Re: [tied] Horses

----- Original Message -----

From: Piotr Gasiorowski

To: cybalist@egroups.com

Sent: Sunday, October 08, 2000 4:18 AM

Subject: [tied] Horses

The genus Equus originated in N America. About a dozen American species are known from the late Pliocene and the Pleistocene (some, e.g. the Laurentide horse, E. laurentius, survived until the early Holocene). During the Pleistocene equids migrated into Eurasia and Africa, giving rise to Old World horses, asses, onagers, zebras and quaggas. The systematic position of various Eurasiatic equids remains debatable, but the recent tendency is to separate the species typified by the domestic horse, E. caballus (32 pairs of chromosomes), from the Asian wild horse, E. ferus (33 pairs). Przewalski's horse, E. ferus przewalskii, is a Mongolian variant of the latter; very probably the recently discovered Riwoche Valley horse from Tibet is another (at any rate it has the same chromosome count); other varieties of the species, including the Siberian tundra pony, are extinct. Genetic evidence suggests that E. caballus and E. ferus diverged about 200,000 years ago, and the fact that no known breed of domestic horse has 66 or 65 chromosomes (the latter number is found in hybrids between the two species) confirms that E. ferus did not contribute significantly to the genetic makeup of domestic horses.

 

The West European Ice Age pony of Lascaux cave paintings was morphologically of the ferus type, though it isn't clear whether it should be regarded as conspecific with Przewalski's horse. There were several (difficult to classify) varieties of wild horse in post-glacial North Africa and Europe; some of them (e.g. the Scandinavian forest horse) were much larger and heavier-built than the Asian wild horse and don't seem to have belonged to the same species. The smaller frizzly-maned and mouse-coloured "forest tarpan" of Northern Germany, Poland and Lithuania is quite mysterious, though it survived in the wild until the 19th century. It was regarded as a game animal in the Middle Ages. Since the so-called Polish "koniki" ('little horses'), which are descended partly from the captive wild "tarpans" of Bialowieza Forest, show no Przewalski-like genetic traits, the Central European forest horse was in all likelihood a local variant of wild E. caballus, closely related to the true tarpan.

 

The East European steppe tarpan, E. caballus gmelini, used to range from western Ukraine and Romania to southern Russia. Like the domestic horse, and like the extinct wild horses of the Middle Eastern deserts, but unlike any other living equid, it had a floppy mane with a forelock. Its range extended more or less to the Volga; the wild horses of Kazakhstan were already of the Przewalski type (though a hybrid zone may have existed north of the Caspian Sea). Obviously, the hydrological conditions of the steppe region separated the two varieties through most of the Pleistocene and part of the Holocene, creating an effective reproduction barrier and letting them evolve into different species.

 

From the genetic point of view only the European steppe tarpan and some of the extinct European and Middle Eastern wild horses can be taken into consideration as possible ancestors of the extant breeds of the domestic horse. It follows that the domestication of the horse can't have taken place farther east than the Volga, and that all the domestic horses of Central Asia came from the west. Presumably Caspian ponies and Arabians derive mainly from the steppe and desert subspecies of E. caballus, while the North European ponies and heavy horses have been influenced by the local forest varieties. North African desert horses possibly contributed to the athletic Barb and Iberian breeds.

 

I invite comments on the implications of horse biology for IE origins.

 

Piotr