I recently read that horses, at the time they were domesticated (sometime from 4000-3500 B.C.) were too small to be ridden by people. The author (his name escapes me at the moment) suggested that people domesticated horses to use them for meat and milk, and it required many generations of breeding before they were big enough for full-grown men and women to ride.
Is this accurate? Were horses domesticated so people could eat them, and only later did people start using them for work and warfare? And what evidence is there for this conclusion?
The challenge here is that, when we have evidence of the horses being used as livestock in abundance, there is nothing precluding that same animal having been used as a working animal. This doesn't necessarily mean a riding animal; remember that chariots were popularized long before cavalry, and there is evidence of chariot use in the form of wheel depressions dating back to the same period as domestication, suggesting that the people who originally domesticated horses quickly utilized them for working purposes. Indeed, among the steppe peoples, cattle, sheep, and goat herding was quite intensive even by this early period.
It is difficult to answer the question about whether horses were originally domesticated as work or livestock animals, simply because I think that requires us to understand the domestication process a hell of a lot more than we do (or probably ever will). What is clear is that the domestication and use as a working animal seem to happen in very close proximity to one another from the evidence we currently have available.
Source: The Prehistory of the Silk Road, E. E. Kuzmina and Victor H. Mair
Hi! So, I recently answered a question similar to this one. Here's the link.
Basically, it's speculated that humans first took baby horses from mares that they killed for food and started keeping them, probably originally as a source of food and then started using them for labor.