The Seedling Stars
by James Blish
You didn't make an Adapted Man with just a wave of the wand. It involved an elaborate constellation of techniques, known collectively as pantropy, that changed the human pattern in a man's shape and chemistry before he was born. And the pantropists didn't stop there. Education, thoughts, ancestors and the world itself were changed, because the Adapted Men were produced to live and thrive in the alien environments found only in space. They were crucial to a daring plan to colonize the universe.