Evolutionary biologist Jerry Coyne, at The New Republic, states the problem succinctly:
The most recent scientific finding that’s causing Christian ferment is the calculation by evolutionary geneticists that the smallest size the population of humans could have experienced when it spread from Africa throughout the world was about 2250 individuals. That comes from back-calculating the minimum size of a human group that could have given rise to the extensive genetic diversity present today in non-African humans. Further, that figure is based on conservative assumptions and is very likely to be an underestimate.
2250 is, of course, not 2. That means that humanity could never have had just two ancestors within the time frame accepted by Biblical literalists. In other words, Adam and Eve did not exist—at least not in the way the Bible says. And that has huge repercussions for Christianity, for if Adam and Eve weren’t the literal parents of humanity, how did their Original Sin spread to us all? Original Sin is, of course, a pivotal part of most Christian doctrine, for without it there is no reason for Jesus to return and exculpate humanity from sin through his death and Resurrection. If Adam and Eve didn’t exist, but were simply a fiction, then Jesus died for a fiction.
Um, is this buh-bye for literalist forms of biblical monotheism?
Science and religion cannot live together–and cannot live apart. That’s the situation. You knew it from the start. And yes, I’m loosely quoting lyrics from a Genesis song.