posted on Jan, 13 2004 @ 04:15 PM
Any and all of the three.
Nessie, Champ, Ogopogo - these could very well be living fossils of some sort, much like the celocanth(sp?).
Cross breeding - well, we know that creatures of similar genetic structure can breed, like the Lion and Tiger cross, the Liger, and all canines can
cross breed (there's a wolf-dog that lives up the road from me).
Mutation - that's how evolution functions. Certian mutations that make a member of a species more suited to it's enviroment, and therefore stronger
than other members survives to pass on it's DNA to all subsiquent generations. Over time, these mutations may cause a new species to arise.
Using sasquatch as an example, you can deduce that A. A giant ape species, Gigantopithicus Blacki, survives extention. B. It crossbreeds with other
simian species similar to it to create a new species, more suited to climate, food supply, etc. C. further mutations in subsiquent generations allow
the new ape to become even more adapted to its enviroment, allowing it to survive to modern day.
That's what I think anyway.