This is inspired by The Time Machine, by H. G. Wells. In the book - in the far future - humans have split into two races, the Eloi, who live aboveground, and the Morlocks, who live underground. The two have become extremely different after living for a long time in different conditions.

Humans can obviously split at some points in time. After all, that's how evolution works. The story also takes place over 800,000 years in the future, when things are much different.

I'd like to know if this is possible in a time closer to our own - not the near future, but a bit beyond that, within about 500 years. The twist it that one group lives on Earth, while the other lives on Mars.

Given these conditions, could humanity split into two different species?