Lost in the Shuffle

Sometimes comments on blogs get lost in the shuffle. I received a comment on my first post on the X-Factor (Large Heart Theory) that I think deserves your attention:

“A fair analysis of the X Factor hypothesis would have to include all potential X passing pedigree positions in which the four sires named above may occur, not just 4 of them. In a male’s 5 gen. pedigree the number of such positions = 7, in females it’s 11.

“It’s a moot point, however, since there is no lack of highly credible genetic evidence debunking this hypothesis which holds that heart size is controlled on the X chromosome. The domestic horse genome was sequenced six years ago, SNP chips developed, and since then the genome of no breed has been scrutinized as closely as the TB. As first proposed ~20 years ago the X factor hypothesis was somewhat simplistic though not altogether implausible and certainly not ‘bizarre.’ But as it turns out the factors controlling heart size aren’t on the X and the hypothesis is false.

“Genomic evidence has already begun to redefine how we study and analyze pedigrees and will no doubt continue to do so. Any ‘transparency’ it might offer must be regarded in full context, i.e. the genome is only one factor in the equation that produces a successful racehorse.”

The important thing about this comment is that it comes from a geneticist who claims (and I do not doubt him in the least) that genetics has already DISPROVED the hypothesis that the large heart gene is carried on the X (female) chromosome. Therefore, my statistics on the subject were all superfluous.

The funny thing is that geneticists and students of pedigrees do not communicate very much or very efficiently (if at all). I feel that my study of the subject was not in vain. After all, it DID elicit the comment above, and the comment above agrees with my analysis that the hypothesis is totally FALSE. You probably would not have heard this comment from a geneticist unless I had raised the subject in the first place.

Incidentally, I did not characterize the theory as “bizarre.” The word “bizarre” was used in another comment on this post.

Lastly, I wholehearted agree with the statement: “The genome is only one factor in the equation that produces a successful racehorse.”

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8 Responses to Lost in the Shuffle

  1. ned williams says:

    One of my football coaches, in the distant past, was fond of the expression, “You can’t make chicken salad out of chicken Sh*%”. While I know that other factors such as environment, training, and pure luck are significant contributing factors as far as “creating” a fast horse. Without the right “genetic stuff” all of the “other stuff” is a waste of time. We can’t, at present, make a genetically slow horses fast. Even with illigal drugs, we cannot make an Arabian outrun a TB going 3/4 of a mile. However, none of us really know what we have each time a new foal hits the ground. Consequently we must train and treat them all like Champions and let them prove otherwise (and treat them well after their racing carreer are finished as well). In summary, I have seen many a bad trainer succeed greatly with a good horse because the horse is/was just too good genetically to foul up. The converse never really seems to happen. The good ones are not called “Freaks” without cause. They are genetic freaks.

    • ddink55 says:


      I would agree that the very best are all genetic freaks. Otherwise, full siblings would all be equally good, which is obviously not the case.The only nag I can think of to refute your argument was John Henry. He had a very mediocre pedigree. On the other hand, I might also say that John Henry was vastly overrated. He was tough and durable and won a lot of good races, but he was not particularly “fast.” He was no match for a Man o’ War nor a Secretariat (nor even a Frankel).


      • ned williams says:

        Yes, I agree about Man o’ War or Big Red, but I think you could still use him (John Henry) as an example because, for his pedigree, he was a freak. He got all the best possible stuff from his sire and first dam. A crazy confluence of genetic soup gave us John Henry. He was probably overated, but still a freak as far as his make up and ability. I am not arguing that pedigree is the key factor, rather that the confluence of genes at conception has a greater role than trainer, jockey, or environment. In my opinion, none of these things can make a slow horse fast. However, some fast horses overcome these things to become good or great horses.

      • ddink55 says:

        Just for the sake of argument/discussion let us postulate the following division of factors that determine racing ability. Pedigree is about 40%. The environment provided by the breeder of the foal and its upbringing is about 20%. The trainer is about 20%. The jockey is about 20%. Does that seem reasonable to you????

        If you agree, then yes, pedigree is the SINGLE most important factor in determining racing ability. But it is NOT more important than all other factors.

        I would also agree that unless you have something good in that 40% pedigree portion of the equation, the remaining factors probably are not going to do you a shit bit of good. You can not make a slow horse fast.

        And when we speak of pedigree, we mean “the confluence of genes at conception.” Not just sire and dam. Although since the former is unknowable at this point in time, the latter is all we have to determine the probabilities of the former being good or bad.

        Incidentally, I always thought that Double Jay (the broodmare sire of John Henry) was the best part of his pedigree. Double Jay was a leading broodmare sire three times, the last time in 1977, when JH was only two and hence not a factor in that title.

  2. JDB says:

    As the author of the comment that is the subject of ‘Lost in the Shuffle’ I’d like to point out that I did not claim (or think) that Mr. Dink’s statistics on any subject were “superfluous” or “in vain”. The main problem I have with his statistical analysis of the ‘X Factor’ theory is the fact that some people will perceive the theory as still being a credible one simply because Mr. Dink elected to do this analysis, and even though his results offer little reason to put any stock in it. Those same people continue to point to Chap. 13 in ‘Racehorse Breeding Theories’, among other sources that present Haun’s theory quite uncritically, as evidence that it is “proven” which, of course, it never was. That’s not to imply that this is in any way the fault of the authors. It’s the responsibility of each individual to do their own critical thinking.

    Mr. Williams, I can’t immediately recall who, but a speaker at one of the Pedigree and Genetics symposia made the point that while most superior runners possess favorable variants at many/most relevant polymorphic loci in the equine genome there are occasional exceptions, horses that don’t have the right genetic stuff but still manage to succeed at the top level. Conversely, it’s quite possible for one with all the right stuff to fail if training and handling are not complementary to the specifics of the genetic profile as far as maturation rate, aptitude, etc. are concerned. In the cases of the superior performers named above, most plausibly the genetic and environmental factors were favorable and exceptionally complementary.

    • ddink55 says:

      I thought I made it pretty clear that I was NOT approving or validating this theory at all. In fact, the opposite. “Still, a man hears what he wants to hear and disregards the rest.” The second post on this theory was even more clearly NOT approving or validating it, I thought.

      • ned williams says:

        I think we agree on the main concepts. However, I do not think that the jockey or trainer make up 20% each or 40% in total. I would put the percentages between 5% and 10%. I tend to believe that good jockeys tend to cancel each other out and that only bad jockeys (of which there are many) have much of an effect over time. A bad jockey can certainly lose a race more easily than a good one can win one. I also think that many trainers cancel each other out…good or bad. Talent is the key for me. In my opinion, a talented horse in average hands will still be a good horse. An average horse in talented hands will still be an average horse. This is my experience at least.

        I think Boojum’s whole point was to debunk the X factor theory.

  3. JDB says:

    Ned – I got Boojum’s point before I posted the comment that is the suject of ‘Lost in the Shuffle’. Unfortunately, the blindly faithful believers in the ‘power of the X’, the only group still inclined to attribute any credibility at all to Haun’s hypothesis, will not perceive that analysis as a debunking. First, because in between her lengthy rhetorical excursions on the various sire-defined “heartlines”, “double copy” mares, and so-and-so’s ears, Haun does occasionally acknowledge that a large heart alone is no guarantee of superior performance, just a powerful edge when all other factors are equal. Second, because the analysis apparently does not take into consideration all X passing pedigree positions.

    At this point in time there is probably nothing anyone could say or do to convince the remaining X factor faithful that there really is no gene controlling heart size on the X chromosome. Not to be punny but they will be heartened simply by the fact that Boojum found the hypothesis worthy of analysis and discussion. I find that fact mystifying. In the last decade or so there has been a veritable blizzard of far more credible evidence in regard to the genomics of superior performance in the Thoroughbred in the form of journal literature (which is how geneticists et al. usually communicate). Like any other form of information that material demands critical analysis, particularly in regard to conclusions being drawn by people with little knowledge of the breed and its history. Why this material has been allowed to escape the scrutiny of many, maybe most, TB pundits yet Haun’s disproven hypothesis is still tabled for discussion is a mystery to me.

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