We hold these truths to be less than self-evident...

If other ancient Near Eastern material is any indication, our material in Gen 1–11 might be arranged literarily to communicate its relevance in very specific ways, even if that relevance is lost or diminished today. It may not have transpired exactly how it is described, and it may also contain anachronisms. We have already spoken of the possible significance of the numbers found in the genealogies of Gen 4 and 5, which should suggest even more strongly the possibility of literary arrangement (and, by implication, a less-than-exact correspondence to reality). Numbers were often used to convey different “truths,” as we have said. — Toward a Poetics of Genesis 1-11, page 236

<idle musing>
This should be self-evident, but it isn't because we import our own presuppositions into the text. We are the measure of all things (thanks for that, Protagoras!), therefore, whatever we want to find, we find there. And if you don't agree with me, then you are wrong! Genesis 3 all over again, eh?
</idle musing>