The avocado stuff its not really true. The avocado shouldn't exist, because the animal that propagated its seeds went extinct a long time ago (if the term "Megafauna" comes to your mind when you think about that, you are not misguided), but wasn't created by humans, in the same way that corn or wheat are, because the avocado survived even when there were no humans around to propagate its seeds.
http://www.smithsonianmag.com/arts-culture/why-the-avocado-s...