The Big Read: Are we more than our guts?

Two of my friends recently made a spaceship. You didn't hear about it because they are publicity-shy, but I've seen it, and it works. I understand only some of the science, but essentially it looks like most spaceships in pop culture: more or less cylindrical, with a bulbous front bit that houses the command centre, a long middle bit where the crew live, and propulsion units sticking out the back.