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new study on Przewalski's horse
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JeanM
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 Posted: Sun Feb 25th, 2018 02:44 am
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Sharing because this might be of interest to readers here (I would bet that Dr. Deb already is well aware of this study)

Interesting new development on the domesticated horse family tree -- Przewalski's horse was not "wild," but was feral from domesticated horses! And, the DNA tests show that other horses came from an as-yet undetermined ancestry, NOT the same as Przewalski's horse.
http://www.sciencemag.org/news/2018/02/ancient-dna-upends-horse-family-tree

DrDeb
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 Posted: Sun Feb 25th, 2018 09:12 am
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Yes, this is a problem I worked on to get my Ph.D. degree; and Sandra Olson, the researcher interviewed, is a friend and colleague.

A few relevant important points:

1. In my recent series on "CSI-style" analysis of four famous stallions which appeared in EQUUS Magazine, I make the statement "Przewalski horses have never been domesticated" -- Olson's research, published just this week, now show this is false. A people called the Botai, who lived east of the Ural Mountains in the Eurasian steppe, domesticated the Przewalski horse.

2. The Przewalski horse is unique in possessing 2N=66 as their chromosome number, whereas all other horses are 2N=64. Olson's results do not change this; the Przewalski horse still has 2N=66 whereas all the other horses that were domesticated, i.e. all the subspecies whose natural home ranges were west of the Ural Mountains, are 2N=64, and so are all the horses descended from them.

3. In the EQUUS Magazine article, I state that the Przewalski horse has had zero to do with the ancestry of 2N=64 domesticated horses. This remains true; the Przewalski horses were domesticated as an entirely separate event, and have not mixed, or at most only very minimally been mixed, with 2N=64 horses.

4. Olson states in the interview that one of the great remaining mysteries is what the original founder population of the 2N=64 horses is. This is not a mystery to me, although Sandra may still feel that more proof is needed and for my part, if she goes out and gets a grant to do further digging and study and gets that evidence, it will make me very happy. As it stands, I published what I believe to be the solution to this "mystery" in 1999 in a paper which I co-authored with Robert S. Hoffmann, the great zoogeographer and mammalogist.

Readers of this Forum can go read that paper at any time: it's posted in an 'upgraded' form at our main website, http://www.equinestudies.org. Click on "Knowledge Base" and then when it takes you there, click on "Mammalian Species" and you'll get the instant free download of the .pdf.

What I would direct your attention particularly to is the maps in this paper. Bob Hoffmann and I spent years perfecting those maps, which are based on all the remains of horses, fossil and sub-fossil, that were known in 1999. The situation as far as that goes has not changed at all during the subsequent years, so you may read the maps as being accurate representations of where the different physical types (i.e., natural subspecies) of the pre-domesticated wild 2N=64 horses occurred (and also the 2N=66 ones, when they were actually wild -- note the map represents 10,000 years ago, which is about 4,000 years before the Botai people or anybody else knew to do more with a horse than kill it with a spear and eat it).

It is a normal commonplace in the study of the zoogeography of mammals to find that a founder population of whatever species expands outward from a central locality. As the population of the given animal increases, the young must move outward to find unoccupied habitat. But as they move outward, the habitat is liable to become less and less similar to the original central location. Over hundreds of years, the species will therefore "differentiate", i.e. peripheral populations will change in physical charateristics and appearance, to more closely adapt them to the different habitats which they have come to occupy. In this way, subspecies -- which are defined as being adapted to particular geographic areas -- arise.

In the case of horses, the original founder population of 2N=64 is central Europe, and Hoffmann and I chose the Mosbach horse -- a very old subfossil population -- as representative of this original type. The Mosbach horse is rather tall, flat-bodied, leggy for its body length, long-headed with rather long bars/muzzle, somewhat heavy-limbed and large of foot. This is a description of an animal that somewhat resembles a moose, and indeed our idea of central European paleoenvironment 10,000 years ago indicates open-forest, cold-rainy climate, with frequent boggy footing. We thus imagine the pelage (the fur) of this kind of horse was lanky and hairy rather than fuzzy and furry, i.e. adapted more to rain than snow; and that the lower parts of the legs had a certain amount of 'feather'.

The Mosbach horse is, further, we believe, the ancestor of all the domestic, semi-domestic, and occasionally feral 'landraces' of central and eastern Europe, and that the Friesian and Lituanian semi-draft horses are its mostly-unadulterated descendants.

Other living examples of horses directly derived from the central European subspecies are rather hard to find, and this too is a normal commonplace which we find in zoogeographic study. For as the population expands and differentiates, the original founder population that occupies the most desirable habitat at the center of the distribution, gradually degrades that habitat; or else there is an overall change in climate which alters the habitat at the center, resulting in a population decrease at the center which may go all the way to zero.

What happened in the case of 2N=64 horses west of the Urals was, we think, that the founder population was actually saved from complete extinction in most parts of its range by having most of its members taken into domestication. People protected the animals, sometimes keeping mare families for many human generations, or at other times permitting the animals to go back into a feral condition, i.e. for example this is what the Karst horses, which are the mare bloodline of the Lipizzan breed, were at the time during the early sixteenth century when that breed came into existence.

So to go back to the original article about the Przewalski horses, what Olson and colleagues have found out is that these animals are feral -- their ancestors had been 'messed with' by people, so that there are no wild horses anywhere on earth and never have been at any time, anywhere, since about six thousand years ago, when in the Steppes where the Botai lived, and west of the Urals where other ancient peoples lived, wild horses were taken into domestication "here" in one place and "there", by another tribe, in another. In  other words, the domestication of the horse occurred in multiple places over a relatively short time period from about six to five thousand years ago.

After that -- horses have been let loose, or escaped, over and over again, just about everywhere you'd like to look. Mustangs are feral; Camargue horses are feral; Chincoteague horses are feral; the Nootka horses are feral; Baguales are feral; Exmoor horses are feral; the Venezuelan Llaneros are largely feral, and now we know that the Przewalski horse is feral, too.

Just this month I have been researching the 'mountain horse' landrace from which my own horse Oliver (a registered and papered member of the Rocky Mountain Horse breed, which has nothing much to do with the Rocky Mountains BTW): did you know that there are quite a number of feral, and an even larger number of semi-feral or 'quasi-domesticated' horses living on the Cumberland Plateau in far western Virginia and far eastern Kentucky, where those states adjoin? I think these 'mountain horses' are the least well known of all the feral herds in the U.S., but they are extremely important as being the ultimate ancestors, especially on the distaff side of the family tree, of both the American Quarter Horse and the American Saddlebred.

Stay tuned, dear reader: I must say, I have been enjoying writing up the history of Anglo-American horse breeding for EQUUS Magazine, as much as I enjoyed it in the 1990's when I wrote up the history of Hispano-American horse breeding and published that in the book 'Conquerors'. Cheers -- Dr. Deb





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