I’ve posted repeatedly (e.g., here) about the dilemma that Adam and Eve pose for some believers, since population genetics shows not only that our species never dipped below a total of about 12,500 in the last 50,000 years or so. That directly contravenes Catholic (and some evangelical) doctrine that Adam and Eve were real people and the ancestors of us all. This is codified in Pope Pius XII’s 1950 statement from De Humani Generis (my emphasis):
37. When, however, there is question of another conjectural opinion, namely polygenism [that we descended from more than just two people], the children of the Church by no means enjoy such liberty. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own.
In other words, the Pope said that all living humans, starting with Adam, had to be descended from him, and that Adam cannot simply stand for a “certain number” of first parents. Not accepting the statement above means you don’t accept Church dogma. Of course, theologians are still busy trying to force the idea of Adam and Eve into the Procrustean Bed of population genetics, with the predictably risible results.
A few days ago I got an email from reader John, who said this:
“There’s one thing I don’t believe you addressed that I’ve recently seen sophists (err, theists) suggesting: that each of us is related to either Adam *or* Eve, but not necessarily to both–i.e. that there was an initial pool of 10,000+ humans, and only Adam and Eve had souls, but at this point all living human beings are distantly related to either Adam or Eve (but not necessarily to both of them).”
He then pointed me to a reddit thread on Adam and Eve, in which one commenter tried to reconcile Catholic doctrine with the evidence that the human population didn’t undergo a bottleneck of only two people. The commenter said this:
You are not engaging my point, and ignoring my argument for it. To remake my point, then. Catholic doctrine does not require a bottleneck of only two people. To insist that all people are descended from one particular pair does not equate to saying that all people are descended from only that particular pair. Here’s a visual representation of my point: all the yellow blocks are descended from the red pair, but at no point is there a bottleneck of only two people.
In other words, Adam and Eve for some reason, were two among many people (A&E in red), but that all living people somehow can trace their ancestry back to the Primal Couple. But this violates both science and the Pope’s doctrine in several ways. First, there are clearly “true men after Adam who did note take their origin through natural generation from him as the first parent at all.” These are the white rectangles in the second row, and of course there would have been many more white rectangles had there been more than six people alive, and those rectangles would have extended into future generations. Second, the Bible clearly says that Adam and Eve were the only two people around then; it doesn’t mention a population of humans created with them. If you’re going to take Adam and Eve as literal ancestors, why not accept that they also were the only two humans on Earth?
Further, as I wrote in the thread above, were Adam and Eve the genetic ancestors of all of us, then
. . . all the genes of every living human should “coalesce” back to the same time and the same two people. But we don’t see that either: each gene segment had its ancestor at a different time (and often at a different place) in the past: the Y chromosome, for instance, coalesces back to an ancestor who lived about 60,000 years more recently than the female ancestor who bequeathed us the genes in our mitochondria. So this solution is also untenable.\\
And that solution is untenable even if you think we all inherited Adam’s Y chromosome (if we’re male) and Eve’s mitochondrion.
Now this of course leaves aside how “Original Sin” is inherited. It cannot segregate like a gene, which is present in pairs and thus a given gene has a 50% chance of getting into a single offspring. Rather, Original Sin must be passed on to EVERY offspring. So if every offspring of an Adam and Eve, and all their descendants, had Original Sin—as if it were a virus spread by both sperm and egg—then yes, every living person could have Original Sin, if you see them as all descended from Adam and Eve. But the genetic data show that even the claim, that Adam and Eve lived at the same time, is wrong. Ergo, there’s no way to save the Catholic dogma on the First Couple. It is, as all rational people realize, a complete fiction: a story descending from the ignorant childhood of our species.