Editing Domestication of the horse (section)

==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"/>