Chapter 9: The Social Life of Plants

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Welcome back to The Deep Dive.

Today we are focusing on a part of the biological world that, let's be honest, we almost always overlook.

A world we tend to see as stationary, passive, and well, completely individualistic.

We're diving into the deep social life of plants.

We are.

And it's such a fundamental bias we carry, isn't it?

We just naturally think of things like

complex sociality, devotion, collective intelligence.

We think that's all for the animal kingdom.

Right.

You think of ant colonies or primate societies, things like that.

Exactly.

But what happens when we, you know, take off those human -centric glasses for a second and really apply concepts like relational intelligence and collective strategy to the world of flora?

Well, we've got a really remarkable stack of sources today that suggests that whole traditional isolated view of plant life is just, well, it's fundamentally wrong.

For sure.

The evidence is pointing to this incredibly complex coordinated social world, you know, happening right under our feet in the soil and even high up on tree trunks.

It's a world of cooperation, of these surprising subterranean negotiations and this really startling ability for them to recognize and even prioritize their own family.

So our mission today is to walk you step by step through the groundbreaking research that's building this new paradigm.

We'll be looking at everything from evolutionary biology to community ecology.

This feels like more than just a deep dive into plant biology.

It is.

It's really a recalibration of how we understand life itself and what it really takes for any organism to be successful here on earth.

Okay, let's unpack this then and maybe we can start with a concept that's usually saved for like the most sophisticated insect societies.

Yeah.

Eusociality.

Yes, eusocial behavior.

It translates literally to truly social and it represents this extremely successful evolutionary strategy.

So what does that actually mean to be truly social?

It describes a lifestyle where individuals are.

They're completely devoted to the well -being of the larger group of the colony.

They basically subvert their own genetic self -interest for the collective.

They make a huge biological sacrifice.

A massive sacrifice.

And that's the key trait here.

You're right.

It just completely upends that traditional idea of individual survival of the fittest.

Because in a lot of these species, some individuals,

they don't even reproduce, do they?

Not at all.

They forego it entirely.

Their whole life is in support roles.

Foraging for food, maintaining the nest, defending the territory.

All for their nest mates who are the ones actually producing the next generation.

So an individual success is, I mean it's totally tied to the colony's success.

100%.

This idea was first formalized back in the 1960s by entomologists, the folks studying bees and hives.

Right, because you see it all there.

You have cooperative care of the young overlapping generations all living together in these really distinct reproductive roles.

Exactly.

And since then, the definition has expanded.

Now it covers ants and termites, of course, but also things like ambrosia beetles and even certain kinds of aphids.

And it pops up across different kingdoms, which is what I find so fascinating.

You see it in crustaceans, right?

Yeah, in certain coral reef dwelling shrimp.

And then of course, the breakout stars of mammalian eusociality.

The naked mole rats.

The naked mole rats.

They have a queen, they have sterile workers.

It's just like an insect colony, but underground with mammals.

So the big insight here, the reason we're starting with this is that this trait, this true sociality, it's so incredibly successful that it has evolved separately over and over again.

Many, many times across completely distinct branches of the tree of life.

You have insects, crustaceans, mammals.

It's what they call convergent evolution.

Exactly.

It suggests that if biology finds a strategy that really works, a way to use cooperation to solve the big environmental challenge, it tends to reappear.

It's a recurring, powerful solution.

Which of course brings us to the main question for this section.

If the strategy is so robust, so successful,

shouldn't we be able to find a plant equivalent?

You would think so, but traditionally, eusociality was completely unconfirmed in the plant world.

Maybe we just weren't looking at it through the right lens.

Until very recently.

Very recently.

That all changed in 2021 with a biologist named Kevin Burns.

He was working on Lord Howe Island off the coast of Australia, looking at staghorn ferns.

And staghorn ferns are epiphytes, right?

They grow on other trees.

They do, usually high up.

But on this particular island, the trees were kind of stunted, which meant these huge fern clusters were right at eye level.

Burns could look at them like you or So he's looking at these dense clumps of individual ferns, and he starts to see them not as individuals, but as a coordinated colony.

Precisely.

They grow in these big hive -shaped structures clinging to the host tree.

And they have two very, very different types of fronds, or leaves.

Okay, what are they?

So first you have the sterile elements.

These are the spongy disc -shaped fronds.

They stick right to the tree, to each other, and they form the base, the structure of the colony.

And the second type.

Those are the long, green, floppy antler farms.

They're covered in the slick wax that's amazing at chameling every single drop of rain right down into the base of that structure.

Ah, and here comes the analogy.

This is what struck Burns.

This is it.

He realized that the spongy, non -reproducing disc fronds,

they were functioning as the plant version of sterile worker bees.

Wow.

They stick to the host, they never ever reproduce, and their entire life's purpose is to dedicate their body to keeping water flowing to the roots of the whole colony.

While only some of the other fronds, the antler fronds, actually have the spores for reproduction.

That's right.

The others just live to feed and water the hole.

And you have to understand the environment here to get why this is so critical.

They're on the side of a tree trink.

There's no soil.

No soil to hold moisture at all.

Water is this incredibly scarce, fleeting resource.

So this dense cooperative structure and the complete devotion of those disc fronds to catching water, it solves this huge life or death problem.

The plants basically evolved a complex social system, a relational aptitude to deal with it.

They had to be willing to give up individual reproduction for the group to flourish.

And when you're talking about that level of complex sociality, of coordination with a shared goal, well, you're inevitably starting to talk about a type of collective intelligence.

The ability to make better choices as a group than any single fern could on its own.

Exactly.

Intelligence isn't just about having a brain.

It's the ability to learn from your surroundings and make decisions that best support life.

And in a tough environment, that often demands collaboration and even self -negation for the greater good.

That's the foundation of community.

This whole idea of collective intelligence is driving some really fascinating new research, even with us, with humans.

It is.

We're now finding that during these high -stakes social interactions, like learning something new or collaborating on a difficult task, the electrical activity in our brains, our brain waves, can actually synchronize between people.

So our brains literally get on the same wavelength.

Literally.

And our sources cite research that's seen this in all sorts of species, from primates to bats.

They talk about studies showing synchronized brain waves in co -pilots during takeoff and landing.

Those critical collaboration points.

Yes.

And teams perform measurably better when their brains align.

I even read that it applies to personal relationships.

Couples with higher brain synchrony report more satisfaction.

They do.

And co -parents' brains sync up when they're in each other's presence.

It suggests this kind of shared neurological state that supports the collective job of raising a child.

Our brains evolved in a social context, and this shows just how deep that wiring goes.

And that right there is the bridge back to plants.

That's the bridge.

Plants evolved in groups, in fields, in forests, in these tight fern colonies.

Interacting with your neighbors isn't optional.

It's just daily life.

So survival and reproduction are always, at their core, social questions for a plant.

Always.

Some, like the staghorn fern, are clearly super collaborative.

Others, as we're about to see, are more competitive.

But the point is, they're indisputably social beings who are constantly adjusting their behavior based on who is next to them.

It's a slight shift in how you look at them, but once you make it, this whole rich world opens up.

And I think nowhere is that richer than how they deal with family.

The groundbreaking discovery of kin recognition, yes.

Okay.

For this part of our deep dive, we're heading to the shores of Lake Michigan.

We are.

This is where, back in the late 1990s, an evolutionary ecologist named Susan Dudley started studying a very tough little beach shrub, the American sea rocket.

And the setting here is so important.

This isn't a lush forest.

It's dune country.

Right.

Shifting sand, constant wind, hardly any water or nutrients.

It's a brutal place to live.

Just surviving there is a feat of adaptation.

Now, at this point, scientists already knew that plants could tell the difference between self and non -self, right?

Yes, that was established.

A plant knows if a root it bumps into is its own or someone else's.

But Dudley was asking a much bigger and much more controversial question.

Could they recognize genetic kin?

Exactly.

And this was, I mean, this was radical.

Zoologists had known for ages that kin recognition gives animals huge evolutionary advantages.

It changes how they cooperate, who they mate with, everything.

But the dogma in botany was what?

That plants were just ruthless, isolated competitors.

Completely.

The idea that a plant could recognize its own family would just instantly overturn decades of ecological theory.

And Dudley, who I love this quote from her, she said she pivoted to botany in grad school because

nobody cares if you chop up plants.

They call that making dinner.

It's a great line.

And she'd found the perfect plant to test this wild idea.

Okay.

So before we get to her experiment, let's just lay out what botanists already knew about how plants reacted to neighbors.

Right.

So above ground, it's all about light.

Plants can see their neighbors by the color of the light.

How does that work?

When sunlight passes through a leaf, the chlorophyll absorbs a lot of the red wavelengths.

So the light that gets through or reflects off is changed.

It's a subtle shift, but plants pick up on it instantly.

And that leads to this thing called phytochrome mediated stem extension.

It's a mouthful.

But basically, if a plant senses that telltale shift in light quality, it knows it's being crowded.

It interprets that as competition and it grows taller aggressively to try and monopolize the sun.

And below ground, the thinking was the same.

If you sense a neighbor's roots, you make more roots.

You fight for the nutrients.

The simple formula was neighbors above grow tall, neighbors below grow more roots.

But that whole formula assumed every neighbor was an equal threat.

Which Dudley was about to challenge.

Why was the C -Racet so perfect for this?

Because of how it disperses its seeds.

Some seeds get blown far away by the wind, but others stay attached to the mother plant and just fall right there when she dies.

So it was really easy for Dudley to find these naturally occurring groups of siblings growing right next to each other.

Okay.

So she has her setup.

What were the results?

The results, which came out in 2007, were just, they were a bombshell.

When C -Racets were planted with unrelated non -kin plants, they did exactly what the old formula predicted.

They went to war.

Total war.

Grew roots like crazy, super aggressively, trying to suck up every last bit of nutrients.

And here's the big reveal.

Here's the game changer.

When those same C -Racets grew next to their kin, their own siblings, they showed what Dudley called polite confinement.

Polite confinement.

I love that.

So they didn't fight.

They did not fight.

They consciously held their root growth back, leaving plenty of space and resources for their siblings to grow right alongside them.

They chose not to compete.

That is just incredible.

And she said she found this just by watching them without any preconceived ideas.

Yeah, just watching what they did.

And this was the very first time a plant had ever been scientifically shown to recognize its family and give it this preferential, you could even say altruistic treatment.

So how did the scientific community react to this?

Well, this is where it gets heated.

Dudley said the initial surprise quickly turned into apprehension.

She knew how controversial it was.

Almost immediately, colleagues wrote papers accusing her of bad study design, faulty methods.

Fuganther -promorphizing,

seeing human traits in plants.

All of it.

It's a classic scientific drama.

When you challenge the very foundation of a field, you're going to face a firestorm.

But she knew her design was solid, and she figured she just had to wait for other labs to replicate it.

And did they?

Oh, yeah.

And the wait wasn't long.

Within a decade, the evidence was pouring in.

One of her own students found the same thing, but above ground, in the impatience flower.

So what did the impatience do?

When planted with strangers, they would aggressively frondess.

That means they'd unfurl these huge leaves to shade out and outcompete their rivals.

But with kin?

With kin, they would kindly arrange their leaves, tilting them, tucking them in, just to avoid shading their siblings.

Just sounds a lot like a concept from animal behavior.

Hamilton's rule.

It aligns perfectly with Hamilton's rule, which comes straight from sociobiology in the 1960s.

Right.

That's the mathematical basis for altruism in nature.

It says you'll help family as long as the cost to you is less than the benefit to your shared genes.

It's all about the survival of the fittest genes, not just the individual.

It's that famous quote, right?

I would lay down my life for two brothers or eight cousins.

That's the one.

It posits that this helping behavior exists on a sliding scale, based on how related you are.

And now, suddenly plants were proving this exact same rule applied to them.

And the studies just kept coming after that.

They did.

In 2017, a study on sunflowers found that farmers could get almost 50 % more oil yield just by packing kin plants closely together.

Why?

What were they doing differently?

Instead of fighting, the kin sunflowers would tilt their stalks at these alternating, complementary angles to make sure no one was shading out their neighbor.

They maximized light for the whole group.

Wow.

And then you had Sagebrush warning their closest relatives first about insect attacks.

You had Arabidopsis, this tiny little lab plant, rearranging a single leaf within two days just to avoid shading a sibling's leaf below it.

The case is becoming undeniable.

So we know that they do it.

The next big question in a deep dive like this is obviously how.

What are the actual physical senses they're using for this?

And the answer is it varies,

which suggests this trait is adaptable.

It just pops up wherever it's needed.

But our sources point to at least two main ways.

The first is pretty straightforward,

chemical sensing.

So underground.

Right, underground.

Siblings can detect each other by specific chemicals that their roots excrete into the soil.

These basically act as like molecular ID tags.

Okay, that makes sense.

But what about the light sensing one?

The one with Arabidopsis sounds way more sophisticated.

You're saying it can tell kin just from reflected light?

It's essentially eavesdropping on the physics of light, yeah.

So sunlight has both red and far -red light in it.

When that light hits a leaf, chlorophyll sucks up most of the red light for photosynthesis.

But it lets the far -red light pass through or bounce off?

Exactly.

So if a plant senses a high ratio of far -red to red light coming from its neighbor, it knows there's a photosynthesizing competitor nearby.

But how does it know if it's family?

That's the amazing part.

The theory is that kin leaves have a slightly different, a unique light absorption signature compared to non -kin leaves.

And the plant's photoreceptors are sensitive enough to decipher that genetic relatedness just from the quality of that reflected light.

That is just, it's incredible sensory awareness, using a basic growth mechanism for a really complex social function.

It is.

So if Hamilton's rule, the whole two brothers or eight cousins idea is really at play here, then this behavior shouldn't just be on or off kin or not kin.

It should be a gradient.

Right.

A sliding scale.

You should be nicer to your brother than your second cousin.

Precisely what Chuihua Kong's research group in China wanted to prove in 2017.

And they used rice to do it.

And rice is good for this because it's so important for agriculture and you can trace its genetics really well.

Perfectly.

Kong's team used all these different lines of indica rice.

They're all related, but to different degrees.

Full siblings, half siblings, first cousins, second cousins, a whole family tree in a lab.

So what did they measure?

How do you measure plant antagonism?

They looked at the growth of lateral roots, how much they grew, and how aggressively they pointed towards a neighbor.

And the results were, well, they were perfect.

It confirmed the hypothesis.

Down to the letter,

the low ground competition increased consistently and measurably, the more distantly related the neighbors were.

And the full siblings.

The full siblings basically refused to compete at all.

Their root growth looked no different than a plant grown all by itself.

But as you went from half sibling to first cousin, you could see the competition just slightly dial up each time.

It's a finely tuned dial based on the genetic payout.

Exactly.

And they proved the mechanism too.

They put a plastic film barrier between the roots, blocking those chemical signals.

And the kin recognition completely stopped.

It vanished.

Even siblings started fighting aggressively.

So what about the other end of the spectrum,

the extreme stranger?

Ah, the stranger effect.

To go one step further, they introduced a totally different, distantly related type of rice called japonica.

And its presence seemed to just inflame the indica lines.

It triggered this fierce territoriality.

So no more politeness.

This was full on plant warfare.

Oh, yeah.

The lateral roots and the indica plants just shot up, expanding flagrantly right toward the foreign neighbor.

And the japonica did the exact same thing back.

A full scale resource war.

That has to be exhausting for the plant, metabolically speaking.

Does that aggression come at a cost?

A huge cost.

And this is the big takeaway for us, for agriculture.

The rice plants that were busy fighting their distant neighbors spent so much energy building those aggressive root systems.

That they had less energy for reproduction.

Exactly.

They produced significantly less fruit.

All that metabolic energy went into defense instead of seeds.

But the cultures of closely related kin, the ones who were polite, they had all that extra energy available.

And their yields were measurably higher.

The cost of competition is literally measured in the food on our plates.

It really is.

So if there's all this family negotiation and defense happening underground, what about the most social interaction of all?

Reproduction.

Well, there's a researcher in Spain, Ruben Torreses, who thinks that plant life has to be seen as an explicitly social question.

Even if that idea is still a little bit taboo for some old school botanists.

And he tested this idea.

He good.

He looked at how social context changes how much a plant invests in reproduction.

He used this Danish herb, Moricandia, which has these big showy magenta flowers.

And the idea is that big flower displays act like a magnet for pollinators, right?

But they cost a lot of energy to make.

It's a classic trade -off.

Energy for big flowers is energy you can't use for making seeds later.

So his team looked at what Moricandia does when it's potted with kin versus with strangers.

And what did they find?

When it was with kin, the plants teamed up.

They all invested heavily in making big showy blooms at the same time.

They created this massive, unmissable billboard for pollinators, maximizing the chance that the whole family gets cross -pollinated.

But with strangers?

With strangers, they hedged their bets.

They made fewer smaller flowers.

They weren't willing to sacrifice their own individual energy to draw pollinators to a group that wasn't family.

That is clear evidence of familial altruism.

They willingly give up some of their own potential for the good of the family's genes.

If the group isn't kin, the plant flips back to selfishness, maximizing its own seed -making power.

It's a direct social calculation that follows Hamilton's rule to the letter.

So discovering this sliding scale of altruism and selfishness.

Yeah.

This must have massive implications for something like agriculture.

Huge real -world implications.

Susan Dudley herself points out that our current crop breeding practices might be completely by accident selecting against these altruistic plants.

How is that possible?

How can you hurt yields by picking the best -looking plant?

Because breeders are trained to pick the single most vigorous individual in a field.

But what we see as vigorous is often just the most competitive, the most aggressive plant.

The one that's winning the underground war for resources.

While the altruistic ones, the ones exhibiting that polite confinement, they look more reserved.

They're not shading their neighbors so they look less dominant.

Exactly.

So they get overlooked, they get weeded out of the breeding process, and we keep selecting for the fighters.

So for generations, we've been accidentally creating these monocultures of highly competitive plants, forcing them to waste energy fighting each other instead of making the fruit and seeds we actually want.

That's the argument.

And the solution Dudley suggests is a total shift.

Start selecting for altruistic plants early on, maybe by seeing how they behave when grown with their siblings.

You could steer the whole crop towards cooperation instead of competition.

Or, even smarter, you could select for plants that have these nuanced social personalities.

The ones that help their kin but fight like hell against outsiders, like weeds.

You could create these super resilient high -yield cultivars just by paying attention to their social traits.

It's a whole new way of thinking about breeding.

Now, going from the field back to the very beginning of life, a key question has to be, when does all this start?

When does kin recognition kick in?

Right.

Do you need a whole plant body with roots and shoots to do this?

And a 2017 experiment by Akira Yamawo suggests the answer is no.

He tested if plantain seeds could sense neighbors while they were still embryos.

So what was his setup?

It was really clever.

He planted plantain seeds with just their siblings, and in another pot with just a stranger species, white clover.

In both the simple setups, nothing special happened.

They just sprouted normally.

I think that's the control.

That's the control.

But, and here's the kicker, when he planted the plantain seeds with both their siblings and the stranger clover present.

The kin seeds immediately synchronized and sped up their sprouting.

They came up sooner and they came up together.

As a team.

As a coordinated team.

He saw that if one seed was a little ahead, the others would actually speed up their germination to match it.

It's like in the presence of a competitor, they decided to rush the stage as a single unified group to get a head start.

He called it embryonic communication.

Which proves that the whole mechanism for this complex kin sensing is already there in the embryo.

You don't need the full plant body.

It's an innate fundamental property.

It is.

Which takes us deep into the world where all of this is happening.

The rhizosphere.

The world of soil, microbes, and roots.

We always focus on what we can see, the leaves and flowers.

But our sources keep reminding us that at least half a plant's life is lived underground.

And the scale of that world is just.

It's mind boggling.

Roots aren't just passive tubes.

They're described as a mass of many thousands of mouths.

All acting on their own but also highly coordinated.

I saw that one study of a single winter rye plant.

It had over 13 million individual roots.

And they covered a surface area 130 times larger than its shoots.

The part we see is truly less than half the story.

And this whole system operates with a kind of swarm intelligence.

Yes.

When one or a few of those 13 million roots finds a good patch of nutrients, a chemical signal goes out and within hours, thousands of other roots will redirect and swarm to that spot.

Each root is like a sensor, gathering local data.

And that data gets integrated into the whole network.

Which then morphs and shifts its shape.

Just like a flock of starlings or a school of fish.

It's a collective organism, constantly exploring and exploiting its environment.

And of course, the roots aren't alone down there.

They are tangled up with fungi.

Inextricably.

Fungal networks, the mycelium, weave through almost every inch of soil, connecting to the roots of nearly every wild plant.

And they aren't just there.

They may be the actual communication network of the soil.

The nervous system of the soil.

It's a powerful metaphor.

And the chemical exchange where plant meets fungus is profound.

They're passing amino acids back and forth, like glutamate and glycine.

Wait, glutamate and glycine, those are major neurotransmitters in our brains, in animal nervous systems.

They're very same ones.

Now, we can't say plants are thinking like we do.

But the fact that they're using the same chemical toolkit for signaling suggests a deep, ancient, shared language for communication.

And these fungal partners can actually change the plant's identity.

Profoundly.

Physically.

Chemically.

Behaviorally.

One experiment took a grass that couldn't handle salt, paired it with a fungus from a salt -loving coastal glass.

And suddenly the grass could tolerate salt.

The fungus just gave it a new superpower.

It did.

And it continues with flavor and medicine.

Fungi can change the sweetness of a tomato, the aroma of basil, the medicinal compounds in echinacea.

You can't draw a clean line where the plant ends and the fungus begins.

Some even argue roots themselves evolve specifically to connect plants to this fungal network.

But this relationship, this symbiosis, it's not always a simple, happy partnership.

It's a negotiation.

A constant negotiation.

The fungi need carbon, the sugars and fats from the plant.

In return, they act as master miners, digging up scarce minerals like phosphorus and zinc for the plant.

And the sources say the fungi can actually charge the plant more carbon for those minerals if they're scarce.

It functions just like a market economy.

They raise the price when supply is low.

But the plant has a counter move.

It does.

It can choose where to send its carbon.

Research shows plants will preferentially reward the fungal strains that give them a better deal that supply more phosphorus.

If one partner is stingy, the plant just cuts off the sugar supply.

It's a dynamic commodities market happening right under our feet.

Neither side has the complete upper hand.

It's all about trade -offs and compromise.

So all of these findings, eusociality, kin recognition, these complex negotiations, they all lead us to a pretty big challenge to the old way of thinking in ecology.

They lead us right to the doorstep of the dogma of competition.

And this is where J .C.

Cahill, an ecologist from the University of Alberta, comes in.

He's known for pushing the idea that roots actively forage.

He deliberately uses words like forage and behavior from animal science to suggest that plants are making intentional, directed decisions.

And he finds that plant behavior really echoes what we see in animals, especially when it comes to stress.

Yeah, in one study, he stressed a plant by just damaging some of its leaves.

And he found that the stressed plant started making bad foraging decisions.

What does a bad decision look like for a root system?

It means it stops being efficient.

Instead of putting all its roots in a known high -nutrient patch, it just sort of distributes them equally everywhere, in good patches and bad.

But once the plant heals, it gets its senses back and starts making smart choices again.

Which Cahill compares to human psychology.

We make worse decisions when we're stressed or tired.

Exactly.

He argues that we have to stop seeing plants and animals as having these fundamentally different motivations.

Natural selection doesn't care what you are, it just cares about effective outcomes.

And this social context completely changes their behavior, which he showed with sunflowers.

Right.

When a sunflower is alone, it finds a good nutrient patch and monopolizes it.

Simple.

But add a neighbor.

And suddenly, this whole complex social etiquette appears.

What are the rules of sunflower etiquette?

Rule one.

If a nutrient patch is exactly halfway between two sunflowers, they actively avoid it.

They'll actually send their roots deeper, or somewhere else, to escape the potential for a fight.

They prioritize peace.

But what if one is just a little bit closer?

If one is even a few centimeters closer, that plant does not hesitate.

It grows roots right into the patch and takes it all.

They're clearly measuring these tiny spatial differences.

Okay, so what's rule two?

Polite sharing.

If resources are abundant and there are other patches nearby, they will share.

Both plants will put roots in the shared patch, but they keep them short.

They stay in their own zone.

No one tries to take over.

So when does the aggressive, ruthless side come out?

That's rule three.

Scarcity changes everything.

When resources are scarce, or a real competitor is introduced, they start secreting a little pathics.

These are the chemical weapons.

The chemical weapons.

They stop other seeds from germinating.

They act as guards.

So the behavior isn't fixed, it's totally conditional.

But Cahill admits there's still a big mystery here.

The spatial mystery.

He says he's completely stumped by how a sunflower senses those tiny differences in distance between itself, its neighbor, and the food, and then uses that triangulation to make a decision.

And all of this led him to question the entire foundation of community ecology.

The whole assumption that neighbors must be antagonists.

He's been running this massive experiment for two decades on the Alberta grasslands, manipulating 17 different variables.

And what has he found?

That the real world is way too complex for our simple models.

Every little shift causes a complex ripple effect in the community.

Species rise and fall, but no single species ever wins for long enough to take over.

So natural variation itself is what maintains biodiversity.

He argues that it is.

He says the simple models, based on just two or three plant lifestyles, are quote, useless.

And the most shocking result was from his vacuum test.

The vacuum test.

When he deliberately removed a species from a patch, the other plants did not necessarily rush in and gorge themselves on the new space and sunlight.

Which is the exact opposite of what the old dogma would predict.

It should have been a feeding frenzy.

It should have been, but often nothing much happened.

And he concludes from this that competition is only one driver, and maybe not even the most important one.

You can explain all the patterns in his grassland without ever using the word competition.

So what's the new paradigm?

The thing that survives is the whole community.

The biome, just in different states of composition.

Survival isn't about destroying your neighbors.

It's driven by complexity and constant, irrepressible change.

Complexity itself is the answer.

And that complexity means the rules aren't always fixed.

Exactly.

The rules are slippery.

Even kin recognition.

Sometimes it's there, sometimes it's absent.

Sometimes it's even antagonistic, depending on the context.

Natural systems are just overwhelmingly complex.

And our theories have been far too simple.

And Cahill thinks this new perspective, that complexity and cooperation are central, will be the new dogma within a decade.

He does.

A fundamental rewrite of how we study life.

What a journey.

From eusocial insects all the way to the staghorn fern and its incredible commitment to its colony.

And then into that powerful, controversial evidence for kin recognition.

From deadly sea rockets being polite to their siblings, to sunflowers tilting their stalks for each other.

It all lines up with Hamilton's rule.

The sensory channels alone are just mind -bending.

Roots using chemical IDs in the soil.

Plants reading the quality of reflected light to recognize family.

And it all starts in the embryo.

Plantain seeds coordinating their sprouting to get a jump on the competition.

It's just staggering.

We also hit on that critical world of the rhizosphere.

The swarm intelligence of roots.

The complex market negotiations with fungi.

And that urgent need to rethink agriculture to breed for altruism.

And finally, G .C.

Cahill's work.

Just turning that old dogma of competition on its head.

Showing us that complexity, variation, and cooperation are probably the real drivers of the ecosystems around us.

Which leaves us with a pretty provocative final thought for you to take away.

If intelligence is the ability to learn from your surroundings and make decisions that best support life, which plants clearly do, and if they coordinate their behavior with family, with strangers, with fungi, even as embryos,

then what are the fundamental differences, really, beyond just our ability to move, that separate the social lives of plants from our own?

It seems the social world is far broader and far deeper than we ever imagined.

Thank you for joining us for the Steep Dive.

We'll see you next time.