In Oklahoma, where I grew up, one of the first plants to show green in the spring was Lamium amplexicaule, which we called henbit. This little plant is in the mint family, although it doesn’t smell “minty” (or even “sagey” or “oreganoesque” like other members of the family).
Henbit and other members of the genus Lamium are also called dead-nettles. This had always puzzled me, because when they came up in the spring, they were one of the few plants “alive”, green and growing.
One day I rode Veronica down to the grass and weeds on the slope below the arena, where she likes to graze (until it all turns brown in the late spring). Both she and Buddy had encountered Urtica urens, the annual stinging nettle. Both were stung on the lips, and both decided they weren’t interested in that plant any more.
Veronica reached down for a patch of what appeared to be stinging nettle. I told her, “I don’t think you’re going to like that,” but as she ate it, I realized it was dead-nettle, and the light bulb went on. It (and other members of the genus Lamium) superficially resembles stinging nettle, but it doesn’t sting—it’s “dead”.
Now if I had looked it up in Wikipedia, I would have learned that, but instead I learned it because a horse has a very different view of plants than a person, even if that person is a botanist.
I’m a botanist. You probably guessed that from the title and the scientific names. I’ve been fortunate in being paid to teach botany to college students for around four decades. But I’ve never stopped learning, and in this as in so many other areas, horses have been my teachers.
Buddy prefers mouse barley (Hordeum murinum) over slender wild oat (Avena barbata). Mouse barley is the commonest source in my region of the foxtails that get caught in dogs’ fur, ears, and nostrils. Buddy eats it before it’s ripe and breaking apart, when the grains are sweet and soft.
He loves Italian thistle (Carduus pycnocephalus), which is related to artichoke, and sow thistle (Sonchus oleraceus) and prickly lettuce (Lactuca serriola), both lettuce relatives. If we ignore the “beards” of the barley, the spines of the thistle, and the bitter milky sap of the last two, these are plants we would eat. The flavor palettes of a horse’s palate are different from ours, but not totally alien.
Most botanists today don’t spend a lot of time with horses. But it wasn’t always so. The early botanical exploration of western North America by botanists of European ancestry was most often carried out on horseback, with pack mules. I wonder what they learned from their horses and mules. Was the knowledge that I’m now discovering once commonplace, in a world where equines were commonplace? Or were the old-time botanists as likely to look to their horses for guidance as I am to look to my truck? Many of their journals still exist, and so perhaps we could learn, if we looked, and if they bothered to write about it.
My days of botanical exploration are largely in the past. And there are real advantages to 4WD vehicles. But the view from a horse, and with the horse’s world in mind, should be part of the experience of every botanist.
Horses see a different world than we do, in large part because of specific differences in their eyes. This article will focus on one aspect, the way horse and human eyes react to the colors of illumination used for enhancing human night vision. If you’re not interested in the details, you can skip straight to the recommendations.
Like humans, horses have two types of light-sensitive cells in their retinas (the retina is the light-sensitive layer at the back of the eye). Rods are sensitive to very low levels of light, but don’t discriminate colors. Cones do the color discrimination, but need more light than rods to do their job. In humans, rods are about a hundred times more light-sensitive than cones, and there’s no reason to expect horses to be any different. Vision involving the cones is called photopic vision and vision involving the rods is scotopic vision.
Photopic vision (colors)
Humans have three different types of cone cells that absorb light of three different wavelengths: 420 nm (nanometers), which appears blue, 534 nm, which appears green, and 564 nm, which appears red. These are “peak sensitivities”; each type of cone detects wavelengths shorter and longer than its peak, and there’s some overlap. We have “trichromatic vision”, and all the different colors we perceive are the result of our brains processing the signals from these blue, green, and red cones.
Humans and other primates are unique among mammals in having trichromatic vision. Horses, dogs, and other mammals have only two kinds of cone cells, and dichromatic vision. In horses, blue-sensitive cones are most absorptive at 428 nm, and the other type of cone is sensitive at 539 nm, which appears yellow-green to us. Some humans have protanopia, a type of color-blindness in which the red cones don’t function; a horse sees the world much like that.
Important for our purposes here, the yellow-green cone can’t detect light with a longer wavelength than around 640 nm, which is a deep red.
Scotopic vision (“night vision”)
Horses have exceptional night vision relative to humans. Their eyes are larger than most other land mammals, to gather more light. They have a tapetum layer that reflects light back onto the retina (this is what causes eyeshine). And their retinas are richer in rods. In environments with moonlight, starlight, or even reflected city lights, horses can see well enough to walk, trot, or even gallop without running into things.
When a rod absorbs light, its visual pigment (rhodopsin, or “visual purple” in older references) is irreversibly changed (“bleached”), so that the cell’s ability to detect light is reduced until new rhodopsin is synthesized. In low light, rhodopsin is regenerated as fast as it is used, but a burst of bright light can bleach all the rhodopsin in all the rod cells, and it can take thirty minutes or more for the cells to fully regain their ability to function. For reasons that are not entirely clear to me, humans regain a useful level of night vision within five minutes of being exposed to bright light, but horses need the full thirty minutes. The same horse that can run across a pasture under the quarter moon cannot easily discriminate details in a dark horse trailer when asked to enter it from bright daylight.
Illumination for night vision
Humans have poorer night vision than many other animals, and there are situations where it’s advantageous to maintain night vision even in the presence of illumination. There are two different approaches in current use.
The first to be developed was the use of red light. Rod cells are insensitive to red light, so they can stay adapted to low-light conditions even while the red cone cells form images. Red nighttime illumination is still used in aviation and some military settings, and in displays of some electronic devices.
Red light has a couple of disadvantages for this use: it requires a higher brightness, since it relies on photopic vision, and it’s sometimes difficult to discriminate shapes and nearly impossible to discriminate colors.
A newer alternative is to use bluish-green light, at about the peak sensitivity of rod cells. Because this is the light that rods see best, extremely low intensities can improve scotopic vision without destroying dark adaptation. In a sense, it’s like carrying around a full moon.
The effect of these two types of light on horses is totally different. Like humans, horses cannot see red with their rod cells, but they also cannot see it (or see it only dimly if it’s more of an orange-red) with their yellow-green cone cells. A human analogy is an infrared remote for an entertainment system: most people cannot see the beam even if it is shining directly in their eyes. For horses, deep red is “infra-yellow-green”, not really a perceived color at all.
And because horses have more rods, and more sensitive rods, than humans, a low-intensity bluish-green light, barely perceptible to a human, would be much brighter to a horse, and would reduce their night vision.
Red light preserves both human and horse night vision. Horses only see it dimly if at all, and continue to rely on their superb night vision. It allows humans to perceive shapes and see text and diagrams that would be much less visible with the inferior human night vision, but at the same time preserves that night vision for seeing in areas where the beam is not directed.
The bluish-green light used for enhancing human night vision is inappropriate for horses. It is only effective for preserving night vision in humans at the lowest level of brightness that a human can usefully perceive, and this is much brighter that the lowest level that a horse can perceive. If the human can see it, the horse’s night vision is already impaired.
Red headlamps or flashlights are useful for night trail riding; they have no effect on the horse’s night vision, and augment the human’s night vision. The use of white light headlamps or flashlights is strongly discouraged; they destroy night vision in both horses and humans in exchange for providing only a narrow area of illumination, and when they are switched off, horses need much longer to regain night vision than humans, and are effectively stumbling in the dark until they do.
Red LED illumination may be more useful for barns and outdoor stables than the usual fluorescent lighting. It allows a human to deal with a specific horse without destroying the night vision of all the other horses in the facility. Horses differ in their response to “having the lights turned on”, but even for the most nonreactive horse, it’s one more thing to put up with. In my ideal facility, there would be red light illumination everywhere that would go on with a single switch, so I could walk down the aisle without tripping on something. Each stall could have an individual white flood lamp, or I could carry a white headlamp or flashlight, if I needed better vision for a specific horse.
Executive summary: Red light, yes. Green light, no.
There’s a dogma among riders and trainers that a horse should move at the gait and speed that you choose, all the time, every time, and that any deviation is disobedience or “disrespect”. Allowing the horse to routinely choose gait, speed, or path is definitely dangerous, and a skilled rider should be able to clearly communicate expectations to the horse. But by being absolute and unyielding in your expectations of the horse, you are cutting off one of the most useful ways your horse has of communicating to you.
At liberty, horses almost always choose their own gait and speed. Even a horse running with a herd is choosing the safety of that herd. About the only exceptions are a horse being chased by a real or imagined predator, and a horse stuck in quicksand. Studies have shown that horses often choose gaits and speeds that are most efficient; this is hardly surprising.
Adding a rider to the mix changes everything. When a horse deals with the weight and balance of the rider, different gait/speed combinations become more efficient. Combinations that are not efficient have to be trained. Classical western horses have to be trained to the jog, which is slower than the trot they might choose themselves, and to the lope, which is slower than their preferred canter. Upper-level competitive dressage horses are trained not only to slower speeds, such as the canter pirouette, passage, and piaffe, but also extended trots. It’s true that some horses and even breeds have conformation that makes these combinations easier, but that doesn’t mean that they are in any way effortless.
So what might a horse be communicating by choosing a gait and speed that you didn’t ask for? The stock answer is “I’m the boss of you!” Some riders and even trainers are so insecure in their connection with horses that they always seize that explanation. Sometimes it’s even correct. But what if the horse had no inclination to be the boss of you yesterday, and is perfectly cooperative tomorrow?
Some other things your horse might be telling you:
I hurt. I’m developing an abscess, or my arthritis is acting up.
I’m not strong enough to do this for an extended period.
I’m scared. If you weren’t on my back, I’d run away, but I’m doing this displacement activity instead.
I’m grumpy, my ovaries hurt, and I’m doing everything I can not to buck you off, which I’d never do anyway.
I feel great! I want to run in the sun, power through the flowers, and I really don’t understand why you’re not down with that.
I feel great! I want to nap in the sun, munch on the flowers, and I really don’t understand why you’re not down with that.
You’re crazy! You’re asking me to risk losing my footing and killing us both.
You’re throwing me off-balance! I hear there are these things called “lessons”.
I’m sick. If you took my temperature, or even looked at my eyes, you’d realize that.
If my horse were trying to tell me any of these things, I’d want to know about it. Various horses at various times have told me most of these things. If I passed it all off as disobedience, I’d be telling my horse “You don’t matter.” That’s not a good basis for a trust relationship.
If I passed it all off as disobedience, I’d be telling my horse “You don’t matter.”
One of the trails Buddy and I take away from the stable has a gentle incline right as we leave the property. He always wants to trot it. If I ask him to walk, he will, but I don’t, because I can learn enough from the speed of that trot, the way his body moves, and the way his head moves to know whether there are any issues that I should address, or that might mean we shouldn’t go out at all. And the time he volunteered a walk, I could tell he wasn’t well, and we turned around and went back.
And then there’s the stop.
It’s true that horses can stop because they are lazy. Or exhausted. Or worried. Or confused. It’s hard to imagine a response that usefully addresses all those things (and more) without knowing (or even caring about) the reason.
When I first rode Buddy in what I like to call “contrived obstacle courses”, he would sometimes stop dead before an obstacle. I was green, and there was peer pressure, and I even thought about getting spurs. But I learned that if I kept him facing the obstacle without pushing him to go forward, he would eventually figure it out and go forward on his own, because he knew that’s what I expected. And once he realized that he wouldn’t be kicked at every obstacle, he calmed down and took them more easily.
So if your horse insists on a different gait or speed from the one you requested, think about letting him take it for a few strides until you figure out why. Remember that horses live in the present. Your horse doesn’t plot disobedience based on your past weaknesses. Give him the chance to tell you what’s on his mind, now.
And chickens. And mountain lion shadows, which can skulk independent of their lions. And missing stable mates...Oh! There you are! What a relief! And stallions...I’ve heard rumors. And water crossings, especially with mud. And that same tree.
This post is inspired by and dedicated to Veronica, a mare’s mare, who reminds us that for horses, safety always comes before food.
I think it’s important to note that I am a firm believer that horses probably don’t, nor will they ever, see us as a member of their herd. Rather, I believe it is just the opposite. I think horses do everything they can to fit into “our” herd.
Just as we can misinterpret horses as other humans, horses in the combined “our herd” interpret us as horses. Some horses/people are dominant, and some are submissive. Some are leaders, and some are followers. Humans can act kind of screwy sometimes, but really there’s no other way to see them than as really strange horses (or as really gnarly predators, but that’s not where we’re going with this).
Virtually every equestrian agrees that humans need to be the leaders. Most horses are looking for leaders, and it ill suits them or the people around them when they think they have to be in charge to stay safe. A very few horses are natural leaders, and it ill suits the people around them to allow them to take this role with humans. And it’s part of the training of every equestrian to be a leader of horses.
We humans also have social hierarchies, and we don’t put those away when we are around horses. And a useful instructor–student relationship requires that the student defer to the instructor, at least during the lesson.
The problem comes when an assertive instructor dominates a submissive student, and the horse decides the student is of lower rank than he is. We’ve all seen horses in lessons defer to the instructor rather than the rider, and this is only natural—the horse is looking for the person in charge, and that’s the instructor. But if the instructor should leave the arena, the horse should always look to the rider. If the instructor so thoroughly dominates the student as to lower the student’s status to less than that of the horse, the instructor has failed, no matter how much teaching or ego gratification might have gone on.
It’s easy to watch for this, and for many instructors it’s easy to correct the problem, by building up the diffident student in the eyes of the horse. For instructors without that ability, or who are challenged by the diffidence of a particular student, the solution is to help the student find an instructor who can work with them.
Putting people below horses, intentionally or inadvertently, has no place in horsemanship.
In philosophy, a razor is a principle or rule of thumb that allows you to eliminate (“shave off”) unlikely explanations for a phenomenon. Perhaps the most famous is Occam’s Razor: “Among competing hypotheses, the one with the fewest assumptions should be selected.” But one of my favorites is Hanlon’s razor: “Never attribute to malice that which can be adequately explained by stupidity.”
Buddy taught me Buddy’s Razor the hard way, for both of us. I regret a lot of the mistakes I made along the way, but he says he’s just glad that I finally figured it out.
Never attribute to defiance anything that can be adequately explained by pain, fear, or miscommunication.
If I had a dollar for every time someone told me “He’s not respecting you! Don’t let him get away with that!”, I still wouldn’t have quite enough for all the vet bills, but it sure would make a dent. There are two big things wrong with that attitude. First, horses are incapable of respect—it requires a level of abstract thought that they don’t have. People load a lot onto the term “disrespect” when they apply it to horses, but the part I’m referring to here is better called “defiance”. The second problem with the statement is that correcting a horse for “defiance” is only useful it you have correctly identified it, and in most other cases is counterproductive.
It’s true that horses are sometimes truly defiant, most often for one very specific reason—a horse may judge your position in the overall social hierarchy of humans and horses to be lower than his (more about this in another post), and so feel no need to follow your direction. But more often, the appearance of defiance is a result of pain, fear, or miscommunication.
Most horses are better than most people at not showing pain. This is adaptive for a prey animal, since a predator is more likely to attack you if you appear incapacitated in any way. But it causes us to miss signs of pain, and in many cases we interpret as “defiance” the reaction to pain.
When I was learning the basics of equitation with Buddy, one of the exercises was the 20 m circle. He did well in a circle to the left, so it was puzzling that he would fall to the outside on the circle to the right. The instructor had me try the traditional corrections, but they didn’t have the “traditional effect”. It turned out that he had an arthritic right hock, so it caused pain for him to reach under his body with the right hind on the circle, and he responded by falling to the outside. When his arthritis was treated, the problem went away.
Horses survive by fear and flight. It’s a wonder that they work with humans at all. There are plenty of jokes about horses being “afraid of silly little things”, but when you ask a horse for something and he says “No way!”, it’s not so silly, and it’s not defiance. Forcing a horse against fear works often enough that people still do it, but it has long-term disadvantages.
You can never rely on a horse that is educated by fear. There will always be something that he fears more than you. But, when he trusts you, he will ask you what to do when he is afraid. —Antoine de Pluvinel
As much trouble as people can have communicating with one another, you’d think that they’d expect even more miscommunication with a different species. But just as the stereotypic American tourist shouts English at people who don’t understand it, to make it more comprehensible, many riders respond to a horse not understanding by “shouting”—increasing the force of the aids, or moving on to punishment.
The order of Buddy’s Razor is important. First, rule out pain. If that’s not the problem, rule out fear (and pain can cause fear, since a painful horse cannot escape danger as easily). With both those ruled out, check to make sure you’re communicating. If the horse is not in pain, not afraid, and is being asked for something he has already shown he knows how to do, only then should you assume defiance.