Przewalski's horse an also-ran

Przewalski's horse Photo by Claudia Feh

CC BY-SA 4.0 

Przewalski's horse has long been seen as the last population of wild horses. No more. A new attempt to find the origins of domestication using ancient DNA is full of surprises (here). 

The Botai Culture of Central Asia has been tied to domestication of horses some 5500 years ago. Ancient DNA was extracted from the bones of Botai horses and the genomes compared with those of other ancient and modern horses.

Cord at term of Przewalski's horse

From Benirschke Comparative Placentation

The first surprise was that Przewalski's horse clustered with the Botai horses. The inescapable conclusion is that Przewalski's is a feral population descended from those domesticated at Botai.

The second finding was that all other horses descend from a separate branch. This was foreshadowed in a previous study (previous post). The most parsimonious explanation is that there was a second centre of domestication yet to be identified.

Benirschke has several images of the placenta of Przewalski's horse (see also previous post).