Horse Brain, Human Brain. Janet Jones

the horse evolved to survive predators on open grasslands, his brain became more dependent on activity within the group. Imagine 10 horses grazing in a field that is familiar to them. By nature, they will adopt slightly different positions with their bodies aimed this way and that for greater surveillance. Although their heads are usually down, each horse pays attention to the others. If the most sensitive horse glances up to check a noise, the others cock an eye or ear toward him. If one horse startles, the group looks in that direction immediately. To stay safe, they need each other.

      When removed from the group, horses transfer their need for leadership from a dominant equine to a human. So, in the absence of a higher-ranking horse, your mount is going to look to you for help. He doesn’t need a friend or a follower—he needs you to be his leader.

      Social behavior among horses is partly learned but largely innate. Brain scientists in 2018 found that mammalian brains are hard wired to regulate the rank hierarchies, group status, social vocalization, and peer observation that horses use all the time. To train well, we need to understand these evolutionary motives.

      Evolution’s Behavioral Tendencies

      Because of their need to escape predators, horses are innately afraid of being restricted or confined. Tying, for example, needs to be taught in a gradual gentle way to overcome the horse’s natural fear. Blocking the horse’s side view in narrow passageways causes trouble —and, unknowingly, people do it all the time. At least 35 million years of evolution tells an equine brain that the dark, restricted, metal box of a trailer spells D-E-A-T-H. A horse who balks at these practices is not being ornery. He’s being a horse.

      We all know that horses are attuned to unexpected sights and sounds. But many people don’t realize that the least obvious of these are the most likely to startle the horse: short rapid movements and low-volume sounds. Predators did not announce their presence in advance—they tried to hide. If you’ve ever seen a non-horse person try to “hide” from a horse so as not to bother him, you know what I mean. Once while I was giving a lesson, a visitor tried to hide her Labrador Retriever under the bleachers in an indoor arena. Every horse in the ring flipped out. Once the dog was in plain view, they settled. Hiding from a horse is impossible, and the very act of attempting to remain unseen and unheard unnerves the horse much more than a serene open approach.

      Some of the most critical brain differences between horses and humans are wrought by the distinctions between predators and their prey. Horses (along with rabbits, deer, cattle, and many other species) are prey animals— food for predators. Their brains evolved to notice tiny movements instantly, hightail it out of there with no analysis, and live in groups for safety. Prey animals are easily identified by sideward-facing eyes that survey a wide horizontal range for potential danger.

      Predators have forward-facing eyes. Their brains evolved for visual focus, depth perception, stalking, and killing. These include lions, wolves, cats, dogs, and um (how can I say this gently?)…humans. You and I are predators, and every horse knows it with one glance at our close-set eyes. The fact that horses allow us to work with them at all—let alone straddle their backs—is a testament to their generosity, curiosity, and domestication. But we do well to remember that the horse’s brain is still hard-wired by evolution to fear us.

      Fear of isolation is another by-product of equine evolution that we can’t change. Safety lies in the group. Even super-chill horses tend to be more nervous when they are alone. Equine misbehavior caused by fear can often be relieved by introducing another horse. Give the worried animal the comfort of a buddy—a horse who walks quietly into a trailer, a horse who relaxes on trail rides, a horse who has seen scary objects but survived to tell the tale.

      Domestication

      Today’s species of horse, equus caballus, includes all breeds and represents the domesticated version of its forest and grassland ancestors. Technically, domestication refers to artificial selection, which has occurred for at least 6,000 years. Key breeding characteristics for the purpose of taming a wild animal are calmness, ability to learn, submission to captivity, and willingness to allow human contact. By selecting mares and stallions with these traits, people have produced horses who are much easier to train than their undomesticated counterparts would be.

      Many people assume that “wild” horses today are undomesticated. That’s not accurate. Some are feral individuals who have lived without much human contact but are descended from domesticated ancestors. They live in bands on their own, but are not truly “wild.” Until recently, the Przewalski horse of Mongolia was thought to be the only remaining undomesticated horse. But DNA evidence now shows that even this breed descends from domesticated ancestors.

      Many allegedly “wild” horses are abandoned. During the 2008 recession in the United States, for example, some impoverished horse owners turned their animals loose in undeveloped areas to fend for themselves. A few lucky survivors formed groups that are sometimes referred to as “wild” even though they grew up in stalls and enjoyed years of training.

      After several thousand generations of domestication, we now have horses whose bodies and brains are mostly naturally selected, but whose behavioral traits of calmness and acquiescence are largely artificially selected. Variation among breeds is also a feature of artificial selection. The American Thoroughbred, for example, is bred to be light, long, lean, and agile—perfect for speed. Belgian Warmbloods are bred to be bulky, thick-muscled, wide, and slow—great for power. Along with these physical traits come differences in temperament, with the flighty nervous racehorse contrasting the stolid reliable Belgian. Within each breed there are individual differences, of course.

      Today’s Brain

      Throughout evolution, brains have become bigger. Yet brain function in both horses and humans is determined far more by neural connection than absolute size. According to the Internet, the horse’s brain is the size of a walnut. Or a human fist. Three baseballs. Next thing ya know, they’ll be likening it to a peanut or a watermelon. Sounds like some facts are in order.

      Pop a human brain out of its skull and you have a 3-pound lump of squishy tofu that’s 75% water. The average horse’s brain has the same consistency but weighs 1 pound 5 ounces, not quite half the weight of its human counterpart. A basketball weighs the same, as does the brain of a six-month-old human baby. In terms of size, the adult human brain is about 4 inches high, 6 inches wide, and 7 inches long. The tissue of both the human and horse brain is especially dense in some areas, often corresponding to “structures” that are identified in diagrams.

      The horse’s brain is about the volume of a grapefruit. In shape, the grapefruit is elongated and partly squashed. It’s lumpy and bumpy but measures about 4 inches high, 4 inches side to side, and 6 inches front to back. It rests on a 45-degree angle pointing downward rather than sitting level as a human brain does.

      Most important for function, the horse’s brain contains slightly over 1 billion neurons, far fewer than the human brain’s 86 billion. Depending on its type, each neuron can accept up to 10,000 connections. These connections are the magic behind equine perception, learning, emotion, and athleticism.

      Brain Change through Maturation and Learning

      One of the linchpins to any form of animal training—or human learning, for that matter—is to identify what can be changed and what cannot be changed. We’ve seen that evolution drives certain equine behaviors that are innate and physiological. By respecting them, we reduce the horse’s fear and can then alter more malleable aspects of his brain.

      Brain connections are built by daily experience. Few people realize just how physical a process learning is. When a foal takes that first step toward you, a new physical connection within a group of brain cells is formed. It’s weak, it will disappear if it’s not repeated, and it’s prone to mistakes. But every time the fledgling connection is used, it becomes stronger. The foal’s second step forward strengthens it, tomorrow’s positive approach reinforces it, and so on. Eventually you have built a brand new network of connected neurons inside your foal’s brain that forms an initial bond.

      That one physical connection is the basis for everything the foal will do in the human world. You will build on it, little by little, until this baby trots