Notes
The Seed of Earth, a standalone novel by Robert Silverberg.

This volume is a "dos-à-dos" omnibus in the Ace Double series. It also includes Next Stop the Stars, also by Robert Silverberg.

Based on the novelette The Winds of Siros (Venture Science Fiction [US], September 1957).

Unrelated to the short story The Seed of Earth (Super-Science Fiction, April 1958), which was originally (and later) called Journey's End but was retitled before publication.

Previously published in a shorter form in Galaxy (June 1962).

Publisher's Blurb – Page One
THE UNWILLING COLONISTS AND THE INHOSPITABLE ALIENS

In a dark cave, on a cold planet, in a distant galaxy, four Earthmen sat and pondered the chance that had sent them there. The Computer had picked them to carry human civilization out beyond the limits of the Solar System. They were to be pioneers of a virgin world.

Do Your Share for Mankind's Destiny read the slogan back on Earth. But Mankind's Destiny had not prepared them for the onslaught of the vicious aliens.

Four humans, alone in a cave, waiting for the outburst that would hurl them at each others' throats, feeling the alien eyes observing their every action, and knowing that whatever they did would determine the future of their entire colony.