Who's Your Great-Great-Grand-Daddy?

The other day at the gym I was surprised to see an issue of the journal Science among the normal fitness/body building ones in a basket in the lobby. I was a little early for yoga, so I sat down for a quick read. As I thumbed through some of the shorter articles I came across one discussing the recently-complicated family tree of we humans that was pretty neat.
For the past 100,000 years or so we have been tooling around the earth doing our "thing" which involved learning, creating culture, reproducing and all that fun stuff. But many of us forget (or maybe never realized to begin with) that we weren't the only folks around at that time. In the past 35,000 years there were Neandertals for one, and archaic humans called the Denisova hominin in addition to ourselves. And if you go back to the beginning of that 100,00 years when Homo sapiens emerged there were probably a few of our older ancestors still running around, like Australopithecus sediba and so on.
Anyway, for almost the entire history of anthropology it was thought that we humans never mated with any of our  early neighbors. But DNA sequencing is turning that idea on it's head. Recent study comparing modern human DNA to Neandertal and Denisovan DNA has produced the following results:

• Eastern Europeans and Asian people have inherited 2%-6% of their DNA from Neadertals.
• Peoples of Southwest Asia have inherited about 5% of their DNA from the Denisovans, and another 4-6% from Neandertals. (Another study found this same distribution in people in the Philippines, Southeast Asia, and Melanesia.) (That's about 10% total!!!)
• Denisovan DNA was found in Australian aboriginals
• Three isolated African groups inherited DNA from an unknown archaic people, long after modern humans arose.
• It has been discovered that over half of the human genes that code for leukocyte antigen proteins, (i.e.the ones that help detect pathogens in the blood) came from some or another "archaic" human.

I guess maybe I should point out before closing what is meant by archaic humans. They were still Homo but their DNA shows them to be distinct from us modern humans. They appear to have evolved from the same ancestors as Neandertals, but were closely enough related to humans to be able to reproduce.

Note: You may notice that I spell Neandertal with a "t" rather than a "th". I believe the "th" is the American version, but in all of my readings (both in school, and in scientific journals) always uses the "t" version, and I figured if it's good enough for Science it's good enough for me.