Here is another really interesting and very long article focusing on the Denisovans and their tine and distance relationship to Neanderthals, modern humans, Chimpanzees, etc.
http://www.nature.com/nature/journal/v468/n7327/full/nature09710.html
I hope this is the right one, it is really late and I am too tired to check. Maybe tomorrow.
What we know to be true fills ten pages in one very small book. What we do not know fills infinite volumes of books in infinite libraries on infinite planets.
As said ... is not pretty but is the truth and being the intelligent person you are gleeaikin, I have to believe you knew this truth, thus pardon my wasted post.