Monique Reed writes:
Paleontologists and botanists theorize that the ancestral avocado
(which had an even bigger pit (!) and very thin flesh) was dispersed
by prehistoric megafauna. Think giant ground sloths. You'd need
something that big to be able to eat one whole and pass the seed.

In general, the dispersion of seed needn't involve it being swallowed,
surviving the digestive passage, and being dispersed in faeces. All you
need is that something pick up the fruit, move away from the parent tree
and discard the seed undamaged. A dog will do this; most love avocados.
I expect there would have existed South American forest floor dwellers
that could be relied on to perform this action without necessarily having
to swallow the seed!

Also, AFAIK, the avocado fruit does not ripen on the tree, and so is
unlikely to be attractive to birds or animals while it hangs on the
branch. The fruit ripens only after it has separated from the tree, so
it may have evolved in conjunction with a forest floor dwelling mammal
that provided the avocado with reliable dispersal.

Something in favour of growing your own avocados: you don't experience
a glut of fruit, just pick some a few days before you need them, let them
ripen while leaving the rest of the fruit hanging on the tree for later.
--
John Savage (news reply email invalid; keep news replies in newsgroup)