Did ancient human species fight?

This came in from the Naked Scientists Forum. Sounds like one for Human Origins expert, Lee Berger.

Lee - I love how questions like this always end with this sort of fight - the neanderthal fight club - kind of idea of human origins. We certainly know that species have interacted in the past - neanderthals are the best example, the best known. Not only did they interact; we don’t have any evidence of violent interaction, but we do have evidence of sex and the fact that many of us carry their DNA - a small part of neanderthal DNA. Usually somewhere in the 1½ to 3½ or 4% of DNA for Europeans or people from that area.

There are others that we know that we interacted with in similar ways - with denisovans, which are only known, in fact, from a fingerbone that’s now destroyed to get ancient DNA out it - we see some people on Earth sharing a small amount of DNA with them. There’s a sort of mystery species “X” that was in Africa about 200 to 300 thousand years ago that interbred with modern humans and we share some of that DNA. So we know that there were those type of exchanges that went on. What we didn’t know were that some species like homo naleti existed at the same time and place that modern humans did.

Now that’s going to be a tricky question right now because we have two lines of evidence in the record. We have fossil record which is very, very poor and very, very rare and we have an archaeological record which is rich and vast because it’s made of stone. And so we see this sort of technological spread and cultural spread across these regions, and we have always, particularly in Africa, assumed that in the last half a million years or so that that was all human - it was large-brained things. But suddenly, you have things like homo naledi popping up that are saying wow, wait a second it’s not that simple, things didn’t just go extinct. Humans and human relatives are a lot like other animals with existing lineages that went on longer. The hobbits on the island of Flores have shown us that and I think we’re going to see a whole lot more of that happening as we begin to open our minds and open up new areas and begin to explore more, there’s a lot more out there, a lot more mysteries to be solved.