I have read that nonhuman cells (bacteria, viruses, etc) vastly outnumber human cells in the body. Going by numbers (though not by mass) you are more "not you" than "you". But most of them are beneficial, so hey! The more the merrier, right?

I have pondered the essence of self for some time now from a slightly different perspective: as a survivor of traumatic brain injury.

I think that most of us think that the essence of self is our brains or, more specifically, the thoughts generated by those brains. But all of those thoughts are processed through real, physical, gooey hardware. If that hardware is changed, the thoughts change too.

This raises the question: am I still me? Am I a different me? Am I someone else entirely who occupies the same body?

What if it hadn't been brain damage? What if it had been a brain transplant? Most people would say that, in the case of a transplant, a new brain = a new person. Strangely, most people would ALSO say that a changed brain = the same old person. But what is the difference, really?

In my case, I retain enough of the traits and memories that I am pretty sure that I am just a different me. But some cases are more extreme. What of them? Are they now new people?

My desire to study

Good video! I was unaware of recent research indicating that DNA can change over time. I shall have to look into that.