Teenage Caveman

The human race has been decimated by a viral plague and the remaining population lives in primitive conditions. The shaman leader gets first pick for his female partners, but his son, David (Andrew Keegan), isn't too pleased when his girlfriend (Tara Subkoff) ends up on the list. David kills his father and is subsequently banished from the tribe. He and his friends stumble upon a community of mutants who indulge their basest desires, and where everyone has a secret.