jeffrey said:
You have the caveman, so to speak, so what happened to him? God killed him off and created Adam and Eve?
Nope. They were around during biblical times. There were many cave dwellers. Even David and Saul spent time in caves, although I'm sure that's not what you are talking about. One "theory", is that there was a degeneration in some humans whether spiritual or physical or financial. Many people in caves were considered poor and savage outcasts in biblical days. Here's some references. My comments are in blue.
Genesis 19:30 Lot and his two daughters left Zoar and settled in the mountains, for he was afraid to stay in Zoar. He and his two daughters lived in a cave.
Job 24:8 They are drenched by mountain rains and hug the rocks for lack of shelter.
You should probably read the whole chapter of Job 24 as it describes these people as poor, wild, and almost animal like. (http://www.biblegateway.com/passage/?search=job%2024&version=31)
Job 30:3 Haggard from want and hunger,
they roamed [
a] the parched land
in desolate wastelands at night.
4 In the brush they gathered salt herbs,
and their food [
b] was the root of the broom tree.
5 They were banished from their fellow men,
shouted at as if they were thieves.
6 They were forced to live in the dry stream beds,
among the rocks and in holes in the ground.
7 They brayed among the bushes
and huddled in the undergrowth. 8 A base and nameless brood,
they were driven out of the land.
This explains one possibility of what might have happened ("they were driven out of the land"). This is all I can come up with for now since I'm at work right now. I'll try to comment more on this later tonight.