Neil << Science (mainstream science, not quacks) have shown that the most recent common ancestor for everyone alive today lived around 5000BC to 2000BC. >>
Not sure where you are getting those numbers, but I would double-check with the geneticists who are experts in this area:
“…the fact that a single ancestor gave rise to all of the diversity present today does not mean that this was the only person alive at the time – only that descendent lineages of the other people alive at the same time died out…we are all the recent descendents of a single woman who lived in Africa less than 150,000 years ago. This result begs the question of where Eve actually lived – where in Africa was the Garden of Eden? In one sense this is a red herring, since we know that there were many women alive all over Africa at this time…the root of the male family tree was placed in Africa – exactly the same answer that mtDNA had given us for women. The shocker came when a date was estimated for the age of the oldest common ancestor. This man, from whom all men alive today ultimately derive their Y-chromosomes, lived 59,000 years ago. More than 80,000 years after that estimated for Eve! Did Adam and Eve never meet? No they didn’t, but the reason is fairly complicated…” (The Journey of Man: A Genetic Odyssey by Spencer Wells [Random House Paperback, 2003], pages 32, 40, 54)
So it is more like 60,000 years ago for “Adam” and 150,000 years ago for “Eve.” These are not the biblical-Genesis Adam/Eve since, as the author explains, the “most recent common ancestor” does not mean they were the only couple alive. There were plenty of other people around at the time, but mathematically and genetically we trace back to this “Adam” and “Eve” (who are separated between themselves by 80,000 years).
There is also a PBS documentary available with Spencer Wells based on the book The Journey of Man.