The Imaginary Worlds podcast looks at Doctor Who’s regeneration, which began nearly 60 years ago as a gimmick to replace a lead actor whose health was failing, and has become central to the Doctor’s story, “about an alien being who is striving to be better but keeps overshooting the mark."

Podcast host Eric Molinsky says the source of regeneration’s narrative power may be that we all change over time and when we look back on our past selves they seem like other people.