The series revolves around Lister being the last human alive, 3 million years from Earth, with his companions (initially Rimmer, Cat and Holly). The crew encounters phenomena such as time distortions, faster-than-light travel, mutant diseases and strange lifeforms (all evolved from Earth, because the series has no aliens) that had developed in the intervening millions of years.[13] Though it has a science fiction setting, much of the humour comes from the interactions of the characters, particularly the laid-back Lister and the stuck-up Rimmer.