The equid family evolved in North America. The first species of the genus Equus to reach Eurasia, more than two million years ago, was the zebra-like or stenonine Equus stenonis. Caballine horses appeared later. The fossil record of caballine horses in Eurasia during the Pleistocene is quite good, but horse taxonomy is complicated and still controversial (e.g., Kurtén 1968; Kahlke 1994; Guérin 1996). In Central Europe, wild horses lived during glacial and interglacial periods on steppes as well as in partly wooded habitats (von Koenigswald et al. 1995). In late Pleistocene and early Holocene times, there was obviously only one species of caballine horse (Equus ferus) in Eurasia, forming several more or less definable subspecies. In large parts of Europe, this horse lived side by side with the stenonine European wild ass (Equus hydruntinus), and in Central Asia it was sympatric with stenonine Asiatic wild asses (Equus hemionus and Equus kiang). About 15,000 years ago, Equus ferus had a continuous range from Iberia in the west to Beringia and Alaska in the east. For thousands of years the wild horse was an important game species for humans, but it became progressively rarer during the Holocene (Uerpmann 1990). The last indisputably undomesticated horses, belonging to the subspecies Przewalski’s horse or takhi (Equus ferus przewalskii) (Figure 2), were seen in Mongolia in 1968 (Volf 1996). Although it went extinct in the wild shortly after that, this subspecies survived in zoos. The breeding program of Przewalski’s horse succeeded in spite of some problems (Knowles & Wakefield 1992; Volf 1996):
- all the about 2500 animals existing today descended from only 12 wild horses, captured in Mongolia between 1899 and 1947, and 1 domestic horse;
- the population has a significant, but incompletely documented, contribution of genes from Mongolian domestic horses;
- some of the genetic diversity represented by the original 13 animals was lost due to, among other things, artificial and variable selection;
- and after five generations in human care certain signs of domestication became already evident, e.g. very early sexual maturation.
Meanwhile, breeding and reintroduction programs have started at at least four sites of the subspecies historic range including since 1989 the Bukhara Breeding Centre, Kyzylkum Desert, Uzbekistan (Pereladova et al. 1999) and since 1993 the Hustain Nuruu Mountain Forest Steppe Reserve, Mongolia (Bouman 1998).
As one subspecies of wild horse is still living, it may not seem necessary to replace the wild horse with any other breed, but the Asiatic subspecies may not be the best horse for European nature reserves as it is adapted to the dry steppes and semideserts found at the species extreme range limits.
Figure 2. Przewalski’s horse (Equus ferus przewalskii) in winter coat
Figure 3. Wild horse drawing from the cave of Niaux (Ariège), France (after Beltran et al. 1973)
