[Aric2000]

This is a BBC article, not a science journal.

But the fact is that it is indeed thought that we split off from our common ancestor about 5-6 million years ago. The chimps went one way and we went another.

There is evidence to support this assertion, fossils, DNA etc, but you will notice again, that is says, "it is thought" again, an assertion, but NOT stated as fact.

You seem to think that science states facts, or PROVES something. It does not, science gives evidence and explanations or theories to explain that evidence.

They are just stating their hypothesis, nothing more, it is up to other scientists to have the built in skepticism to weed out what may be true or what may be false within the hypothesis.

It is not up to the scientists that created the hypothesis to write in the skepticism, It is for other scientists to peer review it and be skeptical.

Be as skeptical as you want, but to say that "it is thought" somehow states a fact, well, that's pretty misleading as well.

[Mamzelle]

The passive voice performs well for those who seek to gloss over a rough patch in the exposition. "It is thought", read quickly, works like "It is established." The 5-6 million (why not ten, fifteen, twenty? One number is as hard to disprove as another) may not be all that "established", but you need some foundation to get started on the next fun theory (and the next grant application).

Pick up some science writing and look for the passive voice--it's there to distract. You won't find much of it when someone's life is on the line, where a dangerous mistake will become quickly obvious. Scientists who deal in the origins of things don't fear such awful accountability. "It is thought that this drug won't kill you..."