Now the horses:
http://www.talkorigins.org/faqs/horses/horse_evol.htmlFrom the site:
"Most horse species, including all the ancestors of Equus, arose in North America."
"During the first major glaciations of the late Pliocene (2.6 Ma), certain Equus species crossed to the Old World. Some entered Africa and diversified into the modern zebras. Others spread across Asia, the Mideast, & N. Africa as desert-adapted onagers and asses. Still others spread across Asia, the Mideast, and Europe as the true horse, E. caballus. Other Equus species spread into South America."
Seems zebras, donkeys and horses have diversified just in the last 2-3 million years. Hybrids are only just infertile. Humans diversified more recently. Were they in fact different species, unable to produce fertile offspring?
And, sorry about this:
"In the late Pleistocene there was a set of devastating extinctions that killed off most of the large mammals in North and South America. All the horses of North and South America died out (along with the mammoths and saber-tooth tigers). These extinctions seem to have been caused by a combination of climatic changes and overhunting by humans, who had just reached the New World. For the first time in tens of millions of years, there were no equids in the Americas."
