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Domestication is a multi-generational mutualistic relationship in which an animal species, such as humans or , takes over control and care of another species, such as sheep or Fungus, 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 affects Gene for behavior in animals, making them less aggressive. In plants, domestication affects genes for morphology, such as increasing seed size and stopping the shattering of cereal seedheads. Such changes both make domesticated Organism 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 Commensalism, at least 15,000 years ago. Other animals, including , sheep, and , were domesticated around 11,000 years ago. Among birds, the chicken was first domesticated in East Asia at least 3,250 years ago. The horse came under domestication around 5,500 years ago in central Asia as a working animal. Among , 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 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 Americas began to cultivate , squash, maize, , 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 Insect, namely , , 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.
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." He comments that insects such as , , and have domesticated some species of Fungus, and notes further that other groups such as weeds and Commensalism have wrongly been called domesticated. Starting from Zeder's definition, Purugganan proposes a "broad" definition: "a Coevolution 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." He comments that this adds niche construction to the activities of the domesticator.
Domestication syndrome is the suite of phenotype traits that arose during the initial domestication process and which distinguish crops from their . 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 Neurotransmitter, prolongations in juvenile behavior, and reductions in brain size and of particular brain regions.
A 2025 article published in PNAS proposed a formal definition of domestication, defined simply:
Furthermore, the term “domestic” should refer solely to those populations that are obligate and have adapted to an anthropogenic environment to the extent that only sink populations (in which the death rate is higher than the birth rate) exist outside of that niche.
| + Timeline of some major domestication events | |||
| > 23,000 | |||
| > 15,000 | |||
| 13,000–11,000 | |||
| 13,000–11,000 | |||
| Cannabis | East Asia | Textiles | 12,000 |
| 11,000–10,000 | |||
| 9,000 | |||
| 5,500 | |||
| > 5,000 | |||
| 3,250 |
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 Cereal began some 28,000 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. The cat was domesticated in the Fertile Crescent, perhaps 10,000 years ago, from , possibly to control that were damaging stored food.
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. Domesticated Mammal 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. 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 Landrace.
Certain animal species, and certain individuals within those species, make better candidates for domestication because of their behavioral characteristics:
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. Although the directed pathway for draft and riding animals proceeded from capture to Tame animal, the other two pathways are not as goal-oriented, and archaeological records suggest that they took place over much longer time frames.
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 , , New and Old World Camelidae, goats, sheep, and pigs – was common. Human selection for domestic traits likely counteracted the homogenizing effect of gene flow from Wild boar 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 gland component; and parasites can modify endocrine activity and . 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.
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 phylum involved are Cnidaria, Platyhelminthes (for biological pest control), Annelida, Mollusca, Arthropoda (marine as well as insects and Spider), and Echinodermata. While many marine Mollusca are used for food, only a few have been domesticated, including Loligo, cuttlefish and octopus, all used in research on animal 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.
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. 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), 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.
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 Herbivore unless protected by humans, but there is only weak support for most of this. Farmers did select for reduced bitterness and lower toxicity and for food quality, which likely increased crop palatability to herbivores as to humans. 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.
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. 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.
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 evolvability such as by chromosomal crossover.
Domestication reduces genetic diversity of the domesticated population, especially of Allele 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 Genetic 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. 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. Further, the genetic diversity of these crops was regularly replenished from the natural population. Similar evidence exists for horses, pigs, cows, and goats.
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