TAURUS FOUR

Paperback Library paperback, 1970. Cover artist uncredited, but
I'm dead sure it's by Robert R. Foster.

"IT IS THE YEAR 2270 A.D. 

A long time ago on Earth, our ancestors did not believe in the industrial-warfare society. They dropped out to live in freedom and do their thing, hated by all the uptight squares.... 

Thus begins a folk legend on Taurus Four, where, during the Saurian Wars, a group of hippies had been transplanted forcibly. Right now the only uptight squares on the planet is a stranded Space Sociologist, Dorian Frank - who has reason to be uptight. The group is about to sacrifice a beautiful virgin to the god in charge of their hemp garden. And the planet is about to be colonized by a nonhuman race even more ruthless than mankind. But all Dorian can do is invent new footnotes to the Space manual, like, 

"For his own piece of mind, the Space Sociologist should sometimes kick the dirty savage on his bare butt."