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Domestication is a multi-generational mutualistic relationship in which an animal species, such as humans or leafcutter ants, takes over control and care of another species, such as sheep or fungi, to obtain from them a steady supply of resources, such as meat, milk, or labor. The process is gradual and geographically diffuse, based on trial and error. Domestication affected genes for behavior in animals, making them less aggressive. In plants, domestication affected genes for morphology, such as increasing seed size and stopping the shattering of cereal seedheads. Such changes both make domesticated organisms easier to handle and reduce their ability to survive in the wild.
The first animal to be domesticated by humans was the dog, as a commensal, at least 15,000 years ago. Other animals, including goats, sheep, and cows, were domesticated around 11,000 years ago. Among birds, the chicken was first domesticated in East Asia, seemingly for cockfighting, some 7,000 years ago. The horse came under domestication around 5,500 years ago in central Asia as a working animal. Among invertebrates, the silkworm and the western honey bee were domesticated over 5,000 years ago for silk and honey, respectively.
The domestication of plants began around 13,000–11,000 years ago with cereals such as wheat and barley in the Middle East, alongside crops such as lentil, pea, chickpea, and flax. Beginning around 10,000 years ago, Indigenous peoples in the Americas began to cultivate peanuts, squash, maize, potatoes, cotton, and cassava. Rice was first domesticated in China some 9,000 years ago. In Africa, crops such as sorghum were domesticated. Agriculture developed in some 13 centres around the world, domesticating different crops and animals.
Three groups of insects, namely ambrosia beetles, leafcutter ants, and fungus-growing termites have independently domesticated species of fungi, on which they feed. In the case of the termites, the relationship is a fully obligate symbiosis on both sides.
DefinitionsEdit
Domestication (not to be confused with the taming of an individual animal<ref name="price2008">Template:Cite book</ref><ref name="macdonald2009">Template:Cite journal</ref><ref name="diamond2012">Template:Cite book</ref>), is from the Latin {{#invoke:Lang|lang}}, 'belonging to the house'.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The term remained loosely defined until the 21st century, when the American archaeologist Melinda A. Zeder defined it as a long-term relationship in which humans take over control and care of another organism to gain a predictable supply of a resource, resulting in mutual benefits. She noted further that it is not synonymous with agriculture since agriculture depends on domesticated organisms but does not automatically result from domestication.<ref name="zeder2015">Template:Cite journal</ref>
Michael D. Purugganan notes that domestication has been hard to define, despite the "instinctual consensus" that it means "the plants and animals found under the care of humans that provide us with benefits and which have evolved under our control."<ref name="Purugganan 2022"/> He comments that insects such as termites, ambrosia beetles, and leafcutter ants have domesticated some species of fungi, and notes further that other groups such as weeds and commensals have wrongly been called domesticated.<ref name="Purugganan 2022"/> Starting from Zeder's definition, Purugganan proposes a "broad" definition: "a coevolutionary process that arises from a mutualism, in which one species (the domesticator) constructs an environment where it actively manages both the survival and reproduction of another species (the domesticate) in order to provide the former with resources and/or services."<ref name="Purugganan 2022"/> He comments that this adds niche construction to the activities of the domesticator.<ref name="Purugganan 2022">Template:Cite journal</ref>
Domestication syndrome is the suite of phenotypic traits that arose during the initial domestication process and which distinguish crops from their wild ancestors.<ref name="Olsen Wendel 2013" /><ref name="hammer1984">Template:Cite journal</ref> It can also mean a set of differences now observed in domesticated mammals, not necessarily reflecting the initial domestication process. The changes include increased docility and tameness, coat coloration, reductions in tooth size, craniofacial morphology, ear and tail form (e.g., floppy ears), estrus cycles, levels of adrenocorticotropic hormone and neurotransmitters, prolongations in juvenile behavior, and reductions in brain size and of particular brain regions.<ref name="Wilkins Wrangham Fitch 2014">Template:Cite journal</ref>
Cause and timingEdit
The domestication of animals and plants was triggered by the climatic and environmental changes that occurred after the peak of the Last Glacial Maximum and which continue to this present day. These changes made obtaining food by hunting and gathering difficult.<ref name="Zalloua2017">Template:Cite journal</ref> The first animal to be domesticated was the dog at least 15,000 years ago.<ref name="MacHugh Larson Orlando 2017">Template:Cite journal</ref> The Younger Dryas 12,900 years ago was a period of intense cold and aridity that put pressure on humans to intensify their foraging strategies but did not favour agriculture. By the beginning of the Holocene 11,700 years ago, a warmer climate and increasing human populations led to small-scale animal and plant domestication and an increased supply of food.<ref name="McHugo Dover MacHugh 2019">Template:Cite journal</ref>
| Event | Centre of origin | Purpose | Date/years ago |
|---|---|---|---|
| Foraging for wild grains | Asia | Food | > 23,000<ref name="Purugganan Fuller 2009"/> |
| Dog | Eurasia | Commensal | > 15,000<ref name="MacHugh Larson Orlando 2017"/> |
| Wheat, Barley | Near East | Food | 13,000–11,000<ref name="Purugganan Fuller 2009"/> |
| Flax | Near East | Textiles | 13,000–11,000Template:Sfn |
| Goat, Sheep, Pig, Cow | Near East, South Asia | Food | 11,000–10,000<ref name="MacHugh Larson Orlando 2017"/> |
| Rice | China | Food | 9,000<ref name="Fornasiero Wing Ronald 2022">Template:Cite journal</ref> |
| Chicken | East Asia | Cockfighting | 7,000<ref name="Lawler Adler 2012"/> |
| Horse | Central Asia | Draft, riding | 5,500<ref name="MacHugh Larson Orlando 2017"/> |
| Honey bee | Ancient Egypt | Honey | > 5,000<ref name="Aizen Harder 2009"/> |
The appearance of the domestic dog in the archaeological record, at least 15,000 years ago, was followed by domestication of livestock and of crops such as wheat and barley, the invention of agriculture, and the transition of humans from foraging to farming in different places and times across the planet.<ref name="MacHugh Larson Orlando 2017"/><ref name="fuller2011">Template:Cite journal</ref><ref name="zeder2006">Template:Cite book</ref><ref name="Galibert Ouignon Hitte 2011">Template:Cite journal</ref> For instance, small-scale trial cultivation of cereals began some 28,000 years ago at the Ohalo II site in Israel.<ref name="Snir Nadel Groman-Yaroslavski Melamed 2015">Template:Cite journal</ref>
In the Fertile Crescent 11,000–10,000 years ago, zooarchaeology indicates that goats, pigs, sheep, and taurine cattle were the first livestock to be domesticated. Two thousand years later, humped zebu cattle were domesticated in what is today Baluchistan in Pakistan. In East Asia 8,000 years ago, pigs were domesticated from wild boar genetically different from those found in the Fertile Crescent.<ref name="MacHugh Larson Orlando 2017"/> The cat was domesticated in the Fertile Crescent, perhaps 10,000 years ago,<ref name="Driscoll 2009">Template:Cite journal</ref> from African wildcats, possibly to control rodents that were damaging stored food.<ref name="Driscoll Menotti-Raymond Roca 2007">Template:Cite journal</ref>
- Centres of origin and spread of agriculture labelled.svg
Centres of origin and spread of agriculture in the Neolithic Revolution as understood in 2003<ref name="DiamondandBellwood2003">Template:Cite journal</ref>
- Domestication Timeline.jpg
Rough timelines of domestication for 11 animal species<ref>Template:Cite journal</ref>Template:Efn
AnimalsEdit
Desirable traitsEdit
The domestication of vertebrate animals is the relationship between non-human vertebrates and humans who have an influence on their care and reproduction.<ref name="zeder2015" /> In his 1868 book The Variation of Animals and Plants Under Domestication, Charles Darwin recognized the small number of traits that made domestic species different from their wild ancestors. He was also the first to recognize the difference between conscious selective breeding in which humans directly select for desirable traits and unconscious selection, in which traits evolve as a by-product of natural selection or from selection on other traits.<ref name="darwin1868">Template:Cite book</ref>Template:Sfn<ref name="Larson Piperno Allaby 2014">Template:Cite journal</ref>
There is a difference between domestic and wild populations; some of these differences constitute the domestication syndrome, traits presumed essential in the early stages of domestication, while others represent later improvement traits.<ref name="Olsen Wendel 2013">Template:Cite journal</ref><ref name="Doust Lukens Olsen 2014">Template:Cite journal</ref><ref name="larson2014" /> Domesticated mammals in particular tend to be smaller and less aggressive than their wild counterparts; other common traits are floppy ears, a smaller brain, and a shorter muzzle.<ref name="Frantz Bradley Larson 2020">Template:Cite journal</ref> Domestication traits are generally fixed within all domesticates, and were selected during the initial episode of domestication of that animal or plant, whereas improvement traits are present only in a proportion of domesticates, though they may be fixed in individual breeds or regional populations.<ref name="Doust Lukens Olsen 2014"/><ref name="larson2014"/><ref name="meyer2013">Template:Cite journal</ref>
Certain animal species, and certain individuals within those species, make better candidates for domestication because of their behavioral characteristics:<ref name="zeder2012">Template:Cite journal</ref><ref name="hale1969">Template:Cite book</ref><ref name="price1984">Template:Cite journal</ref><ref name="price2002">Template:Cite book</ref>
- The size and organization of their social structure<ref name="zeder2012"/>
- The availability and the degree of selectivity in their choice of mates<ref name="zeder2012"/>
- The ease and speed with which the parents bond with their young, and the maturity and mobility of the young at birth<ref name="zeder2012"/>
- The degree of flexibility in diet and habitat tolerance<ref name="zeder2012"/>
- Responses to humans and new environments, including reduced flight response and reactivity to external stimuli.<ref name="zeder2012"/>
MammalsEdit
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The beginnings of mammal domestication involved a protracted coevolutionary process with multiple stages along different pathways. There are three proposed major pathways that most mammal domesticates followed into domestication:<ref name="zeder2012"/><ref name="larson2014"/><ref name="marshall2014"/>
- commensals, adapted to a human niche (e.g., dogs, cats, possibly pigs)<ref name="zeder2012"/>
- prey animals sought for food (e.g., sheep, goats, cattle, water buffalo, yak, pig, reindeer, llama and alpaca)<ref name="zeder2012"/>
- animals targeted for draft and riding (e.g., horse, donkey, camel).<ref name="zeder2012"/>
Humans did not intend to domesticate mammals from either the commensal or prey pathways, or at least they did not envision a domesticated animal would result from it. In both of those cases, humans became entangled with these species as the relationship between them intensified, and humans' role in their survival and reproduction gradually led to formalized animal husbandry.<ref name="larson2014"/> Although the directed pathway for draft and riding animals proceeded from capture to taming, the other two pathways are not as goal-oriented, and archaeological records suggest that they took place over much longer time frames.<ref name="larson2013">Template:Cite journal</ref>
Unlike other domestic species selected primarily for production-related traits, dogs were initially selected for their behaviors.<ref name="Serpell Duffy 2014">Template:Cite book</ref><ref name="Cagan Blass 2016">Template:Cite journal</ref> The dog was domesticated long before other animals,<ref name="larson2012"/><ref name="perri2016">Template:Cite journal</ref> becoming established across Eurasia before the end of the Late Pleistocene era, well before agriculture.<ref name="larson2012">Template:Cite journal</ref>
The archaeological and genetic data suggest that long-term bidirectional gene flow between wild and domestic stocks – such as in donkeys, horses, New and Old World camelids, goats, sheep, and pigs – was common.<ref name="larson2014">Template:Cite journal</ref><ref name="marshall2014">Template:Cite journal</ref> Human selection for domestic traits likely counteracted the homogenizing effect of gene flow from wild boars into pigs, and created domestication islands in the genome. The same process may apply to other domesticated animals. <ref name="frantz2015">Template:Cite journal</ref><ref name="pennisi2015">Template:Cite journal</ref>
The 2023 parasite-mediated domestication hypothesis suggests that endoparasites such as helminths and protozoa could have mediated the domestication of mammals. Domestication involves taming, which has an endocrine component; and parasites can modify endocrine activity and microRNAs. Genes for resistance to parasites might be linked to those for the domestication syndrome; it is predicted that domestic animals are less resistant to parasites than their wild relatives.<ref name="Skok 2023a">Template:Cite journal</ref><ref name="Skok 2023b">Template:Cite journal</ref>
BirdsEdit
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Domesticated birds principally mean poultry, raised for meat and eggs:<ref name="AH">Template:Cite encyclopedia</ref> some Galliformes (chicken, turkey, guineafowl) and Anseriformes (waterfowl: ducks, geese, and swans). Also widely domesticated are cagebirds such as songbirds and parrots; these are kept both for pleasure and for use in research.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The domestic pigeon has been used both for food and as a means of communication between far-flung places through the exploitation of the pigeon's homing instinct; research suggests it was domesticated as early as 10,000 years ago.<ref name="Blechman">Template:Cite book</ref> Chicken fossils in China have been dated to 7,400 years ago. The chicken's wild ancestor is Gallus gallus, the red junglefowl of Southeast Asia. The species appears to have been kept initially for cockfighting rather than for food.<ref name="Lawler Adler 2012">Template:Cite journal</ref>
InvertebratesEdit
Two insects, the silkworm and the western honey bee, have been domesticated for over 5,000 years, often for commercial use. The silkworm is raised for the silk threads wound around its pupal cocoon; the western honey bee, for honey, and, from the 20th century, for pollination of crops.<ref name="Aizen Harder 2009">Template:Cite journal</ref><ref>Template:Cite journal</ref>
Several other invertebrates have been domesticated, both terrestrial and aquatic, including some such as Drosophila melanogaster fruit flies and the freshwater cnidarian Hydra for research into genetics and physiology. Few have a long history of domestication. Most are used for food or other products such as shellac and cochineal. The phyla involved are Cnidaria, Platyhelminthes (for biological pest control), Annelida, Mollusca, Arthropoda (marine crustaceans as well as insects and spiders), and Echinodermata. While many marine mollusks are used for food, only a few have been domesticated, including squid, cuttlefish and octopus, all used in research on behaviour and neurology. Terrestrial snails in the genera Helix are raised for food. Several parasitic or parasitoidal insects, including the fly Eucelatoria, the beetle Chrysolina, and the wasp Aphytis are raised for biological control. Conscious or unconscious artificial selection has many effects on species under domestication; variability can readily be lost by inbreeding, selection against undesired traits, or genetic drift, while in Drosophila, variability in eclosion time (when adults emerge) has increased.<ref name="GonPrice1984">Template:Cite journal</ref>
- Cueva arana.svg
A honey hunter in a cave painting at Cuevas de la Araña, Spain, c. 8,000–6,000 BC
- Sericuturist.jpg
Sericulturalists preparing silkworms for spinning of the silk
- 02-Indian-Insect-Life - Harold Maxwell-Lefroy - Kerria-Lacca.jpg
The lac bug Kerria lacca has been kept for shellac resin.
- Snails for Sale - Djermaa el-Fna (Central Square) - Medina (Old City) - Marrakesh - Morocco.jpg
PlantsEdit
Humans foraged for wild cereals, seeds, and nuts thousands of years before they were domesticated; wild wheat and barley, for example, were gathered in the Levant at least 23,000 years ago.<ref>Weiss, E., Kislev, M.E., Simchoni, O. & Nadel, D. Small-grained wild grasses as staple food at the 23000-year-old site of Ohalo II Economic Botany 58:s125-s134.</ref><ref name="Purugganan Fuller 2009" /> Neolithic societies in West Asia first began to cultivate and then domesticate some of these plants around 13,000 to 11,000 years ago.<ref name="Purugganan Fuller 2009" /> The founder crops of the West Asian Neolithic included cereals (emmer, einkorn wheat, barley), pulses (lentil, pea, chickpea, bitter vetch), and flax.Template:SfnTemplate:Sfn Other plants were independently domesticated in 13 centers of origin (subdivided into 24 areas) of the Americas, Africa, and Asia (the Middle East, South Asia, the Far East, and New Guinea and Wallacea); in some thirteen of these regions people began to cultivate grasses and grains.Template:Sfn<ref>Template:Cite book</ref> Rice was first cultivated in East Asia.<ref name="Normile">Template:Cite journal</ref><ref>"New Archaeobotanic Data for the Study of the Origins of Agriculture in China", Zhijun Zhao, Current Anthropology Vol. 52, No. S4, (October 2011), pp. S295-S306</ref> Sorghum was widely cultivated in sub-Saharan Africa,<ref>Template:Cite book</ref> while peanuts,<ref name="Dillehay Rossen Andres Williams 2007">Template:Cite journal</ref> squash,<ref name="Dillehay Rossen Andres Williams 2007" /><ref name="smith2006">Template:Cite journal</ref> cotton,<ref name="Dillehay Rossen Andres Williams 2007" /> maize,<ref>Template:Cite journal</ref> potatoes,<ref name="Spooner 2005 14694–99">Template:Cite journal</ref> and cassava<ref name="Olsen Schaal 1999">Template:Cite journal</ref> were domesticated in the Americas.<ref name="Dillehay Rossen Andres Williams 2007"/>
Continued domestication was gradual and geographically diffuse – happening in many small steps and spread over a wide area – on the evidence of both archaeology and genetics.<ref name="Gross Olsen 2010">Template:Cite journal</ref> It was a process of intermittent trial and error and often resulted in diverging traits and characteristics.<ref name="Hughes Oliveira 2019">Template:Cite journal</ref>
Whereas domestication of animals impacted most on the genes that controlled behavior, that of plants impacted most on the genes that controlled morphology (seed size, plant architecture, dispersal mechanisms) and physiology (timing of germination or ripening),<ref name="zeder2012"/><ref name="zeder2006"/> as in the domestication of wheat. Wild wheat shatters and falls to the ground to reseed itself when ripe, but domesticated wheat stays on the stem for easier harvesting. This change was possible because of a random mutation 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 it, early farmers selected for this mutation. The result is domesticated wheat, which relies on farmers for its reproduction and dissemination.<ref name="Purugganan Fuller 2009">Template:Cite journal</ref>
- Maler der Grabkammer des Menna 012.jpg
Farmers with wheat and cattle – Ancient Egyptian art 3,400 years ago
- Harold f Weston - Iran11.jpg
Wild wheat ears shatter when ripe, but domesticated wheat has to be threshed and winnowed (as shown) to release and separate the grain. Photograph by Harold Weston, Iran, 1920s
Differences from wild plantsEdit
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Domesticated plants differ from their wild relatives in many ways, including
- lack of shattering such as of cereal ears (ripe heads),<ref name="Purugganan Fuller 2009"/> loss of fruit abscission<ref name="Lenser-Theissen-2013"/>
- less efficient breeding system (e.g. without normal pollinating organs, making human intervention a requirement), larger seeds with lower success in the wild,<ref name="Purugganan Fuller 2009"/> or even sterility (e.g. seedless fruits) and therefore only vegetative reproduction<ref name="Agusti citrus 2020">Template:Cite book</ref><ref name="Perrier banana 2009">Template:Cite journal</ref>
- better palatability (e.g. higher sugar content, reduced bitterness), better smell, and lower toxicity<ref name="Milla Osborne Turcotte Violle 2015" /><ref name="Wu Guo Mu 2019">Template:Cite journal</ref>
- edible part larger, e.g. cereal grains<ref name="Kantar-et-al-2016">Template:Cite journal</ref> or fruits<ref name="Lenser-Theissen-2013">Template:Cite journal</ref>
- edible part more easily separated from non-edible part<ref name="Kantar-et-al-2016" />
- increased number of fruits or grains<ref name="Lenser-Theissen-2013" />
- altered color, taste, and texture<ref name="Lenser-Theissen-2013" />
- daylength independence<ref name="Lenser-Theissen-2013" />
- determinate growth<ref name="Lenser-Theissen-2013" />
- reduced or no vernalization<ref name="Lenser-Theissen-2013" />
- less seed dormancy.<ref name="Lenser-Theissen-2013" />
Plant defenses against herbivory, such as thorns, spines, and prickles, poison, protective coverings, and sturdiness may have been reduced in domesticated plants. This would make them more likely to be eaten by herbivores unless protected by humans, but there is only weak support for most of this.<ref name="Milla Osborne Turcotte Violle 2015" /> Farmers did select for reduced bitterness and lower toxicity and for food quality, which likely increased crop palatability to herbivores as to humans.<ref name="Milla Osborne Turcotte Violle 2015">Template:Cite journal</ref> However, a survey of 29 plant domestications found that crops were as well-defended against two major insect pests (beet armyworm and green peach aphid) both chemically (e.g. with bitter substances) and morphologically (e.g. with toughness) as their wild ancestors.<ref name="Turcotte Turley Johnson 2014">Template:Cite journal</ref>
Changes to plant genomeEdit
During domestication, crop species undergo intense artificial selection that alters their genomes, establishing core traits that define them as domesticated, such as increased grain size.<ref name="Purugganan Fuller 2009"/><ref name="Gepts 2004">Template:Cite journal</ref> Comparison of the coding DNA of chromosome 8 in rice between fragrant and non-fragrant varieties showed that aromatic and fragrant rice, including basmati and jasmine, is derived from an ancestral rice domesticate that suffered a deletion in exon 7 which altered the coding for betaine aldehyde dehydrogenase (BADH2).<ref>Template:Cite journal</ref> Comparison of the potato genome with that of other plants located genes for resistance to potato blight caused by Phytophthora infestans.<ref>Template:Cite journal</ref>
In coconut, genomic analysis of 10 microsatellite loci (of noncoding DNA) found two episodes of domestication based on differences between individuals in the Indian Ocean and those in the Pacific Ocean.<ref name="coco">Template:Cite journal</ref><ref name="zeder">Template:Cite journal</ref> The coconut experienced a founder effect, where a small number of individuals with low diversity founded the modern population, permanently losing much of the genetic variation of the wild population.<ref name="coco" /> Population bottlenecks which reduced variation throughout the genome at some later date after domestication are evident in crops such as pearl millet, cotton, common bean and lima bean.<ref name="zeder" />
In wheat, domestication involved repeated hybridization and polyploidy. These steps are large and essentially instantaneous changes to the genome and the epigenome, enabling a rapid evolutionary response to artificial selection. Polyploidy increases the number of chromosomes, bringing new combinations of genes and alleles, which in turn enable further changes such as by chromosomal crossover.<ref name="Golovnina Glushkov Blinov Mayorov 2007">Template:Cite journal</ref>
Impact on plant microbiomeEdit
The microbiome, the collection of microorganisms inhabiting the surface and internal tissue of plants, is affected by domestication. This includes changes in microbial species composition<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref name=":4">Template:Cite journal</ref> and diversity.<ref>Template:Cite journal</ref><ref name=":4" /> Plant lineage, including speciation, domestication, and breeding, have shaped plant endophytes (phylosymbiosis) in similar patterns as plant genes.<ref name=":4" /><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
FungiEdit
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Several species of fungi have been domesticated for use directly as food, or in fermentation to produce foods and drugs. The cultivated mushroom Agaricus bisporus is widely grown for food.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The yeast Saccharomyces cerevisiae have been used for thousands of years to ferment beer and wine, and to leaven bread.<ref name="Legras Medinoglu Cornuet 2007">Template:Cite journal</ref> Mould fungi including Penicillium are used to mature cheeses and other dairy products, as well as to make drugs such as antibiotics.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
EffectsEdit
On domestic animalsEdit
Selection of animals for visible traits may have undesired consequences for the genetics of domestic animals.<ref>Template:Cite book</ref> A side effect of domestication has been zoonotic diseases. For example, cattle have given humanity various viral poxes, measles, and tuberculosis; pigs and ducks have contributed influenza; and horses have brought the rhinoviruses. Many parasites, too, have their origins in domestic animals.Template:Sfn Alongside these, 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.<ref>Template:Cite journal</ref>
On societyEdit
Scholars have expressed widely differing viewpoints on domestication's effects on society. Anarcho-primitivism critiques domestication as destroying the supposed primitive state of harmony with nature in hunter-gatherer societies, and replacing it, possibly violently or by enslavement, with a social hierarchy as property and power emerged.<ref name="Boyden 1992">Template:Cite journal</ref> The dialectal naturalist Murray Bookchin has argued that domestication of animals, in turn, meant the domestication of humanity, both parties being unavoidably altered by their relationship with each other.<ref name="Bookchin">Template:Cite book</ref> The sociologist David Nibert asserts that the domestication of animals involved violence against animals and damage to the environment. This, in turn, he argues, corrupted human ethics and paved the way for "conquest, extermination, displacement, repression, coerced and enslaved servitude, gender subordination and sexual exploitation, and hunger."<ref>Template:Cite book</ref>
On diversityEdit
Domesticated ecosystems provide food, reduce predator and natural dangers, and promote commerce, but their creation has resulted in habitat alteration or loss, and multiple extinctions commencing in the Late Pleistocene.<ref name="Boivin Zeder Fuller 2016">Template:Cite journal</ref>
Domestication reduces genetic diversity of the domesticated population, especially of alleles of genes targeted by selection.<ref name="Flint-Garcia 2013">Template:Cite journal</ref> One reason is a population bottleneck created by artificially selecting the most desirable individuals to breed from. Most of the domesticated strain is then born from just a few ancestors, creating a situation similar to the founder effect.<ref name="Brown 2019">Template:Cite journal</ref> Domesticated populations such as of dogs, rice, sunflowers, maize, and horses have an increased mutation load, as expected in a population bottleneck where genetic drift is enhanced by the small population size. Mutations can also be fixed in a population by a selective sweep.<ref name="Allaby Ware Kistler 2019">Template:Cite journal</ref><ref name="Shepherd Lange Simon 2016">Template:Cite journal</ref> Mutational load can be increased by reduced selective pressure against moderately harmful traits when reproductive fitness is controlled by human management.<ref name="Frantz Bradley Larson 2020"/> However, there is evidence against a bottleneck in crops, such as barley, maize, and sorghum, where genetic diversity slowly declined rather than showing a rapid initial fall at the point of domestication.<ref name="Allaby Ware Kistler 2019"/><ref name="Brown 2019"/> Further, the genetic diversity of these crops was regularly replenished from the natural population.<ref name="Allaby Ware Kistler 2019"/> Similar evidence exists for horses, pigs, cows, and goats.<ref name="Frantz Bradley Larson 2020"/>
Domestication by insectsEdit
At least three groups of insects, namely ambrosia beetles, leafcutter ants, and fungus-growing termites, have domesticated species of fungi.<ref name="Purugganan 2022"/><ref name="Mueller Gerardo 2005"/>
Ambrosia beetlesEdit
Ambrosia beetles in the weevil subfamilies Scolytinae and Platypodinae excavate tunnels in dead or stressed trees into which they introduce fungal gardens, their sole source of nutrition. After landing on a suitable tree, an ambrosia beetle excavates a tunnel in which it releases its fungal symbiont. The fungus penetrates the plant's xylem tissue, extracts nutrients from it, and concentrates the nutrients on and near the surface of the beetle gallery. Ambrosia fungi are typically poor wood degraders and instead utilize less demanding nutrients.<ref>Template:Cite journal</ref> Symbiotic fungi produce and detoxify ethanol, which is an attractant for ambrosia beetles and likely prevents the growth of antagonistic pathogens and selects for other beneficial symbionts.<ref>Template:Cite journal</ref> Ambrosia beetles mainly colonise wood of recently dead trees.<ref name= Hulcr2017>Template:Cite journal</ref>
Leafcutter antsEdit
The leafcutter ants are any of some 47 species of leaf-chewing ants in the genera Acromyrmex and Atta. The ants carry the discs of leaves that they have cut back to their nest, where they feed the leaf material to the fungi that they tend. Some of these fungi are not fully domesticated: the fungi farmed by Mycocepurus smithii constantly produce spores that are not useful to the ants, which eat fungal hyphae instead. The process of domestication by Atta ants, on the other hand, is complete; it took 30 million years.<ref name="Shik Gomez Kooij 2016">Template:Cite journal</ref>
Fungus-growing termitesEdit
Some 330 fungus-growing termite species of the subfamily Macrotermitinae cultivate Termitomyces fungi to eat; domestication occurred exactly once, 25–40 mya.<ref name="Purugganan 2022"/><ref name="Mueller Gerardo 2005">Template:Cite journal</ref> The fungi, described by Roger Heim in 1942, grow on 'combs' formed from the termites' excreta, dominated by tough woody fragments.<ref name="Heim 1942">Template:Cite journal</ref> The termites and the fungi are both obligate symbionts in the relationship.<ref name="NobreAanen2010">Template:Cite journal</ref>
- Domestication by insects
- Xylosandrus crassiusculus galleryR.jpg
Gallery of the ambrosia beetle Xylosandrus crassiusculus split open, with pupae and black fungus. The fungus decomposes materials in the wood, providing food for the beetles.
- Leaf cutter ants arp.jpg
Leafcutter ants Atta cephalotes carrying discs of leaf material back to their nest to feed to their domesticated fungus
- Ancistrotermes latinotus.jpg
Inside the nest of the fungus-cultivating termite Ancistrotermes
- Termitomyces heimii.jpg
Termitomyces heimii growing on 'comb' inside a termite mound
- Termitomyces reticulatus 37340.jpg
Termitomyces fungi are mutually dependent on Macrotermitinae termites for their survival.
See alsoEdit
- Anthrozoology
- De novo domestication
- Domestication theory
- Experimental evolution
- Genetic erosion
- Self-domestication
- Timeline of agriculture and food technology
ReferencesEdit
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SourcesEdit
- Template:Cite encyclopedia
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External linksEdit
- Crop Wild Relative Inventory and Gap Analysis: reliable information source on where and what to conserve ex-situ for crop gene pools of global importance
- Discussion of animal domestication with Jared Diamond
- The Initial Domestication of Cucurbita pepo in the Americas 10,000 Years Ago
- Cattle domestication diagram Template:Webarchive
- Major topic 'domestication': free full-text articles (more than 100 plus reviews) in National Library of Medicine
Template:Prehistoric technology Template:Animal domestication