An ancient philosophical thought experiment, known as the Ship of Theseus, raises some relevant questions for our robotic times. 

What happens when all the components of Theseus’s ship are gradually replaced over time? Is the rebuilt boat, containing none of its original parts, still the ship of Theseus? Or is it something different? Much wine was doubtless drunk in philosophical symposia contesting the point.

A similar conundrum is true of human identity. All the cells we are born with will be replaced many times over during our lives. But we do not believe our identity changes. So what is the essence of our identity? Is it our visible, mutable wetware, which is constantly being replaced? Or is it our invisible, mostly immutable software — our genetic code — which instructs our cells how to reproduce themselves?