PBS Nova: The Secret Mind of Slime

It creeps!

It crawls!

It's this big, blobby yellow thing.

It's slime mold!

A slithering shape-shifter like no other on this planet.

It reminded us

of this alien organism from a '50s movie

that ate people.

"The Blob"!

This one-celled wonder has no brain.

No brain, no organs, no neurons.

Yet it's able to do some of the behaviors

we normally associate with animals with brains.

How does it solve a maze?

It is amazing.

Escape captivity?

Compete for resources?

Build efficient networks?

You start to think, does this organism

possess intelligence?

All of these are fundamental components

to being smart.

No brain?

No problem.

Clearly now, we see

that this can be done by one cell.

Can this ancient organism shed new light

on the evolutionary origins of intelligence?

We can think of them as how intelligence started

way back.

"The Secret Mind of Slime,"

next, on "NOVA."

Major funding for "NOVA" is provided by the following:

Lurking in the forest's shadowy undergrowth

lies an unlikely predator.

It creeps along, stalking its prey.

Yet it is not an animal.

It has a fondness for dark, humid places,

yet it is not a fungus

nor a plant.

It's a single-celled organism,

but not a bacterium.

It's known as slime mold.

It has no eyes, no mouth, no stomach,

no legs.

Yet it can "see," "smell,"

and move around

through its pulsating network of veins,

gorging itself on bacteria,

fungi,

yeasts,

and growing exponentially.

This strange yet humble creature holds secrets that have

biologists, neuroscientists, and mathematicians

scratching their heads.

Because this organism, without a brain or a nervous system,

seems capable of making choices,

solving complex problems,

and devising strategies.

And it is forcing scientists to rethink intelligence

as something that does not imply a need for a brain.

Tanya Latty is a researcher at the University of Sydney

who studies slime mold.

You can find slime mold all over the place.

They're in leaf litter, they're in the soil,

they're on bits of wood.

They're small structures that almost look like mushrooms.

Not only is Tanya an expert on slime mold,

she's one of its biggest fans.

How could you not love them?

It's this big, blobby, yellow thing, you know,

it's just fundamentally cool.

I stand by that!

"Slime Mold Identification and Appreciation."

There it is.

She even follows them on Facebook.

The spores are gorgeous.

They're, they're beautiful.

The slime molds might be one of the most abundant things

in the soil.

There are spores everywhere.

Biologists have puzzled

over where exactly this creature fits

into the great tree of life.

Slime molds branched off from that tree

before the plants, the fungi, and the animals.

They're single-celled organisms, but the type of cell they have

is quite different from bacteria.

There's at least 900 different species of slime mold

that we know about,

and that number is probably a massive underestimate.

The slime mold most people think about

is Physarum polycephalum.

It's bright yellow, it grows really fast,

and it's become kind of our lab rat

most scientists are studying,

probably because it's the easiest one

to grow in the lab.

Some of them have great names, like the Dog's Vomit.

They also come in reds and grays and browns and white.

Tanya was a latecomer to slime mold research.

She began her career studying the behavior of insects.

I'm an entomologist by training.

I work with ants,

bees, and other invertebrates.

But ten years ago,

while researching bees at Hokkaido University,

she had a chance encounter with slime mold

through one of the most respected experts in the field:

Professor Toshiyuki Nakagaki.

Slime mold is a serious subject of study in Japan,

one going back generations.

The Emperor Hirohito himself

was a learned biologist

who established a taxonomy of slime mold,

and even discovered a new species of the organism.

In my research, I focus on this single, simple cell

through the disciplines of physics and math.

I was able to see how he was doing things

and learn a little bit about the slime mold.

Toshiyuki had been studying

how this curious organism would react

when faced with a challenge traditionally posed to animals.

He did some of the first really awesome experiments

on slime molds solving mazes.

Could a slime mold find food

placed at the far end of a labyrinth?

I had never even heard of slime mold before I took this job.

So here you have this organism that has no brain, no organs,

no neurons of any kind.

Yet it's able to do some of the behaviors

we normally associate with animals with brains.

It is mysterious.

Astounding.

Solving a maze is amazing.

How can a single-celled organism

have such a capacity?

Toshiyuki has devoted his career to studying this question.

I mean, when you think about it,

99% of the living things on our planet are brainless.

But they need to find food,

they need to find partners to reproduce often.

They may need to hide from predators.

How do you do all of that when you don't have a brain?

When I came back to Australia, I thought

it would be awesome to have one of these as a lab pet.

And it lived in my desk for a few weeks.

I started to notice that it was doing things

a lot like my ants were doing.

So she introduced Physarum to one of her colleagues,

Audrey Dussutour.

I was a post-doc in Australia

studying nutrition in ants.

It looked like an old omelet.

The next day, it had escaped from the box we had put him in.

It reminded us

of this alien organism from a '50s movie

that ate people...

And grew and grew as it ate.

It's unstoppable, it just kind of keeps coming.

And then the world could fall before the blood-curdling threat

of "The Blob"!

Physarum doesn't eat people.

It eats oatmeal, but it's really a glutton.

It doubles in size every day.

I nicknamed it "Blob."

Physarum began consuming their time and attention.

And soon, Tanya and Audrey

shifted the focus of their research

to this remarkable creature,

so radically different than any other they'd studied,

with abilities beyond what could be expected

from a single cell,

beginning with an unmistakable knack

for finding food.

Slime molds have receptors all over the cell body.

And that allows them to detect

different chemicals in the environment.

It's very similar to our sense of smell.

We have receptors in our noses,

and we're actually detecting chemicals

coming off of our food in the air.

Slime molds are doing the same thing,

but they're doing it through the soil or through a liquid medium.

Like the surface of a petri dish.

They're able to sense the chemical cue

and that's what draws them towards the food.

Slime mold's receptors sense a wide range

of these cues in their environment.

It can detect moisture and perceive the pH.

It can perceive light because it has photoreceptors.

So even though it is a single cell, it is, all at once,

an eye, nose, ear, and so on.

But it was how Physarum used these senses

that captured their attention:

an awareness of its environment;

an ability to navigate;

and how it moved with seeming purpose.

Here's an organism that knows how to react

and adapt to its environment, consistently and efficiently.