Answer:
Civilization vs. the wild
Step-by-step explanation:
A cave-dweller is a prehistoric person who lived in caves. The dog was a man's best friend even during the prehistoric period.
The prehistoric man was still a part of nature, wilderness, while the modern man is assosicated with civilization. The definition of civilization is: a complex human society, usually made up of different cities, with certain characteristics of cultural and technological development. All of this can't apply to the said cave-dweller.