[1] Sandoval-Castellanos et al.: Coat colour adaption of post-glacial horses to increasing forest vegetation. 2017
Friday, 30 October 2020
The Holocene European wild horse
Recently I did a life reconstruction for the Holocene European wild horse: Since there is not a single complete skeleton of a Holocene European wild horse, I based the body, head and proportions on Przewalski's horses and also primitive pony breeds. A recent study suggests that Holocene European wild horses were predominantly black [1]. As for the mane, it cannot be ascertained today if the western wild horse subspecies, Equus ferus ferus, had an erect mane or a falling mane. All cave paintings show erect manes, and all extant wild equines have an erect mane. It has been suggested that a falling mane would be advantageous in a more humid climate because it diverts rain water, but domestic horses were domesticated in the arid steppe. It is well possible that a falling mane is a trait that arose during domestication. Hence, I drew my horse with an erect mane.
I would suggest that cave paintings aren't necessarily a good indicator for the appearance of Equus ferus ferus, as these would have represented the glacial period and consequently a more przewalski-like ecotype adapted to arid steppes. Considering that at least one variety of extinct horse is known to have possessed a falling mane, it does not seem unlikely that the European wild horse did as well. Horses domesticated on the steppe may have acquired the trait later through introgression. It is certainly also possible that the wildtype is a falling mane which has been exaggerated through domestication as well.
ReplyDeleteConcerning the extinct horse with a falling mane, are you referring to that Equus lambei carcass? It's extremely hard to get reliable information on that specimen, let alone good photos. From what I have seen so far, it is not unambiguous that it had a falling mane. It could also be an erect mane that got frizzy postmortally as the hair is not that long (based on what I have seen, I am open to be proven otherwise).
DeleteYes, that is the one I'm referring to. The pictures I've seen seem to show a falling mane pretty clearly, and I've heard that specimens from Siberia show the same trait but unfortunately I've not seen pictures.
DeleteDo you have a link maybe? The only picture I can find is this one: https://www.beringia.com/sites/default/files/styles/media_large/public/horse-hide_0.jpg,qitok=USW8l7aJ.pagespeed.ce.68ltIt-2zr.jpg
DeleteAt least one description of the Siberian wild horse (Equus ferus lenensis) includes a mane measurement of 15 cm, significantly longer than would be typical for a Przewalski's horse. http://www.rhinoresourcecenter.com/pdf_files/140/1400026668.pdf
DeleteI've seen better photos than that, but I can't seem to relocate them. I know somebody at the Yukon Beringia Interpretive Center who might know better. I can send him a message to ask.
DeleteIt would be great if you could ask that person, many thanks. 15 cm would be exactly the mane length of a Przewalski's horse. I visited a herd just yesterday, and 15 cm would be a very probable estimation for the mane length of those individuals.
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ReplyDeleteRhys Lemoine, Not all the European parietal art horse depictions are glacial, but as far as I know all of them have erect manes.
ReplyDeleteThe Holocene ones seem pretty hard to discern. I've read some interpretations that say they depict falling manes.
DeleteI haven't heard of Holocene horse depictions yet, does anyone have a link maybe?
DeleteBTW, since the cave paintings at lascaux and chauvet show horses among aurochs, I think it may be likely that those horses depicted were from the Palaeoloxodon faunal assemblage, thus adapted to temperate biomes, and not the arid steppe biome. But that's just a thought of mine.
Rhys Lemoine, while the consensus seems to be that Lascaux is Solutrean in age, the fauna depicted there is of a decidedly interglacial character, even including fallow deer. Maybe the culture that created it was close to a temperate refugium. Chauvet is more ambiguous, but Stepahanorhinus might be depicted there (working on an article on that) so it may represent mostly an interglacial assemblage too. All the horse depictions I've seen at both these sites have manes much like those of a Przewalski horse. I also heard one source say horses with falling manes had been found in Pleistocene cave art, but I asked to see some images and nothing ever turned up...I've never heard of Holocene wild horse images, do you have any links to them?
DeleteI think that claiming that black wild horses existed in the European Holocene may be an incorrect deduction. To date, it has not been possible to determine whether these specimens carrying the black allele (a) also carried the nondun allele (d1). This allele has only been found in specimens of the Russian steppe, on the borders of Europe, a region whose habitat was more similar to the Asian steppes of the przewalski horse than to the ecosystems of Europe at that time.
ReplyDeleteMario
I think it is very likely that the nondun1 allele was present in Europe too. Genetics suggest one large panmictic population from the Russian steppe to the pyrenees during the Pleistocene, and cave paintings also show non-dun horses of a dark brown to black colour, f.e. in lascaux. Those Pleistocene European horses likely were the ancestors of Holocene European wild horses according to a recent study.
DeleteI'm sorry, but I don't entirely agree. Regarding the genes that determine color, genetics don't suggest a homogeneity of alleles throughout Eurasia. An example is the leopard gene, present only in central and eastern Europe. If only the leopard gene had been analyzed in samples from central and eastern Europe, it could have been the mistake of saying that leopard horses existed throughout Eurasia during the Pleistocene. A black color pattern is in stark contrast to any type of environment, even forest ones. It may be that this fact favored the prevalence of the "D" allele. In the case of the Russian specimens, they did not carry the "a" allele. The "d1" allele in combination with bay colors doesn't provide such a marked contrast, it can even favor mimicry in forest environments.
ReplyDeleteRegarding cave paintings, for me they can never be a proof in themselves if there are no scientific studies that corroborate or deny them. In Lascaux, for example, there are spotted white aurochs and paint horses.
I am not saying that it is not possible that European horses were black.
I'm just saying that this cannot be firmly stated until it is proven with genetic testing.
I agree that it is a shame they have not tested the dun locus of the horses homzogote for the allele a, so that we don't know their phenotype. Regarding the other points, I am not so sure if a black dun horse is really better camouflaged than a black horse in a forested environment, I think the opposite is more likely. Concerning the cave paintings, lascaux does not show white aurochs but aurochs that are indicated only by lines. No white colour was used. The dots more likely represent curly hair.
DeleteI think arguing about whether or not black enhances mimicry can lead to subjectivity (see the two images below). It also seems subjective to me to assume that mimicry was the determining factor in color selection. An example is zebras, whose stripes were also thought to serve as a mimicry and are now known to be a deterrent to tsetse flies and horseflies.
DeleteRegarding the Lascaux cave, I still think that the interpretation can also be subjective. You yourself raised in a very interesting article the hypothesis that there were aurochs with a white pattern, leaning on the bull we are talking about.
For me all hypotheses are valid, but until genetics prove them, they are hypotheses, not facts.
https://elcorreodeburgos.elmundo.es/media/elcorreodeburgos/images/2015/08/29/105428_1.jpg
https://i1.wp.com/thepixelnomad.com/wp-content/uploads/2019/07/20190308-Konik-Primigenius701.jpg?fit=1500%2C1000&ssl=1
It is indeed subjective and we need hard facts, that's why I wrote in my previous comment they should have tested the Dun locus too, otherwise we can't know the colour phenotype of those wild horses.
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