Cofty
In my opinion, God caused life to come to existence, shaped its biological rules, and then allowed life to thrive on its own, with an unknown degree of direct intervention on some events = call it "design" or call it "driven evolution" if you will. When the first modern humans appeared on earth, I believe that they caused much interest in the heavenly realm. (see Proverbs 8:31) God decided he wanted to elevate this intelligent species to a new dignity. So he created the first man that he could correctly call his son - because it was a direct creation from Him. I don't think there is any reason to believe that Adam was any different than the others. He simply was "son of God", and the others weren't. While I have no basis to question the dates that science has produced regarding the age of the Homo Sapiens and/or civilization on Earth, I think that the chronology of the Bible may be plausible regarding the creation of Adam, that is circa 6.000 years ago. As for who we descend from, Adam and Eve or the "others", I don't think it's a relevant question since Adam and Eve's genetic footprint is probably untraceable, and their DNA is irrelevant for our salvation. "Sin" isn't some sort of genetically transmitted condition.
Eden