Hey, that's cool! I've been pondering something I read once actually - we know that people in Europe are genetically more disposed towards lactose tolerance than people in Asia most likely because cattle livestocks were more common during the neolithic revolution. Could this be called an instance of human evolutionary divergence?
Well it's certainly a result of the mechanism behind evolution, but whether or not you'd actually call it evolutionary divergence is a matter of semantics.
Most people define 'macroevolution' (which is what most people call normal evolution) as when a species splits into two species, and two species are considered distinct when they can no longer interbreed to produce fertile offspring (although in many cases they can still breed, for example to produce ligers (lion/tiger) or mules (donkey/horse)). This isn't a perfect definition, but it's the best we've got at the moment, and divergence in this manner is complicated, something I don't entirely understand as quite a young student, and technically unproven. Nonetheless, it's fairly well agreed that for it to happen, a certain degree of isolation is needed, although this need not necessarily be physical isolation (genetic isolation of populations can be caused by subtle shifts in behaviour.)
It's entirely possible that, given loads and loads of time, the example you gave could have led to true divergence, since the two populations were extremely isolated, but due to modern transport technology, the human race is turning more and more into one super population, which will almost certainly mess up the system in ways we don't really understand. As a result, I doubt
this factor will be particularly important in any future divergence, but who knows? Nonetheless, the example you gave is, in everything but name, evolution in action, and pretty cool no matter what you call it.
Sorry, that ended up quite long, I hope I explained it OK. I should also say again that I'm not a particularly experienced student at this point, and this is all based on my understanding, which could be wrong.
EDIT: Hmm... the forums seem a little patchy in taking my posts at the moment. This post didn't show up the first time, but luckily I'm a smidge paranoid and had copied it
just in case.