Wild horse | |
---|---|
Top left: Equus ferus caballus (horses) Top right: Equus ferus przewalskii (Przewalski's horse) Below left: Equus ferus ferus † (tarpan) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Perissodactyla |
Family: | Equidae |
Genus: | Equus |
Subgenus: | Equus |
Species: | E. ferus |
Binomial name | |
Equus ferus Boddaert, 1785 | |
Subspecies | |
The wild horse (Equus ferus) is a species of the genus Equus, which includes as subspecies the modern domesticated horse (Equus ferus caballus) as well as the endangered Przewalski's horse (Equus ferus przewalskii, sometimes treated as a separate species i.e. Equus przewalskii). [2] [3] The European wild horse, also known as the tarpan, that went extinct in the late 19th or early 20th century has previously been treated as the nominate subspecies of wild horse, Equus ferus ferus, but more recent studies have cast doubt on whether tarpans were truly wild or if they actually were feral horses or hybrids. [4] [5] [6]
Other subspecies of Equus ferus may have existed and could have been the stock from which domesticated horses are descended. [7] Przewalski's horse had reached the brink of extinction, but was reintroduced successfully into the wild. [8] The tarpan became extinct in the 19th century, but is theorized to have been present on the steppes of Eurasia at the time of domestication. [9] [10] [11] [12] Since the extinction of the tarpan, attempts have been made to reconstruct its phenotype using domestic horses, resulting in horse breeds such as the Heck horse. [13] [14] However, the genetic makeup and foundation bloodstock of those breeds is substantially derived from domesticated horses, so these breeds possess domesticated traits.
The term "wild horse" is also used colloquially in reference to free-roaming herds of feral horses; for example, the mustang in the United States, [15] and the brumby in Australia. [16] These feral horses are untamed members of the domestic horse (Equus caballus), not to be confused with the truly "wild" horse subspecies extant into modern times.
Evidence supports E. ferus as having evolved in North America about 1.1 - 1.2 million years ago. Around 800,000 - 900,000 years ago, E. ferus migrated west to Eurasia via the Bering Land Bridge, and south to South America via the Isthmus of Panama as part of the Great American Interchange. By the mid-late Pleistocene, it had an extremely large range across the Americas, Eurasia, and North Africa, across which it was abundant. There have been several fossil horse taxa from throughout this range, such as Equus lambei and Amerhippus , that were formerly considered distinct species, but genetic and morphological analysis supports them as being conspecific with E. ferus. [17] [18] [19] [20]
By the latest Pleistocene or early Holocene, American populations had disappeared as part of the Quaternary extinction event, leaving only the Old World populations. It remained widespread there and was ultimately also domesticated around 3600 B.C., but wild populations continued to decline. The last completely wild populations of the tarpan went extinct in Eastern Europe and the southern parts of Russia around the late 19th century, and Przewalski's horse of Central Asia became extinct in the wild in 1969. However, over the past few centuries feral horses have been introduced to all continents except Antarctica, and Przewalski's horses have been reintroduced to their former habitats in Mongolia. [17]
In general, wild horses are grazers that prefer to inhabit open areas, such as steppes and grasslands. They may have seasonal food preferences, as seen in the Przewalski's subspecies. [21] Horses may fall prey to native predators including wolves, [22] cougars, [23] and spotted hyenas. [24]
E. ferus has had several subspecies, those of which survived into modern times are: [25]
The latter two are the only never-domesticated "wild" groups that survived into historic times. However, other subspecies of Equus ferus may have existed. [7]
In the Late Pleistocene epoch, there were several other subspecies of E. ferus which have all since gone extinct. The exact categorization of Equus remains into species or subspecies is a complex matter and the subject of ongoing work. [26]
The horse family Equidae and the genus Equus evolved in North America during the Pliocene, before the species migrated across Beringia into the Eastern Hemisphere. [28] Studies using ancient DNA, as well as DNA of recent individuals, suggest the presence of two equine species in Late Pleistocene North America, a caballine species, suggested to be conspecific with the wild horse, [29] [30] and Haringtonhippus francisci , the "New World stilt-legged horse"; the latter has been taxonomically assigned to various names, and appears to be outside the grouping containing all extant equines. [31] In South America there appear to have been several species of equine, Equus ( Amerhippus ) neogeus, which had previously thought to represent 5 taxa due to morphological variability, [32] and several species of Hippidion, which also lie outside the group containing all living horses. [33] (It had previously been suggested to have been nested within Equus based on incomplete sequence data [34] )
Currently, three subspecies that lived during recorded human history are recognized. [25] One subspecies is the widespread domestic horse (Equus ferus caballus), [25] as well as two wild subspecies: the recently extinct European wild horse (E. f. ferus) and the endangered Przewalski's horse (E. f. przewalskii). [10] [11] [25]
Genetically, the pre-domestication horse, E. ferus, and the domesticated horse, E. caballus, form a single homogeneous group (clade) and are genetically indistinguishable from each other. [29] [34] [35] [36] The genetic variation within this clade shows only a limited regional variation, with the notable exception of Przewalski's horse. [29] [34] [35] [36] Przewalski's horse has several unique genetic differences that distinguish it from the other subspecies, including 66 instead of 64 chromosomes, [10] [37] unique Y-chromosome gene haplotypes, [38] and unique mtDNA haplotypes. [39] [40]
Besides genetic differences, osteological evidence from across the Eurasian wild horse range, based on cranial and metacarpal differences, indicates the presence of only two subspecies in postglacial times, the tarpan and Przewalski's horse. [7] [41]
In some sources including MSW 3 (2005), the domesticated and wild horses were considered a single species, with the valid scientific name for such a single horse species being Equus ferus, [42] although MSW erroneously used E. caballus for this (enlarged) taxon on account of a mis-interpretation of the then-recent ICZN ruling on the matter, [43] refer Groves & Grubb, 2011. [44] The wild tarpan subspecies is E. f. ferus, Przewalski's horse is E. f. przewalskii, while the domesticated horse is nowadays normally (but not exclusively) treated as a separate species E. caballus. The rules for the scientific naming of animal species are determined in the International Code of Zoological Nomenclature, which stipulates that the oldest available valid scientific name is used to name the species. [45] Previously, when taxonomists considered domesticated and wild horse two subspecies of the same species, the valid scientific name was Equus caballus Linnaeus 1758, [46] with the subspecies labeled E. c. caballus (domesticated horse), E. c. ferus Boddaert, 1785 (tarpan) and E. c. przewalskii Poliakov, 1881 (Przewalski's horse). [47] However, in 2003, the International Commission on Zoological Nomenclature decided that the scientific names of the wild species have priority over the scientific names of domesticated species, therefore mandating the use of Equus ferus for both the wild and the domesticated horse if the two taxa are considered conspecific. [48]
Przewalski's horse occupied the eastern Eurasian Steppes, perhaps from the Urals to Mongolia, although the ancient border between tarpan and Przewalski's distributions has not been clearly defined. [49] Przewalski's horse was limited to Dzungaria and western Mongolia in the same period, and became extinct in the wild during the 1960s, but was reintroduced in the late 1980s to two preserves in Mongolia. [50] Although earlier researchers such as Marija Gimbutas theorized that the horses of the Chalcolithic period were Przewalski's, a 2003 study indicated that the Przewalski's horse is not an ancestor to modern domesticated horses. [51] [52] A 2015 study determined that the Przewalski and domesticated horse lineages diverged from a common ancestor about 45,000 years ago. [53]
In 2018, a DNA study revealed that the horses raised for meat and milk [54] by the Botai culture 5500 years ago were Przewalski's horses. The paper claims specifically that modern Przewalski's horses are the feral descendents of the domesticated [55] [56] Botai horse, although it is also possible both groups could have descended separately from the same ancient wild Przewalski's horses. [57] [58]
Przewalski's horse is still found today, though it is an endangered species and for a time was considered extinct in the wild. [40] Roughly 2000 Przewalski's horses are in zoos around the world. [59] A small breeding population has been reintroduced in Mongolia. [60] [61] As of 2005, a cooperative venture between the Zoological Society of London and Mongolian scientists has resulted in a population of 248 animals in the wild. [62]
Przewalski's horse has some biological differences from the domestic horse; unlike domesticated horses and the tarpan, which both have 64 chromosomes, Przewalski's horse has 66 chromosomes due to a Robertsonian translocation. [63] However, the offspring of Przewalski and domestic horses are fertile, possessing 65 chromosomes. [64]
Horses that live in an untamed state but have ancestors that have been domesticated are called "feral horses". [65] For instance, when the Spanish reintroduced the horse to the Americas, beginning in the late 15th century, [66] some horses escaped, forming feral herds; the best-known being the mustang. [67] Similarly, the brumby descended from horses strayed or let loose in Australia by English settlers. [68] Isolated populations of feral horses occur in a number of places, including Bosnia, Croatia, New Zealand, Portugal, Scotland and a number of barrier islands along the Atlantic coast of North America from Sable Island off Nova Scotia, to Cumberland Island, off the coast of Georgia. [69] Even though these are often referred to as "wild" horses, they are not truly "wild" if wildness is defined as having no domesticated ancestors. [65]
In 1995, British and French explorers encountered a new population of horses in the Riwoche Valley of Tibet, unknown to the rest of the world, but apparently used by the local Khamba people. [70] It was speculated that the Riwoche horse might be a relict population of wild horses, [71] but testing did not reveal genetic differences with domesticated horses, [72] which is in line with news reports indicating that they are used as pack and riding animals by the local villagers. [73] These horses only stand 12 hands (48 inches, 122 cm) tall and are said to resemble the images known as "horse no 2" depicted in cave paintings alongside images of Przewalski's horse. [72]
Equidae is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. The family evolved around 50 million years ago from a small, multi-toed ungulate into larger, single-toed animals. All extant species are in the genus Equus, which originated in North America. Equidae belongs to the order Perissodactyla, which includes the extant tapirs and rhinoceros, and several extinct families.
The horse is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of Equus ferus. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, close to Eohippus, into the large, single-toed animal of today. Humans began domesticating horses around 4000 BCE, and their domestication is believed to have been widespread by 3000 BCE. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses. These feral populations are not true wild horses, which are horses that never have been domesticated and historically linked to the megafauna category of species. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior.
Perissodactyla is an order of ungulates. The order includes about 17 living species divided into three families: Equidae, Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). They typically have reduced the weight-bearing toes to three or one of the five original toes, though tapirs retain four toes on their front feet. The nonweight-bearing toes are either present, absent, vestigial, or positioned posteriorly. By contrast, artiodactyls bear most of their weight equally on four or two of the five toes: their third and fourth toes. Another difference between the two is that perissodactyls digest plant cellulose in their intestines, rather than in one or more stomach chambers as artiodactyls, with the exception of Suina, do.
How and when horses became domesticated has been disputed. Although horses appeared in Paleolithic cave art as early as 30,000 BC, 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 c. 2000 BC. However, an increasing amount of evidence began to support the hypothesis that horses were domesticated in the Eurasian Steppes in approximately 3500 BC. 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. Warmouth et al. (2012) pointed to horses having been domesticated around 3000 BC in what is now Ukraine and Western Kazakhstan.
Przewalski's horse, also called the takhi, Mongolian wild horse or Dzungarian horse, is a rare and endangered horse originally native to the steppes of Central Asia. It is named after the Russian geographer and explorer Nikolay Przhevalsky. Once extinct in the wild, since the 1990s it has been reintroduced to its native habitat in Mongolia in the Khustain Nuruu National Park, Takhin Tal Nature Reserve, and Khomiin Tal, as well as several other locales in Central Asia and Eastern Europe.
The onager, also known as hemione or Asiatic wild ass, is a species of the family Equidae native to Asia. A member of the subgenus Asinus, the onager was described and given its binomial name by German zoologist Peter Simon Pallas in 1775. Six subspecies have been recognized, two of which are extinct.
The tarpan was a free-ranging horse subspecies of the Eurasian steppe from the 18th to the 20th century. It is generally unknown whether those horses represented genuine wild horses, feral domestic horses or hybrids. The last individual believed to be a tarpan died in captivity in the Russian Empire in 1909.
Equus is a genus of mammals in the family Equidae, which includes horses, asses, and zebras. Within the Equidae, Equus is the only recognized extant genus, comprising seven living species. Like Equidae more broadly, Equus has numerous extinct species known only from fossils. The genus most likely originated in North America and spread quickly to the Old World. Equines are odd-toed ungulates with slender legs, long heads, relatively long necks, manes, and long tails. All species are herbivorous, and mostly grazers, with simpler digestive systems than ruminants but able to subsist on lower-quality vegetation.
The kiang is the largest of the Asinus subgenus. It is native to the Tibetan Plateau in Ladakh, northern Pakistan, Tajikistan, China and northern Nepal. It inhabits montane grasslands and shrublands. Other common names for this species include Tibetan wild ass, khyang and gorkhar.
The African wild ass or African wild donkey is a wild member of the horse family, Equidae. This species is thought to be the ancestor of the domestic donkey, which is sometimes placed within the same species. They live in the deserts and other arid areas of the Horn of Africa, in Eritrea, Ethiopia and Somalia. It formerly had a wider range north and west into Sudan, Egypt, and Libya. It is Critically Endangered, with about 570 existing in the wild.
Equus lambei, commonly known as the Yukon horse or Yukon wild horse, is an extinct species of the genus Equus. Equus lambei ranged across North America until approximately 10,000 years ago. Based on recent examinations of the mtDNA of Equus lambei remains, scientists have concluded that E. lambei was probably much like the extinct tarpan, also known as the Eurasian wild horse, and the living Przewalski's horse. A partial carcass of Equus lambei is on display at the Yukon Beringia Interpretive Centre in Whitehorse, Yukon.
Wild horse is a species of the genus Equus that includes domesticated and undomesticated subspecies.
The Mongolian horse is the native horse breed of Mongolia. The breed is purported to be largely unchanged since the time of Genghis Khan. Nomads living in the traditional Mongol fashion still hold more than 3 million animals, which outnumber the country's human population. In Mongolia, the horses live outdoors all year, dealing with temperatures from 30 °C (86 °F) in summer down to −40 °C (−40 °F) in winter, and they graze and search for food on their own. The mare's milk is processed into the national beverage airag. Some animals are slaughtered for meat. Other than that, they serve as riding and transport animals; they are used both for the daily work of the nomads and in horse racing.
The European wild ass or hydruntine is an extinct equine from the Middle Pleistocene to Late Holocene of Europe and West Asia, and possibly North Africa. It is a member of the subgenus Asinus, and closely related to the living Asiatic wild ass. The specific epithet, hydruntinus, means from Otranto.
Hippidion is an extinct genus of equine that lived in South America from the Late Pliocene to the end of the Late Pleistocene (Lujanian), between 2.5 million and 11,000 years ago. They were one of two lineages of equines native to South America during the Pleistocene epoch, alongside Equus (Amerhippus) neogeus.
The evolution of the horse, a mammal of the family Equidae, occurred over a geologic time scale of 50 million years, transforming the small, dog-sized, forest-dwelling Eohippus into the modern horse. Paleozoologists have been able to piece together a more complete outline of the evolutionary lineage of the modern horse than of any other animal. Much of this evolution took place in North America, where horses originated but became extinct about 10,000 years ago, before being reintroduced in the 15th century.
Primitive markings are a group of hair coat markings and qualities seen in several equine species, including horses, donkeys, and asses. In horses, they are associated with primitive breeds, though not limited to such breeds. The markings are particularly associated with the dun coat color family. All dun horses possess at least the dorsal stripe, but the presence of the other primitive markings varies. Other common markings may include horizontal striping on the legs, transverse striping across the shoulders, and lighter guard hairs along the edges of a dark mane and tail.
The Heck horse is a horse breed that is claimed to resemble the tarpan, an extinct wild equine. The breed was created by the German zoologist brothers Heinz Heck and Lutz Heck in an attempt to breed back the tarpan. Although unsuccessful at creating a genetic copy of the extinct species, they developed a breed with grullo coloration and primitive markings. Heck horses were subsequently exported to the United States, where a breed association was created in the 1960s.
The history of horse domestication has been subject to much debate, with various competing hypotheses over time about how domestication of the horse occurred. The main point of contention was whether the domestication of the horse occurred once in a single domestication event, or that the horse was domesticated independently multiple times. The debate was resolved at the beginning of the 21st century using DNA evidence that favored a mixed model in which domestication of the stallion most likely occurred only once, while wild mares of various regions were included in local domesticated herds.
Horses have been an important component of American life and culture since before the founding of the nation. In 2008, there were an estimated 9.2 million horses in the United States, with 4.6 million citizens involved in businesses related to horses. There are an estimated 82,000 feral horses that roam freely in the wild in certain parts of the country, mostly in the Western United States.
{{cite web}}
: CS1 maint: numeric names: authors list (link){{cite news}}
: CS1 maint: multiple names: authors list (link)