Editing Domestication of the horse (section)

==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"/>