There's some discussion of embodiment as an important factor in intelligence such that it would defy pure software implementation. I’m personally of the opinion that even to the extent this is true, it probably just means the compute capacity required for software is higher than we might otherwise think, to simulate the other parts, alternatively, with the right interfaces and hardware, we don't need that cheat. But “everything involved can be simulated in software at the required level”, while I believe it, somewhat speculative.
This spider could be evidence of "software based intelligence" in biological brains - it exhibits much more complex behaviors than other animals it's size, more comparable to cats and dogs.
What I mean is that some believe that their brain is "emulating" all parts of the larger "brain", but one at a time, and passing the "data" that comes out of one into the next.
