This is going to sound weird, but it's something I've kind of wondered about for a while. Maybe some of you science types will have some insight.
There was an article about Neanderthals on a website today, and it reminded me of something I've observed before. First, let me mention that scientists seem to agree that 1-2% of modern European DNA comes from Neanderthals. Many modern African populations do not share this Neanderthal ancestry. Scientists also seem to think that Neanderthals were white and possibly red-haired. One of the features of Neanderthal skulls is the large occipital protuberance in the back of the head. I think I've seen explanations for this feature having to do with balance perhaps?
I've always thought that the distinction made by many scientists of the early lineages of hominids was artificial. I mean, obviously different populations of human type creatures interbred successfully. It seems to me that it's possible that all of these different early hominids were just variations on the same species.
That brings me back to the occipital bun. I've noticed that many Kenyan runners (like Wilson Kipsang) seem to have this occipital protuberance that is a trait of the white, red-headed, robust Neanderthals. I wonder if you presented the skull of a modern Kenyan (sorry to sound morbid) and the much differently shaped (flat back of head) skull from a white Ukrainian guy I know--if you presented these to a scientist and told him these were ancient skulls from different parts of the world, would he try to claim they were from two distinctly different hominid species? They are obviously not. They're just people. And maybe it's possible that's what these "different" populations millions and hundreds of thousands of years ago were. Just people.
I'm certainly not a scientist, so anyone knowledgable about this stuff please feel free to set me straight.