Mack Reynolds 
Adaptation 

Hardly had man solved his basic problems on the planet of his origin than he began to fumble into space. Barely a century had elapsed in the exploration of the Solar System than he began to grope for the stars.

And suddenly, with an all but religious zeal, mankind conceived its fantasy dream of populating the galaxy. Never in the history of the race had fervor reached such a peak and held so long. The question of why was seemingly ignored. Millions of Earth-type planets beckoned and with a lemming-like desperation humanity erupted into them.

But the obstacles were frightening in their magnitude. The planets and satellites of Sol had proven comparatively tractable and those that were suited to man-life were quickly brought under his dominion. But there, of course, he had the advantage of proximity. The time involved in running back and forth to the home planet was meaningless and all Earth's resources could be thrown into each problem's solving…