So I stand before you
as an evolutionary biologist,

a professor of evolutionary biology,

which sounds like a rather fancy title,
if I may say so myself.

And I'm going to talk about two topics

that aren't normally
talked about together,

and that's market economies and fungi.

Or is it fun-GUY, or,
as we say in Europe now, fun-GEE?

There's still no consensus
on how to say this word.

So I want you to imagine a market economy

that's 400 million years old,

one that's so ubiquitous that it operates
in almost every ecosystem of the world,

so huge that it can connect
millions of traders simultaneously,

and so persistent

that it survived mass extinctions.

It's here, right now, under our feet.

You just can't see it.

And unlike human economies

that rely on cognition to make decisions,

traders in this market,
they beg, borrow, steal, cheat,

all in the absence of thought.

So hidden from our eyes,

plant roots are colonized by a fungus
called arbuscule mycorrhizae.

Now the fungus forms
these complex networks underground

of fine filaments
thinner than even threads of cotton.

So follow one of these fungi,

and it connects multiple
plants simultaneously.

You can think of it
as an underground subway system,

where each root is a station,

where resources are loaded and unloaded.

And it's also very dense,

so roughly the length
of many meters, even a kilometer,

in a single gram of dirt.

So that's the length of 10 football fields

in just a thimbleful of soil.

And it's everywhere.

So if you passed over a tree,
a shrub, a vine, even a tiny weed,

you passed over a mycorrhizal network.

Roughly 80 percent of all plant species

are associated with these
mycorrhizal fungi.

So what does a root covered in fungi

have to do with our global economy?

And why as an evolutionary biologist
have I spent the last 10 years of my life

learning economic jargon?

Well, the first thing
you need to understand

is that trade deals
made by plant and fungal partners

are surprisingly similar

to those made by us,

but perhaps even more strategic.

You see, plant and fungal partners,

they're not exchanging stocks and bonds,

they're exchanging essential resources,

and for the fungus,
that's sugars and fats.

It gets all of its carbon
directly from the plant partner.

So much carbon, so every year,
roughly five billion tons of carbon

from plants go into
this network underground.

For the root, what they need
is phosphorus and nitrogen,

so by exchanging their carbon

they get access to all of the nutrients
collected by that fungal network.

So to make the trade,

the fungus penetrates
into the root cell of the host

and forms a tiny structure
called an arbuscule,

which is Latin for "little tree."

Now, you can think of this
as the physical stock exchange

of the trade market.

So up until now, it seems very harmonious.

Right? I scratch your back,
you scratch mine,

both partners get what they need.

But here is where we need to pause

and understand the power
of evolution and natural selection.

You see, there's no room
for amateur traders on this market.

Making the right trade strategy

determines who lives and who dies.

Now, I use the word strategy,

but of course plant and fungi,
they don't have brains.

They're making these exchanges

in the absence of anything
that we would consider as thought.

But, as scientists,
we use behavioral terms

such as strategy

to describe behaviors
to certain conditions,

actions and reactions

that are actually programmed
into the DNA of the organism.

So I started studying
these trade strategies

when I was 19 years old

and I was living in
the tropical rainforests of Panama.

Now, everybody at the time was interested
in this incredible diversity aboveground.

And it was hyperdiversity.
These are tropical rainforests.

But I was interested
in the complexity belowground.

We knew that the networks existed,
and we knew they were important,

and I'm going to say it again,
by important I mean important,

so the basis of all plant nutrition

for all the diversity
that you do see aboveground.

But at the time, we didn't know
how these networks worked.

We didn't know how they functioned.

Why did only certain plants
interact with certain fungi?

So fast-forward to when
I started my own group,

and we really began to play
with this trade market.

You see, we would manipulate conditions.

We would create a good trading partner
by growing a plant in the sun

and a poor trading partner
by growing it in the shade.

We would then connect these
with a fungal network.

And we found that the fungi
were consistently good

at discriminating among
good and bad trading partners.

They would allocate more resources
to the host plant giving them more carbon.

Now, we would run
the reciprocal experiments

where we would inoculate a host plant
with good and bad fungi,

and they were also good at discriminating
between these trade partners.

So what you have there is the perfect
conditions for a market to emerge.

It's a simple market,

but it's a market nonetheless,

where the better trading partner
is consistently favored.

But is it a fair market?

Now this is where you need
to understand that, like humans,

plants and fungi
are incredibly opportunistic.

There's evidence that the fungus,
once it penetrates into the plant cell,

it can actually hijack the plant's
own nutrient uptake system.

It does this by suppressing
the plant's own ability

to take up nutrients from the soil.

So this creates a dependency
of the plant on the fungus.

It's a false addiction, of sorts,

whereby the plant has to feed the fungus

just to get access to the resources
right around its own root.

There's also evidence that the fungi are
good at inflating the price of nutrients.

They do this by extracting
the nutrients from the soil,

but then rather than
trading them with the host,

they hoard them in their network,

so this makes them unavailable
to the plant and other competing fungi.

So basic economics,

as resource availability goes down,
the value goes up.

The plant is forced to pay more
for the same amount of resources.

But it's not all in favor of the fungus.

Plants can be extremely cunning as well.

There are some orchids --

and I always think orchids somehow
seem like the most devious

of the plant species in the world --

and there are some orchids

that just tap directly into the network

and steal all their carbon.

So these orchids, they don't even make
green leaves to photosynthesize.

They're just white.

So rather than photosynthesizing,

tap into the network,

steal the carbon

and give nothing in return.

Now I think it's fair to say
that these types of parasites

also flourish in our human markets.

So as we began to decode these strategies,

we learned some lessons.

And the first one was that
there's no altruism in this system.

There's no trade favors.

We don't see strong evidence

of the fungus helping
dying or struggling plants

unless it directly benefits
the fungus itself.

Now I'm not saying
if this is good or bad.

Unlike humans, a fungus, of course,
cannot judge its own morality.

And as a biologist,

I'm not advocating for these types
of ruthless neoliberal market dynamics

enacted by the fungi.

But the trade system,

it provides us with a benchmark

to study what an economy looks like

when it's been shaped by natural selection

for hundreds of millions of years

in the absence of morality,

when strategies are just based

on the gathering and processing
of information,

uncontaminated by cognition:

no jealousy, no spite,

but no hope, no joy.

So we've made progress

in decoding the most basic
trade principles at this point,

but as scientists we always
want to take it one step further,

and we're interested in more complex
economic dilemmas.

And specifically we're interested
in the effects of inequality.

So inequality has really become
a defining feature

of today's economic landscape.

But the challenges of inequality

are not unique to the human world.

I think as humans we tend to think
that everything's unique to us,

but organisms in nature

must face relentless variation
in their access to resources.

How does a fungus
that can again be meters long

change its trade strategy
when it's exposed simultaneously

to a rich patch and a poor patch?

And, more generally,

how do organisms in nature
use trade to their advantage

when they're faced with uncertainty

in terms of their access to resources?

Here's where I have
to let you in on a secret:

studying trade underground
is incredibly difficult.

You can't see where or when
important trade deals take place.

So our group helped pioneer
a method, a technology,

whereby we could tag nutrients
with nanoparticles,

fluorescing nanoparticles
called quantum dots.

What the quantum dots allow us to do

is actually light up the nutrients

so we can visually track their movements

across the fungal network

and into the host root.

So this allows us finally
to see the unseen,

so we can study how fungi bargain
at a small scale with their plant hosts.

So to study inequality,

we exposed a fungal network

to these varying concentrations
of fluorescing phosphorus,

mimicking patches
of abundance and scarcity

across this artificial landscape.

We then carefully quantified fungal trade.

And we found two things.

The first thing we found

was that inequality encouraged
the fungus to trade more.

So I can use the word "encouraged"
or "stimulated" or "forced,"

but the bottom line is
that compared to control conditions,

inequality was associated
with higher levels of trade.

This is important,

because it suggests that evolving
a trade partnership in nature

can help organisms cope with
the uncertainty of accessing resources.

Second, we found that,
exposed to inequality,

the fungus would move resources
from the rich patch of the network,

actively transport them
to the poor side of the network.

Now, of course, we could see this

because the patches
were fluorescing in different colors.

So at first, this result
was incredibly puzzling.

Was it to help
the poor side of the network?

No. We found that the fungus gained more
by first moving the resources

to where demand was higher.

Simply by changing where
across the network the fungus was trading,

it could manipulate
the value of those resources.

Now this stimulated us to really
dig deeper into how information is shared.

It suggests a high level
of sophistication,

or at least a medium level
of sophistication

in an organism with no cognition.

How is it that a fungus can sense
market conditions across its network

and then make calculations
of where and when to trade?

So we wanted to look about information
and how it's shared across this network,

how the fungus integrates cues.

So to do that, what you need to do is
dive deep in and get a higher resolution

into the network itself.

We began to study complex flows
inside the hyphal network.

So what you're looking at right now
is a living fungal network

with the cellular contents
moving across it.

This is happening in real time,

so you can see the time stamp up there.

So this is happening right now.
This video isn't sped up.

This is what is happening
under our feet right now.

And there's a couple of things
that I want you to notice.

It speeds up, it slows down,
it switches directions.

So we're working now with biophysicists

to try to dissect this complexity.

How is the fungus using
these complex flow patterns

to share and process information

and make these trade decisions?

Are fungi better at making
trade calculations than us?

Now here's where we can potentially
borrow models from nature.

We're increasingly reliant
on computer algorithms

to make us profitable trades
in split-second time scales.

But computer algorithms and fungi,

they both operate in similar,
uncognitive ways.

The fungi just happens to be
a living machine.

What would happen
if we compare and compete

the trading strategies of these two?

Who would win?

The tiny capitalist that's been around

since before and
the fall of the dinosaurs?

My money is on the fungus.

Thank you.

(Applause)