Domesticated by humans over 3,500 years ago, the modern horse has long been inextricably linked with human progress.


Image: Horses by David Feltkamp


Order: Perissodactyla

Family: Equidae

Species: Equus ferus caballus

IUCN Status: The wild Przewalski's horse is endangered, but domesticated breeds are not.

Habitat: Wild horses live on steppes and open grasslands. The domesticated horse is found all around the world and, as such, no longer has a true habitat. 

Size: Varies by breed from 1.4m to 1.8m at the shoulder in non miniature types. 

Weight: 380 - 1000 kg dependent on breed.

Life Span: 25 to 30 years with a few exceptions living as long as 60 years. 

Gestation: 11-13 months (usually one foal only, twins are rare)

Photo: Owain Davies


History of the Horse

To go back to the very beginning of the history of the horse we must try to imagine a small animal, about the size of a fox, that lived some 50 to 60 million years ago during the Eocene period. We call that ancient ancestor of the horse Hyracotherium. Although it did faintly resemble the horse as we know it today, Hyracotherium had four toes on its front feet and three toes on its hind feet. This is particularly interesting in view of the fact that the Tapir (a relative of the horse) still has this arrangement of toes.

Hyracotherium lived and browsed in the forests of what we would now call Europe and Asia. Meanwhile in another part of the world which we now know as America - but which was at that time still connected to the main land mass of Asia - another and rather similar animal was developing. This animal, also small, a forest dweller and eater of leaves, we call Eohippus (or dawn horse).

Some 30 million years after the appearance of Eohippus a new horse-like animal appeared. It was larger than Eohippus (about the size of a lamb) and had only three toes, with the middle toe beginning to evolve into the main support for the foot. This animal, Mesohippus had stronger teeth than Eohippus and it was able to eat both leaves and grass. In the millions of years that followed, these prototype horses were followed by Merychippus and Pliohippus, both bigger and better models. Pliohippus evolved about 12 to 13 million years ago and it had single toes or hooves and ate grass. The scientific Order to which the horses belong is known as Perissodactyla, which means quite simply 'one toe’.

Today, the Family Equidae includes all the surviving horse-like animals (horses, asses and zebras). There is only one true species of wild horse remaining in the world today - the Przewalskis' or Mongolian wild horse.

By the time humans arrived on Earth some 5 to 6 million years ago, the horse was already firmly established - having arrived some 50 million years earlier!


What do Horses Eat?

Horses are adapted to graze on grass. They have a relatively small stomach, but long intestines to provide them with a steady stream of nutrients throughout the day. Unlike cows, horses are not ruminants and they only have one stomach. They are, however, able to  use cellulose (a main component in grass) as a food source, unlike humans. 


Photo: MUSE Science Museum

An adult horse has twelve incisors at the front of the mouth, for cutting grass as they bite. They have twenty four further molars and pre-molars for chewing. Horses have a very good sense of taste, so they can pick through their feed using their prehensile (capable of gripping) lips, sorting out even the smallest grains to select their favourites.

Horses are unable to vomit, so if they develop problems with their digestion, these can prove fatal. 


Breeding and Life Stages

Horses can be capable of breeding from 18 months old, but domesticated horses are usually allowed to mature to at least three years old before breeding.  Gestation lasts between 11 and 13 months, depending on the breed, and usually results in the birth of just one foal. The foal is capable of standing and running within a short time after birth. 

There is specific terminology used to describe horses depending on their age:

    •    Foal: A horse of either sex less than one year old.

    •    Yearling: A horse of either sex that is between one and two years old.

    •    Colt: A male horse under the age of four. 

    •    Filly: A female horse under the age of four.

    •    Mare: A female horse four years old and older.

    •    Stallion: A non-castrated male horse four years old and older.

    •    Gelding: A castrated male horse of any age.

Regardless of when a horse is born, for horses that enter into racing competitions, a year is added to its age every January 1st in the Northern Hemisphere and every August 1st in the Southern Hemisphere!

Horses and Humans

The horse has been associated with humans for thousands of years. We know that the Persian Wild Ass (or Onager) was used by the Sumerians around 3,000 BC, and that in Britain some 2,300 years ago, the Iron Age people used horses for transportation of people and goods. 

As well as being domesticated for day to day transport, horses have been used extensively by  humans during times of war. Horses are prey animals and their quick responses and speed mean that they were well suited for use by soldiers. The oldest known manual for training horses to pull a chariot for use in battles dates back to c. 1350 B.C. By the end of World War II, horses tended to be used less in British battle, but they were still used for transportation of troops and supplies. There is a statue called The Animals In War Memorial in Hyde Park, London commemorating the millions of horses and mules that have been killed over the years in battles. 

Photo: Dario Crespi

When the motor car became widespread, it was predicted that, after centuries of association with humans, the horse would be completely replaced by our new mechanical inventions.  Some people believed that by the end of the twentieth century, the horse would disappear from the world completely.

However, horses remain popular with humans to this day. In some parts of the world, they are still used for transport and in war. Police forces often have mounted officers and horses are deployed during search and rescue activities in mountainous terrains where it would be difficult for a motor vehicle to drive. Cattle ranchers still use horses to help them round up herds of cattle and an estimated 100 million horses, mules and donkeys are still used for agricultural purposes worldwide.

Horses are also ridden for sport, entertainment and ceremonial purposes across the world.

It’s important to note that humans also use horses for food, both for human consumption and for pet feed, and that horse hooves are still used for the production of some types of glue. The hairs from horses tails are used to string bows for musical instruments and their hormones are used in medicines. 


Protecting the Horse

Whilst it would seem that modern horses are in no danger of dying out, wild horses (which include the asses and zebras) are not in such an enviable position. Some species, such as the Przewalski wild horse, are in great danger of disappearing in the very near future unless something can be done to save them.

Photo: Denis Egan

Rapidly decreasing populations of wild asses live in Africa and Asia, and the three species of zebra are still found in parts of Africa.  Only one hundred years ago the last known wild Tarpan died. Attempts have been made to revive this interesting species of steppe horse by back-breeding, but the resulting horses, although very interesting, could never be regarded as authentic as their genes are still based on those of domesticated horses.

In 1883, another interesting member of the horse family became extinct when the last surviving Quagga died in Amsterdam Zoo. The Quagga was a large equid (horse-like animal) some 2.74 metres in length and standing 1.37 metres at the shoulder. In appearance it resembled the front end of a zebra and the rear end of a horse! It lived only in South Africa on the open plains - but now it has gone forever.

The modern horse has served humans well over the centuries, so perhaps the time has now come for humans to do something in return by helping to preserve and protect the species that still survive in the world.

There are also associations that have been established to care for horses that are at risk of mistreatment. World Horse Welfare is one example of a group that works to rescue and re-home domesticated horses at risk of harm or cruelty across the world.

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