[T]here’s one bedrock of Abrahamic faith that is eminently testable by science: the claim that all humans descend from a single created pair—Adam and Eve—and that these individuals were not australopithecines or apelike ancestors, but humans in the modern sense. Absent their existence, the whole story of human sin and redemption falls to pieces.In another place he adds:
Unfortunately, the scientific evidence shows that Adam and Eve could not have existed, at least in the way they’re portrayed in the Bible. Genetic data show no evidence of any human bottleneck as small as two people: there are simply too many different kinds of genes around for that to be true. There may have been a couple of “bottlenecks” (reduced population sizes) in the history of our species, but the smallest one not involving recent colonization is a bottleneck of roughly 10,000-15,000 individuals that occurred between 50,000 and 100,000 years ago. That’s as small a population as our ancestors had, and—note—it’s not two individuals.
Further, looking at different genes, we find that they trace back to different times in our past. Mitochondrial DNA points to the genes in that organelle tracing back to a single female ancestor who lived about 140,000 years ago, but that genes on the Y chromosome trace back to one male who lived about 60,000-90,000 years ago. Further, the bulk of genes in the nucleus all trace back to different times—as far back as two million years. This shows not only that any “Adam” and “Eve” (in the sense of mitochondrial and Y-chromosome DNA alone) must have lived thousands of years apart, but also that there simply could not have been two individuals who provided the entire genetic ancestry of modern humans. Each of our genes “coalesces” back to a different ancestor, showing that, as expected, our genetic legacy comes from many different individuals. It does not go back to just two individuals, regardless of when they lived.
These are the scientific facts. And, unlike the case of Jesus’s virgin birth and resurrection, we can dismiss a physical Adam and Eve with near scientific certainty. LINK.
Even conservative Christians, it seems, have trouble believing that Adam and Eve were the literal ancestors of humanity. That historicity has become increasingly problematic since the appearance of new papers in population genetics, showing that over the last few hundred thousand years, the population of Homo sapiens could not have been smaller than about 12,250 (10,000 who remained in Africa and 2,250 who migrated out of Africa to populate the rest of the globe).
In other words, the human population never comprised only two people. And if Adam and Eve weren’t the literal ancestors of humanity, then a critical part of the Genesis story is wrong: the acquisition of Original Sin. And if there were no Original Sin accrued by a literal Adam and Eve, then all of us—their supposed descendants—aren’t sinful by birth, and Jesus’s return wasn’t necessary. LINK.