NARRATOR: If you wanted to study how aliens might think, but you didn't have the ability to travel light years into space to find them, where would you look?

For scientist, Dominic Sivitilli, the answer is under the sea.

[gentle music] [hose bubbling] DOMINIC: It feels like being on some alien planet, especially in the Pacific Northwest, where you're just floating among this green haze and with how dark it is and with how cold it is.

And then surrounded by this incredible diversity of invertebrates and other life forms down there.

It definitely does feel like I'm on a completely different planet, or almost in a completely different dimension.

NARRATOR: There is a creature in these murky waters that has a mind so foreign to ours, it might as well be an alien.

The trouble is finding it.

DOMINIC: Well one of the interesting things about this, is that octopuses have one of the best camouflage systems in the entire world.

And so we're effectively going out and trying to find an animal that evolved to not be found.

You do see them bob their head up and down, so you can kind of see a piece of kelp or rock playing peek-a-boo, and then realizing that this is actually a very intelligent being that is staring at me, and assessing what I am.

It gives me a very uncanny feeling.

NARRATOR: Of course, octopuses and squids have long captivated, inspired and terrified humans.

I think it's appropriate that we base so many of our monsters and aliens off of them, because they are extremely alien-looking creatures, just they're multiple limbs and their camouflage and their unblinking eyes.

[suspenseful music] NARRATOR: But the reason Dominic and other scientists see them as models for alien intelligence, is that they branched away from humans on the evolutionary tree, some 500 million years ago.

The octopuses' long separate evolution toward cognitive complexity makes them a very appropriate model for what intelligence might look like, if it evolves on a completely different planet.

The main question that drives me is like, really what are the different forms that the mind can take?

What are all the different kinds of ways that the mind is experiencing the world out in the universe?

This is Lizbeth.

She's our giant Pacific octopus.

She can grow to being 20 feet long if she spread her arms out.

NARRATOR: And those spreading arms, they're not like ours.

They're far more sensitive.

Our fingertip might have 400 mechanical receptors.

A given sucker might have tens of thousands of mechanical and chemical receptors on it.

So each sucker is many times more mechanically sensitive than one of our fingertips is.

And also has the benefit of being able to taste and smell the world around it.

And it's able to do this, because each sucker has a local computation center, where most of this information's being processed.

Good girl.

NARRATOR: A computation center.

In other words, the suckers not only feel, they not only taste and smell, each sucker basically has a mini mind of its own.

Dominic calls it distributed intelligence, and it's the focus of his research.

DOMINIC: See, they're just like cats.

They really like boxes.

NARRATOR: To find out how these suckers think for themselves, Dominic uses a tank, a puzzle and some juicy shrimp bits.

But before we break it down, let's see the entire octopus in motion, doing what it does best.

Their web is something that blows my mind, just like, wow, how do they use that?

It shows what they are doing, right?

I mean, these again are very cognitively-complex animals.

And so looking at what they do best, which is find and capture food, is quite impressive.

NARRATOR: Watching Lizbeth hunt, it's easy to think her central brain is controlling all her movements and the color and texture changes in her skin.

But that's not really what's happening.

DOMINIC: It's really hard to imagine how these animals are experiencing the world.

Their nervous system and their perceptions and sensory systems are built entirely differently from ours.

While most of our neurons are in our brain, most of their neurons exist beyond their central brain, in their arms and suckers.

NARRATOR: So their arms are in essence, thinking on their own.

To try to figure out how this distributed intelligence works, Dominic has created a puzzle box that contains changeable rows of crevices, like the octopus would find naturally in the wild.

He hides a piece of shrimp in one of the crevices, and then sets the octopus loose to explore the box with its suckers, and he films it all with a high speed camera.

DOMINIC: There seems to be a strategy that the sucker is used to coordinate.

And this strategy seems to rely on a recruitment mechanism.

So if one sucker finds something of interest, say if it's like a clam or a muscle or some kind of prey, a sucker will find that prey.

And then it will tell the next sucker over, hey I found something of interest, and that sucker will turn toward that prey.

WOMAN: Oh, she got it.

She got it?

Yeah.

DOMINIC: Good girl.

NARRATOR: It's a bit like a sucker chain reaction.

And the more suckers that get involved, the higher a signal they send to the brain.

DOMINIC: The octopus' mind at work.

NARRATOR: Using a CT scanner, Dominic has actually been able to create a visual of the octopus' distributed mind.

The brain itself has about 50 million neurons.

Each of the optic lobes has about 60 million neurons.

And then beyond the brain in the arms and suckers, is where 350 million of the octopus' 500 million neurons are.

NARRATOR: Spreading its brain out amongst its arms serves an evolutionary purpose.

Unlike humans and other simple vertebrates, which can only move our arms and legs in a couple directions, an octopus can bend its eight arms with seemingly infinite freedom.

Add the fact that they mostly hunt at night when they can't see well, and you can see that's a lot of information for the brain to process on its own, all at once.

DOMINIC: What the brain will do is send out a very generalized command to multiple arms at once, and let the arms kind of figure it out from there.

And the suckers with all their chemo receptors, all their mechanical receptors, are very well equipped to then find interesting objects out there in the world.

[water bubbling] NARRATOR: And in the lab, Dominic is one of the most interesting things for them to find.

If they see me around the lab, they will approach, go to the edge of their tank, and just watch the interesting things that are happening.

You never really feel like you're alone in that lab.

That was one of the first things that fascinated me about them, was their curiosity.

Gonna throw them in.

Here I am studying them, and yet they seem to also somehow be studying me in their own way.

[gravel crunching] [water lapping] NARRATOR: But like all studies, this one comes to an end with the end of summer.

It's always sad to see an animal go that you've grown close with.

But they're also going back home into their natural habitat, so it's really hard to stay sad about it for too long.

In my time studying the octopus, I've really learned to appreciate that there are many varieties of intelligence out in the world and possibly the universe.

The human mind is just one of many different varieties.

It's not about how intelligent they are, it's about how they are intelligent.

[gentle music]