March 2012

My oldest son has been struggling with freshman Biology, so the concept of evolution has been on my mind a lot lately. I have also been reminded that evolution applies, not just to organisms, but of points of view. Sometimes it can be easy to forget that you once held a different view – unless of course you are foolish enough to write it down for others to find later. I have been writing about horse color long enough now that I have had that happen!

The reminder of this came from my husband. Longtime readers of the blog have probably picked up on the fact that I have a strong interest in the issues surrounding genetic diversity. It is, as I have mentioned, one of the themes that runs through the upcoming books. My close friends could probably warn readers that it is a tempting soapbox for me, particularly when it comes to the topic of dogs. That was exactly what I was doing – standing on that soapbox – when my husband reminded me that I once held a very different point of view on the subject.

He has every reason to remember this, since there was a time when the topic came up often between us. My husband is a physicist working in the field of optics. When we first met, he was intrigued by the possibilities of using genetic algorithms to solve complex design problems. A genetic algorithm is a mathmatical tool that narrows down variables by “breeding” the possibilities until an optimal solution is found. He was experimenting with genetic algorthims, and I had recently bought my first Arabian mare after spending most of my teen years planning my future breeding program. I was more than happy to explain all the different inbreeding, linebreeding and outcrossing schemes breeders had developed over the years.

My husband used this diagram to illustrate a chapter on genetic algorithms in his book. My understanding of how he used the idea doesn’t go much deeper!

I was familiar with them because I had my heart set on breeding animals, most specifically Arabian horses and Rough Collies. Since I could not convince my parents of the pressing need to start populating our home with dogs, or to acquire land for horses, I used the time to learn all I could for the day when I could do those things. When the time came, I was determined to be the most informed breeder possible. I devoured issues of Arabian Horse World. It was the 1980s and  the market for Arabians was at its peak, so each issue brought countless images for a horse crazy girl trying to determine just what qualities she would emphasize in her hypothetical breeding program. While other girls were pouring over fashion magazines and beginning to notice boys, I was filling ring binders with notes on bloodlines and affixing sticky notes to the important pages. As you can see, many of them are still there today.

I was smitten by pictures of the stallion *El Shaklan. The more something looked like an imaginary elven horse, the better. I was not an especially practical kid.

Arabians appealed to my artistic sensibilities. My interest in Collies came about in a more personal way. My grandfather was a Collie man, and encouraged me to read Albert Peyson Terhune’s books. Mr. Terhune had lived in the same town, and traveled in many of the same dog circles, as my grandfather’s family had when he was a boy. Like so many, I fell in love with the breed as it was portrayed in Mr. Terhune’s books. When my parents offered to give me my very own dog for my twelfth birthday, getting a Collie seemed a natural choice.

My grandfather’s favorite Collie, Glengay Sandy Boy. The inscription on the back of his photo is the Terhune quote, “a thoroughbred in body and in soul.”

I knew the “proper” way to obtain a quality dog. My parents, however, had different ideas. I wanted the perfect bitch with which to start my grand breeding program. My parents wanted something within their price range and a reasonable driving distance. The result was the dog at the top of this post. She came from a local farmer who raised a few Collies on the side. She wasn’t the potential foundation female I would have liked to have gotten, but she was a dog of my very own. When you are twelve, that counts for a lot.

My grandfather, when he received her photos, was quite critical. She had a pronounced stop, which was not proper. The angles of her face were all wrong, and she carried her tail in something awful close to a curl. But the real deal-breaker was her prick ears. As soon as she left the puppy stage and those ears went up, he ceased to consider her a Collie. Purebred Collies had tipped ears. She was, he insisted, nothing more than a “Whiffle Hound.” She was no relative of his beloved childhood Collie, Sandy.

Looking back, perhaps that reaction planted the seeds of doubt about what was valued in the animal fancies. It was obvious to anyone familiar with the standard that Brandy was a Collie of inferior type. I would have readily admitted as much. She was, however, a wonderful companion for a young girl. I thought she hung the moon, and her over-large, erect ears seemed like such a little thing in comparison to all that was great about her. We competed in obedience for much of her youth and mine, and it was pretty clear which of us did the better job. (Her ears were less of a limiter than my tendency to confuse left and right.)

Pictures of my grandfather with his ‘thoroughbred’ Collie, Sandy, and me with my ‘wiffle hound’, Brandy. Interestingly enough, we are the same age in these photos and adopting quite similar poses as we encouraged our dogs to do tricks for the camera.

But when Brandy passed away at fifteen years of age, I was explaining close linebreeding (the word I used at the time) to my husband. I had absorbed those ideas from the cultures that surrounded Arabians and Collies, and if anything was going to marinate a young animal lover in the twin concepts of “blood purity” and the usefulness of inbreeding, it would be the world of those two breeds.

But something happened along the way. Soon after we married, my husband’s work took us away from our small farm in Alabama, and to city life here in Charlotte.  I had already begun to question the consuming nature of raising dogs and horses, having seen that more closely through the experience of a number of friends. My interest in breeding animals became more academic, and less about laying the foundation for future activities. My mindset shifted from future breeder to a person who would own a series of beloved family companions, and who just happened to be very interested in the topic of genetics and breeding.

It was the academic interest in animal breeding that exposed me to a new way of thinking about breeding programs. My interest in color motivated me to read journal articles. Many of the authors of those articles also wrote about breed conservation and genetic diversity. Over time, the ideas presented in those papers brought about an evolution in my thinking. Like classical evolution, the change was gradual – a shifted position here, and new insight there, until something quite different took the place of what had been before.

Thankfully for me, this process occurred in the peace and isolation of my own research. I could think about the issues involved in a fairly objective, unemotional manner because no one was clamoring for me to reach a specific conclusion. Now many of those issues have become a source of controversy and bitter battles within the animal fancies. This has played out most visibly in the British dog show world, which was rocked three years ago by the documentary Pedigree Dogs Exposed. That program brought genetic diversity out of the realm of academic papers and into the public square. It is pretty safe to say that unemotional is not a feature of the situation!

In this reaction, many have called the focus on genetic diversity a passing fashion. That is not surprising, since fashion has long driven animal fancies. That is a natural frame for viewing motivations behind breeding decisions. I do believe, however, that calling the subject a fashion does a disservice to kind of thought that goes into breeding decisions. The acceptable angles of a Collie head, and the proper carriage of their ears, is a fashion. The acceptable amount of white on the legs and face on a horse are a fashion. The benefits and hazards of an increasingly homozygous population is a much larger issue. The truth is that breeders are dealing with competing concerns, with uniformity and predictibility being the very essence of selective breeding, and with its opposite, heterogenity, being so closely tied to health. That is not fashion: that is about the limits of the system as it really is. It is essential to understand those trade-offs if breeders are to make good decisions.

As I have said, the Equine Tapestry books touch on the subject of genetic diversity. Because the way a registry defines “breed” and “purity” has a huge impact on colors – both what is ruled in and what is ruled out – it is quite relevant. It is also true that misconceptions about purity and breed integrity have big implications for animal coloring. Because color is so easy to see, and is often the result of far more straight-forward inheritance than things like conformation or breed type, it tends to be on the front line of selective pressures. But beyond those issues, it is my hope that the books will raise questions about how we integrate our growing understanding of genetics into real world breeding decisions.

I have a few more posts to make that expand on some of these ideas, since I want to bring some of these ideas back to issues that touch more directly on color. I also plan to add another page (much like the Splashed White Project page) to the blog with a collection of links for further reading on genetic diversity. Perhaps they can plant the seeds for a more rational dialogue on the topic.

Twenty years ago, when I talked to my husband about linebreeding, I never mentioned genetic diversity. It was not a concept that had come up in my reading at that point. Today when I pulled the copy of my husband’s book, thinking I might find some of the images that came from his work in genetic algorithms, I found the following passage:

We intuitively know that larger populations will bring greater diversity and better sample the solution space. If the ranking function is nearly flat, poor attributes will stay in the population longer. If the ranking function is steep, the population swiftly becomes inbred. A lot of mutation can slow the convergence, while no mutation will lead to premature stagnation through inbreeding.

That passage pretty much sums up the situation facing breeders. If the selection process (what he calls a ‘ranking function’) is minimal, we will get a mix of good and bad attributes and not a lot of control over which we get from any particular breeding. That is the part I knew. At the other end, if we use extremely strict selection, we run the risk of a dead end where the variables present are too limited to provide the answer to a problem. For many, my younger self included, that is the missing piece. I may not have understood then, but the math certainly gave my husband a more complete picture. It almost makes me wish I hadn’t spent so much of my high school algebra classes doodling horses in the margins of my notebook.

Body-clipping a horse can give some really strange results, but I thought this warmblood was particularly interesting. I’ve noticed that clipping a horse sometimes reveals dappling that is not evident on the regular coat. That seems especially true for silver dilutes. I’ve also noticed that some clipped horses are rather unevenly colored, and that even more of them grow back with uneven color, but this is the first one that I have seen where those uneven areas look so much like a dappling pattern in reverse.

Here are some more angles on the same horse. (And thank you again to Kim Smith for sharing her pictures. Getting such numerous clear shots of unusual colors is such a treat!)

Notice on this last one how the dark area on the hind leg follows the pattern of the veins, just like ordinary dappling does in reverse.

I must admit that my own experience with clipping is very limited, so I don’t know how common reverse dappling might be, and whether it is something seen when the horse is clipped or something that appears as the coat grows back. Perhaps owners of Miniature Horses, which are often clipped for showing purposes, can share their experience with color changes.

I do know that horses like this are often mistaken for roans or even for duns, especially in photos where the difference in hair length cannot always be seen, because of the contrast between the head and the body color.

I apologize for the delay in getting these images up. I had hoped to slip them in before I got caught up trying to meet a few deadlines, but that did not work out as planned. Posts to this blog don’t really follow a set schedule, but I suspect they will once again be a bit erratic as I try really hard to finish the revisions to the book. (Yes, I did decided to revise the sections on splashed white to reflect the current studies.)

These are more examples of the kind of color shift seen in some black appaloosas. As I mentioned in the previous post, many – but not all – black appaloosas have a base color that is diluted to a pewtery bronze color. The elderly fewspot gelding in the picture above was mentioned in the comments section of the previous post. Colt was owned by my friend Marge Para, who said he had been registered as a red roan. I suspect a lot of these horses end up registered that way. Here is a close up of Colt’s feet showing a color very similar to that of my mare.

Here is Colt’s lower leg coloring alongside the legs from the previous post. The tone is very similar.

Here are a few more images of an Appaloosa that has this same kind of hard-to-describe body coloring. Although the testing status is not known, it matches the tone seen in other color-shifted black appaloosas enough that I would suspect her of being black rather than dark chestnut.

This one is another difficult color to classify. Because this horse has areas that are more red-gold in tone than pewter-bronze, I suspect he is genetically brown or dark bay.

Here is a face shot that shows the reddish-gold on the end of the nose, contrasting with the more chocolate tones of much of the rest of his coat. On a  brown non-appaloosa those chocolate areas would be black – or at least have a lot of black shading.

Horses like this one, where there are red tones along with cooler, chocolate tones can be especially hard to identify. Many silver dilutes on brown or dark bay can be like this, too. What often makes them stand out compared to a liver chestnut is the discordant warm and cool tones, with the warm tones usually falling where a dark bay or brown horse would be red-gold. With appaloosa patterns, this is even harder to see (particularly in pictures) because the roaning can make areas appear brighter when in fact it is caused by white hairs and not a change in actual color.

I have to thank Kimberley Smith for sharing her photos. I am always grateful for permissions to use photos on the blog, since multiple images are great for showing the range of a color or pattern.

I also mentioned the well-known diluted mare Ava Minted Design in the comments. I decided to save her for a future post, since her situation is a little unique.

One of the things that used to stump me, when I first began painting horses, was the base color on many of the Appaloosas. Often the horses had an odd pewter brown coloring that did not look quite like chestnut – not even liver chestnut – and was not really black. Many years later, I found myself owning just such a horse. The picture above is my mare, Sprinkles. In that particular picture, she is three years old. If you look closely, you can see that her lower legs are a bronze color. In bright sunlight, that is the best term for her coloring. In lower light, and when she is in her winter coat, she is closer to a dull pewter.

Her previous owners thought she was a grulla, probably because they mistook the split in her blanket for a dorsal stripe. I also wonder if they weren’t subconsciously seeing what seemed pretty clear to me, which was that the tones in her coat were all wrong for even the dullest red-pigmented horse. She looked like a diluted black horse of some kind.

And that is exactly what her tests from UC Davis showed her to be. She is genetically black (Eeaa) without any known dilution gene. Her coloring isn’t the result of sun-fading. Most blacks that sun-fade retain a certain amount of darker pigment on their lower legs. Her lower legs are the palest tones on her body. This photo was taken last summer, when she was eight years old. The lighter area at the top of her leg is appaloosa-related roaning. Although there are a few white spots on her legs (none visible in this shot), there are no roan hairs below her knees. The hair itself is lighter and somewhat iridescent.

When I got her results back in 2008, I posted a series of comparison photos on my studio blog to show how the tones on lower legs differed. This is the sort of thing that artists need to be able to see in order to capture different colors in a believable way. It’s also something that artistically inclined people tend to do well, which is probably why many artists are good at guessing color when tests are not available.

I’ll give the same caveat about these photos that I did when I first posted them. Photographs are not the best way to really see these differences, even for people that are good at noticing them. All the ways we record and transmit images (film, printing, monitors) can distort color, and with something like this what we are dealing with are very subtle differences in tone. These images were taken with the same equipment in close proximity to one another, but still viewing these colors in real life – preferrably side-by-side – is the best way to see. Indeed, the tone in color is really best studied from life because the camera rarely captures what is so obvious in person. But this is as close as we can get over the internet!

These are the legs of a sooty palomino pony. Notice how yellow in tone the lightest areas are. “Yellowness” is one of the best indicators for the presence of the cream gene.

These are the legs of a red silver pony. This horse is genetically bay, and you can see the unaltered red hairs on the upper leg. His black lower leg has been diluted by the silver gene, turning it a bluish chocolate. The overall tone on the lower legs is very cool, especially compared to the yellow of the palomino above.

And these are Sprinkle’s legs. Again, she’s genetically black so like the silver legs above, this is a diluted form of black. The color isn’t cool, however. It isn’t yellow, but it’s not really red either. If I had to call it something, I would say it is a bronze tone.

Here is a side-by-side comparison of the leg color, with an addition of a sooty chestnut to compare against a truly red leg.  (The image links to a much larger version.)

And finally here are bronzed legs beside a flaxen chestnut leg and a truly black leg, showing the contrasting tones.

To my knowledge, no formal studies have been done to determine what causes this. It does not happen to all black appaloosas, but it is not especially rare either. Tomorrow I will post a few more examples.


It can be really hard to get good shots of horse eyes, so I was really pleased to get a number of good shots of this Pintaloosa mare and her partially blue eyes. The placement of the blue segments certainly give her an unusual expression. This first image shows how her left eye has a blue section towards the upper front of her eye. The apparent shape is accurate – none of the bluish area is glare – since it is consistent across a number of images.

Here is her right eye, with a blue section on the lower side. Notice how a thin line wraps up along the back edge, and how uneven and inconsistent the blue area is. (The blue coloring on the left eye was uniform.)

Here she is looking forward with her mismatched eyes, one with a blue bottom and one with a blue top.

Here are some full-body shots of her, showing her varnish roan (leopard complex) and tobiano patterns. The varnish mark on the top of her tear bone is particularly noticeable in the first picture, and the mark across the nasal bones in the second one.