
| Dromedary (Camelus dromedarius) | 4000 BCE | Arabia |
| Llama (Lama glama) | 6000 BCE | Peru |
| Silkworm (Bombyx mori) | 3000 BCE | China |
| Reindeer (Rangifer tarandus) | 3000 BCE[46] | Russia |
| Rock pigeon (Columba livia) | 3000 BCE | Mediterranean Basin |
| Goose (Anser anser domesticus) | 3000 BCE[47] | Egypt |
| Bactrian camel (Camelus bactrianus) | 2500 BCE | Central Asia |
| Yak (Bos grunniens) | 2500 BCE | Tibet |
| Banteng (Bos javanicus) | Unknown | Southeast Asia |
| Gayal (Bos gaurus frontalis) | Unknown | Southeast Asia |
| Alpaca (Vicugna pacos) | 1500 BCE | Peru |
| Ferret (Mustela putorius furo) | 1500 BCE | Europe |
| Muscovy Duck (Cairina momelanotus) | Unknown | South America |
| Guineafowl | Unknown | Africa |
| Common carp (Cyprinus carpio) | Unknown | East Asia |
| Domesticated turkey (Meleagris gallopavo) | 500 BCE | Mexico |
| Goldfish (Carassius auratus auratus) | Unknown | China |
| European Rabbit (Oryctolagus cuniculus) | CE 600 | Europe |
Second circle[clarification needed]
| Species | Date | Location |
|---|---|---|
| Zebu (Bos primigenius indicus) | 8000 BCE | India |
| Honey bee | 4000 BCE | Multiple places |
| Asian Elephant (Elephas maximus) (endangered) | 2000 BCE | Indus Valley civilization |
| Fallow Deer (Dama dama) | 1000 BCE | Mediterranean Basin |
| Indian Peafowl (Pavo cristatus) | 500 BCE | India |
| Barbary Dove (Streptopelia risoria) | 500 BCE | North Africa |
| Japanese Quail (Coturnix japonica) | 1100–1900 | Japan |
| Mandarin Duck (Aix galericulata) | Unknown | China |
| Mute Swan (Cygnus olor) | 1000–1500 | Europe |
| Canary (Serinus canaria domestica) | 1600 | Canary Islands, Europe |
| This section possibly contains original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (September 2007) |
| Species | Date | Location |
|---|---|---|
| Fancy rat (Rattus norvegicus) | 1800s | UK |
| Fox (Vulpes vulpes) | 1800s | Europe |
| European Mink (Mustela lutreola) | 1800s | Europe |
| Budgerigar (Melopsittacus undulatus) | 1850s | Australia |
| Cockatiel (Nymphicus hollandicus) | 1870s | Australia |
| Zebra Finch (Taeniopygia guttata) | 1900s | Australia |
| Hamster (Mesocricetus auratus) | 1930s | United States |
| Silver Fox | 1950s | Soviet Union |
| Muskox (Ovibos moschatus) | 1960s | United States |
| Corn Snake (Pantherophis guttatus guttatus) | 1960s | United States |
| Ball python (Python regius) | 1960s | Africa |
| Madagascar hissing cockroach (Gromphadorhina portentosa) | 1960s | Madagascar |
| Red Deer (Cervus elaphus) | 1970s | New Zealand |
| Hedgehog (Atelerix albiventris) | 1980s | United States |
| Sugar Glider (Petaurus breviceps) | 1980s | Australia |
| Skunk (Mephitis mephitis) | 1980s | United States |
| Capybara (Hydrochoerus hydrochaeris) | 1990s | United States |
Researchers at the Max Planck institute in Germany are attempting to find a genetic basis for the processes of taming and domestication. They have obtained two strains of grey rats which were bred by Dmitry Konstantinovich Belyaev at the Institute of Cytology and Genetics in Novosibirsk, Russia, research which was later continued by Irina Plyusnina. One strain had been selected for aggressiveness while the other had been selected for tameness, mimicking the process by which neolithic farmers are thought to have first domesticated animals. A similar experiment studying silver foxes has been ongoing at the same institute since 1959.[48] Richard Wrangham of Harvard suggests that similar genes could be involved in human self-domestication.[48]
Some species are said to have been domesticated, but are not any more, either because they have totally disappeared, or since their domestic form no longer exists. Examples include the Jaguarundi,[49] the Kakapo, the Ring-tailed Cat, Caracal and Bos aegyptiacus.[citation needed]
Animals of domestic origin and feral ones sometimes can produce fertile hybrids with native, wild animals which leads to genetic pollution in the naturally evolved wild gene pools, many times threatening rare species with extinction. Cases include the mallard duck, wildcat, wild boar, the rock dove or pigeon, the Red Junglefowl (Gallus gallus) (ancestor of all chickens), carp, and more recently salmon.[citation needed] Another example is the dingo, itself an early feral dog, which hybridizes with dogs of European origin. On the other hand, genetic pollution seems not to be noticed for rabbits. There is much debate over the degree to which feral hybridization compromises the purity of a wild species. In the case of the mallard, for example, some claim there are no populations which are completely free of any domestic ancestor.[citation needed]
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| リンク元 | 「acclimatization」「acclimation」「conditioning」「acclimatisation」「栽培化」 |