Wednesday, 1 October 2014

Horse Ancestry

Do you really understand your horse?

We often think we know our horses .... but do we really?  If you take a bit of time to understand them, their ancestry and their social interactions you may find you develop a better bond with your horse.

Sixty five million years ago, Eohippus ('dawn horse') was roaming the forests and woodlands on earth eating leaves and soft fruit.  There were various sizes with some not much bigger than a cat this is the ancestor of the horse we now know. These horses had a flexible, slightly arched backbone a long tail and 4 toes on the front and 3 on the back of the feet.  These toes ended in a small hoof but pads carried the main weight of the animal, in the same way dogs do today! 

25 million years ago, Mesohippus replaced Eohippus.  He was beginning to look a bit more like the horse we know today, the toes on the front reduced to 3 and he was taller - perhaps 6 hands high.  The eyes were set further back and the brain was larger.  Longer and more slender legs also helped with sustained running.

Merychippus appeared as the climate became drier and forests were replaced by open plains thus they needed to be able to run from predators.  They had to learn to survive eating grass and this led to a special digestive system.  Some Merychippus were 10 hands high, they still had 3 toes but their weight now rested on the central larger toe. 

Merychippus gave rise to several different groups but about 1 million years ago one of the groups gave us Equidae (our own horse family) which includes zebra and asses.  As this group was refined through natural selection - breeding in the wild would have favoured horses with speed and stamina as those that could not keep up with the herd would be caught by the predators - Equus became the athletic animal we now know.  The 2 smaller toes disappeared as they were no longer of use and all lateral leg movement was lost.  

The Przewalski's horse looks very similar to cave paintings found dating from about 15,000 years ago.

12,000 years ago horses were being kept to be eaten by people.  However, as the nomadic tribes drove their horses (food sources) along they must have realised that the horses could also carry burdens eg: tents and water containers.  Selective breeding is likely then to have developed with horses not suited to their work being eaten and those best for carrying goods and being led allowed to breed.  It was probably then a small step to riding horses and the breeding would then have been for 2 different purposes; horses suited for riding and horses suited for carrying goods.

2000 years ago there is evidence of horses being ridden - their skulls show damage from the use of harsh bits. We can then look back over the centuries to see how man has used the horse to see that this would have influenced breeding.  Horses for pulling chariots, carrying medieval knights with heavy armour, infantry for warfare and then horses for pulling carriages and carts as roads developed. 

Horses became the cornerstone of life, used on the land (eg: ploughing), to take goods to market, to take people to church and much much more.

100 years ago the increase in the use of mechanised machinery meant the horse was no longer needed for work and was kept for recreation.  Selective breeding still continues; to find the best riding horse, jumping horse, endurance, reining horse etcetera.

The horse we know today has the largest eye of any land mammal which helps give them their acute vision.  These eyes are high on the head so that it is possible to continue grazing but maintain a view all around.  The pupil of a horses' eye does not contract like ours do but becomes a horizontal rectangle this along with how their whole eye is constructed means that any movement at the edge of their field of vision is exaggerated.  So if your horse spots something behind it is likely to be startled and take 'flight'.

Always remember where our horses and ponies came from, it is one step to understanding them better. 

Until next time!

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