The Przewalski horse: a prehistoric horse who lived through the Ice Age (Part 3)

N.B.: This clear chronostratigraphy may be helpful to situate the various dates, periods and events discussed in this article.

Equids first appeared on the earth 4-4,5 millions years ago[1] and went through tremendous evolution phases to acquire their contemporary appearance[2]. Horses originated in North America and subsequently migrated to South America and Eurasia through Beringia, which connected the continents during prehistoric glaciation periods[3]. Eurasian Steppe MapHorse populations significantly fluctuated in size over the past 2 million years in phase with colder and warmer periods[4], and the latest research suggest that climate has been “a major driving force” in megafauna population dynamics, including wild horses, over the past 50,000 years[5]. This latter period roughly corresponds to the second half of the Late Pleistocene (126,000-11,700 years ago) and is concurrent to the last glaciation commonly known as the Ice Age. During this period and until the end of the Last Glacial Maximum (LGM), which lasted from 26,500 to 20-19,000 years ago[6], horse populations boomed due to the expansion of their favored open steppe-type habitat to the detriment of woodland as a result of colder temperatures and a drier climate[7]. Continue reading

The Przewalski horse: the last extant wild horse (Part 2)

A single trait―wild―defines and distinguishes the Przewalski horse from any of its congeners. In Mongolia, where it originates from, its name Takh or Takhi (монголын тахь) means spirit horse. Yet, the residents of the Haus zur Wildnis are tame, much tamer than some semi-feral and feral horses I encountered in Canada, and most people would probably not call them wild. Appearances are often misleading: their affable disposition results from decades of captivity, hence familiarity to men, and does not prejudice their wildness at all. To determine the wild trait, one must investigate the history of the species through its biology, i.e. its DNA.

Thistle Creek, Yukon, Canada

Thistle Creek in Yukon (YT), Canada / Source: click here for original map

Two DNA research cast light on the complex evolutionary history and phylogeny of the Przewalski horse within the Equus genus, which until now remained unclear. The intent of the first study[1] was to determine the genetic relationship between Przewalski and modern domestic horses through assessing levels of genetic variation on sexual chromosomes and autosomes. The second research[2] was performed on the foot bone of an equid that lived 560,000 to 780,000 years ago (Middle Pleistocene). Recently fetched from the permafrost soils of the Canadian Arctic near Thistle Creek (Yukon), the foot had been well preserved Continue reading