It's funny that we humans think we know things about the ancient past, everything is always a guess with data that we have no concept of how incomplete it is.
That's true for history, as well. Archeological digs in the US have rewritten colonial history, and even Civil War history. I've often wondered how much we "know" about history is completely false.
For one small example, some years back, an office building had a natural gas leak, and at one point the roof blew off. (I was a witness.) The fire trucks came, the news choppers, and the reporters on the ground. That evening, I taped each of the local news broadcasts.
Every one of them got the fundamental facts wrong (such as calling the office building a warehouse), the timeline was wrong, etc. But those news reports are probably the only record of the event, and will go down in history as what happened.
Not that what happened there mattered, but it has made me suspicious of the veracity of news reports ever since. It doesn't even have to be malicious, the errors were just sloppy work in their desire to be done with it and move on to the next story.
I always find it really interesting how thin the evidence is, in many cases, when some of these paleontological discoveries are announced. Somebody digs up a partial skeleton, or even sometimes a single, fractured bone, and bam, it's a new, previously undiscovered species. Then we get artists renderings and theories about how this long-dead animal lived. There are some great examples from dinosaur studies - Brontosaurus vs Apatosaurus (which it seems are not the same thing anymore, haha), or the initial discoveries of the Igaunodon.
I think the DNA work is interesting and somewhat more credible than purely physiological bone work, but I'd be skeptical to read into it too much. The article says they retrieved "1 to 2 million base pairs of ancient nuclear DNA" from fragments as small as 25-40 basepairs. Wikipedia tells me that humans have over 3 billion base pairs in their genome. Assuming the Sima hominid genome is somewhere within the same order of magnitude, they found less than 1% of the total genome. I'm not a geneticist, so I have no idea how they figured out how to piece those tiny fragments of 1% of the genome together in the right order, but it seems a thin branch to go out on to draw serious conclusions.
That's right; we can't know for sure and I'm sure you'll get some backlash for this comment. As with everything though, we need a balance.
If we say that we can't know for sure and give up, then no advancements would ever be made in any field. On the other hand, we should recognize that science does not claim to provide us with certainty. Many of us speaking "objectively" with scientific "facts" often become emotional and arrogant when speaking to anyone who doesn't agree with our conclusions.
For one small example, some years back, an office building had a natural gas leak, and at one point the roof blew off. (I was a witness.) The fire trucks came, the news choppers, and the reporters on the ground. That evening, I taped each of the local news broadcasts.
Every one of them got the fundamental facts wrong (such as calling the office building a warehouse), the timeline was wrong, etc. But those news reports are probably the only record of the event, and will go down in history as what happened.
Not that what happened there mattered, but it has made me suspicious of the veracity of news reports ever since. It doesn't even have to be malicious, the errors were just sloppy work in their desire to be done with it and move on to the next story.