Metazoa

In some cases, the everyday life of a split-brain patient shows signs of ongoing disunity, as evidenced by disagreement; there are cases where one hand will put on a shirt or get out a cigarette, for example, and the other hand will oppose this action. If that sort of behavior was common, it would be tempting to say that the two-minds condition was permanent (as Schechter thinks it is).

But there is a lot of it, from sea angels (perhaps) to sea dragons (for sure).

Still, I’d bet on a view in which definite sentience exists not just in vertebrates, but in some groups very distant from our own: at least in cephalopods and some arthropods.

A second possibility is that a primordial form of experience arose just once, longer ago, early in animal evolution.

Sentience arose in animals from its absence, in this view, and did so at least a handful of times.

but a lot of other invertebrates (corals, bryozoans) just do not have what it takes.

although precursors to experience exist in much of the animal part of the tree, felt experience arose several times in different evolutionary lines.

Going back and forth over these questions, I’ve come to a sense of the importance of nervous systems, and—again—the unique way they organize nature’s energies.

However, I think this is a mistake.

a path not to panpsychism, but to what can be called biopsychism, the idea that all life is sentient.