A recent study about jellyfish found that even species that only have about a thousand neurons are capable of conceptualizing past experiences and adapting their behavior. These are animals that barely have a brain, and even they are entirely aware that they have a life and wish to live it comfortably. I like jellyfish, the little baby ones you can see at an aquarium are cute.

A human being has 100 billion neurons. We are like galaxies compared to that jellyfish. We hold emergent mental processes in our heads that can conceive of things beyond our own lives, beyond our own times, beyond time itself. And there are other humans willing to snuff all of that out by just firing a rocket, just to keep from feeling a little discomfort, to avoid some guilt.