Hello and welcome to the After-On Podcast.

Today we'll be talking with Roger Hamlin of the Marine Biological Laboratory at Woods Hole,

about cognition in octopuses, as well as loads of other underwater topics.

But I'm shining a spotlight on octopus cognition because it's a subject that's always fascinating.

Part of the reason is that octopuses evolve their exclusive intelligence completely and

independently of the other creatures we usually think of as intelligent.

Like monkeys, puppies, horses, and birds, we share much more recent common ancestors with each of them

than we do with octopuses.

And they all share more recent common ancestors with one another than they do with octopuses.

Our last common ancestor with the octopus was way, way back,

and didn't look a thing like either of us.

Specifically, it was a flatworm that lived on the ocean floor 750 million years ago.

That's how long it's been since our ancestry diverged from the octopuses.

This means their hereditary line followed an entirely different path to intelligence,

resulting in radically novel brain anatomy, which could entail equally unique ways of perceiving,

reacting, and processing information.

Remarkably, there are more neurons in an octopus's body than there are in its main brain.

And yes, I said main brain because the octopus basically has nine brains, one in each arm,

plus the main one, which lives in that muscular central bulb which most of us think of as the octopus's

head. As for the raw intelligence and conscious experiences of octopuses, well, I'll leave that

to Roger to discuss. Roger is what's called a sensory ecologist, which means he studies the

sensory apparatus of different species and how that influences their behaviors, experiences,

...