The Superpowers of Slime Molds

You see the yellow substance in the plastic case.

Can you guess what it is?

It's a slime mold.

Slime molds are primitive creatures that have inhabited the Earth since long before the dawn of mankind.

Amazingly, this is all one single cell.

Even more amazing, these creatures, with no brain or nerves, can process information like a computer!

Studying slime molds may tell us something
about the origins of intelligent life.

In fact, they've inspired the development of a new type of computer chip.

I think there may be new frontiers
in what we learn from biology.

So don't underestimate what you can do with a single cell.

On today's episode, we'll look at the superpowers of slime molds!

Prepare to be surprised.

And later, in our J-Innovators segment,

Michelle brings us a report about the person behind the latest delicacy for astronauts.

Hello and welcome to Science View. I'm your host Tomoko Tina Kimura.

Joining us is Mr. David Hajime Kornhauser, Director of Kyoto University's Office of Global Communications.

- Thank you for joining us today.
- It's my pleasure.

Today's topic is "slime molds."

There are said to be over 1,000 species of these in the world.

And we have one of them here.

The one we saw in the opening video was yellow, but this one is red.

Wow, it really is red.

Yes. It looks kind of like a mold, but it's a brighter color.

And the large form is known as a "plasmodial" slime mold.

That's really amazing.

The biggest difference is that this is a single-celled organism.

The whole thing is really just one cell.

I know. It's hard to believe this is somehow all just a single cell, like an amoeba or something.

Yeah. We've all seen videos of single-celled organisms moving around on their own,

finding food to take into their bodies for example.

This slime mold works the same way, moving around and foraging for food.

It doesn't look like it's in much of a hurry at the moment.

How fast do these things move?

These speed demons tear up the road at about 1 cm per hour.

They slowly advance toward the bacteria and other microorganisms that they eat.

Or, once they've gotten big enough, even entire mushrooms.

Mushrooms! Wow!

This next video tells us about the types and habitats of slime molds.

Where do slime molds usually live?

Our guide is Mr. Fumihiko Arai.

He's been photographing slime molds for almost 20 years.

It's basically a microscopic world, about 1 mm in size.
If you don't sit down or crawl around, you'll miss them.

Just then...

Oh, there's a slime mold here.

This is wolf's milk.

Wolf's milk has a pastel pink color.

This one is about 1 cm across.

That's pretty big for a slime mold.

They're often found under trees,
where they won't get wet when it rains.

If you just look around in parks and near trees in
residential areas, I'm sure you'll find some.

They vary in size, from less than a millimeter to several centimeters across.

And then...

This is the seldom-seen "Elaeomyxa cerifera." Wow!

This is the "Elaeomyxa cerifera" that Arai just found for the first time in 15 years.

It has a jewel-like luster and turns lavender or green in the light.

There's a colorful little world at our feet.

But these look a lot different from the yellow slime mold we saw before.

Why's that? Although they remain single-celled, the appearance of a slime mold can vary dramatically.

This is the life cycle of a slime mold.

An amoeba-like single-celled life form emerges from a spore.

When this creature meets another of the opposite sex, they merge.

The result is a larger single cell with multiple nuclei.

Repeating this over time, it grows into a slime-like form, a "plasmodium."

Some plasmodium can even consume mushrooms.

When the surroundings make life difficult, the plasmodium creates mushroom-looking organs

called "fruiting bodies" that disperse spores to create the next generation.

This is how slime molds grow and thrive.

It's such a unique creature.

Its shape changes so dramatically.

Yes it does. It's unusual to find an organism whose appearance changes so much over its lifespan.

And slime molds are said to be able to process information.

How does that work?

Well, we saw in the video, slime molds live under fallen trees and leaves.

These can be very diverse and challenging habitats.

The food they need to live on isn't always in the same direction or location.

There are obstacles along the way, and competition from other species.

Nevertheless, they're well-adapted at sensing food and moving toward it.

That could be considered a type of information processing ability.

I see. Even though they're a simple one-celled organism,

in order to have survived for hundreds of millions of years,

they would have to sense and react to where food might be.

But they don't have any organ that makes decisions, like a brain or nerves.

No, they don't.

But, recent experiments have harnessed their distinctive sensory behaviors when seeking out food,

and applied those in situations where judgments and calculations are required.

And these simple creatures showed that they can process data at a level comparable to animals with actual brains.

The Research Institute for Electronic Science, at Hokkaido University.

This is a plasmodium we keep in our laboratory.

This is all one creature.

It's pretty big.

The findings from Professor Toshiyuki Nakagaki's unique experiments have taken the world by surprise.

Amazingly, he uses this brainless plasmodium to process information.

This slime mold even manages to solve a maze!

When food is placed in two nearby locations,

the plasmodium reacts by extending outwards, reaching toward both food sources.

To get as much nutrition as possible, it shifts most of its body around the food,

leaving a thin tube-like structure in between.

Nakagaki thought the plasmodium's ability to rearrange itself for efficient nutrition like this

might be used to find the shortest solution to a maze.

This is the maze he used in his experiments.

First, pieces of the plasmodium were cut off and placed in the maze.

Because these came from the same specimen, the plasmodium can reconnect along the passageways.

Once it's reconnected its body and filled in the entire maze,

the food is placed and the experiment begins!

There are several possible routes to connect the start and end points.

After some time, the sections of the plasmodium along the less useful routes shrank.

Meanwhile, the sections along the more efficient routes stayed thicker.

So, the plasmodium kept mostly to the shortest path, completing the maze!

Even better! The way it bends its body is also a feature!

It forms the most efficient shape to navigate the sharp turns.

It doesn't have a brain, so it shouldn't be able to think.

So, how does it process information to figure out the shortest path?

After careful observation, they identified a certain principle that governs how the plasmodium behaves.

It gets nutrients from food flowing through tubes in its body.

The tubes closer to the food source are busier, and, therefore, thicker.

Conversely, tubes farther from the food are less active, narrowing, and eventually disappearing.

They discovered that each section acts autonomously according to this principle, without instructions.

That was impressive! It solved the maze.

So, if they can process data, that means they're intelligent?

It seems there are still some doubts about whether this ability can be called proper "intelligence."

Still, the slime molds performed well in a lab environment.

And surviving in a natural outdoor environment can be even more challenging.

So, it doesn't seem like an overstatement to say there's some sort of intelligence there.

So, what the slime molds have might be comparable to something like an early version of our brain.

I think it's fair to say that.

According to evolution, even more complex creatures like us humans

presumably trace back to some single-celled organism.

So, our brain and other specialized organs would have to have undergone a tremendous amount of differentiation.

And yet, the core unit is still individual cells.

So, in that sense, we could imagine each of the cells that comprise life on Earth

has some common underlying means of processing information.

There's also research aimed at using the data processing abilities of slime molds to develop a new computer.

Businessman Masashi Aono is working on a new computer that incorporates the abilities of slime molds.

I wanted to use the plasmodium's abilities
to make a computer that works like a brain.

This is the "plasmodium bio-computer" Aono came up with.

He puts a real live plasmodium inside, and it does the data processing.

Inside the device, this slime mold can stretch its legs.

Plasmodium has the behavior of extending out in random directions to search for food.

Another behavior... they avoid bright light.

When a light is turned on, the plasmodium retreats.

Aono had the idea of applying these behaviors to build a device that can do math.

He used this plasmodium bio-computer...

...to take on a mathematical optimization problem known as the "traveling salesman problem."

The salesman must visit several cities and then return home.

The challenge is finding the shortest route.

If a simple solution is found, it could be applied in many other fields,

such as making package delivery services more efficient.

Regular computers attack this problem with "brute force," checking every possible route, one at a time.

But as the number of cities increases, the number of possible routes grows factorially,

taking regular computers ever longer to complete.

Meanwhile, this biological data processor gives a "reasonably good answer" in a short amount of time.

Let's look at a simple version of the problem, with only four cities.

If, for example, the plasmodium extends into the groove labelled "A1,"

that means city "A" is the first city the salesman will visit.

When a camera inside detects this, the computer shines a light on grooves A2, A3, and A4,

effectively disabling those options for the plasmodium, since the salesman visits each city only once.

Similarly, lights are used to eliminate grooves B1, C1, and D1,

since the first city to visit has already been chosen.

So, this computer does math problems by using light to stimulate a living plasmodial slime mold.

It drives the plasmodium into complex situations,

to make use of its natural information-processing abilities.

If it ultimately chooses A1, B2, C3, and D4, for example,

then the route will be A→B→C→D, and back home to A.

Extending in various combinations of multiple directions at the same time

allows this biological computer to test out different possibilities in parallel,

giving it an advantage over conventional computers.

The problem was...

this plasmodium bio-computer worked... but slowly.

Hokkaido University professor Seiya Kasai wanted to address this issue.

This robot has the data processing abilities of the plasmodium built in.

Kasai is working on digital electronic circuits based on the analog plasmodium bio-computer.

Plasmodia move slowly.

I thought replacing them with ultra-fast electrons
would make the calculations much quicker.

They've dubbed their resulting computer the "Electronic Amoeba."

A problem that took the plasmodium bio-computer an hour...

...was solved by the "Electronic Amoeba" in only 40 microseconds!

Plasmodiums advance and retreat with distinctively hesitant motion,

sort-of "three steps forward and two steps back," as the saying goes.

Kasai believes this seemingly needless wavering, characteristic of living creatures,

actually gives this computer an advantage.

Electronic circuits and computers are engineered to
minimize uncertainties. That's standard.

But in the past several years, plasmodia with that
wavering have gotten quite good at computing.

Our "Electronic Amoeba" circuitry replicates that.

They also want to produce a smaller and faster version that fits onto a 1 cm semiconductor chip!

If it works like they're hoping, we might one day have electronic amoebas inside our smartphones.

I think it'll excel in disasters like earthquakes
and tsunamis, for finding the safest escape route.

The "Electronic Amoeba" will quickly find
the best route based on its risk calculations.

That'll be very helpful in disaster situations.

Computers that are partly alive, or electronic circuits that behave like they're alive.

- These really sound like science fiction.
- They sure do.

But amazingly, they already exist.

And more importantly, they produce a valid answer to the given problem.

Professor Kasai cited finding the best escape routes in a disaster situation.

What other ways can this approach be applied?

Typically, earthquakes and typhoons cause only partial damage to communications networks.

So, a common challenge is how best to utilize the remaining sections to start to rebuild to full capacity.

And it's not just communications.

- This technology could also be applied to rebuilding things like gas and water systems.
- That's right.

The various utilities and infrastructure, both inside cities and between cities.

And that includes traffic grids and transportation routes.

As in, where should the roads go and how wide should they be

to accommodate the expected amounts of freight and commuters that'll use them.

Slime molds may turn out to be quite good at coming up with novel solutions to those sorts of problems.

Up next, is our J-Innovators segment.

A story about a new item on the dinner menu in space.

Hi, I'm Michelle. I love eating dried fish which is a traditional Japanese dish.

But it takes a lot of time and effort to remove the bones to eat it.

However, there is an amazing dried fish that is processed in a special way,

in which you can eat bones as a whole.

And this technique is recognized even by NASA and JAXA as space food.

Dried fish is a traditional Japanese dish that is made by drying raw fish in the sun

to preserve its shelf life and enhance its flavor.

How is it possible to make the hard bones of dried fish edible?

We visited Toon City, the only city in Ehime Prefecture that does not have an oceanfront.

We went to a marine products processing plant that handles unique fish products.

Hello, I'm Michelle.

Hello, my name is Kishimoto Kenji.

This is today's Takumi and Innovator, Kishimoto Kenji.

And here is the groundbreaking dried fish.

Even the bones can be eaten whole.

It looks like normal dried fish with the head and bones.

First, let's compare the hardness of the bones.

In normal dried horse mackerel, even with a lot of force, the bone cannot be crushed.

On the other hand, this is the bone of the Takumi's dried horse mackerel.

It is as soft as the meat and falls apart.

I had a chance to check it out.

It's so soft!

You can hardly feel the bones, can you?

I ate the backbone, but I couldn't tell at all.

Kishimoto has been involved in the dried fish industry for almost 50 years,

and has always strived to provide delicious, easy-to-eat dried fish.

However, he always had concerns that children and the elderly found it difficult to eat,

because of the hard bones.

So, 20 years ago, he came up with the idea of making a dried fish with no bones at all,

so that children and the elderly could eat it with peace of mind.

He developed a machine for this purpose, but it was impossible to remove all the small bones.

Five years after he began, he found himself at a standstill.

Just then, a research institute approached him about a joint development project.

It was the Ehime Prefectural Institute of Industrial Technology,

which was also looking for a solution to the problem, but by softening the bones rather than removing them.

Fish bones are made mainly of calcium and collagen.

The fibrous collagen running through the calcium reinforces the bones.

High pressure is used when heating the dried fish.

The high pressure raises the boiling point, dissolving the collagen in the bones,

without boiling away the water content in the fish meat.

If there is moisture, the collagen becomes gelatin and dissolves into it.

And the bones become brittle.

In other words, to soften bones, along with temperature and pressure,

moisture is needed to act as a receptacle for the collagen.

The laboratory had already succeeded in softening the bones of dried fish

with its high-temperature, high-pressure sterilization equipment.

However, there was a problem that could not be solved.

The gelatin dissolved in the water remaining in the fish meat,

and some of the gelatin leaked out, resulting in dried fish that was sticky.

Having reached a dead end, the institute contacted Kishimoto in search of a breakthrough.

We worked with Mr. Kishimoto, who is
an expert in dried fish, to improve the process.

For Kishimoto, it was a timely offer.

He accepted the project without hesitating.

Almost every day, he went to the laboratory with dozens of horse mackerel to repeat the experiment.

By experimenting with countless combinations of factors such as the dryness of the dried fish,

the pressure, temperature, and heating time, he was able to achieve success on rare occasions.

But when they tried it with other fish, it was always a failure.

We ran into all kinds of problems with
different sizes of fish and species of fish.

With relentless testing, we overcame the problems.

That took about a year and a half.

After acquiring a certain amount of know-how in the laboratory,

Kishimoto installed his own high-temperature, high-pressure sterilization equipment

and repeated further experiments.

In the process, he discovered a point at which the gelatin hardly leaks at all

and only the bones become brittle when subjected to high temperature and pressure at a specific degree of dryness.

The key was the water content in the bones.

Dried fish contain a small amount of water in the bones as well as in the meat.

The gelatin dissolved into this moisture in just the right amount, preventing it from leaking out.

The gelatin dissolves out, but it dissolves back
into the bone, or rather, there is such a cycle.

It doesn't overflow.

With this discovery, after about 10 years of work, dried fish with bones that could be eaten was finally accomplished.

Data on the hardness of the bones of each type of fish was collected,

and conditions suitable for each type were derived,

resulting in the successful commercialization of a total of six types of dried fish.

This remarkable achievement was conveyed to JAXA through an acquaintance.

It's been developed into a food for astronauts, who often lack calcium in space.

To be adopted as a space food, it had to meet a number of criteria,

including shelf life, nutritional value, taste, and smell.

In particular, since most astronauts aren't Japanese, the unique smell of dried fish,

which the Japanese are accustomed to, had to be eliminated.

Kishimoto solved this problem by soaking the fish in a smoky flavor solution before drying.

In addition, the plastic packs were changed to aluminum, which allows the product to be stored for more than 600 days.

The product was then approved as a space food.

Astronaut Soichi Noguchi actually tasted the dried fish made in this way on the ISS in 2021.

It's dried fish, but it has a nice softness.

It's delicious. I'm very satisfied.

It took Kishimoto 10 years to create a dried fish that can be eaten bones and all, and he even sent it to space.

What was the driving force behind this development?

It wasn't about the money. It was about the fun.

I'd think to myself: "Yesterday, I tried that,
and got this result. Maybe I should change that."

I'd be thinking about it even while driving to work.
That's how much fun I was having.

I realized that the more we have fun,
the better the results.

I'm always trying to get enough calcium.

So, I would love to make this a part of my diet.

Dried fish in space! If it's popular with the extraterrestrial, we might have to increase production.

Yes. Having gotten a good look at the surprising abilities of slime molds, what are your closing thoughts?

Well, I'd be pleasantly surprised by any new computing technology inspired by nature.

But in this case, it's a single-celled organism!

These simple creatures managed to come up with practical solutions to complex problems.

So, clearly, we can't underestimate what can be done with a single cell.

And personally, I think there might also be a lesson in there for

how doing things the simple way can be better, or "less is more."

That does sound like a good approach!

Mr.Kornhauser, Thank you so much for joining us today.

Thanks for having me.