The
European wild horse probably was of a similar build like the Przewalski’s
horse, that means a 130-140 cm tall stocky body with a large and robust head.
Numerous eyewitness accounts confirm that, as well as that it had a short but
falling mane. But what
about the exact colour? Genetic information tells us
about the two basic colours that were present in European wild horse
populations, but the phenotype of these horses is uncertain as long as we don’t
know if the basic colour was diluted by dun or not.
To make
more clear what I am about, let’s have a deeper look into the coat colour genetics
of horses. Horses have two alleles on their Extension locus, which defines the basic colour: E, the wild type
allele, resulting in the production both red and black pigmentation, and the domestic mutation e,
which is recessive and produces totally red colours such as chestnut or sorrel.
The amount of black pigmentation in wildtype coloured horses is controlled by
the Agouti locus. The allele A restricts black to the legs, mane and
tail and results in bay horses; the allele a on the other hand produces totally
black horses. We know that both A and a are wild type alleles, they were
present in undomesticated European horse populations [1]. There is another variant
called At, producing colours like seal brown. This allele is not
mentioned by Pruvost et al., but it might indeed be another wildtype allele;
according to this website, it might even be present in donkeys as well (if
that’s the case, it’s a very old allele). Countershading, also called pangare, which produces the mealy mouth and light belly in bay and bay dun (but not black and black dun) horses, serves the so-called somatolysis and is present in a variety of animals of all sizes and habitat preferences, so it doesn't say much on whether we look at a forest-dwelling animal or open land animal.
Dun is the
only dilution locus which is wildtype. Dun reduces the intensity of
pigmentation; bay and seal brown horses with dun are sand-coloured (bay dun)
while black horses with dun are grayish or tan-coloured (black dun), also
called grullo. The so-called wild markings including the dark dorsal stripe and
the leg striping are certain indication of the presence of dun since the former
trait is barely visible and the latter invisible without dun. All living
equines are dun-coloured (bay dun in particular), so it sounds logic that European
wild horses were too. On the other hand, all living wild equines live in open
habitats, while Europe likely had more closed, forest-based natural landscapes.
Therefore the loss of dun resulting in a darker colour (a more
efficient camouflage in forests) seems conclusive as well. And indeed
bay/brown and black ponies like the Exmoor, Asturcon or Fell pony seem to fit
closed or bushy environment much better than do bay dun and black dun
Przewalskis or Koniks. Since there are no preserved skins of undomesticated
native European horses, we have to ascertain that question using two sources of
information: genetic information and historic accounts. Cave paintings could
provide a clue as well, but they are not very reliable for two reasons: 1) they
stem from the age of the last glacial, and therefore the horses depicted were
most likely adapted to more steppe-like habitat than that of modern Europe, and
2) probably not all colours on the cave walls are an accurate representation of
what was found within the population because the cave artists had to work with
what was available.
Black dun Konik: perfectly camouflaged in open, grassy landscapes |
Dark bay Exmoor: perfectly camouflaged in more closed environments |
Genetic
data is by far most reliable because it is unambiguous. Pruvost et al. 2011 tested
predomestic wild horse remains from Europe of both the Holocene and Pleistocene
for a number of colour alleles. It showed that the basic colours all were bay,
black and leopard spotted (the latter is not relevant for the topic of this
post, so let’s ignore it) [1]. No dilution allele was detected within the wild
horse populations, but the dun mutation was not yet resolved, therefore
it was impossible to distinguish between dun and non-dun horses [1].
Historic references
describe a variety of colours. They are less clear because there are numerous
words to describe one and the same colour, translation errors are another factor. Eyewitness accounts often are ambiguous because the colour terms we use colloquially are not congruent with the terminology of coat colour
genetics: mouse-coloured might refer to shades of bay, bay dun or black dun,
but in coat colour genetics it is used only for black dun. That means we have
to be cautious when interpreting historic accounts.
Another
problem is that we don’t know for sure the status of the free-roaming horses described
as “wild”. As I wrote in previous posts, there are good reasons to
believe that many of the texts actually describe wild horses, but domestic
introgression can never be ruled out. Therefore we should stick with what is
likely to be a variation of those colour genetically proven to be predomestic,
and consider other colours to be the result of intermixture.
So let’s
have a look on what historic references actually say.
Herodot
describes lightly coloured wild horses on the area of the Ukraine in the 5th
century before Christ. “light” is quite vague, but it most likely means that
the horses were dun-coloured. Albertus Magnus writes of mouse-coloured horses
with a dark eel stripe in Germany of the 13th century. Balthazar
Hacquet saw wild horses at the Zoo of Zamosc, Poland, in the 18th
century and reported that they were of a blackish-brown colour. Kajetan Kozmian
saw the wild horses of the same park and same century, and described them being
uniformly of a dark mouse-colour. The reports of S. G. Gmelin and Peter Pallas
refer to the wild horses of the Russian steppe (which also showed clear signs
of intermixture), so they are of little value for the European forest horses [2].
The
naturalist C. H. Smith described free-roaming “sturdy mountain-forest ponies”
in his 19th century work The
Natural history of horses, with memoir of Gesner (see here for his full
description of western wild horses). These wild ponies were found in western
Europe and according to him had “a livery in general pale dun, yellowish brown
and a streak along the spine and cross bars on the limbs, or the limbs entirely
black, as well as all the long hair and mostly having a tendency to ashy and
gray, often dappled on the quarter and shoulders” [3]. Genuine wild horses extant
in western Europe during the 19th century sound a bit far-fetched, but
all the behavioural and phenotypic features Smith describes for these horses
imply that they were wild or at least primitive feral ponies. The colour he
describes certainly refers to bay dun (“yellowish brown and streak along the
spine”) and black dun (“tendency to ashy and gray”), and also Herodot’s text
supports that European wild horses were dun-coloured.
Dark brown
might either refer to dark expressions of black dun or to the seal brown (bay)
colour of ponies like the Exmoor. We probably will never know which colour that
actually was, but the mealy mouth of bay horses could be a hint – this white
area around the mouth is pretty apparent on an otherwise brownish coat,
therefore it might have been mentioned if it was there. No historic reference
mentions it, what might support the view that these horses had a brownish
expression of black dun; but this is just a pure speculation of mine. The term “mouse
coloured” also leaves big room for speculation. It is probably hard to figure
out which colour they actually intended to describe with that term. European
mice species display various shades of brown and gray, and no-one can know if
the writer actually had any of these particular species in mind when speaking
of mouse-coloured horses or just used it in the colloquial sense, and this
colloquial sense might also be influenced by time and region. So we really have
to guess.
All in all,
it seems that historic references suggest European wild horses were
dun-coloured, so both the colour of the Przewalski’s horse and brownish Koniks
appeared. Intuitionally I consider it quite likely that there were non-dun wild
horses in Europe as well because they are perfectly camouflaged in forested and
bushy landscapes. But to
be sure we have to wait until the mutations on the dun locus are identified so
that dun and non-dun wild horses can be genetically distinguished. It would also be very interesting to know if the At allele was present in predomestic horse populations as well.
Literature
[1] Pruvost et al.: Genotypes of predomestic horses match phenotypes painted in paleolithic works of cave art. 2011
[2] Tadeusz Jezierski, Zbigniew Jaworski: Das Polnische Konik. 2008.
[3] Smith, Charles Hamilton: The Natural history of Horses, with Memoir of Gesner.(1814/1866)
Hello, first of all thank you for this blog that I confess I am reading quite often. We have a similar passion for nature and for it's recovery and for that I am missing a couple of species that almost no one mentions as present in Europe and they certainly were, among them just a few that I would like to see maybe in one of your future posts: wild onager, forest reindeer, water buffalo, dhole, etc. My best regards, J. Ferro
ReplyDeleteHi, thank you for your kind words! Water buffalo will be in the focus of a future post, I didn't yet get to write about them. The onager (or E. hydruntinus if it was a seperate species) has a solid record in holocene Europe, yes, but they are not really a subject of breeding-back. I don't know about the evidence of the dhole in Holocene Europe. I think they were only known from the Pleistocene on that continent, didn't they? I haven't heard of a forest reindeer as such yet, but there is indeed evidence that they were present more southwards than today. But like the onager, reindeer isn't really in the focus of breeding back. Best wishes
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