Hi Lost,
"That millions of years ago, species accidently wandered off and seperated far from each other" I mentioned earlier that is is unlikely that under the current circumstances humans will split into two species that live at the same time. Because there is no physical separation between one group of humans and another. However, if a group of humans left earth and colonized Mars it is possible, in fact almost certain, Martians would evolve into a new species. In the future it may then be hard to imagine the very different looking Humans and Martians once had the same a great-great-great-times-X grandmother.
If the theory of evolution is true one of the things we should see this effect. Namely we should see that when a life form becomes isolated it takes a different path and becomes unique to its environment. That is why islands were such interesting places to Darwin. Yet, the idea all have a common ancestor, should show that even a very odd life form on a remote island has some relation to another species on nearby larger land mass.
It is also important to consider every form of separation. The most common one is time. While it is important for the survival of humans that a current male and female can mate and reproduce a fertile off-spring that grows to maturity and repeats the cycle. We must remember it is impossible for a human today to mate with a human who lived 200 years ago. So for evolution to be believable we want to see some evidence of balance here. We don't want evolution so loose that new species are generated willy-nilly because the inability to inter-breed would lead to extinction. Yet evolution would not be possible if species were so solidly established that they litterally could not change.
The example of hair lice I mentioned earlier wasn't a case of wandering as much as the body (land if you will) itself changed wherein a huge vast desert of hairless region between the head and the pubic area developed. This combined with basic texture difference lead to a distinction between head lice and pubic lice. Kind of a eeewww example, but a facinating nonetheless. Maybe one day there will be an Awake! article on these wonderful creatures ;-)
Cheers,
-Randy