The question of whether or not there our human species began with just two people has caught my interest. It's not that I think it is essential in order to accept the truth of Christianity. I think there are legitimate ways of understanding the Adam and Eve story, without insisting that it is literally true. And I think there are theologically acceptable ways of understanding the origin of our sinful natures without pinning the blame on the first pair of human beings. I think what first made me interested in the question was a series of posts by Edward Feser, who was looking for a way to harmonize the doctrine of original sin with modern evolutionary theory regarding human origins. Professor Feser is a strict Catholic, who takes Catholic doctrine very seriously. What I didn't know at the time was that Catholic doctrine appears to insist that Adam and Eve were responsible for original sin. Now many traditional Protestant denominations also pin the blame on Adam and Eve. It could be that all these denominations are wrong and that they must revise their doctrines. Or it could be that present science is wrong, and that humanity began with two people. I try to maintain an open mind about these things, so I've been reading arguments by Young Earth Creationists who are attempting to explain the genetic data without abandoning a literal Adam and Eve. Well, it turns out that there are also Old Earth Creationists who also insist on a literal Adam and Eve. A recent attempt is being made by Dr. Patricia Fanning at Reasons to Believe (I added them to my sidebar, I'm afraid to say. "Will his whackoness never end?" I hear you mutter. I'm afraid not):
Assumptions, and Circular Reasoning, and a Literal Adam and Eve".