Given what we actually know about human biology.
I think that it is more accurate to conclude that it would have been impossible for Adam and Eve to create a separate line of descendants in the land of Nod.
First of all, Adam and Eve did exist. We can prove this using common logic.
Using common logic of course, we cannot concur what their names were, except from reference to the bible, but we can prove that they existed.
You had a dad, and you dad had a dad, and etc.
Human population increases as time moves on, so it is safe to assume that the population decreases if we go backwards.
Meaning at some point or another (whether you believe in long term evolution) there were indeed two humans, male and female.
So, Nod and it's people remain an insurmountable contradiction at the very basis of the biblical social hypothesis.
It's not a contradiction.
A contradiction is something without a shadow of a doubt disproves or provides evidence to the contrary of a certain story or idea.
Not knowing the exact way, the people of Nod came to be in their place in the world is not a contradiction.
There are many tribes in the world, that we don't know how they came to that area or island. Is that a contradiction to history?
As for where they came from, they obviously came from Adam and Eve, as did all humans.
We can use "guesses and ideas" to explain anything.
Therefore you can guess and idea you way out of any biblical contradiction....Thereby not proving anything other than the futility of the exercise.
Again, not a contradiction.
