thumb|upright=1.5|[[Dogs and sheep were among the first animals to be domesticated, at least 15,000 and 11,000 years ago respectively.), is from the Latin ', 'belonging to the house'. 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.

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."

thumb|upright=2|Diagram of domestication as a process where one species, not only humans, actively manages another to obtain resources or services, as defined by [[Michael D. Purugganan It can also mean a set of differences now observed in domesticated mammals, not necessarily reflecting the initial domestication process. The changes in mammals 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.

<!--By insects-->

Purugganan 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.

<!--basically, the whole of this article, see below for chapters on animals, plants, fungi, etc, it isn't a matter of a "history" subsection-->

Cause and timing

The domestication of animals and plants by humans was triggered by the climatic and environmental changes that occurred after the peak of the Last Glacial Maximum <!--,which was around 21,000 years ago,--> and which continue to this present day. These changes made obtaining food by hunting and gathering difficult. The first animal to be domesticated was the dog at least 15,000 years ago. 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.

{| class="wikitable" style="margin:1em auto;"

|+ Timeline of some major domestication events

|-

! Event !! Centre of origin !! Purpose !! Date/years ago

|-

| Foraging for wild grains || Asia || Food || > 23,000

|-

| Goat, Sheep, Pig, Cow || Near East, South Asia || Food || 11,000–10,000

|-

| Horse || Central Asia || Draft, riding || 5,500

|}

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. For instance, small-scale trial cultivation of cereals began some 23,000 years ago at the Ohalo II site in Israel.

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. from African wildcats, possibly to control rodents that were damaging stored food.

<gallery mode="packed" heights="275" style="float:center;">

File:Centres of origin and spread of agriculture labelled.svg|Centres of origin and spread of agriculture in the Neolithic Revolution as understood in 2003

File:Domestication Timeline.jpg|Rough timelines of domestication for 11 animal species

</gallery>

Animals

Desirable traits

thumb |Domesticated animals tend to be smaller and less aggressive than their wild counterparts; many have other [[domestication syndrome traits like shorter muzzles.

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. 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.

Certain animal species, and certain individuals within those species, make better candidates for domestication because of their behavioral characteristics:<!--Fig 1-->

  1. The size and organization of their social structure

Unlike other domestic species selected primarily for production-related traits, dogs were initially selected for their behaviors. The dog was domesticated long before other animals, becoming established across Eurasia before the end of the Late Pleistocene era, well before agriculture.

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. 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.

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.

Birds

thumb|The [[chicken was domesticated from the red junglefowl (illustrated) of Southeast Asia.]]

Domesticated birds principally mean poultry, raised for meat and eggs: 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. 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.

The chicken's wild ancestor is Gallus gallus, the red junglefowl of Southeast Asia. The date and place of chicken domestication has been debated by scientists: fossils in China and Pakistan have been suggested as early chickens at dates as old as 11,000 years ago. A 2020 study of chicken genomes confirmed that domestication occurred in Southeast Asia. Re-examination and dating of bones from many sites identified the earliest probable chicken bones as from central Thailand some 3250 years ago.

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 molluscs 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.

<gallery mode=packed heights=175px>

File:Cueva arana.svg|A honey hunter in a cave painting at Cuevas de la Araña, Spain, c. 8,000–6,000 BC

File:Sericuturist.jpg|Sericulturalists preparing silkworms for spinning of the silk

File:02-Indian-Insect-Life - Harold Maxwell-Lefroy - Kerria-Lacca.jpg|The lac bug Kerria lacca has been kept for shellac resin.

File:Snails for Sale - Djermaa el-Fna (Central Square) - Medina (Old City) - Marrakesh - Morocco.jpg|Snails being sold as food

</gallery>

Plants

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. Rice was first cultivated in East Asia. Sorghum was widely cultivated in sub-Saharan Africa, while peanuts, squash, cotton, potatoes, and cassava were domesticated in the Americas. It was a process of intermittent trial and error and often resulted in diverging traits and characteristics.

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),

<gallery mode=packed heights=150px>

File:Maler der Grabkammer des Menna 012.jpg|Farmers with wheat and cattle – Ancient Egyptian art 3,400 years ago

File: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

</gallery>

Differences from wild plants

thumb|upright=0.8|[[Einkorn wheat shatters into individual spikelets, making harvesting difficult. Domesticated cereals do not shatter.

  • better palatability (e.g. higher sugar content, reduced bitterness), better smell, and lower toxicity
  • edible part larger, e.g. cereal grains or fruits
  • edible part more easily separated from non-edible part 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.

Changes to plant genome

thumb|upright=2|Domesticated [[wheat evolved by repeated hybridization and polyploidy from multiple wild ancestors, increasing the size and evolvability of the genome. 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). Comparison of the potato genome with that of other plants located genes for resistance to potato blight caused by Phytophthora infestans.

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.

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.

Impact on plant microbiome

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 and diversity.

Fungi

thumb|[[Agaricus bisporus|Cultivated mushrooms are widely grown for food.]]

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. The yeast Saccharomyces cerevisiae have been used for thousands of years to ferment beer and wine, and to leaven bread. Mould fungi including Penicillium are used to mature cheeses and other dairy products, as well as to make drugs such as antibiotics.

Effects

On domestic animals and pathogens

Selection of animals for visible traits may have undesired consequences for the genetics of domestic animals. 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. 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.

On society

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. 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. 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."

On diversity

thumb|Industrialized agriculture on land with a simplified ecosystem

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.

Domestication reduces genetic diversity of the domesticated population, especially of alleles of genes targeted by selection. 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. 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. Mutational load can be increased by reduced selective pressure against moderately harmful traits when reproductive fitness is controlled by human management. 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. Ambrosia beetles mainly colonise wood of recently dead trees.

Leafcutter ants

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.

Fungus-growing termites

Some 330 fungus-growing termite species of the subfamily Macrotermitinae cultivate Termitomyces fungi to eat; domestication occurred exactly once, 25–40 mya. The fungi, described by Roger Heim in 1942, grow on 'combs' formed from the termites' excreta, dominated by tough woody fragments. The termites and the fungi are both obligate symbionts in the relationship.

<gallery class=center mode=nolines widths=180 heights=180 caption="Domestication by insects">

File: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.

File: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

File:Termitomyces heimii.jpg|Termitomyces heimii growing on 'comb' inside a termite mound

File:Termitomyces reticulatus 37340.jpg|Termitomyces fungi are mutually dependent on Macrotermitinae termites for their survival.

</gallery>

See also

  • Anthrozoology
  • De novo domestication
  • Domestication theory
  • Experimental evolution
  • Genetic erosion
  • Self-domestication
  • Timeline of agriculture and food technology

References

Sources

  • <!--not an academic source: use with caution-->
  • 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
  • Major topic 'domestication': free full-text articles (more than 100 plus reviews) in National Library of Medicine