Humans are constantly coming in contact and breeding with other types (races) of humans. Unless we can isolate a group from the rest of the world for at least 1,000's of years (I'm guessing on the time frame, as there are many variables that play a role in determining how fast something evolves, so it could take a lot longer), you'll never have a variety of human that has evolved dramatically from the rest. Unfortunately, with the ability to travel to any country we want at any time, it may be impossible for humans to evolve into separate groups of humans.
You can consider other apes our "ring species" relative, since we cannot mate with other apes, nor can other apes mate with other types of apes (such as gorillas and orangutans), however it's obvious we are closely related. Unfortunately our closest relative (the Neanderthals) died out a long time ago. By now they would have been a prime "ring-species" example, unless we had started interbreeding again sometime inbetween.
Now if all life is just a variance of the original life as evolutionist posit, then why wouldn't humans be able to diversify at the genetic level that soon? Unless you really do think "talk origins" and leprechauns supersedes real science?
So intelligence has in a way, trumped evolution?Unfortunately, with the ability to travel to any country we want at any time, it may be impossible for humans to evolve into separate groups of humans.