Who is Kazz from To Your Scattered Bodies Go; a Science Fiction Novel and what is their importance?

Kazz is a subhuman whom Burton quickly befriends because his simple nature and knowledge of living in the Neolithic era are highly useful in the new world. Kazz is also able to see a slightly different spectrum of light than normal humans, which allows him to identify agents of the Ethicals. He is also responsible for saving Burton from slavery while posing as a member of Goring's followers.