Horses. To some people, a horse is a beautiful thing, and they love them. I am in the camp that regards them as random bone breakers, possessing four iron-shod clubs designed to deal damage at the whim of the maddened equine brain. This is because my only experience of horses involves leaving them at high speed to be greeted by an unyielding turf.

But, as one of our few domesticated species, horses have evolved to live with us. While I might not understand them, is it possible they understand me? A small study performed by a group of British researchers suggests that they can respond to emotion in voices.

Cows vs. goats

Allow me to interject some ignorant ramblings at this point. I am not in the “animals are all instinct" camp. I spent a lot of time driving small herds of cows and flocks of sheep without the aid of a fast bike or farm dogs. When you are alone like that, you really rely on the animal—somehow—understanding what you want it to do. Small herds of cows, for instance, when offered a choice between going through a gate (and into the unknown) and charging off down the fence line to apparent freedom, will often go in the direction that you point. This happens even when they are clearly nervous about going through the gate. When the cows don’t go through, you know it’s going to be a long day.

The cow's response to pointing also seems like learned behavior: your cows have not the faintest idea what you mean when you point.

Sheep, on the other hand, do not respond to pointing. Sheep are idiots led by a cunning few that seek out and destroy weak fences. Goats will go to whatever location they believe will allow them to chew the sleeve off your shirt. Especially if you are still wearing it. They express their dissatisfaction in your sartorial choices by trying to remove sensitive body parts with their horns. All in all, I prefer cows.

Anyway, I’m in the animals are uncomfortably smart camp (except for bulls—bulls are like teenage boys without the charm and double the aggression). But they're not smart in the same way we are, as animals don’t think like we do.

A lot of the early work on animal cognition showed us many things that animals weren't capable of primarily because the researchers had a poor understanding of the animals themselves. This has changed in the last 30 years, with tests and observational studies that are more attuned to natural animal behavior. These have demonstrated some quite remarkable feats of learning—and even things like empathy.

Mr. Ed likes to hear you laugh

In this study, researchers led horses into an outdoor riding arena, where they were held gently in place by a handler. A speaker was placed out of sight about 15m from the horse’s position. The speaker either played a happy human sound (a laugh) or an angry human sound (a growl). Each horse was exposed a couple of times, but with more than a week between exposures so they would not acclimatize to invisible angry people. The handler was unaware of the speaker sounds, because they were listening to loud music through headphones throughout the test.

That last point is important, because domestic animals are incredibly good at picking up cues from their handlers. The story of Clever Hans the counting horse is the archetypical example of this. Clever Hans, given a number, could tap his hoof the right number of times… but only if his handler was in the room. Essentially, the horse knew when to stop tapping from subtle (unconscious) cues from his handler.

To further reduce bias, the horses were filmed from different angles, and their behavioral cues were coded by independent workers using a database of standard horsey behaviors.

It turns out that horses are more likely to present an “uh-oh” response—ears forward and freeze—to an angry noise than to a happy noise. It’s a small study, so the error bars are fairly large, but the separation between the response to a laugh and response to a growl was quite large, and it was enough that the researcher could claim significance by a good margin.

The researchers had suspected that the horse’s response to emotion would mostly be due to the tone of the sound: a growl is lower pitched than a laugh. They tested this by comparing vocalizations from women and from men. Surprisingly, the horses don’t care if the growl comes from a man or a woman; they just don’t like growly noises. That means the horse is not just responding to the absolute frequency, but rather to the whole sound.

However, the researchers left open the question of what the horses do when there is no apparent sound. At the moment, we have measurements for two different vocalizations. But a measurement for a neutral or no vocalization, or both, would have strengthened the study considerably. Of course, extra measurements would have changed the statistics considerably and, in a small study, possibly changed the results.

Uncovering animal understanding

Even if this particular result doesn’t hold up, the range of things animals apparently understand is steadily increasing. Of course, when I use the word understand, I exclude cats. It is well known that the only things that cats do are sleep, drag in dead animals, and trip people on staircases, presumably so they can be eaten later.

The cool thing about animal behavior research is how it shows the intriguing differences between humans and the rest of the animal kingdom. Sometimes the differences are small enough to make me wonder why there aren’t crow or dolphin cities. And for other cases, the gap is large enough to reassure even the most human-centric human. In all cases, the results (and the reasoning behind the studies) are fascinating.

Scientific Reports, 2018, DOI: 10.1038/s41598-018-30777-z. (About DOIs)