http://www.ditext.com/diamond/mistake.htmlYou've read Collapse, how does he explain the difference between what the Haitians went through on Hispanola, and what happened to the Dominicans? Strange, how the book abandons the pretense of absolute determinism by geography, almost as if there are other factors. Maybe because he actually went into detail, instead of having a massively reductionist overview of the entire history of human existence? No, that couldn't be.
Incidentally, zebra can be domesticated. Russian researchers managed to domesticate a wild fox species in a mere 6 generations. There are plenty of domesticated zebra around. If the species had gone through the same process wild horses underwent throughout the world (except in America, where they were hunted to extinction), it would probably be just as docile and shaped to serve as the horse. Of course some zebra can't be domesticated, that's the point of breeding programs. You take those that are docile, breed them, and you progressively get a more domesticated species. zebras have been used as beasts of burden and to ride since the late 19th, mostly to show off, since the only benefit was that it was much more resistant to african diseases than horses. You can even breed them with horses!