Human minds remain substrate-dependent in that they are known to exist only on brains.

“We can imagine the same letter or the same face. And that's really fascinating that we have this substrate agnosticism, that we, uh, evolve a causal pattern that exists over a very wide range of substrate properties, that we become somewhat independent of the substrate, and we are still bound to our substrate in a certain way because you and me, we can only exist on brains, right?”

“We are patterns that so far can only exist on brains, and if we wanted to move into the environment after our body dies, we would need to find a way to crack the codes of our environment, right?”