DNA Studies that pertain to sport horse breeding.
We have a tremendous advantage the breeders of previous generations did not possess: we live in the era of DNA revelations. Never before have breeders been supplied with such powerful knowledge. Tesio, working at the dawn of genetics, was feeling his way in the dark (it makes his results all the more astonishing). We should be able to do incredibles things now with so many genetic mysteries solved through the ongoing DNA studies. So, let's look at the accomplishments of our current day geneticists, and see how we can apply their findings to our own work.
Before we look at what science can tell us about equine origins, speed, stamina, gaits and sex-linked traits, it will help us if we understand how they structure their findings. Most researchers, no matter their field, begin with a working theory--because it provides a starting point and structure to the investigation. According to Webster a theory is:
"systematically organized knowledge applicable in a relatively wide variety of circumstances--especially a system of assumptions, accepted principles and rules of procedure designed to analyze, predict or otherwise explain the nature or behavior of a specified set of phenomena"
For example, in my studies presented on this site I have isolated breeding principles in the study of Tesio Methods, and I boiled down the horse breeds used in creating sport horses in a 'sport horse recipe', as an example of my 'working theories'.
Webster goes on to put it more simply:
"theory is a assumption or guess based on limited knowledge or information: hypothesis."
So what is the working theory in equine DNA studies? It is Darwinism--that species evolve into higher forms, and that the changes come about by mutations. From this base hypothesis it is then presumed then the primitive or wild horse (Przewalskii Horse) must then be close to the original primeval horse, the ancestor to our modern horse, therefore its DNA would be the normal horse base. The theory assumes our modern horse evolved then from a primitive ancestral horse that is the common ancestor to both types. With this foundation of belief they have proceeded to evaluate the DNA findings that are of interest to us.
Above is Przewalskiis Horse, a living remnant of the primeval horse--the alleged ancestor to the modern horse (Wiki Commons - public domain image taken by Claudia Feh in 2005).
The scientists' have taken the DNA of the wild horse and salvaged DNA from the permafrost of Sweden and Alaska of extinct primitive horses and set those results then as the base normal.
However sensible this sounds, you should be aware there are some large cracks in this foundation provided by the scientists themselves.
1. Work by Jansen et al, Vila et al and others using mitochondrial DNA (mtDNA) for tracing migrations of horse breeds, have determined that the modern domestic horse DOES NOT descend from the wild horse.
2. Further studies conducted by groups led by Lingren, Wallner and others, who approached the problem from the Y chromosome descent trails, showed that while the wild horse is related to the modern Zebra and Ass, it is NOT related to the modern domestic horse. And they also were able to determine that all modern horse breeds descend from ONE stallion--and that stallion is not found in the wild or primitive horse.
Huh? So our sport horse is not descended from the wild or primitive horse? But knowing this the scientists still are using the wild horse model--some saying that some unknown or undiscovered wild horse remains will prove to be the domestic horses' ancestor--the proverbial 'missing link'! So accepting this working theory requires 'faith' in Darwinism.
So where does this leave us, the breeders? We must separate the real science in all this from the hopeful structure surrounding it. The important thing is for us to glean the useful information these studies provide--and make no mistake, the scientists have found some very helpful and interesting things that we can apply to our work.
Another thought is we need to use some perspective when applying the information. In order to study these genes the scientist must isolate the gene and determine the properties it alone carries. In doing so the findings then give a limited view by necessity, because genes in our horses do not act alone, but in concert with the other present genetics, and this may modify or even change the expression noted by the study. We will see this plainly in the speed gene and gait-keeper gene review.
For your own further investigation please access the original published work on all these studies, which I have listed for you on the attached pdf.
The Large Heart Gene - this article was written many years ago and still is one of my most viewed pages. Sadly, since the discovery by Marianna Haun and her team and their published findings, she has passed on. Marianna did us all a wonderful service by her work, she was a true ground breaker, and she will be missed.
Speed Gene - Historic genetic breakthrough, isolating a speed gene, discussion on the findings and how it applies to our breeding programs, also some question on scientific assumptions on its reach
Gait-Keeper Gene -discussion on the claims made for the gait-keeper gene
Origins -sport ability in our modern horses can be traced right back to its source, and the breeds and bloodlines that have maintained potency in the original source have proven to be the superior sport transmitters.
Warmblood Fragile Foal Syndrome : dangerous recessive in the wb gene pool, and the interesting cover up.
All of these studies are enlarged in Standardbred Sport Horses.