When they find the remains of midgets 10000 years from now would they also call them 'other species'? I never read any real proof of other 'human' species. Only 'possibilities' and 'believes'.
There are things I think most HNers basically take for granted (at least I do): the theory of evolution closely matches reality, all animals that ever existed on Earth (including humans), are subject to it, and basically all life on Earth is a big family of more or less distantly related cousins (you don't even need the fossil record for this one, DNA is enough).
This article doesn't challenge that. In fact, the idea that our hominids ancestors split in several cousin species flows quite naturally from the above assumptions. Now the question it raised is, why we don't have closer cousins than chimps? We may not unique in that respect, and the big gap between us and our closest cousins may not be that much surprising. But given that our ancestors and elder cousins colonised most of the world, wondering what happened to them is an interesting question, if only to understand how a thriving specie can go extinct.
Now, basic rationalist question: How do I know that?
Well, it's a bit complicated. First, as a child, I was interested in science. I had few religious influences (I only attended church at Christmas). The History I'm aware of tells be that Science is to date the most successful way to describe our world, and the engineering successes I see every day tells me that it indeed works. For instance, the computer I'm typing on right now depends on a fair bit of science. Most of it is magic to me, but I'm confident I could find a comprehensive explanation on the Internet. Science also just makes plain sense. I "get it" when I read science aimed for lay people.
The bottom line is, I trust scientists. I trust journalists that talk about science a bit less. I trust settled science best. I acknowledge that the current state of the art is probably mistaken on many many things, but I'm confident that subsequent discovery won't shake the foundations of everything we know, though we may discover earth shaking new things. (For instance, relativity is a refinement of Newton's theory, not a complete revolution. It confirmed that under "ordinary" conditions, Newton's theory will give almost exact results.)
This particular article looks like a journalist's report about a bit of reasonably settled science, that just makes sense. Therefore I trust it. On the spot. No need for further proof.
