Editing Domestication of the horse

{{Short description|none}}
{{Use dmy dates|date=September 2020}} 
It is not entirely clear how, when or where the '''domestication of the horse''' took place. Although horses appeared in [[Paleolithic]] [[cave art]] as early as 30,000&nbsp;BCE, these were wild horses and were probably hunted for meat. The clearest evidence of early use of the horse as a means of transport is from chariot burials dated {{circa|2000&nbsp;BCE}}.<ref name="Anthony2007" /><ref name="Kuznetsov2006"/> However, an increasing amount of evidence began to support the hypothesis that horses were domesticated in the [[Eurasian Steppe]]s in approximately 3500 BCE.<ref name="Dance"/><ref name="Librado"/>
Discoveries in the context of the [[Botai culture]] had suggested that Botai settlements in the [[Akmola Province]] of [[Kazakhstan]] are the location of the earliest domestication of the horse.<ref name="Outram">{{Cite journal | last1=Outram | first1=Alan K.| title=The Earliest Horse Harnessing and Milking | journal=Science | volume=323 | pages=1332–1335 | date=2009 | doi=10.1126/science.1168594 | issue=5919|display-authors=etal | pmid=19265018| bibcode=2009Sci...323.1332O| s2cid=5126719}}</ref> However, Taylor and Barrón-Ortiz (2021) argue that Botai findings only reflect intensive exploitation of wild horses—possibly involving some level of management, herding, or seasonal capture—but not full domestication in the way we see in later horse-using societies. <ref>{{Cite journal |last=Taylor |first=William Timothy Treal |last2=Barrón-Ortiz |first2=Christina Isabelle |date=2021-04-02 |title=Rethinking the evidence for early horse domestication at Botai |url=https://www.nature.com/articles/s41598-021-86832-9 |journal=Scientific Reports |language=en |volume=11 |issue=1 |pages=7440 |doi=10.1038/s41598-021-86832-9 |issn=2045-2322|pmc=8018961 }}</ref> Warmuth et al. (2012) pointed to horses having been domesticated around 3000&nbsp;BCE in what is now [[Ukraine]] and [[West Kazakhstan Region|Western Kazakhstan]].<ref>[https://www.science.org/content/article/whence-domestic-horse Whence the Domestic Horse? | Science | AAAS]</ref> The evidence is disputed by archaeozoologist Williams T. Taylor, who argues that domestication did not take place until around 2000&nbsp;BCE.<ref>{{cite journal| last=Taylor |first=William T. | journal=Scientific American |title=When Horse became Steed|volume=331 |number=5  |date=December 2024 |pages=24–30 |doi=10.1038/scientificamerican122024-7qfHkaSxwWOJpTcwY2J0bg |bibcode=2024SciAm.331e..22T |issn= }}</ref>

Genetic evidence indicates that domestication of the modern horse's ancestors likely occurred in an area known as the [[Volga region|Volga–Don]], in the [[Pontic–Caspian steppe]] region of eastern Europe, around 2200&nbsp;BCE. From there, use of horses spread across [[Eurasia]] for transportation, agricultural work, and warfare. Scientists have linked the successful spread of domesticated horses to observed genetic changes. They speculate that stronger backs (GSDMC gene) and increased docility (ZFPM1 gene) may have made horses more suitable for riding.<ref name="Dance"/><ref name="Librado"/>

==Background==
[[File:Terracotta urn in the shape of a horse (Iran, 1000&nbsp;BCE), stored at the Lyndon B. Johnson Presidential Library.jpg|thumb|Terracotta urn in the shape of a horse (Iran, 1000&nbsp;BCE) at the [[Lyndon Baines Johnson Library and Museum|Lyndon B. Johnson Presidential Library]]]]

The date of the domestication of the horse depends to some degree upon the definition of "domestication". Some zoologists define "domestication" as human control over breeding, which can be detected in ancient skeletal samples by changes in the size and variability of ancient horse populations. Other researchers look at the broader evidence, including skeletal and dental evidence of working activity; weapons, art, and spiritual artifacts; and lifestyle patterns of human cultures. There is evidence that horses were kept as a source of meat and milk before they were trained as working animals.<ref name="Dance"/><ref name="Outram"/>

Attempts to date domestication by genetic study or analysis of physical remains rest on the assumption that there was a separation of the [[genotypes]] of domesticated and wild populations. Such a separation appears to have taken place, but dates based on such methods can only produce an estimate of the latest possible date for domestication without excluding the possibility of an unknown period of earlier gene flow between wild and domestic populations (which will occur naturally as long as the domesticated population is kept within the habitat of the wild population).<ref name="Apfel">{{cite news |last1=Apfel |first1=Karin |title=Horses and Man: Digging Up the Truth about Domestication |url=https://horse-canada.com/magazine/miscellaneous/horses-and-man-digging-up-the-truth-about-domestication/ |access-date=20 May 2022 |work=Horse Canada |date=March 25, 2020 |language=en-CA}}</ref> 

Whether one adopts the narrower zoological definition of domestication or the broader cultural definition that rests on an array of zoological and archaeological evidence affects the time frame chosen for the domestication of the horse. The date of 4000&nbsp;BCE is based on evidence that includes the appearance of dental pathologies associated with [[Bit (horse)|bitting]], changes in butchering practices, changes in human economies and settlement patterns, the depiction of horses as symbols of power in artifacts, and the appearance of horse bones in human graves.<ref name="Anthony2007">{{cite book |title=The Horse, the Wheel, and Language: How Bronze Age Riders from the Eurasian Steppes Shaped the Modern World |last=Anthony |first=David W. |year=2007 |publisher=Princeton University Press |location=Princeton, NJ |isbn=978-0-691-05887-0 |url=https://archive.org/details/horsewheelandlanguage }}</ref> On the other hand, measurable changes in size and increases in variability associated with domestication occurred later, about 2500–2000&nbsp;BCE, as seen in horse remains found at the site of Csepel-Haros in [[Hungary]], a settlement of the [[Beaker culture|Bell Beaker culture]].<ref name="Benecke and von den Dreisch 2003">{{cite book |title=Prehistoric Steppe Adaptation and the Horse |last=Benecke |first=Norbert |author2=Von den Dreisch, Angela |editor=Levine, Marsha |editor2=Renfrew, Colin |editor3=Boyle, Katie |year=2003 |publisher=McDonald Institute |location=Cambridge |isbn=978-1-902937-09-0 |pages=69–82 |chapter=Horse exploitation in the Kazakh steppes during the Eneolithic and Bronze Age }}</ref>

Use of horses spread across [[Eurasia]] for transportation, agricultural work and warfare. Horses and mules in agriculture used a [[Breastplate (tack)|breastplate]] type harness or a [[yoke]] more suitable for [[ox]]en, which was not as efficient at utilizing the full strength of the animals as the later-invented padded [[horse collar]] that arose several millennia later.<ref>{{cite book |title=Science and Civilization in China; Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering |last=Needham |first=Joseph |year=1986 |publisher=Caves Books |location=Taipei }}</ref><ref name="Clutton-Brock1992">{{cite book |title=Horse Power: A History of the Horse and the Donkey in Human Societies |last=Clutton-Brock |first=Juliet |year=1992 |publisher=Harvard University Press |location=Cambridge, Massachusetts |isbn=978-0-674-40646-9 |page=138 }}</ref>

==Predecessors to the domestic horse==
{{Main|Evolution of the horse|wild horse}}
[[File:Lascaux2.jpg|thumb|left|A horse painting from a cave in [[Lascaux]]]]
<!--cut down some of this to eliminate material that belongs in the evolution article. Here we are only concerned about the lineage of the domestic horse-->
A 2005 study analyzed the [[mitochondrial DNA]] (mtDNA) of a worldwide range of [[Equidae|equids]], from 53,000-year-old fossils to contemporary horses.<ref name = Weinstock>{{cite journal|last=Weinstock |first=J.|year=2005 |title=Evolution, systematics, and phylogeography of Pleistocene horses in the New World: a molecular perspective |journal=[[PLOS Biology]]|volume=3|issue=8|doi=10.1371/journal.pbio.0030241 |pmid=15974804|pages=e241|pmc=1159165 |display-authors=etal |doi-access=free }}</ref> Their analysis placed all equids into a single [[clade]], or group with a single [[common ancestor]], consisting of three [[Genetic divergence|genetically divergent]] species: the South American ''[[Hippidion]]'', the North American [[New World stilt-legged horse]], and ''[[Equus (genus)|Equus]]''<!-- genus name has to always be capitalized -->, the true horse. The true horse included prehistoric horses and the [[Przewalski's horse]], as well as what is now the many breeds of modern domestic horses, belonged to a single [[Holarctic]] species.<ref name = Weinstock/><!--all material to this point is Weinstock, don't need to cite every sentence to same source-->

The true horse migrated from the Americas to Eurasia via [[Beringia]], becoming broadly distributed from North America to central Europe, north and south of [[Pleistocene]] ice sheets.<ref name = Weinstock/><!--all material to this point is Weinstock, don't need to cite every sentence to same source--> It became extinct in Beringia around 14,200 years ago, and in the rest of the Americas around 10,000 years ago.<ref name = IberianOrigins>{{cite journal |last=Luís |first= Cristina |year=2006
|title=Iberian Origins of New World Horse Breeds |journal=[[Journal of Heredity]] |volume=97 |issue=2 |url=http://jhered.oxfordjournals.org/cgi/content/full/97/2/107 |pages=107–113 |doi=10.1093/jhered/esj020 |pmid=16489143 |display-authors=etal|doi-access=free }}</ref><ref name = Buck>{{cite journal|last=Buck |first=Caitlin E. |author2=Bard, Edouard |year=2007 |title=A calendar chronology for Pleistocene mammoth and horse extinction in North America based on Bayesian radiocarbon calibration |journal=[[Quaternary Science Reviews]]|volume=26|issue=17–18|doi=10.1016/j.quascirev.2007.06.013|pages=2031–2035|url=https://zenodo.org/record/886512|bibcode=2007QSRv...26.2031B }}</ref> This clade survived in Eurasia, however, and it is from these horses which all domestic horses appear to have descended.<ref name = Weinstock/> These horses showed little [[Phylogeography|phylogeographic]] structure, probably reflecting their high degree of mobility and adaptability.<ref name = Weinstock/>

Therefore, the domestic horse today is classified as ''Equus ferus caballus''. No genetic originals of native wild horses currently exist. The Przewalski diverged from the modern horse before domestication. It has 66 [[chromosome]]s, as opposed to 64 among modern domesticated horses, and their [[Mitochondrial DNA]] (mtDNA) forms a distinct cluster.<ref name="Jansen2002">{{cite journal | last = Jansen | first = Thomas | year = 2002 | title = Mitochondrial DNA and the origins of the domestic horse | journal =  Proceedings of the National Academy of Sciences| volume = 99 | issue = 16 | pages = 10905–10910 | doi = 10.1073/pnas.152330099 | pmid = 12130666 | pmc = 125071 |display-authors=etal| bibcode = 2002PNAS...9910905J | doi-access = free }}</ref> Genetic evidence suggests that modern Przewalski's horses are descended from a distinct regional gene pool in the eastern part of the Eurasian steppes, not from the same genetic group that gave rise to modern domesticated horses.<ref name="Dance">{{cite journal |last1=Dance |first1=Amber |title=The tale of the domesticated horse |journal=Knowable Magazine |date=4 May 2022 |doi=10.1146/knowable-050422-1 |s2cid=248656633 |doi-access=free |url=https://knowablemagazine.org/article/living-world/2022/tale-domesticated-horse |access-date=18 May 2022}}</ref><ref name="Jansen2002"/> Nevertheless, evidence such as the [[cave painting]]s of [[Lascaux]] suggests that the ancient wild horses that some researchers now label the "Tarpan subtype" probably resembled Przewalski horses in their general appearance: big heads, [[dun gene|dun coloration]], thick necks, stiff upright [[mane (horse)|manes]], and relatively short, stout legs.<ref name="Bennett1998">{{cite book |title=Conquerors: The Roots of New World Horsemanship |last=Bennett |first=Deb |year=1998 |publisher=Amigo Publications |location=Solvang, CA |edition=1st |isbn=978-0-9658533-0-9 }}</ref>
[[File:Equus caballus germanicus.jpg|thumb|upright|''Equus caballus germanicus'' front leg, teeth and upper jaw at the Museum für Naturkunde, Berlin]]

The horses of the [[Last Glacial Period|Ice Age]] were hunted for meat in Europe and across the Eurasian steppes and in North America by early modern humans. Numerous kill sites exist and many [[cave painting]]s in [[Europe]] indicate what they looked like.<ref name="Olsen1996">{{cite book |title=Horses Through Time |last=Olsen |first=Sandra L. |year=1996 |publisher=Roberts Rinehart Publishers |location=Boulder, CO |isbn=978-1-57098-060-2 |chapter=Horse Hunters of the Ice Age |chapter-url-access=registration |chapter-url=https://archive.org/details/horsesthroughtim00olse |url-access=registration |url=https://archive.org/details/horsesthroughtim00olse }}</ref> Many of these Ice Age subspecies died out during the rapid climate changes associated with the end of the last Ice Age particularly in [[North America]], where the horse became completely [[extinct]].<ref name="MacPhee1999">{{cite book |title=Extinctions in Near Time: Causes, Contexts, and Consequences |editor1-first=Ross D. E |editor1-last=MacPhee |year=1999 |publisher=Kluwer Press |location=New York |isbn=978-0-306-46092-0 |doi=10.1007/978-1-4757-5202-1 |s2cid=21839980 }}</ref>

Two undomesticated sub-species survived into historic times: [[Przewalski's horse]] (''Equus ferus przewalski'') and the [[Tarpan]] (''Equus ferus ferus'').<ref name="Groves1986">{{cite book |title=Equids in the Ancient World |series=Beihefte zum Tübinger Atlas des Vorderen Orients: Reihe A (Naturwissenschaften) |volume=19 |last=Groves |first=Colin |editor=Meadow, Richard H. |editor2=Uerpmann, Hans-Peter |year=1986 |publisher=Ludwig Reichert Verlag |location=Wiesbaden |pages=11–65 |chapter=The taxonomy, distribution, and adaptations of recent Equids }}</ref> The Tarpan became [[extinct]] in the late 19th century and Przewalski's horse is [[endangered]]; it became extinct in the wild during the late 1960s, but was re-introduced in the early 1990s to two preserves in Mongolia. Although researchers such as [[Marija Gimbutas]] theorized that the horses of the [[Chalcolithic]] (Copper Age) were Przewalski's, more recent genetic studies indicate that Przewalski's horse is not an ancestor to modern domesticated horses.<ref name="Jansen2002"/><ref name="Librado"/>

==Genetic evidence==
{{See also|Genomics of domestication|History of horse domestication theories}}
[[File:Horse phenotypes over time.png|thumb|right|260px|The early stages of domestication were marked by a rapid increase in coat colour variation.<ref name=Wutke2016>{{cite journal|date=2016-12-07 |title=Spotted phenotypes in horses lost attractiveness in the Middle Ages |vauthors=Wutke S, Benecke N, Sandoval-Castellanos E, Döhle H, Friederich S, Gonzalez J, Hallsson JH, Hofreiter M, Lõugas L, Magnell O, Morales-Muniz A, Orlando L, Pálsdóttir AH, Reissmann M, Ruttkay M, Trinks A, Ludwig A |display-authors=4 |doi=10.1038/srep38548  |pmid=27924839 |pmc=5141471 |journal=Scientific Reports |volume=6 |pages=38548 |bibcode=2016NatSR...638548W }}</ref>]]

A 2014 study compared DNA from ancient horse bones that predated domestication and compared them to DNA of modern horses, discovering 125 genes that correlated to domestication.  Some were physical, affecting muscle and limb development, cardiac strength and balance. Others were linked to cognitive function and most likely were critical to the taming of the horse, including social behavior, learning capabilities, fear response, and agreeableness.<ref name=Schubert>{{cite journal|last1=Schubert|first1=Mikkel| last2=Jónsson |first2=Hákon | last3=Chang |first3=Dan|last4=Der Sarkissian|first4=Clio|last5=Ermini|first5=Luca| last6=Ginolhac |first6=Aurélien|last7=Albrechtsen |first7=Anders|last8=Dupanloup|first8=Isabelle|last9=Foucal |first9=Adrien|last10=Petersen |first10=Bent|last11=Fumagalli|first11=Matteo|last12=Raghavan |first12=Maanasa |last13=Seguin-Orlando |first13=Andaine| last14=Korneliussen| first14=Thorfinn S.|last15=Velazquez|first15=Amhed M. V. |last16=Stenderup |first16=Jesper|last17=Hoover |first17=Cindi A.|last18=Rubin |first18=Carl-Johan|last19=Alfarhan|first19=Ahmed H.|last20=Alquraishi|first20=Saleh A.|last21=Al-Rasheid|first21=Khaled A. S.|last22=MacHugh|first22=David E.|last23=Kalbfleisch|first23=Ted|last24=MacLeod|first24=James N.|last25=Rubin|first25=Edward M.|last26=Sicheritz-Ponten|first26=Thomas|last27=Andersson|first27=Leif|last28=Hofreiter|first28=Michael|last29=Marques-Bonet|first29=Tomas|last30=Gilbert|first30=M. Thomas P.|last31=Nielsen|first31=Rasmus|last32=Excoffier|first32=Laurent|last33=Willerslev|first33=Eske|last34=Shapiro|first34=Beth|last35=Orlando|first35=Ludovic |display-authors=5 |title=Prehistoric genomes reveal the genetic foundation and cost of horse domestication|journal=Proceedings of the National Academy of Sciences|volume=111|issue=52|pages=E5661–E5669|doi=10.1073/pnas.1416991111|pmid=25512547|pmc=4284583|date=2014|bibcode=2014PNAS..111E5661S|doi-access=free}}</ref> The DNA used in this study came from horse bones 16,000 to 43,000 years ago, and therefore the precise changes that occurred at the time of domestication have yet to be sequenced.<ref name=Begley>{{cite web|last1=Begley|first1=Sharon|title=How did we domesticate horses? Genetic study yields new evidence|url=http://www.csmonitor.com/Science/2014/1216/How-did-we-domesticate-horses-Genetic-study-yields-new-evidence.-video|website=Christian Science Monitor|date=16 December 2014}}</ref>

The domestication of stallions and mares can be analyzed separately by looking at those portions of the DNA that are passed on exclusively along the maternal ([[mitochondrial DNA]] or mtDNA) or paternal line ([[Y-chromosome]] or Y-DNA). DNA studies indicate that there may have been multiple domestication events for mares, as the number of female lines required to account for the genetic diversity of the modern horse suggests a minimum of 77 different ancestral [[mare]]s, divided into 17 distinct lineages.<ref name="Jansen2002"/> Studies of modern horses showed very little Y chromosome diversity, which was originally interpreted as evidence of a single domestication event for a limited number of stallions combined with repeated restocking of wild females into the domesticated herds.<ref name=Lau>{{cite journal | doi = 10.1093/molbev/msn239 | last1 = Lau | first1 = A. N. | last2 = Peng | first2 = L. | last3 = Goto | first3 = H. | last4 = Chemnick | first4 = L. | last5 = Ryder | first5 = O. A. | last6 = Makova | first6 = K. D. | year = 2009  |display-authors=5 | title = Horse Domestication and Conservation Genetics of Przewalski's Horse Inferred from Sex Chromosomal and Autosomal Sequences | journal = Molecular Biology and Evolution | volume = 26 | issue = 1| pages = 199–208 | pmid = 18931383 | doi-access = free }}</ref><ref name="Lindgren2004">{{cite journal | last = Lindgren | first = Gabriella |author2=Niclas Backström |author3=June Swinburne |author4=Linda Hellborg |author5=Annika Einarsson |author6=Kaj Sandberg |author7=Gus Cothran |author8=Carles Vilà |author9=Matthew Binns |author10=Hans Ellegren | year =2004 | title = Limited number of patrilines in horse domestication | journal = [[Nature Genetics]] | volume = 36 | issue = 4| pages = 335–336 | doi = 10.1038/ng1326 | pmid = 15034578 | doi-access =free }}</ref><ref name="Vila2001"/> However, more recent studies of ancient DNA show that Y chromosome diversity was significantly higher a thousand years ago.<ref name=Bailey2020>{{cite book|isbn=9781786392596 |title=Horse Genetics |last1=Bailey |first1=Ernest |last2=Bailey |first2=Ernest Frank |last3=Brooks |first3=Samantha A. |date=26 May 2024 }}</ref><ref name=Wutke2018>{{cite journal|doi=10.1126/sciadv.aap9691 |title=Decline of genetic diversity in ancient domestic stallions in Europe |date=2018 |last1=Wutke |first1=Saskia |last2=Sandoval-Castellanos |first2=Edson |last3=Benecke |first3=Norbert |last4=Döhle |first4=Hans-Jürgen |last5=Friederich |first5=Susanne |last6=Gonzalez |first6=Javier |last7=Hofreiter |first7=Michael |last8=Lõugas |first8=Lembi |last9=Magnell |first9=Ola |last10=Malaspinas |first10=Anna-Sapfo |last11=Morales-Muñiz |first11=Arturo |last12=Orlando |first12=Ludovic |last13=Reissmann |first13=Monika |last14=Trinks |first14=Alexandra |last15=Ludwig |first15=Arne |journal=Science Advances |volume=4 |issue=4 |pages=eaap9691 |pmid=29675468 |bibcode=2018SciA....4.9691W |pmc=5906072 }}</ref> The low present diversity may be partially explained by the popularity of Arabian and Turkoman studs, especially the three foundation stallions of the Thoroughbred breed.<ref name=Wallner2017>{{cite journal|doi=10.1016/j.cub.2017.05.086 |title=Y Chromosome Uncovers the Recent Oriental Origin of Modern Stallions |date=2017 |last1=Wallner |first1=Barbara |last2=Palmieri |first2=Nicola |last3=Vogl |first3=Claus |last4=Rigler |first4=Doris |last5=Bozlak |first5=Elif |last6=Druml |first6=Thomas |last7=Jagannathan |first7=Vidhya |last8=Leeb |first8=Tosso |last9=Fries |first9=Ruedi |last10=Tetens |first10=Jens |last11=Thaller |first11=Georg |last12=Metzger |first12=Julia |last13=Distl |first13=Ottmar |last14=Lindgren |first14=Gabriella |last15=Rubin |first15=Carl-Johan |last16=Andersson |first16=Leif |last17=Schaefer |first17=Robert |last18=McCue |first18=Molly |last19=Neuditschko |first19=Markus |last20=Rieder |first20=Stefan |last21=Schlötterer |first21=Christian |last22=Brem |first22=Gottfried |journal=Current Biology |volume=27 |issue=13 |pages=2029–2035.e5 |pmid=28669755 |bibcode=2017CBio...27E2029W |doi-access=free }}</ref>

A study published in 2012 that performed [[Comparative genomics|genomic sampling]] on 300 work horses from local areas as well as a review of previous studies of archaeology, [[mitochondrial DNA]], and [[Y-DNA]] suggested that horses were originally domesticated in the western part of the Eurasian steppe.<ref name=Warmuth>{{cite journal | last1 = Warmuth | first1 = Vera | last2 = Eriksson | first2 = Anders | last3 = Ann Bower | first3 = Mim | last4 = Barker | first4 = Graeme | last5 = Barrett | first5 = Elizabeth | last6 = Kent Hanks | first6 = Bryan | last7 = Li | first7 = Shuicheng | last8 = Lomitashvili | first8 = David | last9 = Ochir-Goryaeva | first9 = Maria | last10 = Sizonov | first10 = Grigory V. | last11 = Soyonov | first11 = Vasiliy | last12 = Manica | first12 = Andrea | year = 2012  |display-authors=5 | title = Reconstructing the origin and spread of horse domestication in the Eurasian steppe | journal = Proceedings of the National Academy of Sciences| volume = 109 | issue = 21| pages = 8202–8206 | doi = 10.1073/pnas.1111122109 | pmid=22566639 | pmc=3361400| doi-access = free }}</ref> Both domesticated stallions and mares spread out from this area, and then additional wild mares were added from local herds; wild mares were easier to handle than wild stallions.  Most other parts of the world were ruled out as sites for horse domestication, either due to climate unsuitable for an indigenous wild horse population or no evidence of domestication.<ref name=LesteLasserre>[http://www.thehorse.com/ViewArticle.aspx?ID=20162 Lesté-Lasserre,Christa. Researchers: Horses First Domesticated in Western Steppes, The Horse 13 June 2012, Article # 20162]</ref>

Genes located on the [[Y-chromosome]] are inherited only from sire to its male offspring and these lines show a very reduced degree of genetic variation (aka genetic homogeneity) in modern domestic horses, far less than expected based on the overall genetic variation in the remaining genetic material.<ref name=Lau/><ref name="Lindgren2004" /> This indicates that a relatively few stallions were domesticated and that it is unlikely that many male offspring originating from unions between wild stallions and domestic mares were included in early domesticated breeding stock.<ref name=Lau/><ref name="Lindgren2004" />

Genes located in the mitochondrial DNA are passed on along the maternal line from the mother to her offspring. Multiple analyses of the mitochondrial DNA obtained from modern horses as well as from horse bones and teeth from archaeological and palaeological finds consistently shows an increased genetic diversity in the mitochondrial DNA compared to the remaining DNA, showing that a large number of mares has been included into the breeding stock of the originally domesticated horse.<ref name="Achilli"/><ref name="Jansen2002" /><ref name="Vila2001">{{cite journal | last = Vilà | first = C. | year = 2001 | title = Widespread origins of domestic horse lineages | journal = [[Science (journal)|Science]] | volume = 291 | issue = 5503 | pages = 474–477 | doi = 10.1126/science.291.5503.474 | pmid = 11161199 |display-authors=etal| bibcode = 2001Sci...291..474V }}</ref><ref>{{cite journal|author=Cozzi, M. C., Strillacci, M. G., Valiati, P., Bighignoli, B., Cancedda, M. & Zanotti, M. |title=Mitochondrial D-loop sequence variation among Italian horse breeds|journal=Genetics Selection Evolution|volume=36|issue=6|pages=663–672|pmc=2697199|year=2004|pmid=15496286|doi=10.1051/gse:2004023}}</ref><ref name=Lira>{{cite journal| title=Ancient DNA reveals traces of Iberian Neolithic and Bronze Age lineages in modern Iberian horses| author=Lira, Jaime| journal=Molecular Ecology| volume=19| issue=1| pages=64–78| year=2010| doi=10.1111/j.1365-294X.2009.04430.x| pmid=19943892| bibcode=2010MolEc..19...64L| s2cid=1376591| display-authors=etal| url=http://eprints.ucm.es/10548/2/Mol_Ecol_2009_Lira_et_al_Ancient_Iberian_horses.pdf| access-date=20 April 2018| archive-date=10 August 2017| archive-url=https://web.archive.org/web/20170810142737/http://eprints.ucm.es/10548/2/Mol_Ecol_2009_Lira_et_al_Ancient_Iberian_horses.pdf| url-status=dead}}</ref><ref name=priskin>{{cite journal | doi = 10.1007/s10709-009-9411-x | last1 = Priskin | first1 = K. | last2 = Szabo | first2 = K. | last3 = Tomory | first3 = G. | last4 = Bogacsi-Szabo | first4 = E. | last5 = Csanyi | first5 = B. | last6 = Eordogh | first6 = R. | last7 = Downes | first7 = C. S. | last8 = Rasko | first8 = I. | year = 2010 | title = Mitochondrial sequence variation in ancient horses from the Carpathian Basin and possible modern relatives | journal = Genetica | volume = 138 | issue = 2| pages = 211–218 | pmid = 19789983 | s2cid = 578727 }}</ref><ref name=Cai>{{cite journal | doi = 10.1016/j.jas.2008.11.006 | last1 = Cai | first1 = D. W. | last2 = Tang | first2 = Z. W. | last3 = Han | first3 = L. | last4 = Speller | first4 = C. F. | last5 = Yang | first5 = D. Y. Y. | last6 = Ma | first6 = X. L. | last7 = Cao | first7 = J. E. | last8 = Zhu | first8 = H. | last9 = Zhou | first9 = H. | year = 2009 | title = Ancient DNA provides new insights into the origin of the Chinese domestic horse | url =https://www.sfu.ca/~donyang/adnaweb/Cai%20DW%20JAS2009.pdf| journal = Journal of Archaeological Science | volume = 36 | issue =3 | pages = 835–842 | bibcode = 2009JArSc..36..835C }}</ref> 

Variation in the mitochondrial DNA is used to determine so-called [[haplogroup]]s.  A haplogroup is a group of closely related [[haplotype]]s that share the same common ancestor. In horses, eighteen main haplogroups are recognized (A-R).<ref name="Achilli">{{cite journal |last1=Achilli |first1=Alessandro |last2=Olivieri |first2=Anna |last3=Soares |first3=Pedro |last4=Lancioni |first4=Hovirag |last5=Kashani |first5=Baharak Hooshiar |last6=Perego |first6=Ugo A. |last7=Nergadze |first7=Solomon G. |last8=Carossa |first8=Valeria |last9=Santagostino |first9=Marco |last10=Capomaccio |first10=Stefano |last11=Felicetti |first11=Michela |last12=Al-Achkar |first12=Walid |last13=Penedo |first13=M. Cecilia T. |last14=Verini-Supplizi |first14=Andrea |last15=Houshmand |first15=Massoud |last16=Woodward |first16=Scott R. |last17=Semino |first17=Ornella |last18=Silvestrelli |first18=Maurizio |last19=Giulotto |first19=Elena |last20=Pereira |first20=Luísa |last21=Bandelt |first21=Hans-Jürgen |last22=Torroni |first22=Antonio |display-authors=5  |title=Mitochondrial genomes from modern horses reveal the major haplogroups that underwent domestication |journal=Proceedings of the National Academy of Sciences |date=14 February 2012 |volume=109 |issue=7 |pages=2449–2454 |doi=10.1073/pnas.1111637109 |pmid=22308342 |pmc=3289334 |bibcode=2012PNAS..109.2449A |language=en |issn=0027-8424|doi-access=free }}</ref> Several haplogroups are unequally distributed around the world, indicating the addition of local wild mares to the domesticated stock.<ref name="Jansen2002"/><ref name="Vila2001"/><ref name=Lira/><ref name=priskin/><ref name=Cai/>
[[File:Indo-European migrations.jpg|thumb|260px|The dispersal of the DOM2 genetic lineage, believed to be the ancestor of all modern domesticated horses, is linked with the populations which preceded the [[Sintashta culture]] and their expansions.<ref name="Librado"/>]]
In 2018, genomic comparison of 42 ancient-horse genomes, 20 of which were from Botai, with 46 published ancient and modern-horse genomes yielded surprising results. It was found that modern domestic horses are not closely related to the horses at Botai. Rather, Przewalski’s horses were identified as feral descendants of horses herded at Botai. Evidence suggested that "a massive genomic turnover" had occurred along with the domestication of horses and large-scale human population expansion in the Early Bronze Age.<ref name="Gaunitz">{{cite journal |last1=Gaunitz |first1=Charleen |last2=Fages |first2=Antoine |last3=Hanghøj |first3=Kristian |last4=Albrechtsen |first4=Anders |last5=Khan |first5=Naveed |last6=Schubert |first6=Mikkel |last7=Seguin-Orlando |first7=Andaine |last8=Owens |first8=Ivy J. |last9=Felkel |first9=Sabine |last10=Bignon-Lau |first10=Olivier |last11=de Barros Damgaard |first11=Peter |last12=Mittnik |first12=Alissa |last13=Mohaseb |first13=Azadeh F. |last14=Davoudi |first14=Hossein |last15=Alquraishi |first15=Saleh |last16=Alfarhan |first16=Ahmed H. |last17=Al-Rasheid |first17=Khaled A. S. |last18=Crubézy |first18=Eric |last19=Benecke |first19=Norbert |last20=Olsen |first20=Sandra |last21=Brown |first21=Dorcas |last22=Anthony |first22=David |last23=Massy |first23=Ken |last24=Pitulko |first24=Vladimir |last25=Kasparov |first25=Aleksei |last26=Brem |first26=Gottfried |last27=Hofreiter |first27=Michael |last28=Mukhtarova |first28=Gulmira |last29=Baimukhanov |first29=Nurbol |last30=Lõugas |first30=Lembi |last31=Onar |first31=Vedat |last32=Stockhammer |first32=Philipp W. |last33=Krause |first33=Johannes |last34=Boldgiv |first34=Bazartseren |last35=Undrakhbold |first35=Sainbileg |last36=Erdenebaatar |first36=Diimaajav |last37=Lepetz |first37=Sébastien |last38=Mashkour |first38=Marjan |last39=Ludwig |first39=Arne |last40=Wallner |first40=Barbara |last41=Merz |first41=Victor |last42=Merz |first42=Ilja |last43=Zaibert |first43=Viktor |last44=Willerslev |first44=Eske |last45=Librado |first45=Pablo |last46=Outram |first46=Alan K. |last47=Orlando |first47=Ludovic |display-authors=5  |title=Ancient genomes revisit the ancestry of domestic and Przewalski's horses |journal=Science |date=6 April 2018 |volume=360 |issue=6384 |pages=111–114 |doi=10.1126/science.aao3297 |pmid=29472442 |bibcode=2018Sci...360..111G |hdl=10871/31710 |s2cid=3491575 |url=https://www.science.org/doi/full/10.1126/science.aao3297 |access-date=20 May 2022 |language=en |issn=0036-8075|hdl-access=free }}</ref>
Subsequent research showed that horse lineages from Iberia and Siberia, also associated with early domestication, had little influence on the genetics of modern domestic horses.<ref name="Fages">{{cite journal |last1=Fages |first1=Antoine |last2=Hanghøj |first2=Kristian |last3=Khan |first3=Naveed |last4=Gaunitz |first4=Charleen |last5=Seguin-Orlando |first5=Andaine |last6=Leonardi |first6=Michela |last7=Constantz |first7=Christian McCrory |last8=Gamba |first8=Cristina |last9=Al-Rasheid |first9=Khaled A. S. |last10=Albizuri |first10=Silvia |last11=Alfarhan |first11=Ahmed H. |last12=Allentoft |first12=Morten |last13=Alquraishi |first13=Saleh |last14=Anthony |first14=David |last15=Baimukhanov |first15=Nurbol |last16=Barrett |first16=James H. |last17=Bayarsaikhan |first17=Jamsranjav |last18=Benecke |first18=Norbert |last19=Bernáldez-Sánchez |first19=Eloísa |last20=Berrocal-Rangel |first20=Luis |last21=Biglari |first21=Fereidoun |last22=Boessenkool |first22=Sanne |last23=Boldgiv |first23=Bazartseren |last24=Brem |first24=Gottfried |last25=Brown |first25=Dorcas |last26=Burger |first26=Joachim |last27=Crubézy |first27=Eric |last28=Daugnora |first28=Linas |last29=Davoudi |first29=Hossein |last30=Damgaard |first30=Peter de Barros |last31=Villa-Ceballos |first31=María de los Ángeles de Chorro y de |last32=Deschler-Erb |first32=Sabine |last33=Detry |first33=Cleia |last34=Dill |first34=Nadine |last35=Oom |first35=Maria do Mar |last36=Dohr |first36=Anna |last37=Ellingvåg |first37=Sturla |last38=Erdenebaatar |first38=Diimaajav |last39=Fathi |first39=Homa |last40=Felkel |first40=Sabine |last41=Fernández-Rodríguez |first41=Carlos |last42=García-Viñas |first42=Esteban |last43=Germonpré |first43=Mietje |last44=Granado |first44=José D. |last45=Hallsson |first45=Jón H. |last46=Hemmer |first46=Helmut |last47=Hofreiter |first47=Michael |last48=Kasparov |first48=Aleksei |last49=Khasanov |first49=Mutalib |last50=Khazaeli |first50=Roya |last51=Kosintsev |first51=Pavel |last52=Kristiansen |first52=Kristian |last53=Kubatbek |first53=Tabaldiev |last54=Kuderna |first54=Lukas |last55=Kuznetsov |first55=Pavel |last56=Laleh |first56=Haeedeh |last57=Leonard |first57=Jennifer A. |last58=Lhuillier |first58=Johanna |last59=Lettow-Vorbeck |first59=Corina Liesau von |last60=Logvin |first60=Andrey |last61=Lõugas |first61=Lembi |last62=Ludwig |first62=Arne |last63=Luis |first63=Cristina |last64=Arruda |first64=Ana Margarida |last65=Marques-Bonet |first65=Tomas |last66=Silva |first66=Raquel Matoso |last67=Merz |first67=Victor |last68=Mijiddorj |first68=Enkhbayar |last69=Miller |first69=Bryan K. |last70=Monchalov |first70=Oleg |last71=Mohaseb |first71=Fatemeh A. |last72=Morales |first72=Arturo |last73=Nieto-Espinet |first73=Ariadna |last74=Nistelberger |first74=Heidi |last75=Onar |first75=Vedat |last76=Pálsdóttir |first76=Albína H. |last77=Pitulko |first77=Vladimir |last78=Pitskhelauri |first78=Konstantin |last79=Pruvost |first79=Mélanie |last80=Sikanjic |first80=Petra Rajic |last81=Papeša |first81=Anita Rapan |last82=Roslyakova |first82=Natalia |last83=Sardari |first83=Alireza |last84=Sauer |first84=Eberhard |last85=Schafberg |first85=Renate |last86=Scheu |first86=Amelie |last87=Schibler |first87=Jörg |last88=Schlumbaum |first88=Angela |last89=Serrand |first89=Nathalie |last90=Serres-Armero |first90=Aitor |last91=Shapiro |first91=Beth |last92=Seno |first92=Shiva Sheikhi |last93=Shevnina |first93=Irina |last94=Shidrang |first94=Sonia |last95=Southon |first95=John |last96=Star |first96=Bastiaan |last97=Sykes |first97=Naomi |last98=Taheri |first98=Kamal |last99=Taylor |first99=William |last100=Teegen |first100=Wolf-Rüdiger |last101=Vukičević |first101=Tajana Trbojević |last102=Trixl |first102=Simon |last103=Tumen |first103=Dashzeveg |last104=Undrakhbold |first104=Sainbileg |last105=Usmanova |first105=Emma |last106=Vahdati |first106=Ali |last107=Valenzuela-Lamas |first107=Silvia |last108=Viegas |first108=Catarina |last109=Wallner |first109=Barbara |last110=Weinstock |first110=Jaco |last111=Zaibert |first111=Victor |last112=Clavel |first112=Benoit |last113=Lepetz |first113=Sébastien |last114=Mashkour |first114=Marjan |last115=Helgason |first115=Agnar |last116=Stefánsson |first116=Kári |last117=Barrey |first117=Eric |last118=Willerslev |first118=Eske |last119=Outram |first119=Alan K. |last120=Librado |first120=Pablo |last121=Orlando |first121=Ludovic |display-authors=5  |title=Tracking Five Millennia of Horse Management with Extensive Ancient Genome Time Series |journal=Cell |date=30 May 2019 |volume=177 |issue=6 |pages=1419–1435.e31 |doi=10.1016/j.cell.2019.03.049 |pmid=31056281 |pmc=6547883 |language=English |issn=0092-8674}}</ref>

More than 150 scientists collaborated in gathering 264 ancient horse genomes from across Eurasia, dating from 50,000 to 200 B.C.E.<ref name="Dance"/> In October 2021, results of the analysis were published in ''Nature''. They indicated that domestication of the modern horse's ancestors likely occurred in the [[Volga region|Volga-Don]] region of the [[Pontic–Caspian steppe]] grasslands of [[Western Eurasia]].<ref name="Dance"/><ref name="Librado"/> Both Tarpan and Przewalski’s horse were related to different ancestral populations than those underlying the modern domestic horses (DOM2).<ref name="Librado"/><ref>{{Cite journal |last1=Taylor |first1=William Timothy Treal |last2=Barrón-Ortiz |first2=Christina Isabelle |date=2021-04-02 |title=Rethinking the evidence for early horse domestication at Botai |journal=Scientific Reports |language=en |volume=11 |issue=1 |pages=7440 |doi=10.1038/s41598-021-86832-9 |pmid=33811228 |issn=2045-2322|pmc=8018961 |bibcode=2021NatSR..11.7440T }}</ref> 

In addition, researchers were able to map population changes over time as modern domestic horses expanded rapidly across Eurasia and displaced other local populations, from about 2000&nbsp;BCE onwards.  The genetic profile for DOM2 horses is associated with horses buried in [[Sintashta culture|Sintashta]] [[kurgan]]s with early spoke-wheeled chariots, and with horses in Central Anatolia where two-wheeled vehicles were depicted. DOM2 horses also occur in some areas prior to the earliest evidence for chariots, suggesting that both horseback riding and chariot use were factors in expansion.<ref name="Librado"/>

Genetic data may also provide clues as to why this particular domestication event had far more widespread impact than other domestication events in Botai, Iberia, SIberia and Anatolia.  The genetic lineage that leads to modern domestic horses shows evidence of strong selection for  locomotor and behavioural adaptations.  Changes relate to the GSDMC gene and the ZFPM1 gene. The GSDMC gene is linked to back problems in people, and scientists speculate that changes may have made horses' backs stronger.  The ZFPM1 gene is related to mood regulation, and scientists speculate that this may have made horses more docile and easier to tame and manage. Strength and docility would have made horses more suitable for riding and other uses.<ref name="Dance"/><ref name="Librado"/>

==Archaeological evidence==
[[File:Modern loose interpretation at the The Pharaonic Village in Cairo of a Battle scene from the Great Kadesh reliefs of Ramses II on the Walls of the Ramesseum.jpg|thumb|225px|Chariots of [[Ramesses II]] and the [[Hittites]] in the [[Battle of Kadesh]], 1274 BCE. Modern interpretation of a relief on the walls of the [[Ramesseum]]]]
Archaeological evidence for the domestication of the horse comes from three kinds of sources: 1) changes in the skeletons and teeth of ancient horses; 2) changes in the geographic distribution of ancient horses, particularly the introduction of horses into regions where no wild horses had existed; and
3) [[archaeology|archaeological]] sites containing artifacts, images, or evidence of changes in human behavior connected with horses.

Examples include horse remains [[horse burial|interred in human graves]]; changes in the ages and sexes of the horses killed by humans; the appearance of horse [[corral]]s; equipment such as [[bit (horse)|bits]] or other types of [[horse tack]]; horses interred with equipment intended for use by horses, such as [[chariot]]s; and depictions of horses used for equestrianism, driving, draught work, or symbols of human power.

Few of these categories, taken alone, provide irrefutable evidence of domestication, but the cumulative evidence becomes increasingly more persuasive.
[[File:Рисунок лошади, мамонта, носорога. Пещера Шульган-Таш.png|thumb|225px|Drawing of a horse, a mammoth, and a rhinoceros in the [[Kapova Cave|Shulgan-Tash Cave]], 25-10 thousand years B.C.]]

===Horses interred with chariots===
The least ancient, but most persuasive, evidence of domestication comes from sites where horse leg bones and skulls, probably originally attached to hides, were interred with the remains of chariots in at least 16 graves of the [[Sintashta]] and [[Petrovka settlement|Petrovka]] cultures. These were located in the steppes southeast of the [[Ural Mountains]], between the upper [[Ural River|Ural]] and upper [[Tobol River]]s, a region today divided between southern [[Russia]] and northern [[Kazakhstan]]. Petrovka was a little later than and probably grew out of Sintashta, and the two complexes together spanned about 2100–1700 BCE.<ref name="Anthony2007" /><ref name="Kuznetsov2006">{{cite journal | last = Kuznetsov | first = P. F. | year = 2006 | title = The emergence of Bronze Age chariots in eastern Europe | journal = [[Antiquity (journal)|Antiquity]] | volume = 80 | issue =  309| pages = 638–645 | doi = 10.1017/s0003598x00094096 | s2cid = 162580424}}</ref> A few of these graves contained the remains of as many as eight sacrificed horses placed in, above, and beside the grave.

In all of the dated chariot graves, the heads and hooves of a pair of horses were placed in a grave that once contained a chariot. Evidence of chariots in these graves was inferred from the impressions of two spoked wheels set in grave floors 1.2–1.6m apart; in most cases the rest of the vehicle left no trace. In addition, a pair of disk-shaped antler "cheekpieces," an ancient predecessor to a modern [[bit shank]] or [[bit ring]], were placed in pairs beside each horse head-and-hoof sacrifice. The inner faces of the disks had protruding prongs or studs that would have pressed against the horse's lips when the [[rein]]s were pulled on the opposite side. Studded cheekpieces were a new and fairly severe kind of control device that appeared simultaneously with chariots.

All of the dated chariot graves contained wheel impressions, horse bones, weapons (arrow and javelin points, axes, daggers, or stone mace-heads), human skeletal remains, and cheekpieces. Because they were buried in teams of two with chariots and studded cheekpieces, the evidence is extremely persuasive that these steppe horses of 2100–1700 BCE were domesticated. Shortly after the period of these burials, the expansion of the domestic horse throughout Europe was little short of explosive. In the space of possibly 500 years, there is evidence of horse-drawn chariots in Greece, Egypt, and Mesopotamia. By another 500 years, the horse-drawn chariot had spread to China.

===Skeletal indicators of domestication===
Some researchers do not consider an animal to be "domesticated" until it exhibits physical changes consistent with [[selective breeding]], or at least having been born and raised entirely in captivity. Until that point, they classify captive animals as merely "tamed". Those who hold to this theory of domestication point to a change in skeletal measurements detected among [[skeletal system of the horse|horse bones]] recovered from middens dated about 2500 BCE in eastern [[Hungary]] in [[Beaker culture|Bell-Beaker]] sites, and in later [[Bronze Age]] sites in the [[Russia]]n steppes, [[Spain]], and [[Eastern Europe]].<ref name="Benecke and von den Dreisch 2003"/><ref name="Bökönyi1978">{{cite journal | last = Bökönyi | first = Sándor | year = 1978 | title = The earliest waves of domestic horses in east Europe | journal = [[Journal of Indo-European Studies]] | volume = 6 | issue = 1/2 | pages = 17–76 }}</ref> Horse bones from these contexts exhibited an increase in variability, thought to reflect the survival under human care of both larger and smaller individuals than appeared in the wild; and a decrease in average size, thought to reflect penning and restriction in diet. Horse populations that showed this combination of skeletal changes probably were domesticated. Most evidence suggests that horses were increasingly controlled by humans after about 2500 BCE. However, more recently there have been skeletal remains found at a site in [[Kazakhstan]] which display the smaller, more slender limbs characteristic of corralled animals, dated to 3500 BCE.<ref name="Outram"/>

===Botai culture===
Some of the most intriguing evidence of early domestication comes from the [[Botai culture]], found in northern [[Kazakhstan]]. The Botai culture was a culture of [[Hunter-gatherer|forager]]s who seem to have adopted horseback riding in order to hunt the abundant wild horses of northern Kazakhstan between 3500 and 3000 BCE.<ref name="Olsen2003">{{cite book |title=Prehistoric Steppe Adaptation and the Horse |last=Olsen |first=Sandra L. |editor=Levine, Marsha |editor2=Renfrew, Colin |editor3=Boyle, Katie |year=2003 |publisher=McDonald Institute |location=Cambridge |isbn=978-1-902937-09-0 |pages=83–104 |chapter=The exploitation of horses at Botai, Kazakhstan }}</ref><ref name="Anthony and Brown 2000" /> Botai sites had no cattle or sheep bones; the only domesticated animals, in addition to horses, were dogs. Botai settlements in this period contained between 50 and 150 pit houses. Garbage deposits contained tens to hundreds of thousands of discarded animal bones, 65% to 99% of which had come from horses. Also, there has been evidence found of horse milking at these sites, with horse milk fats soaked into pottery shards dating to 3500 BCE.<ref name="Outram"/> Earlier hunter-gatherers who lived in the same region had not hunted wild horses with such success, and lived for millennia in smaller, more shifting settlements, often containing less than 200 wild animal bones.

Entire herds of horses were slaughtered by the Botai hunters, apparently in hunting drives. The adoption of horseback riding might explain the emergence of specialised horse-hunting techniques and larger, more permanent settlements. Domesticated horses could have been adopted from neighboring herding societies in the steppes west of the Ural Mountains, where the [[Khvalynsk culture]] had herds of cattle and sheep, and perhaps had domesticated horses, as early as 4800 BCE.<ref name="Anthony and Brown 2000"/>

Other researchers have argued that all of the Botai horses were wild, and that the horse-hunters of Botai hunted wild horses on foot. As evidence, they note that zoologists have found no skeletal changes in the Botai horses that indicate domestication. Moreover, because they were hunted for food, the majority of the horse remains found in Botai-culture settlements indeed probably were wild. On the other hand, any domesticated riding horses were probably the same size as their wild cousins and cannot now be distinguished by bone measurements.<ref name="Benecke and von den Dreisch 2003"/> They also note that the age structure of the horses slaughtered at Botai represents a natural demographic profile for hunted animals, not the pattern expected if they were domesticated and selected for slaughter.<ref name="Levine1999" /> However, these arguments were published before a Copper Age corral was discovered at Krasnyi Yar in 2006 and mats of horse-dung at two other Botai sites.<ref name="Biello">{{cite news |last1=Biello |first1=David |title=Horsemen of the Steppes: Ancient Corrals Found in Kazakhstan |url=https://www.scientificamerican.com/article/horsemen-of-the-steppes-a/ |access-date=18 May 2022 |work=Scientific American |date=October 27, 2006 |language=en}}</ref> Current findings continue to support the Botai as having domesticated horses.<ref name=Outram2023>{{cite journal| doi=10.3389/fearc.2023.1134068| doi-access=free| title=Horse domestication as a multi-centered, multi-stage process: Botai and the role of specialised Eneolithic horse pastoralism in the development of human-equine relationships| date=2023| last1=Outram| first1=Alan K.| journal=Frontiers in Environmental Archaeology| volume=2| hdl=10871/133044| hdl-access=free}}</ref>

A study in 2018 revealed that the Botai horses did not contribute significantly to the genetics of modern domesticated horses, and that therefore a subsequent and separate domestication event must have been responsible for the modern domestic horse. Genetic evidence also connects Botai horses with [[Przewalski's horse]] in Mongolia, which has led to debates over whether Przewalski's horses should be considered a never-domesticated population or feral descendants of domesticated Botai horses.<ref name="Dance"/><ref name="Librado">{{cite journal |last1=Librado |first1=Pablo |last2=Khan |first2=Naveed |last3=Fages |first3=Antoine |last4=Kusliy |first4=Mariya A. |last5=Suchan |first5=Tomasz |last6=Tonasso-Calvière |first6=Laure |last7=Schiavinato |first7=Stéphanie |last8=Alioglu |first8=Duha |last9=Fromentier |first9=Aurore |last10=Perdereau |first10=Aude |last11=Aury |first11=Jean-Marc |last12=Gaunitz |first12=Charleen |last13=Chauvey |first13=Lorelei |last14=Seguin-Orlando |first14=Andaine |last15=Der Sarkissian |first15=Clio |last16=Southon |first16=John |last17=Shapiro |first17=Beth |last18=Tishkin |first18=Alexey A. |last19=Kovalev |first19=Alexey A. |last20=Alquraishi |first20=Saleh |last21=Alfarhan |first21=Ahmed H. |last22=Al-Rasheid |first22=Khaled A. S. |last23=Seregély |first23=Timo |last24=Klassen |first24=Lutz |last25=Iversen |first25=Rune |last26=Bignon-Lau |first26=Olivier |last27=Bodu |first27=Pierre |last28=Olive |first28=Monique |last29=Castel |first29=Jean-Christophe |last30=Boudadi-Maligne |first30=Myriam |last31=Alvarez |first31=Nadir |last32=Germonpré |first32=Mietje |last33=Moskal-del Hoyo |first33=Magdalena |last34=Wilczyński |first34=Jarosław |last35=Pospuła |first35=Sylwia |last36=Lasota-Kuś |first36=Anna |last37=Tunia |first37=Krzysztof |last38=Nowak |first38=Marek |last39=Rannamäe |first39=Eve |last40=Saarma |first40=Urmas |last41=Boeskorov |first41=Gennady |last42=Lōugas |first42=Lembi |last43=Kyselý |first43=René |last44=Peške |first44=Lubomír |last45=Bălășescu |first45=Adrian |last46=Dumitrașcu |first46=Valentin |last47=Dobrescu |first47=Roxana |last48=Gerber |first48=Daniel |last49=Kiss |first49=Viktória |last50=Szécsényi-Nagy |first50=Anna |last51=Mende |first51=Balázs G. |last52=Gallina |first52=Zsolt |last53=Somogyi |first53=Krisztina |last54=Kulcsár |first54=Gabriella |last55=Gál |first55=Erika |last56=Bendrey |first56=Robin |last57=Allentoft |first57=Morten E. |last58=Sirbu |first58=Ghenadie |last59=Dergachev |first59=Valentin |last60=Shephard |first60=Henry |last61=Tomadini |first61=Noémie |last62=Grouard |first62=Sandrine |last63=Kasparov |first63=Aleksei |last64=Basilyan |first64=Alexander E. |last65=Anisimov |first65=Mikhail A. |last66=Nikolskiy |first66=Pavel A. |last67=Pavlova |first67=Elena Y. |last68=Pitulko |first68=Vladimir |last69=Brem |first69=Gottfried |last70=Wallner |first70=Barbara |last71=Schwall |first71=Christoph |last72=Keller |first72=Marcel |last73=Kitagawa |first73=Keiko |last74=Bessudnov |first74=Alexander N. |last75=Bessudnov |first75=Alexander |last76=Taylor |first76=William |last77=Magail |first77=Jérome |last78=Gantulga |first78=Jamiyan-Ombo |last79=Bayarsaikhan |first79=Jamsranjav |last80=Erdenebaatar |first80=Diimaajav |last81=Tabaldiev |first81=Kubatbeek |last82=Mijiddorj |first82=Enkhbayar |last83=Boldgiv |first83=Bazartseren |last84=Tsagaan |first84=Turbat |last85=Pruvost |first85=Mélanie |last86=Olsen |first86=Sandra |last87=Makarewicz |first87=Cheryl A. |last88=Valenzuela Lamas |first88=Silvia |last89=Albizuri Canadell |first89=Silvia |last90=Nieto Espinet |first90=Ariadna |last91=Iborra |first91=Ma Pilar |last92=Lira Garrido |first92=Jaime |last93=Rodríguez González |first93=Esther |last94=Celestino |first94=Sebastián |last95=Olària |first95=Carmen |last96=Arsuaga |first96=Juan Luis |last97=Kotova |first97=Nadiia |last98=Pryor |first98=Alexander |last99=Crabtree |first99=Pam |last100=Zhumatayev |first100=Rinat |last101=Toleubaev |first101=Abdesh |last102=Morgunova |first102=Nina L. |last103=Kuznetsova |first103=Tatiana |last104=Lordkipanize |first104=David |last105=Marzullo |first105=Matilde |last106=Prato |first106=Ornella |last107=Bagnasco Gianni |first107=Giovanna |last108=Tecchiati |first108=Umberto |last109=Clavel |first109=Benoit |last110=Lepetz |first110=Sébastien |last111=Davoudi |first111=Hossein |last112=Mashkour |first112=Marjan |last113=Berezina |first113=Natalia Ya |last114=Stockhammer |first114=Philipp W. |last115=Krause |first115=Johannes |last116=Haak |first116=Wolfgang |last117=Morales-Muñiz |first117=Arturo |last118=Benecke |first118=Norbert |last119=Hofreiter |first119=Michael |last120=Ludwig |first120=Arne |last121=Graphodatsky |first121=Alexander S. |last122=Peters |first122=Joris |last123=Kiryushin |first123=Kirill Yu |last124=Iderkhangai |first124=Tumur-Ochir |last125=Bokovenko |first125=Nikolay A. |last126=Vasiliev |first126=Sergey K. |last127=Seregin |first127=Nikolai N. |last128=Chugunov |first128=Konstantin V. |last129=Plasteeva |first129=Natalya A. |last130=Baryshnikov |first130=Gennady F. |last131=Petrova |first131=Ekaterina |last132=Sablin |first132=Mikhail |last133=Ananyevskaya |first133=Elina |last134=Logvin |first134=Andrey |last135=Shevnina |first135=Irina |last136=Logvin |first136=Victor |last137=Kalieva |first137=Saule |last138=Loman |first138=Valeriy |last139=Kukushkin |first139=Igor |last140=Merz |first140=Ilya |last141=Merz |first141=Victor |last142=Sakenov |first142=Sergazy |last143=Varfolomeyev |first143=Victor |last144=Usmanova |first144=Emma |last145=Zaibert |first145=Viktor |last146=Arbuckle |first146=Benjamin |last147=Belinskiy |first147=Andrey B. |last148=Kalmykov |first148=Alexej |last149=Reinhold |first149=Sabine |last150=Hansen |first150=Svend |last151=Yudin |first151=Aleksandr I. |last152=Vybornov |first152=Alekandr A. |last153=Epimakhov |first153=Andrey |last154=Berezina |first154=Natalia S. |last155=Roslyakova |first155=Natalia |last156=Kosintsev |first156=Pavel A. |last157=Kuznetsov |first157=Pavel F. |last158=Anthony |first158=David |last159=Kroonen |first159=Guus J. |last160=Kristiansen |first160=Kristian |last161=Wincker |first161=Patrick |last162=Outram |first162=Alan |last163=Orlando |first163=Ludovic |display-authors=5  |title=The origins and spread of domestic horses from the Western Eurasian steppes |journal=Nature |date=October 2021 |volume=598 |issue=7882 |pages=634–640 |doi=10.1038/s41586-021-04018-9 |pmid=34671162 |pmc=8550961 |bibcode=2021Natur.598..634L |language=en |issn=1476-4687}}</ref>

===Bit wear===
[[File:Persianbit1.jpg|thumb|A [[Luristan bronze]] horse [[bit (horse)|bit]]]]

The presence of [[bit (horse)|bit]] wear is an indicator that a horse was ridden or driven, and the earliest of such evidence from a site in Kazakhstan dates to 3500 BCE. The absence of bit wear on [[horse teeth]] is not conclusive evidence against domestication because horses can be ridden and controlled without bits by using a [[noseband]] or a [[hackamore]], but such materials do not produce significant physiological changes nor are they apt to be preserved for millennia.

The regular use of a bit to control a horse can create wear facets or bevels on the anterior corners of the lower second [[premolars]]. The corners of the horse's mouth normally keep the bit on the "bars" of the mouth, an [[diastema|interdental space]] where there are no teeth, forward of the premolars. The bit must be manipulated by a human or the horse must move it with its tongue for it to touch the teeth. Wear can be caused by the bit abrading the front corners of the premolars if the horse grasps and releases the bit between its [[horse teeth|teeth]]; other wear can be created by the bit striking the vertical front edge of the lower premolars,<ref name="Brown1998">{{cite journal | last = Brown | first = Dorcas |author2=Anthony, David W. | year = 1998 | title = Bit Wear, Horseback Riding and the Botai site in Kazakstan | journal = Journal of Archaeological Science | volume = 25 | issue = 4 | pages = 331–347 | doi = 10.1006/jasc.1997.0242 | bibcode = 1998JArSc..25..331B }}</ref><ref name="Bendry2007">{{cite journal | last = Bendry | first = Robin | year = 2007 | title = New methods for the identification of evidence for bitting on horse remains from archaeological sites | journal = Journal of Archaeological Science | volume = 34 | issue = 7 | pages = 1036–1050 | doi = 10.1016/j.jas.2006.09.010 | bibcode = 2007JArSc..34.1036B }}</ref> due to very strong pressure from a human handler.

Modern experiments showed that even organic bits of rope or leather can create significant wear facets, and also showed that facets 3mm (.118 in) deep or more do not appear on the premolars of wild horses.<ref name="Anthony2006">{{cite book |title=Horses and Humans: The Evolution of the Equine-Human Relationship |last=Anthony |first=David W. |author2=Brown, Dorcas R. |author3=George, Christian  |editor=Olsen, Sandra L. |editor2=Grant, Susan |editor3=Choyke, Alice |editor4=Bartosiewicz, Laszlo |year=2006 |publisher=Archaeopress |location=Oxford |isbn=978-1-84171-990-0 |pages=137–156 |chapter=Early horseback riding and warfare: the importance of the magpie around the neck |series=British Archaeological Reports International Series |volume=1560 }}</ref> However, other researchers disputed both conclusions.<ref name="Levine1999">{{cite book |title=Late Prehistoric Exploitation of the Eurasian Steppe |last=Levine |first=Marsha A. |editor=Levine, Marsha |editor2=Rassamakin, Yuri |editor3=Kislenko, Aleksandr |editor4=Tatarintseva, Nataliya |year=1999 |publisher=McDonald Institute Monographs |location=Cambridge |isbn=978-1-902937-03-8 |pages=5–58 |chapter=The Origins of Horse Husbandry on the Eurasian Steppe }}</ref>

Wear facets of 3&nbsp;mm or more were found on seven horse premolars in two sites of the Botai culture, Botai and Kozhai 1, dated about 3500–3000 BCE.<ref name="Anthony and Brown 2000" /><ref name="Anthony1991" /> The Botai culture premolars are the earliest reported multiple examples of this dental pathology in any archaeological site, and preceded any skeletal change indicators by 1,000 years. While wear facets more than 3&nbsp;mm deep were discovered on the lower second premolars of a single [[stallion]] from [[Dereivka]] in [[Ukraine]], an [[Eneolithic]] settlement dated about 4000 BCE,<ref name="Anthony1991">{{cite journal | doi = 10.1038/scientificamerican1291-94 | last = Anthony | first = David W. |author2=Telegin, Dimitri |author3=Brown, Dorcas | year = 1991 | title = The origin of horseback riding | journal = [[Scientific American]] | volume = 265 | issue = 6 | pages = 94–100 | bibcode = 1991SciAm.265f..94A }}</ref> dental material from one of the worn teeth later produced a radiocarbon date of 700–200 BCE, indicating that this stallion was actually deposited in a pit dug into the older Eneolithic site during the [[Iron Age]].<ref name="Anthony and Brown 2000">{{cite journal | last = Anthony | first = David W. |author2=Brown, Dorcas | year = 2000 | title = Eneolithic horse exploitation in the Eurasian steppes: diet, ritual and riding | journal = Antiquity | volume = 74 | issue = 283| pages = 75–86 | doi = 10.1017/S0003598X00066163 | s2cid = 163782751 }}</ref>

===Dung and corrals===
[[Soil scientist]]s working with Sandra Olsen of the [[Carnegie Museum of Natural History]] at the [[Chalcolithic]] settlements of Botai and [[Krasnyi Yar (Kazakhstan)|Krasnyi Yar]] in northern Kazakhstan found layers of horse dung, discarded in unused house pits in both settlements.<!--dated to when??--><ref name="French2003">{{cite book |title=Prehistoric Steppe Adaptation and the Horse |last=French |first=Charly |author2=Kousoulakou, Maria |editor=Levine, Marsha |editor2=Renfrew, Colin |editor3=Boyle, Katie |year=2003 |publisher=McDonald Institute |location=Cambridge |isbn=978-1-902937-09-0 |pages=105–114 |chapter=Geomorphological and micromorphological investigations of paleosols, valley sediments, and a sunken-floored dwelling at Botai, Kazakstan }}</ref> The collection and disposal of horse dung suggests that horses were confined in corrals or stables. An actual corral, dated to 3500–3000 BCE was identified at Krasnyi Yar by a pattern of post holes for a circular fence, with the [[soil]]s inside the fence yielding ten times more [[phosphorus]] than the soils outside. The phosphorus could represent the remains of manure.<ref name="Olsen2006">{{cite conference |first=Sandra L. |last=Olsen |title=Geochemical evidence of possible horse domestication at the Copper Age Botai settlement of Krasnyi Yar, Kazakhstan |conference=Geological Society of America Annual Meeting |date=2006-10-23 }}</ref>

===Geographic expansion===
The appearance of horse remains in human settlements in regions where they had not previously been present is another indicator of domestication. Although images of horses appear as early as the [[Upper Paleolithic]] period in places such as the caves of [[Lascaux]], France, suggesting that wild horses lived in regions outside of the Eurasian steppes<!--i.e. what today is the Ukraine and Eastern Europe--> before domestication and may have even been hunted by early humans, concentration of remains suggests animals being deliberately captured and contained, an indicator of domestication, at least for food, if not necessarily use as a working animal.

Around 3500–3000 BCE, horse bones began to appear more frequently in archaeological sites beyond their center of distribution in the Eurasian steppes and were seen in central [[Europe]], the middle and lower [[Danube]] valley, and the North [[Caucasus]] and [[South Caucasus|Transcaucasia]]. Evidence of horses in these areas had been rare before, and as numbers increased, larger animals also began to appear in horse remains. This expansion in range was contemporary with the Botai culture, where there are indications that horses were corralled and ridden. This does not necessarily mean that horses were first domesticated in the steppes, but the horse-hunters of the steppes certainly pursued wild horses more than in any other region.<ref name="Bökönyi1978" /><ref name="Benecke1994" /><ref name="Bökönyi1991" />

European wild horses were hunted for up to 10% of the animal bones in a handful of [[Mesolithic]] and [[Neolithic]] settlements scattered across [[Spain]], [[France]], and the marshlands of northern [[Germany]], but in many other parts of Europe, including [[Greece]], the [[Balkans]], the [[British Isles]], and much of central Europe, horse bones do not occur or occur very rarely in Mesolithic, Neolithic or Chalcolithic sites. In contrast, wild horse bones regularly exceeded 40% of the identified animal bones in Mesolithic and Neolithic camps in the Eurasian steppes, west of the Ural Mountains.<ref name="Benecke1994" /><ref name="Benecke1997">{{cite journal | last = Benecke | first = Norbert | year = 1997 | title = Archaeozoological studies on the transition from the Mesolithic to the Neolithic in the North Pontic region |url=http://sciencepress.mnhn.fr/sites/default/files/articles/pdf/az1998n25-26a73.pdf| journal = Anthropozoologica | volume = 25–26 | pages = 631–641 }}</ref><ref name="Uerpmann1990">{{cite journal | last = Uerpmann | first = Hans-Peter | year = 1990 | title = Die Domestikation des Pferdes im Chalcolithikum West– und Mitteleuropas | journal = Madrider Mitteilungen | volume = 31 | pages = 109–153 }}</ref>

Horse bones were rare or absent in [[Neolithic]] and [[Chalcolithic]] kitchen garbage in western [[Turkey]], [[Mesopotamia]], most of [[Iran]], South and Central [[Asia]], and much of Europe.<ref name="Benecke1994">{{cite book |title=Archäozoologische Studien zur Entwicklung der Haustierhaltung in Mitteleuropa und Südskandinavien von Anfängen bis zum ausgehenden Mittelalter |last=Benecke |first=Norbert |year=1994 |publisher=Akademie Verlag |location=Berlin |isbn=978-3-05-002415-8 |series=Schriften zur Ur– und Frühgeschichte |volume=46 }}</ref><ref name="Bökönyi1991">{{cite book |title=Equids in the Ancient World |series=Beihefte zum Tübinger Atlas des Vorderen Orients: Reihe A (Naturwissenschaften) |volume=19 |last=Bökönyi |first=Sándor |editor=Meadow, Richard H. |editor2=Uerpmann, Hans-Peter |year=1991 |publisher=Ludwig Reichert Verlag |location=Wiesbaden |pages=123–131 |chapter=Late Chalcolithic horses in Anatolia }}</ref><ref>{{cite journal | last = Meadow | first = Richard H. |author2=Patel, Ajita | year = 1997 | title = A comment on 'Horse Remains from Surkotada' by Sándor Bökönyi | journal = South Asian Studies | volume = 13 | pages = 308–315| doi=10.1080/02666030.1997.9628545}}</ref> While horse bones have been identified in Neolithic sites in central Turkey, all [[equid]]s together totaled less than 3% of the animal bones. Within this three percent, horses were less than 10%, with 90% or more of the equids represented by [[onager]]s (''Equus hemionus'') or another ass-like equid that later became extinct, the hydruntine or European wild ass (''[[Equus hydruntinus]]'').<ref name="Russell2005">{{cite book |title=Inhabiting Çatalhöyük: Reports From the 1995–1999 Seasons |volume=4 |last=Russell |first=Nerissa |author2=Martin, Louise |editor=Hodder, Ian |year=2005 |publisher=McDonald Institute for Archaeological Research |location=Cambridge |pages=33–98 |chapter=Çatalhöyük Mammal Remains }}</ref> Onagers were the most common native wild equids of the Near East. They were hunted in [[Syria]], [[Anatolia]], [[Mesopotamia]], [[Iran]], and Central Asia; and domesticated asses (''[[Equus asinus]]'') were imported into Mesopotamia, probably from [[Egypt]], but wild horses apparently did not live there.<!--where? Egypt or Mesopotamia?--><ref name="Oates2003">{{cite book |title=Prehistoric Steppe Adaptation and the Horse |last=Oates |first=Joan |editor=Levine, Marsha |editor2=Renfrew, Colin |editor3=Boyle, Katie |year=2003 |publisher=McDonald Institute |location=Cambridge |isbn=978-1-902937-09-0 |pages=115–125 |chapter=A note on the early evidence for horse and the riding of equids in Western Asia }}</ref>

====Other evidence of geographic expansion====
[[File:Ashurbanipal inspects booty and prisoners from Babylon, 645-640 BCE.jpg|thumb|225px|Relief depicting [[Assyria]]n king [[Ashurbanipal]] in a chariot, inspecting booty and prisoners from [[Babylon]]]]
In [[Northern Caucasus]], the [[Maikop culture]] settlements and burials of c. 3300 BC contain both horse bones and images of horses. A frieze of nineteen horses painted in black and red colours is found in one of the Maikop graves. The widespread appearance of horse bones and images in Maikop sites suggest to some observers that horseback riding began in the Maikop period.<ref name="Anthony2007"/>{{rp|291}}

Later, images of horses, identified by their short ears, flowing manes, and tails that bushed out at the dock, began to appear in artistic media in Mesopotamia during the [[Akkadian Empire|Akkadian]] period, 2300–2100 BCE. The word for "horse", literally translated as ''ass of the mountains,'' first appeared in [[Sumer]]ian documents during the [[Third dynasty of Ur]], about 2100–2000 BCE.<ref name="Oates2003" /><ref name="Drews2004">{{cite book |title=Early Riders: The beginnings of mounted warfare in Asia and Europe |last=Drews |first=Robert |author-link=Robert Drews |year=2004 |publisher=Routledge |location=London |isbn=978-0-415-32624-7 }}</ref> The kings of the Third Dynasty of Ur apparently fed horses to lions for royal entertainment, perhaps indicating that horses were still regarded as more exotic than useful, but King [[Shulgi]], about 2050 BCE, compared himself to "a horse of the highway that swishes its tail", and one image from his reign showed a man apparently riding a horse at full gallop.<ref name="Owen1991">{{cite journal | last = Owen | first = David I. | year = 1991 | title = The first equestrian: an Ur III glyptic scene | journal = Acta Sumerologica | volume = 13 | pages = 259–273}}</ref> Horses were imported into Mesopotamia and the lowland Near East in larger numbers after 2000 BCE in connection with the beginning of [[Chariot tactics|chariot warfare]], replacing the long-established [[Kunga (equid)|kunga]] (a hybrid between the now-extinct [[Syrian wild ass]] and a [[domestic donkey]]) as the main equid for warfare.

[[File:Shirenzigou panorama.png|thumb|Surroundings of the [[Barkol Kazakh Autonomous County|Shirenzigou]] archaeological site in Barkol County.]]
A further expansion, into the lowland [[Near East]] and northwestern [[China]], also happened around 2000 BCE. Although ''Equus'' bones of uncertain species are found in some Late Neolithic sites in China dated before 2000 BCE, ''Equus caballus'' or ''Equus ferus'' bones first appeared in multiple sites and in significant numbers in sites of the [[Qijia culture|Qijia]] and [[Siba culture|Siba]] cultures, 2000–1600 BCE, in [[Gansu]] and the northwestern provinces of China.<ref name="Linduff2003">{{cite book |title=Prehistoric Steppe Adaptation and the Horse |last=Linduff |first=Katheryn M. |editor=Levine, Marsha |editor2=Renfrew, Colin |editor3=Boyle, Katie |year=2003 |publisher=McDonald Institute |location=Cambridge |isbn=978-1-902937-09-0 |pages=139–162 |chapter=A walk on the wild side: late Shang appropriation of horses in China }}</ref> Skeletal evidence from sites in [[Shirenzigou]] and Xigou in eastern [[Xinjiang]] indicate that by the fourth century BCE both horseback riding and mounted archery were practiced along China’s northwest frontier.<ref name="Li">{{cite journal |last1=Li |first1=Yue |last2=Zhang |first2=Chengrui |last3=Taylor |first3=William Timothy Treal |last4=Chen |first4=Liang |last5=Flad |first5=Rowan K. |last6=Boivin |first6=Nicole |last7=Liu |first7=Huan |last8=You |first8=Yue |last9=Wang |first9=Jianxin |last10=Ren |first10=Meng |last11=Xi |first11=Tongyuan |last12=Han |first12=Yifu |last13=Wen |first13=Rui |last14=Ma |first14=Jian  |display-authors=5 |title=Early evidence for mounted horseback riding in northwest China |journal=Proceedings of the National Academy of Sciences |date=24 November 2020 |volume=117 |issue=47 |pages=29569–29576 |doi=10.1073/pnas.2004360117 |pmid=33139545 |pmc=7703595 |bibcode=2020PNAS..11729569L |language=en |issn=0027-8424|doi-access=free }}</ref>

A few horse bones, and an iron horse bit, have been found at [[Gandhara grave culture]] (c. 1200 - 800 BCE) sites, of Pakistan's, Swat Valley.<ref>{{Cite journal |last=Azzaroli |first=Augusto |date=1975 |title=Two Proto-historic Horse Skeletons from Swāt, Pakistan |url=https://www.jstor.org/stable/29756092 |journal=East and West |volume=25 |issue=3/4 |pages=353–357 |issn=0012-8376}}</ref> While the contemporary [[Vedas]] (c. 1500–500 BCE) make numerous references to both the use of [[History of the horse in the Indian subcontinent|horses and chariots within the Indian subcontinent]].<ref>{{Cite book |last=Sparreboom |first=M. |url=https://books.google.co.uk/books/about/Chariots_in_the_Veda.html?id=6alT6zhVUlAC&redir_esc=y |title=Chariots in the Veda |date=1985 |publisher=BRILL |isbn=978-90-04-07590-0 |language=en}}</ref>

In 2008, archaeologists announced the discovery of rock art in [[Somalia]]'s northern [[Dhambalin]] region, which the researchers suggest is one of the earliest known depictions of a hunter on horseback. The rock art is in the Ethiopian-Arabian style, dated to 1000 to 3000 BCE.<ref name="Tdodras">{{cite journal|last=Mire|first=Sada|title=The Discovery of Dhambalin Rock Art Site, Somaliland|journal=African Archaeological Review|year=2008|volume=25|issue=3–4|pages=153–168|url=http://www.mbali.info/doc494.htm|doi=10.1007/s10437-008-9032-2|s2cid=162960112|url-status=dead|archive-url=https://web.archive.org/web/20130627100400/http://www.mbali.info/doc494.htm|archive-date=27 June 2013}}</ref><ref name="Guafcpaonas">{{cite news|last=Alberge|first=Dalya|title=UK archaeologist finds cave paintings at 100 new African sites|url=https://www.theguardian.com/world/2010/sep/17/cave-paintings-found-in-somaliland|newspaper=The Guardian|date=17 September 2010}}</ref>

===Horse images as symbols of power===
[[File:Uffington-White-Horse-sat.jpg|thumb|left|alt=A Bronze Age hill figure of a running horse.|The [[Uffington White Horse]], a British [[Bronze Age]] [[hill figure|chalk-carved figure]] associated with the construction of a nearby [[hill fort]].<ref>{{cite book |last=Darvill |first=Timothy |year=1996 |title=Prehistoric Britain from the Air |page=223 |isbn=0521551323 |publisher=Cambridge University Press}}</ref>]]
About 4200-4000 BCE, more than 500 years before the geographic expansion evidenced by the presence of horse bones, new kinds of graves, named after a grave at [[Suvorovo]], appeared north of the [[Danube]] delta in the coastal steppes of Ukraine near [[Izmail]]. Suvorovo graves were similar to and probably derived from earlier funeral traditions in the steppes around the [[Dnieper River]]. Some Suvorovo graves contained polished stone mace-heads shaped like horse heads and horse tooth beads.<ref name="Dergachev1999">{{cite journal | last = Dergachev | first = Valentin | year = 1999 | title = Cultural-historical dialogue between the Balkans and Eastern Europe, Neolithic-Bronze Age | journal = Thraco-Dacica (București) | volume = 20 | issue = 1–2 | pages = 33–78 }}</ref> Earlier steppe graves also had contained polished stone mace-heads, some of them carved in the shape of animal heads.<ref name="Kuzmina2003">{{cite book |title=Prehistoric Steppe Adaptation and the Horse |last=Kuzmina |first=E. E. |editor=Levine, Marsha |editor2=Renfrew, Colin |editor3=Boyle, Katie |year=2003 |publisher=McDonald Institute |location=Cambridge |isbn=978-1-902937-09-0 |pages=203–232 |chapter=Origins of pastoralism in the Eurasian steppes }}</ref> Settlements in the steppes contemporary with Suvorovo, such as [[Sredni Stog]] II and [[Dereivka]] on the Dnieper River, contained 12–52% horse bones.<ref name="Telegin1986">{{cite book |title=Dereivka: a Settlement and Cemetery of Copper Age Horse Keepers on the Middle Dnieper |last=Telegin |first=Dmitriy Yakolevich |year=1986 |series=British Archaeological Reports International Series |volume=287 |publisher=BAR |location=Oxford |isbn=978-0-86054-369-5 }}</ref>

When Suvorovo graves appeared in the Danube delta grasslands, horse-head maces also appeared in some of the indigenous farming towns of the [[Trypillia]] and [[Hamangia culture|Gumelnitsa]] cultures in present-day [[Romania]] and [[Moldova]], near the Suvorovo graves.<ref>{{cite book |title=Ancient Interactions: East and West in Eurasia |last=Dergachev |first=Valentin A. |editor=Boyle, Katie |editor2=Renfrew, Colin |editor3=Levine, Marsha |year=2002 |publisher=McDonald Institute Monographs |location=Cambridge |isbn=978-1-902937-19-9 |pages=93–112 |chapter=Two studies in defense of the migration concept }}</ref> These agricultural cultures had not previously used polished-stone maces, and horse bones were rare or absent in their settlement sites. Probably their horse-head maces came from the Suvorovo immigrants. The Suvorovo people in turn acquired many copper ornaments from the Trypillia and Gumelnitsa towns. After this episode of contact and trade, but still during the period 4200–4000 BCE, about 600 agricultural towns in the Balkans and the lower Danube valley, some of which had been occupied for 2000 years, were abandoned.<ref name="Todorova1995">{{cite book |title=Prehistoric Bulgaria |last=Todorova |first=Henrietta |editor=Bailey, Douglass W. |editor2=Panayotov, Ivan |year=1995 |publisher=Prehistoric Press |location=Madison, WI |isbn=978-1-881094-11-1 |pages=79–98 |chapter=The Neolithic, Eneolithic, and Transitional in Bulgarian Prehistory |series=Monographs in World Archaeology |volume=22 }}</ref> Copper mining ceased in the Balkan copper mines,<ref name="Pernicka1997">{{cite journal | last = Pernicka | first = Ernst | year = 1997 | title = Prehistoric copper in Bulgaria | journal = Eurasia Antiqua | volume = 3 | pages = 41–179 }}</ref> and the cultural traditions associated with the agricultural towns were terminated in the Balkans and the lower Danube valley. This collapse of "Old Europe" has been attributed to the [[Indo-European migrations|immigration of mounted Indo-European warriors]].<ref name="Gimbutas1991">{{cite book |title=The Civilization of the Goddess |url=https://archive.org/details/civilizationofgo0000gimb |url-access=registration |last=Gimbutas |first=Marija |year=1991 |publisher=Harper |location=San Francisco |isbn=978-0-06-250368-8 }}</ref> The collapse could have been caused by intensified warfare, for which there is some evidence; and warfare could have been worsened by mounted raiding; and the horse-head maces have been interpreted as indicating the introduction of domesticated horses and riding just before the collapse.

However, mounted raiding is just one possible explanation for this complex event. Environmental deterioration, ecological degradation from millennia of farming, and the exhaustion of easily mined oxide copper ores also are cited as causal factors.<ref name="Anthony2007" /><ref name="Todorova1995" />

===Artifacts===
Perforated antler objects discovered at Derievka (mistakenly, Dereivka) and other sites contemporary with Suvorovo have been identified as cheekpieces or ''psalia'' for horse [[bit (horse)|bits]].<ref name="Kuzmina2003" /><!--did this one have a full cite somewhere? Let's use the "ref name" tag for these multiple refs, more consistent with wikipedia citation form--> This identification is no longer widely accepted, as the objects in question have not been found associated with horse bones, and could have had a variety of other functions.<ref name="Dietz1992">{{cite journal | last = Dietz | first = Ute Luise | year = 1992 | title =  Zur Frage vorbronzezeitlicher Trensenbelege in Europa | journal = Germania | volume = 70 | issue = 1 | pages = 17–36 }}</ref> However, through studies of microscopic wear, it has been established that many of the bone tools at Botai were used to smooth rawhide thongs, and rawhide thongs might have been used to manufacture of rawhide cords and ropes, useful for [[horse tack]].<ref name="Olsen2003" /> Similar bone thong-smoothers are known from many other steppe settlements, but it cannot be known how the thongs were used. The oldest artifacts clearly identified as horse tack—bits, [[bridle]]s, cheekpieces, or any other kind of horse gear—are the antler disk-shaped cheekpieces associated with the invention of the chariot, at the [[Sintashta-Petrovka]] sites.

===Horses interred in human graves===
The oldest possible archaeological indicator of a changed relationship between horses and humans is the appearance about 4800–4400 BCE of horse bones and carved images of horses in Chalcolithic graves of the early [[Khvalynsk culture]] and the [[Samara culture]] in the middle [[Volga River|Volga]] region of Russia. At the Khvalynsk cemetery near the town of [[Khvalynsk]], 158 graves of this period were excavated. Of these, 26 graves contained parts of sacrificed domestic animals, and additional sacrifices occurred in ritual deposits on the original ground surface above the graves. Ten graves contained parts of lower horse legs; two of these also contained the bones of domesticated cattle and sheep. At least 52 domesticated sheep or [[goat]]s, 23 domesticated cattle, and 11 horses were sacrificed at Khvalynsk. The inclusion of horses with cattle and sheep and the exclusion of obviously wild animals together suggest that horses were categorized symbolically with domesticated animals.{{Citation needed|date=November 2007}}

At S'yezzhe, a contemporary cemetery of the Samara culture, parts of two horses were placed above a group of human graves. The pair of horses here was represented by the head and hooves, probably originally attached to hides. The same ritual—using the hide with the head and lower leg bones as a symbol for the whole animal—was used for many domesticated cattle and sheep sacrifices at Khvalynsk. Horse images carved from bone were placed in the above-ground ochre deposit at S’yezzhe and occurred at several other sites of the same period in the middle and lower Volga region. Together these archaeological clues suggest that horses had a symbolic importance in the Khvalynsk and Samara cultures that they had lacked earlier, and that they were associated with humans, domesticated cattle, and domesticated sheep. Thus, the earliest phase in the domestication of the horse might have begun during the period 4800-4400 BCE.{{Citation needed|date=November 2007}}

==Methods of domestication==
[[Equidae]] died out in the [[Western Hemisphere]] at the end of the [[last glacial period]]. A question raised is why and how horses avoided this fate on the Eurasian continent. It has been theorized that domestication saved the species.<ref name="Budiansky1997">{{cite book |title=The Nature of Horses |last=Budiansky |first=Stephen |year=1997 |publisher=Free Press |location=New York |isbn=978-0-684-82768-1 |url-access=registration |url=https://archive.org/details/natureofhorsesex00budi }}</ref> While the environmental conditions for equine survival were somewhat more favorable in Eurasia than in the Americas, the same stressors that led to extinction for the [[mammoth]] had an effect upon horse populations. Thus, some time after 8000 BCE, the approximate date of extinction in the Americas, humans in Eurasia may have begun to keep horses as a [[livestock]] food source, and by keeping them in captivity, may have helped to preserve the species.<ref name="Budiansky1997" /> Horses also fit the [[Domestication of animals#Behavioral preadaption|six core criteria for livestock domestication]], and thus, it could be argued, "chose" to live in close proximity to humans.<ref name="Diamond1997">{{cite book |title=Guns, Germs and Steel: The Fates of Human Societies |last=Diamond |first=Jared |author-link=Jared Diamond |year=1997 |publisher=W. W. Norton |location=New York |isbn=978-0-393-03891-0 |title-link=Guns, Germs, and Steel }}</ref>

One model of horse domestication starts with individual [[foal]]s being kept as pets while the adult horses were slaughtered for meat. Foals are relatively small and easy to handle. Horses [[horse behavior|behave]] as herd animals and need companionship to thrive. Both historic and modern data shows that foals can and will bond to humans and other domestic animals to meet their social needs. Thus domestication may have started with young horses being repeatedly made into pets over time, preceding the great discovery that these pets could be ridden or otherwise put to work.{{cn|date=March 2025}}

However, there is disagreement over the definition of the term ''domestication''. One interpretation of ''domestication'' is that it must include physiological changes associated with being [[selective breeding|selectively bred]] in captivity, and not merely "tamed."<!--we need to cite to Diamond's domestication criteria here--> It has been noted that traditional peoples worldwide (both hunter-gatherers and [[horticulturist]]s) routinely tame individuals from wild species, typically by hand-rearing infants whose parents have been killed, and these animals are not necessarily "domesticated." {{Citation needed|date=September 2007}}<!--this is an argument over terminology. For Levine, people can depend on riding in herding and war and ride horses every day, and they still are just tamed, not domesticated, if they show no signs of controlled breeding.--><!--so, cite it-->

On the other hand, some researchers look to examples from historical times to hypothesize how domestication occurred. For example, while [[Indigenous people of the Americas|Native American]] cultures captured and rode horses from the 16th century onwards, most tribes did not exert significant control over their breeding, thus their horses developed a [[genotype]] and [[phenotype]] adapted to the uses and climatological conditions in which they were kept, making them more of a [[landrace]] than a planned breed as defined by modern standards, but nonetheless "domesticated".{{citation needed|date=July 2019}}

==Horses in historic warfare==
{{Main|Horses in warfare}}
While riding may have been practiced during the 4th and 3rd millennia BCE, and the disappearance of "Old European" settlements may be related to attacks by horseback-mounted warriors, the clearest influence by horses on [[ancient warfare]] was by pulling [[chariot]]s, introduced around 2000 BCE.

Horses in the [[Bronze Age]] were relatively small by modern standards, which led some theorists to believe the ancient horses were too small to be ridden and so must have been used for driving. Herodotus' description of the [[Sigynnae]], a steppe people who bred horses too small to ride but extremely efficient at drawing chariots, illustrates this stage. However, as horses remained generally smaller than modern equines well into the [[Middle Ages]],<ref name="Gravett2002">{{cite book |title=English Medieval Knight 1300–1400 |last=Gravett |first=Christopher |year=2002 |publisher=Osprey Publishing |location=Oxford |isbn=978-1-84176-145-9 }}</ref> this theory is highly questionable.

The [[Iron Age]] in Mesopotamia saw the rise of mounted [[cavalry]] as a tool of war, as evidenced by the notable successes of [[mounted archer]] tactics used by various invading [[eurasian nomads]] such as the [[Parthia]]ns. Over time, the chariot gradually became obsolete.

The horse of the Iron Age was still relatively small, perhaps {{hands|12.2|to|14.2}} high (measured at the [[withers]].) This was shorter overall than the average height of modern riding horses, which range from about {{hands|14.2|to|17.2}}. However, small horses were used successfully as light cavalry for many centuries. For example, [[Fell pony|Fell ponies]], believed to be descended from Roman cavalry horses, are comfortably able to carry fully grown adults (although with rather limited ground clearance) at an average height of {{hands|13.2}} Likewise, the [[Arabian horse]] is noted for a short back and dense bone, and the successes of the [[Muslim]]s against the heavy mounted [[knight]]s of Europe demonstrated that a horse standing {{hands|14.2}} can easily carry a full-grown human adult into battle.

Mounted warriors such as the [[Scythians]], [[Huns]] and [[Vandals]] of late Roman antiquity, the [[Turkic peoples|Turks]] and [[Mongols]] who invaded eastern Europe in the 7th century through 14th centuries CE, the [[Arab]] warriors of the 7th through 14th centuries CE, and the [[Indigenous peoples of the Americas|Native American]]s in the 16th through 19th centuries each demonstrated effective forms of light cavalry.

== See also ==
* [[Anthrozoology]]
* [[Equestrian nomad]]
* [[History of horse domestication theories]]

==References==
{{reflist}}

{{Horse topics}}
{{Animal domestication}}

{{DEFAULTSORT:Domestication Of The Horse}}
[[Category:Domesticated animal genetics]]
[[Category:Domestication of particular species]]
[[Category:Horse history and evolution]]
[[Category:4th millennium BC]]