<p>Built from the debris of exploding stars that floated through space for billions of years, home to a zoo of tiny aliens, and controlled by a brain with more possible connections than there are atoms in the universe, the human body is the most incredible thing in existence.<br><br>In the sequel to his bestselling Inflight Science, Brian Clegg explores mitochondria, in-cell powerhouses which are thought to have once been separate creatures; how ...