This is a fascinating wrinkle to add. I started wondering how many children one could then posit Adam and Eve had, since getting that number as high as possible would create the scenarios most difficult to scientically rule out. I thought the most children any human couple has had was in the low 20s, but Wikipedia has reports of instances in the 30s, 40s, and higher. It’s when you add in extreme life spans then you can really stretch this number.
Of course, in order to get to a really large number, we must also assume that the reports of great patriarchal age applied also to the women, for Eve to live a sufficiently long time to disperse as many of her egg cells as possible into the population. Did the women live as long as the men? Sarah is the only woman whose age at death is mentioned, and at 127 could be either a normally long-lived human or a shorter-lived patriarchal lifespan. And then there’s the question of what portion of Eve’s lifespan she would have remained fertile … did she go through menopause? … Sarah bore a child at the advanced age of 90, but she’d also said she was too old: it was a special miracle from God.
Genetically unrelated eggs and sperm does neatly address the incest question —if all humans born of Adam and Eve were artificially genetically diverse, then perhaps there was no (genetic) reason for them not to intermarry. We could even expand the population diversity further by having Adam breed with his daughters … the limiting factor being the rate at which Eve can go through pregnancies … but Lot’s daughters got in trouble for that, so let’s assume it didn’t happen.
So what rate could Eve have had babies at? Hunter-gatherer societies, as mentioned above, tend to space them out. I once read one child every four years was all that was sustainable, because if you have to be on the move constantly, a four-year-old can walk enough to make carrying a baby feasible. But once you get agricultural (I don’t know how you can read Genesis as anything but agricultural) that rate can go up.
IF Eve lived as long as Adam (930 years) and due to her miraculously good health and divine command (“Go forth and multiply”) or curse (“I will greatly multiply your pain in childbirth”) was able to have a child every year, we’re looking at a starting population of ~900. It could be more with twins, triplets, etc, but it could also be less on account of not all children making it to successfully reproduce. I think trying to stretch it past 1,000 would be more than sobriety could bear; we’re already on pretty shaky thought-experiment ground as is.
A starting population of 1,000 is still not in agreement with the scientific consensus of ~10,000, but you could certainly have a reasonable debate about it if you wanted.
The real question is, is this a good interpretation of the story Genesis is telling us?
