Tuesday, 10 January 2012

A horse of a different colour part 5 - '..."it is of an original colour," said Athos...'

...by which he meant yellow, and was referring to D'Artagnan's rather distinctively coloured horse, which is a source of much amusement in the early chapters of Dumas pére's "The Three Musketeers". So, today - yellow horses. Creams, palominos, buckskins, cremellos, and other things of that ilk.

Unlike the previous post, this is a case where we are much better off starting with a gene, the CR gene, also known as the cream gene. Also, this post is a good test of whether you've been paying attention. Once I tell you what the CR gene does, you can, pretty much, figure out what it will do in combination with other genes.

CR is, like some of the genes mentioned in the previous post, an incomplete dominant gene, in that CR/N has different effects to CR/CR, but those effects are pretty well understood, viz:
  • one copy of CR: all red pigment becomes gold, black is largely unaffected, light brown eyes
  • two copies of CR: cream coloured coat, rosy-pink skin, blue eyes
These tend to be written as CR and CRCR. Don't ask me why :D

A classic palomino.
Image from Wikipedia,
in public domain
So. Let's start with the easy one. Take a horse with aa ee CR. Now, ignoring the cream gene, that's a chestnut, as you should all be aware - remember, E means there's black in the coat, A means if there's black, its only on the mane, tail and legs. The presence of CR gets us a palomino: golden coat, flaxen mane, light brown eyes. Unmistakeable.
"For our young man had a steed which was the observed of all observers. It was a Bearn pony, from twelve to fourteen years old, yellow in his hide..." 
-- Alexandre Dumas, "The Three Musketeers", chapter 1
As an aside, while we're mentioning flaxen, the flaxen mane in ordinary chestnut horses is a single separate dominant gene, apparently.

A buckskin New Forest pony.
Image from Wikipedia,
in public domain
Right. Let's switch the ee for an Ee (or an EE, of course) and the aa for an Aa. Without the CR that's going to be a bay, with dark mane and tail. With the CR, obviously enough, it's going to have dark mane and tail but a golden coat: this is known as a buckskin. It's also potentially mistaken for a bay dun, just to complicate matters - the dun markings (the eel mark, particularly) do allow you to tell them apart.

If we don't have an A present, but still have an E, then the underlying horse will be black: the CR gene does affect this to a slight degree, producing what's known as a smoky black, which are, actually, quite hard to spot from an ordinary black or very dark bay unless you know what to look for, and certainly not at normal figure painting scales!

Right - let's move on to the double-dose of CR: this, as we've said, produces a cream coloured coat and blue eyes. So:
  • CRCR + chestnut is called a cremello,
  • CRCR + bay is called a perlino,
  • CRCR + black is called a smoky cream.
And they're all really difficult to tell apart! Perlinos may have a slightly reddish tail compared to a cremello, but in general - they're another 'almost-white' horse. 

I shall leave as an exercise for the reader to figure out what a horse with EE aa CRCR To/to would look like. Have a think, then have a peek at Wikipedia.

As ever, now we're down the weird and fun end of horse genetics, there are other genes which behave similarly to cream. The main one is champagne: it's a simple dominant gene, that lightens red/brown to gold, and black to chocolate. For more details, check Wikipedia, 'cause, frankly, we're also at the point where the number of possible permutations is starting to make my head spin, and my wife (who's a vet) is telling me I know more about horse genetics than she does, now!

And to answer the question from the previous article: Why do Romanies have black and white horses?

Well, thereby hangs a tale. On a trip to the Ironbridge Gorge Industrial Museum many years ago, my future wife got chatting to a chap (who may well have been a genuine Romany) sitting on the steps of a caravan and demonstrating various things,... well, being Anne, she was making more fuss of his horse, and owned up to being a vet. So, he asked her, seeing as how she was miss-well-educated-veterinary and all, if she could answer him that, with a twinkle in his eye. And, being miss-well-educated-veterinary, she racked her brains through a lot of what I've talked about in the last few posts, and after several good but wrong guesses, she was forced, to his gentle amusement, to give up.

And he smiled, and said, "Well, I'll tell you why we have black and white horses. To pull our caravans."

Next time? I'll wrap up, including some suggestions on painting groups of horses for (for example) barbarian tribes etc.

5 comments:

  1. Hi Mike,
    Just painted the horse in yer 1st pic last week for a Saxon officer, hope they were around europe in 1812-13?
    Interesting post.
    Cheers
    Paul

    ReplyDelete
  2. *grin* Thanks.

    I'll cover a bit of historical horse breeds/colours in the final article, but suffice it to say that I doubt that the CR gene mysteriously mutated its way into existence in the last couple of centuries :D There are cave paintings of yellow horses!

    ReplyDelete
  3. I found this quite helpful, especially as I have two boxes of Perry ACW cavalry sitting on my paint bench and I am always puzzled how to paint the sodding horses, other than brown and black. I am not sure how genetics in 19th Century North America made horse colours different than Europe, but you've given me some ideas for other paint schemes.
    Cheers,
    Mike

    ReplyDelete
  4. To be honest, Padre, I doubt they did much :D The predominant horse colour is still going to be some variant on bay, followed by black and chestnut, as that's the wildtype genetic makeup. The rest are all, ultimately, genetic mutations that have stuck, over some of the past umpteen millennia, and any predominance of rarer coat colours is largely a product of human interference and selective breeding.

    ReplyDelete

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