Behavioral Genetics, The Nature of Breeding

November 4, 2019

Rules of Nature

Natural herd dynamic structure, societal and interdependent, operates successfully owing to the laws of its nature; there can be no leadership without hierarchy, there can be no authority without there being consequences from it. The only way the social animal survives successfully and sustainably is when the individuals within it work together to form an alliance of social intelligence, which itself is only possible because of the individual emotional intelligence that comprise the group. Herd leadership, which certainly can be and is emergent in physicality we can see, is inherently rooted in and initiated from, emotional intelligence. Where every horse may not be “equal”, every horse is equally important to the herd survival.

Emotional intelligence is the core of leadership; it should then also be of primary consideration in any selective breeding program. In nature, the horse as a social animal supersedes the horse as an athlete. Designed breeding programs should always be a converging of two parts; physical genetics and behavioral genetics. The psychology is the operating system that runs the physical machine; it can contribute tremendously to optimizing talent, or frustrate and pinion its development.

Planning a mating is an assemblage of ingredients. You start with an “image” or vision of the ideal horse athlete, yet long before this jigsaw puzzle of the image can be realized the pieces are loosely scattered inside the box. There are ideal physical pieces to find and fit together, and then there are psychological pieces to identify and fit together that overlay the image, giving it life. These behavioral genetic pieces have long been honed and designed by nature to manifest into a herd structure, and because roughly 85% of horses fall into the mid-level herd dynamic ranges, (horses with naturally occurring herd dependencies) sifting through these individual pieces can be a daunting task. But not sifting through them only compounds what is already seemingly a largely random endeavor.

As I say time and again, race horses are not inanimate race cars fabricated in a shop; in a horse you’re getting both car and driver. Even when you’re “investing” in one aspect, you’re actually investing in two. If there were only one, then every perfectly designed physical mating would deliver a high probability of a world class athlete, no one would have to allow for the random, and fewer horses would need to be bred to find “the one.”

Behavioral Genetic Code; Prevailing Traits

When push comes to shove in competition, when the physical athletes are evenly matched, the deciding factor quite often is described in terms such as grit, determination, heart. Whatever term you use for it, none of them are describing the physical ability of the horse, they’re all relating to the psychological athlete. Grit, determination, heart, hard-knocking, all are traits often assigned to describe the characteristics of certain family lines, when these are consistent in behavioral genetic codes, they are an example of prevailing characteristics.

Prevailing character traits take the lead in what we ascribe to certain horses or families, be they positive and useful or negative and detrimental. But the on-the-surface assumed can also veil the underlying reality; misunderstood character traits are often characterized as “that’s just the way he/she is”, and for better or worse, these prevailing traits ride along as collateral influencers when physical/paper mating’s are being planned. Family genetics are one thing, what’s actually manifested quite often something else completely; similar yes but vastly different in many ways more often than not. My two brothers and I have the same parents, though we collectively have similar prevailing traits, physically as well as mentally, we also are individually very different, with different prevailing skills and talents, tendencies, all forged from the same genetic code. Buying or breeding along the same family lines or even having the exact same parents, promises you nothing in duplication, it only promises you many of the similar ingredients were involved. A little less here and a little more there, and the flavors can be quite different.

Family lineage is an intelligent and useful study of prevailing similarities of character traits, and there is most certainly any number of congruencies of nature to be found; but nonetheless, each individual is unique and presents their own version of this “stamping”.

Capturing lightning in a bottle has more to do with identifying the singularly displayed prevailing character traits of an individual in the family than it does casting the net of hope over several in the family line. The sought for magic mixture of ingredients is in the smallest of details, finding them is essential if you hope to do all you can to sway the odds of chance in your favor. Consistency of traits is an essential key to maximizing breeding potential, and individually more influential than a blanket of general characteristics. Selecting a specific family member in a line you prefer based upon how they express their family characteristics is far more useful in strategy than simply breeding to that family alone.

There is another aspect to prevailing traits that has to be considered because of the rules of nature; male and female behavioral genetics. Mother Nature has given each sex a different inflection on the same behavioral genetic language. Owing to the specific herd dynamic and structural roles each is inherently equipped to play in the family unit, the expression of prevailing traits will come with a male/female slant. Because of this, the lens with which a stallion is evaluated and considered has different emphasis points than does the lens placed upon a broodmare. In nature, by and large the mares have a lot to say about whom they breed to year to year, and following this same natural pattern I feel it is wisest to first select specific mare(s) who carry the traits you desire, and seek a stallion that fits after as opposed to random selection based off general similarities; let nature guide you beyond the paper.

Selecting broodmares with the proportionally correct psychological traits for breeding can be a far more challenging task than the more often than not straight forward psychologies of the stallions. Broodmares after all not only deliver their physical and behavioral genetics, they also greatly influence the developing interpretational abilities of the foals. This point is essential; understanding how the mother will slant her imprint upon the foal. Is she prone to stress, does she overreact, does she assimilate well and so on, are highly important questions to answer and carry great influence from and within the female families.

The influence ability of a stallion should be fitted to the influence ability of the broodmare in such a way they have a chance to compliment more than they have a chance to overlap.

Mare traits can often be more slanted toward the Group Herd Dynamic because of her role in the herd structure, and the stallion because of his role, most often will have a slant to the Individual Herd Dynamic. Each of these, though not put in place instinctively for athletics, do have athletic influences; they lend themselves to a horse’s natural psychological rhythm, herd placement, ability to assimilate to rapidly changing environments and ultimately how they express themselves – how they compete. IHD and GHD, found in both male and female to varying degrees, when in the proper proportions, helps to balance the horses psychology and when that balance is proportionally correct it allows them to elevate through the herd environment to leadership roles. You want this natural ability to lead in your physically capable athlete lest they be incapable by natural law, of fulfilling their physical potential.

This does not mean you have to have a “perfectly” proportioned IHD/GHD stallion or broodmare in order to get the emotional intelligence you need to optimize ability, but it does mean these things must be considered in each that a complimentary match is made.

Much consideration is wisely and necessarily given to breeding physical strength and structure, the same should be so for herd dynamic strengths and efficiency. A friend recently sent me a picture of horse and wanted a recommendation, I told him this isn’t like auto-trader, “this car is equipped with a driver, and you’d better know as much as you can about them before you write your check”.

Traits & Tendencies; Stress, the Great Antagonist

Stress is the great antagonist. An inability to manage and filter emotional stresses not only affects athletic performance, it places more stress on the physical horse, intensifying the wear and tear and ultimately increasing the risk of injury and the shortening of a career.

Individual stress management is essential to understand for breeding purposes, not just for training and performing. When you’re considering which stallion or which broodmare for your breeding program and you’re using as part of your guide their particular racing results, you would do well to dig far deeper than just what the numbers tell you. When it comes to breeding decisions, evaluating how an athlete achieves is more important than what they achieved. Keep in mind that you’re not breeding to an accessorized horse, or a horse complimented by weak peers or interesting training methods; things like shadow rolls and blinkers for example, don’t transfer their DNA however the reasons they were needed, do.

Every sentient life experiences emotional stress it is an unavoidable circumstance of living, however not all manage it in the same manner; stress management is what separates horses in a herd and influences athletes in competition.

As an individual horse within the herd structure, there is a big difference between outsourcing to others or something in the environment (dependency) and the ability to filter emotional stress swiftly, smoothly, internally. It is the difference athletically between a horse moving with required guidance in space or moving independently through space. Something quite important to know for breeding purposes if you’re goal is to breed top level athletic potential.

Traits or inherited characteristics can be both physical as well as psychological in nature, but tendencies are purely psychological; tendencies are the expression of both traits and learned behaviors and are often the visually reflective aspect of emotional stress, filtered or unfiltered. (Both the stallion and the broodmare stand a chance to hand down many of their traits and tendencies, and as mentioned, broodmare tendencies will govern the manner in which she educates her baby.)

Because emotional stress carries with it so much influence on how a horse lives its life, within and more importantly without, the herd environment, determining how they’re dealing with and expressing it becomes one of the most important pieces of the breeding jigsaw puzzle. If you’re future progeny is to be an athlete that competes alone in an arena, your evaluation process can be more slanted on how the stallion and mare handle stress while independent of the herd. If your future prospect will be geared toward a discipline that will require them to operate amidst a herd as well as independent of it, such as racing, your evaluation necessarily involves both aspects.

How stress affects a horse’s tendencies can change from circumstance to circumstance, there are some forgivable traits and tendencies because they ultimately have little effect on the athletic goal, and there are those that simply cannot be overlooked in the equation. It is also possible that the nature of physically expressed stress can be useful even if it causes strong directional “push” or strongly expressed physical knee-jerk reaction, (some horses are what we call physical processors, and are able to use emotional stress to physical advantages) so long as it is consistently expressed in the desired direction. A race horse that is being “squeezed” between horses, for example, and needs to physically filter that moment of stress, and has the tendency to move forward as opposed to hang or drop back, has an acceptable expression of stress. That said it’s important to remember that the art of your breeding program is as much a breeding of emotional expression as it is anything physical.

Another element of the trait, tendency and stress equation is time. The influence of stress upon tendency is not always easily realized until, like a balloon filling with air over time, it builds up too much pressure and explodes. This is another piece of the puzzle worth knowing, for stress that builds over time, easy to overlook, affects the horses ability to train at length and to perform a task beyond a certain pressure-point; time-in-motion. Horses that are affected by stress built up over time have what seems to be a wide space between “calm” and “erratic” behavior, often times displaying physical disruptions out-of-nowhere. This doesn’t come from “nowhere” of course; it is an indicator of accumulated stress that impacts how the horse distributes emotional energy, which directly affects the competitive nature of the horse.

A horse-athlete not only has to be able to physically handle the demands of becoming an athlete, they must also be able to handle the psychological demands. The last thing you want heading to the wire is to have your horse succumb to the accumulation of stress, having their patterns of motion affected by a pattern in their behavior.

Internalized stress unprocessed mentally or unfiltered physically can have highly antagonistic side effects. The “calm” time in waiting prior to competing or the protracted time, often largely sedentary, during convalescing from injury, can be nearly overwhelming for a horse bred for athletics. Both of these can ultimately affect the horse negatively in a physical manner; whether needing to optimize physical ability or fully healing from injury, depending on their natural tendencies.

Tendency strung together during times of chaos and assimilation demands develop into patterns in their behavior, patterns in their behavior translates in the competitive athlete to patterns in their motion.

Natural ability to manage stress is the gateway of hope for a successful breeding. The high functioning athletic psychology stays well ahead of physical motion; interpreting, clearing space like a blocker for a running back, optimizing talent, keeping them safe; once again, it’s the difference between a horse moving in space and moving freely through it. A fluent and supple psychology paves the way for a fluent and supple physical performance.

Traits & Tendencies; Corrective V/S Non-Corrective

Emotional stress is not something that you can breed-out of a horse because it manifests externally and itself is not a trait, but you can work toward breeding strength of tendency. Before you can do that you have to consider how emotional stresses enter the psyche which in large part happens in two ways; environmental stress and perceived stress. Environmental stress is collateral to the information being brought in to the psyche through the medium of the sensory system where the senses detect something that causes interpretational anxiety.  Perceived stresses anxiety that stems from learned behaviors and the pre-existing psychological triggers that are related to them accompanied with an inability to interpret or discriminate what is environmental or perceived. The common denominator is the interpretation process of either real or perceived stimulus.

An inability to interpret creates stress; stress creates internal anxiety which leads to outsourcing and dependency. For the herd animal asked to compete this means that in times of emotional stress they can become herd bound and dependent while moving, compromising speed, pace, efficiency, causing drag in the fluency of motion and so on. None of which are productive athletically.

Just because you cannot breed out the infusion of stress doesn’t mean you can’t take steps to breed out sensory disruptions that lead to psychological weakness, for there are both corrective and non-corrective traits and tendencies.

Mating “elite” physical athletes doesn’t mean you’re going to get elite progeny as a result, if that were the case every Grade 1 winner bred to a Grade 1 winner would gift you a Grade 1 winner. Life isn’t that simple, and neither are the herd dynamics. Herd animals rely on one another for their safety and survival and this means that by nature the majority of horses born will have incompletion in their psychological makeup creating dependency one to another. The law of averages is against your breeding program from the start. The question that has to be answered is what are the psychological ingredients of those rare natural herd leaders? The ability to manage stress individually starts with the ability to interpret it properly.

Horses with naturally occurring (mid-level herd dynamic) interpretational issues and outsourcing dependencies in a mating program will at a high percentage rate deliver these traits and subsequent tendencies in their progeny. Any trait or tendency that is inherently borne from the psyche is non-corrective meaning that once it is there by nature it is a behavioral genetic trait that is geared toward herd dependency. You’re not going to “train it out of them” you can only help manage it by the environment you create for them. These horses are highly subject to outsourcing and operate most efficiently when being lead by others in times of stress. These horses will also have incomplete sensory soundness preceding their inclination to outsource.

The sensory system itself is a physical aspect funneling information into the psyche for processing, making breeding for sensory soundness just as essential as breeding for a certain hip, shoulder angle, hock, and pastern and so on. It is vital to evaluate fully either your stallion or your mare and gain a detailed mapping of sorts of their sensory system and its efficiency. Once you identify the strengths and weaknesses in the sensory system you are armed with information to help you breed away from subsequent dependency of nature by finding a mate that strengthens the areas in question. Herd and environmental dependency as a tendency under stress becomes less an auto-response when the horse is equipped with a highly efficient sensory system.

Your stallion or your mare need not be perfectly efficient in every area physically or mentally, so long as their mated with a horse that compliments and strengthens; this is how you breed away from dependency.

The key is that neither mare nor stallion have too deeply set and highly erratic interpretational issues and environmental/herd dependencies. These horses are much harder to “correct” through a breeding program and is often a costly experiment in futility. Horses with sensory weaknesses that are otherwise largely devoid of herd dependencies have a much higher probability of success in a breeding program than horses with both sensory and interpretational dependency because you can intelligently match them with a mate whose traits are stronger in those areas. Trait to trait correction is far more likely than trait/tendency to trait/tendency corrective efforts.

Natural Laws; Sustainable Herd

The bottom line, according to Mother Nature; your primary consideration is to breed an emotionally intelligent and herd dynamically sound horse, your secondary consideration is a focus on the physical athlete. In truth these of course work together and both are required to optimize ability, yet physically selecting a match is less intensive than matching psychologies and perhaps too often takes the lead in the process; the driver of your machine becoming at best a conversational afterthought. In controlled breeding programs where pedigrees and physicals embody the largest part, if not the only part, of the decision making process, a wide range of behavioral genetics gets forwarded along randomly. No worse thing for an otherwise strong herd dynamic stallion or mare to be mated improperly, it can unfairly label them as “non-producers” and at length they’re sold, retired, given-up on.

In the natural herd dynamics where human caprice is not a factor, the behavioral genetic traits and tendencies are much closer together. Nature has employed natural selection to ensure the weak minded and overly dependent do not endanger the overall herd survival. There’s a reason there are two herds roaming in nature, the usually thought of family herd and a bachelor herd. Lead stallions emerge from bachelor herds and take over family groups owing to their emotional sagacity, fortitude and intelligence combined with, not because of, their physical strength and athleticism. Lower level herd dynamic horses in both herd groups are less likely to breed consistently; low level stallions rarely get the chance, and lower level mares who aren’t culled off naturally find themselves nonetheless mating with the lead stallion of her herd.

Mother Nature is ultimately quite discriminatory when it comes to her breeding program. In order to sustain herd survival a tight grip on emotional intelligence has to be embraced; too much weakness of mind waters down the gene pool, widening the breadth of behavioral traits too far from the balance intended. Inefficiency of mind leads to emotional stress, leads to loud physical expressing horses, leads to undue attention upon the herd from predators and a frailty of nature in individuals.

Closing Thoughts; Thinking Forward

Instinct drives the machine, breeding for success means breeding in strengths, breeding out weakness both physically and mentally. Among the many things to consider are breeding for sensory and psychological consistency, identifying the psychological growth patterns of both broodmare and stallion which will help you understand their emotional intelligence, and never overlooking the fact that your horses are not inanimate objects.

There are no guarantees or “can’t miss” scenarios no matter how much homework you do, but under appreciating the value of the herd dynamics in your breeding decisions and leaving it to random fate alone is unnecessary and unwise.  The strongest body being operated with a weak mind and inefficient sensory system only gives you a better chance of failure or an unfortunate catastrophe in a game where the chips are already stacked against your success even when everything goes right. Utilizing herd dynamic evaluations as a part of the mating decision investment strategy helps bring clarity to your direction and to the decisions you make, like a version of “e-harmony” for horses I always say. It is just my personal opinion, but if a product isn’t standing up to normal and expected wear and tear once sold, perhaps the manufacturing of it may need a tweak or two?

If we consider the current perceived state of the sport, every bit of information that can be obtained and applied, should be. I’ll be the first to admit that I’m no leading authority on the minute details of neither pedigree nor physical conformation, but I’ve dedicated a large enough portion of my life to the study of herd dynamics and the psychology of the equine athlete to know, that the economics of behavior simply makes sense.

 ~ Kerry M Thomas

Founder of  THT Bloodstock

*Recommended reading* “Sensory Soundness, The Psychology of Motion” which can be found on Kerry’s Corner section.

For more information on herd dynamic evaluation services feel free to get in touch with us; contact Pete Denk @petedenk on Twitter and via email

To follow Kerry on Twitter go to @thomasherding  and THT Bloodstock FB Page or visit at

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Kerry Thomas

THT Bloodstock Kerry Thomas is a pioneer of equine athletic psychological research and Herd Dynamics. He created emotional conformation profiling, which measure’s the mental and...

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