Why Do Domestic Horses Have Withers?

A horse's "withers" are the small bump where the neck and back meet. The withers are actually a series of spines that extend upwards from the vertebrae.

This is a zebra. (Image source: Joachim Huber via Wikimedia Commons). As you can see, she has no withers.

This is a Quarter Horse. Withers.

Equines that have never been domesticated do not have much in the way of withers. The zebra has the very beginnings of them, but it's nothing compared to that of the Quarter Horse.

So, why is this?

There are two possible answers, which have worked together to create the withers.

The spines of the withers provide an elevated and stable anchor point for certain muscles in the shoulder. The higher withers of the domestic horse (and this can be seen in the unusually high "shark fin" withers of racing horses) raise the shoulder muscles, increasing the reach of the forelegs, which increases stride length and thus short distance speed. This is not an advantage over longer distances and may even be a slight disadvantage, explaining why wild horses, that rarely sprint, have never evolved high withers.

The other reason is deliberate selection for higher withers (within reason - those shark fins are actually a pain). A moderate wither height anchors the front of the saddle, except on gaited horses, helping prevent it from slipping sideways. Little or no wither is considered a fault, especially in riding horses - in the US this is called "mutton withers." With horses that have no wither, and this is more common in ponies, extra straps are often needed to ensure the saddle stays in place. Donkeys tend to have lower withers, in no small part because donkeys are seldom used for speed work and are more commonly used for harness work than for riding, so there's less selection pressure.

Why Didn't We Domesticate Zebras?

National Geographic was talking about this today here.

The zebra group (there are several different species) are the only true wild equines remaining with the exception of the endangered Przewalski's horse.

A (quite pregnant) Grevy's Zebra mare. Source: Joachim Huber via Wikimedia Commons.

Zebras can be trained and ridden. Some circuses use them. There's a small market, especially in the US, for "zorses" - zebra/horse crosses, with the idea being that the resulting animal gets pretty zebra stripes and a horse temperament. However, because they are not a domestic species, they are harder to train and more aggressive than horses.

This has led to the myth that zebras were never domesticated because they are "too aggressive." The National Geographic article addresses this quite nicely.

Zebras were simply not the equine species that lived where people in Africa domesticated equines - their range was further south. Instead, they domesticated the ass - the ancestor of the modern domesticated donkey - as northern Africa dried out and cattle herders had to travel longer distances. However, zebras may have given us one thing - it's probable that natural interbreeding that occurs between zebras and wild asses where their ranges overlap gave humans the initial idea behind creating the mule.

An African wild ass. Source pats via Wikimedia Commons.

Asses were domesticated independently of horses but zebras, thanks to geography, escaped that fate.

Why Are There No "Floppy" or "Lop" Eared Horse Breeds?

Just about every other domesticated animal has some breeds with "floppy" or "lop" ears. Nubian goats, spaniels, Scottish Fold cats, you name it. The lop ear mutation (actually a cartilage deficiency) is part of "domestication syndrome" and associated with tameness.

So, why are there no lop eared horses?

Actually, there are. The lop ear mutation does exist in the horse - follow this link to see Eeyore, a flop-eared horse.

However, unlike in other animals, the mutation has never been bred for and, indeed, any horses with flop or lop ears are culled out and not bred.

Why?

It has to do with equine communication. Horses are so dependent on their ears for communication that a lop eared horse is unable to properly communicate with other horses. The mustang pictured was thrown out of his herd and beaten up because he could not send the right signals.

This might not seem a huge problem in a domestic animal, except that communication with your horse is a two-way street. Horses are large, dangerous animals, and their primary back off warning...is ear position. So, a lop eared horse not only can't communicate with the rest of the herd, he can't properly communicate with humans, making him dangerous to handle.

Hence. No lop eared horses.

(This horse's ears are saying "Hi. Do you have any treats?")

As an ironic note, I found out today that somebody spent money on a study to prove what every 8 year old Pony Club kid knows - that horses talk with their ears. Sigh.

Why Do We Shoe Horses?

So, why do we take a piece of metal and nail it to the bottom of a horse's hoof? Part of the answer is - we don't always. Many working horses, especially ponies, do their jobs fine without shoes. And some modern horsemen prefer to put hoof boots on only for work and leave horses unshod the rest of the time.

The actual answer? There are three reasons we put a shoe on a horse's hoof:

1. To prevent the added wear and tear of work - from the weight of a rider or hard surfaces - from wearing the horse's hoof faster than it can grow. This is why many ponies and mustangs aren't shod. If a horse's hoof can handle the wear without shoes it's generally better (and cheaper!) not to shoe.

2. To give a horse extra traction when working. Specialist shoes are designed for different disciplines and some horses are shod with studs - these screw into the hoof or are permanently attached and stick out a little bit. Carriage horses are shod with road studs designed to improve grip on tarmac. Jumpers have studs put on their front hooves to help them "dig in" after a jump and basically stick their landing. Racehorses are also shod with studs to help them get better traction at speed.

3. To correct hoof and foot problems. Special shoeing (called surgical shoeing) can be used to help ease the pain of horses with certain conditions, most especially navicular syndrome (which deserves its own post) and also to correct issues with a horse's action. Club foot can also be partially corrected by trimming and shoeing when the horse is still a foal.

But, again, many working horses never have a shoe put on their feet. I'll talk about how we can nail a shoe to a horse's foot without bothering it tomorrow.

Draft horses like this Belgian often have special shoes designed to increase traction when pulling.

Why Are Most Male Horses Gelded?

A quick look through horse ads and you'll see that most of the male horses advertised are geldings.

The vast majority of male horses are neutered. This practice may date back to very close to the beginnings of domestication. The Lapps capture, neuter, and release many of the male reindeer in the herds they follow.

Gelding is not done to limit the number of foals produced per se. You can only reduce population growth in a harem breeder species by removing females - despite the fact that some people promote geld and release as a way of controlling Mustang populations (it won't work).

We geld most male horses for two reasons:

1. To remove inferior males from the breeding pool.
2. To reduce aggression and make the animals easier to handle.

Male horses produce a lot of testosterone. Stallions have a high libido and are very aggressive. They are harder to train than mares and can be dangerous to handle at times, especially if not properly trained and socialized.

Castration just makes them much more mellow, even, and easy to deal with - to the point where many horsemen prefer geldings to mares (not all - I actually have a fondness for a good mare myself). Castrating before puberty can also cause a slight, but noticeable increase in adult height.

Most domestic horses are gelded at a year. Some people believe in gelding at a younger age, but this is controversial. Ideally, though, you want your riding or work horse to be gelded prior to puberty, as horses gelded afterwards can retain some stallion-like behavior.

The exception is the racing industry, where colts are often kept intact until they can be tried on the racetrack. As performance is the only thing these horses are judged by (sometimes to the expense of soundness and temperament) it makes sense to keep them as entires until they've raced a few times. This does mean that some male Thoroughbreds can be a little studdy...I've had one go into display behavior on me because a strange gelding went off on a trail ride with a mare he fancied. He's a gelding, but he clearly wasn't "done" until after puberty.

Miniature horses are often kept entire because people think they're easier to handle because of their size.

A Paint/Draft cross gelding.

When And Where Were Horses Domesticated?

Although we can't know for sure, we have a good answer for this one.

We know that the modern horse, Equus caballus was descended from a wild horse, Equus ferus (now extinct) that existed all across Asia and Europe.

We know that most of the male lines of the modern horse came from somewhere in central Asia - with a wide variety of female lines that suggested people were augmenting their herds by catching wild mares.

Archaeological evidence also points this way. For example, in Botai, in northern Kazakhstan, we have evidence of established horse domesticating dating back to at least 3100 B.C. The evidence? Skeletal changes caused by being ridden, marks on the teeth that clearly came from bits, and traces of horse milk on pottery.

Horses were, thus, first domesticated by the people of the central Asian steppes, who used them (and still use them) for transportation, meat, and even dairy. (I'll address why we don't often use horses for dairy in another post).

For worldbuilding purposes, you could easily pin the domestication of horses down to any steppe or plains-related human group. Horse riding was probably invented as a way to go faster than your own legs could carry you in open areas.

This Icelandic mare represents a primitive and isolated breed and is probably very close to the first European domestic horses in size and build.