Horse breeds of the World - Overview

From cave paintings it is believed that the equid from which modern horses are derived resemble the modern Przewalski Horse. The large strong heads and erect manes depicted in these paintings bear a striking resemblance to this modern breed.

The first domestication of the horses was probably in the steppes of central Asia between 3000 and 4000 B.C. These first animals were kept for meat and milk. As early man became more mobile undoubtedly horses began to be used as pack animals.

Oxen were being used in the Middle East at approximately 4000 B.C. for plowing. Progressively they were used on sleds, which were eventually mounted on rollers, with the final evolution of wheels. Early in the 3rd millennium B.C. there is archeological evidence that vehicles drawn by equid, generally onagers or ass hybrids, were being used in warfare. As horses from the north became more numerous the carts moved to the familiar two-wheeled chariot with spoked wheels. Due to his greater speed the horse rapidly replaced other equid as harness animals.
 

What is a breed?

The classic definition of a "breed" is usually stated as a variation of this statement.

Animals that, through selection and breeding, have come to resemble one another and pass those traits uniformly to their offspring.

Unfortunately this definition leaves some unanswered questions. For example, when is a crossbred animal considered a composite breed and when do we stop thinking about them as composites? Perhaps this definition from The Genetics of Populations by Jay L. Lush helps explain why a good definition of "breed" is elusive.

A breed is a group of domestic animals, termed such by common consent of the breeders, ... a term which arose among breeders of livestock, created one might say, for their own use, and no one is warranted in assigning to this word a scientific definition and in calling the breeders wrong when they deviate from the formulated definition. It is their word and the breeders common usage is what we must accept as the correct definition.

As you can see from Dr. Lush's definition it is at least in part the perception of the breeders and the livestock industry which decides when a group of individuals constitutes a "breed".

The development of the breeds takes different routes also. In some breeds you can see the amount of change that can occur as the result of selection for a small number of traits. As an example, Holstein cattle have been selected primarily for milk production and are the highest milk producing cattle in the world. Other breeds have traits that result from natural selection pressure based upon the environment in which they were developed. An example of this might be the N'dama cattle from west Africa. These animals have, through the centuries, developed a resistance to trypanosomiasis or sleeping sickness spread by the tse-tse fly, which is fatal to most other breeds of cattle.