In article , "J. Clarke" wrote:

I seem to recall that part of the problem with the Mesoamerican
civilizations and the wheel was that they did not have a large draft animal
of any kind and that soil conditions were such that in the absence of
something with the brute force to pull a cart through the mud a man could
carry more on his back than in a wheeled conveyance.

That's obviously incorrect. Never mind large draft animals -- anyone who's
ever used a wheelbarrow or a two-wheel dolly knows that a man can carry more
on a wheeled conveyance than he can on his back. You don't need draft animals
to make wheels useful.