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Picture in your mind the creatures we
study to reveal how life works.

What do you see?

Fruit flies, which revolutionize genetics?

Chimpanzees, which teach us about the
origins of intelligence?

What about mice, which help us understand
human diseases?

Whatever you're imagining, it probably
isn't a lizard in a suburban backyard.

But researchers studying
one special group of lizards are

discovering answers to big
questions about life on Earth.

How do animals adapt to different
environments?

How can so many species coexist in one
place?

And how fast can evolution happen?

When scientists have had big questions
about the world around us, time and time

again over the last century, they've
turned to anoles to answer those questions.

My name is Neil Lozen.

And my name is Nate Dappen.

Neil and I are biologists and wildlife
filmmakers.

We're on a year-long journey, traveling
from remote forests and tiny islands to

high-tech labs in big
cities, all in pursuit

of these lizards that
defy our expectations.

As they battle their rivals, evade
predators, and survive in hostile

environments, these
little lizards seem to meet

every challenge with
an ingenious adaptation.

In the process, they reveal how simply you
and us, what Neil and I call the laws of

the lizard, can explain the complexity of
nature.

Yes, yes, yes, yes, yes.

You got him.

Ha, ha, ha, ha.

One of the rarest anoles in the world.

Come with us and discover
how these unassuming lizards

are changing the way we
think about life on Earth.

Every lizard biologist remembers their
first.

That is, the first lizard they ever
studied.

The lizard that took
Nate's innocence was a

strange Costa Rican
species called the river anole.

Nate and I both got our PhDs studying
lizards.

And over the last 10 years, we've become
collaborators, business partners,

and best friends.

Through all of that, Nate has not shut up
about that river anole.

So we're starting our
journey in Nate's old

stomping grounds in the
mountains of Costa Rica.

To find the lizard that was so interesting,
it convinced Nate to become a biologist.

If you get a chance to see a river anole,
the first thing that it'll do is sort of

move to the other side of the rock or the
branch that it's on.

If it thinks that you're a real threat,
it'll do something amazing.

Sometimes, river anoles reappear
downstream after just a few seconds.

It's hard to predict exactly where they'll
pop up.

Other times, they just seem to vanish.

What are they doing when they disappear?

Almost as soon as we got our
camera under the water, we were

documenting a behavior that's
essentially unknown to science.

One female clung to a rock underwater for
almost 10 minutes.

We figured she must be holding her breath.

But when we watched our footage,
we saw something that blew us away.

Look carefully, and
you can see a little air

bubble growing and
shrinking on her head.

It looks like she's
rebreathing her air, like

a deep-sea diver
recycling her oxygen supply.

Researchers at the
University of Toronto are now

trying to understand
this rebreathing behavior.

The first law of the lizard?

Expect surprises.

It's an exciting start to a quest we've
been thinking about ever since we met.

I met Nate Dappen in 2008
in Costa Rica when we were

both students on the same
tropical biology course.

We were so similar, it was kind of spooky.

And so we're the same
height, same size, we can

fit into each other's
clothes if we need to.

And we were both studying evolution,
and we were both really into photography.

And so we either had the decision to
destroy each other or join forces.

Luckily for Nate, we decided not to
destroy each other.

Instead, we started working together on
experiments, photography projects,

and eventually on films.

We sort of had this decision to make.

Did we want to continue
on and be researchers

or did we want to
go into film full time?

And we sort of decided together
that we were going to take

the plunge and start making
science films professionally.

Ever since, Nate and I
have traveled around the

world making films
about wildlife and science.

One film we've always wanted to make is
the story of these little creatures that

have had a huge impact on our
understanding of life.

We wanted to tell the story of anoles.

We've all seen documentaries with lions
and sharks and elephants, but none of

those species have had
remotely the same kind of

impact on our understanding
of biology as anoles have.

From evolution to ecology, genetics,
physiology, even conservation biology.

So what are anoles?

They're a group of
closely related lizard

species that live all
over the American tropics.

There are more than 400 species of anoles,
with a wide range of colors, sizes,

and behaviors.

But despite all this
variation, anoles share two

traits that set them
apart from other lizards.

And that's the dewlap, which is a colorful
flap of skin that extends from the throat,

and sticky adhesive toe
pads on their feet, which

allow them to climb on
smooth surfaces like leaves.

Some other lizards have dewlaps or toe
pads, but only anoles have both.

The dewlap is used to communicate with
members of the same species.

Males use it to tell other males, hey,
this is my territory, don't mess with me.

Or they use it to show
females, hey, come over here,

I've got this great territory
and I'm really attractive.

To ward off a potential
rival, a male anole

will perform a sort
of ritualized display.

He'll do push-ups.

And he'll flash his dewlap.

If that doesn't
intimidate his rival, their

encounter can escalate
into a violent battle.

If the male can defend his territory,
he'll have opportunities to court females.

And, if he's lucky, a chance to mate.

Anoles are fierce hunters.

They chase down and eat almost anything
that fits in their mouths.

From insects and spiders to other lizards.

Even members of their own species.

One of the most surprising things about
anoles is that generations of scientists

have dedicated their lives to studying
these critters.

To understand why, we
need to introduce you to

the man at the center
of the anole universe.

If you mention anoles to anybody,
they're gonna think of Jonathan Lassoes.

The first person that jumps to mind is
Jonathan Lassoes.

Jonathan Lassoes.

Jonathan Lassoes.

Yeah, I would say Jonathan Lassoes is the
Bob Dylan of anole lizard biology.

The Leonardo da Vinci.

The Godfather.

The John Lennon.

The Barack Obama.

The Albus Dumbledore of lizard biology.

And Jonathan has literally written the
book on anole biology.

The two most common ways of pronouncing it
are anole and anole.

And there's no right or wrong.

And I actually go back and forth either
one for no particular reason.

He just really loves anoleless lizards.

He just also happens to be a brilliant
scientist.

We caught up with
Jonathan in Costa Rica to find

out how his name became
synonymous with anoles.

There's a picture of me when I was about
eight in Miami.

And I just caught a little green anole.

It's a picture of me looking very goofy
with a green anole.

So I go way back with him.

It sounded like destiny that Jonathan
would become an anole researcher.

And so I've been studying anoles ever
since.

And do you know any good anole puns?

Well, only one.

It's anole-y but a goody.

I first met Jonathan when I was a graduate
student.

And he tried to convince me to study
anoles.

I remember that.

I said, the guy's living in
Miami and he wants to go to

Spain to do his PhD when
there are anoles in his backyard.

Crazy, man.

I know, but what I did instead is I
convinced this guy.

He paid it forward.

Yeah, well, alright.

Excellent.

So, failure, success.

That's how I looked at it.

I spent three years studying anoles in
Miami where they're just part of life.

You'd run into people,
joggers, dog walkers,

and most people have
some awareness of anoles.

But people are usually surprised to learn
that I'm not just this one random weirdo

out there in the park, but there are
actually hundreds of biologists,

including some of
the top scientists in the

world, who are studying
these particular lizards.

It's hard to know for
sure how many papers

on anoles have been
published over the years.

I would guess 5,000, maybe 10,000?

So, a lot of people study anoles.

But where does the anole story begin?

A good place to start is the world's
largest collection of reptiles and

amphibians at the Smithsonian National
Museum of Natural History.

We have almost 600,000 specimens of
amphibians and reptiles.

Of those 600,000, about 18,000 of them are
anolis lizards.

These scientific collections
are like a combination

dictionary and
encyclopedia of life on Earth.

They show scientists what species look like
today and how they've changed over time.

Unfortunately, anole fossils are
incredibly rare.

So, until recently,
the fossil record didn't

shed much light on the
ancient history of anoles.

But all that changed with recent
discoveries on the island of Hispaniola.

There's a famous amber industry that's
been going on there for a long time.

They're used for jewelry.

But occasionally, you find baby lizards in
there too.

One of the most beautiful
things I've ever seen

was a 20 million year old
anole trapped in amber.

There are bubbles in the stone that truly
contain the air that that lizard breathed.

These lizards trapped in amber show us
that anoles have been living and evolving

on the islands of the Caribbean for tens
of millions of years.

That history is preserved in the jars that
line the walls of these collections.

Look closely and you'll
start to appreciate that

these little lizards are
the key to a big story.

The story of life and how it evolves.

To discover the secrets that
only anoles can reveal, we need

to follow in the footsteps
of generations of scientists.

We need to go to the Caribbean.

Here in Puerto Rico, a world of surprises
is waiting.

In the Caribbean, land comes in all shapes
and sizes.

If you visit the biggest islands
in the Caribbean, the first

thing you'll notice is that
they're crawling with anoles.

Look closely and you'll see that these
anoles come in all shapes and sizes, too.

And just like bodybuilders
and ballerinas, an anole's

anatomy can tell us a lot
about how it makes a living.

Step into a Puerto Rican forest and you
can see what I mean.

You won't have to wait long to see your
first anole.

Maybe it'll be a brown anole with long
legs on the trunk of a tree.

Higher in the tree, you
might find a green anole with

shorter legs, climbing in
the leaves and branches.

And down by your feet,
an anole with a long tail and

stripes that disappears into
the grass if you get too close.

High in the canopy, if
you're lucky, you might see a

massive green anole with
strong jaws and huge toe pads.

And if you sit really still, you could
spot a tiny anole with a short tail and

stubby legs clinging to the smallest twigs
in the forest.

All of these anoles live side by side here
in Puerto Rico.

But they aren't just randomly scattered
all over.

They specialize.

So you tend to find each type in a
different part of the forest.

Some low.

Some high.

Some on the tree trunks.

And others out in the forest.

Some on the smallest twigs.

Hop over to a second island and the
pattern becomes clearer.

Here in the Dominican
Republic, the anole species

are different than the
ones in Puerto Rico.

But look around and it'll feel like deja
vu.

You'll find anoles in all the same places
you saw them in Puerto Rico.

Long-legged breakfast and brown anoles on
the tree trunks.

Anoles with long tails and stripes in the
grasses.

Giant green anoles in the canopy and so
on.

The species playing
these roles are different,

but they look strikingly
similar between islands.

It's almost as if different, look-alike
actors were performing the same show.

Across the Caribbean, anoles that live in
the same part of the forest share similar

anatomical features no matter which island
they inhabit.

It's such an unusual pattern that anole
researchers invented a word to describe it.

They called these anole types that repeat
from island to island ecomorphs.

The ecomorphs are named for where in the
environment you usually find them.

Trunk ground, trunk, trunk crown,
the crown giant, the twig, and grass bush.

Cuba, Hispaniola, Jamaica,
and Puerto Rico each have

different species, but they
all have the same ecomorphs.

The question is, why do lizards living in
the same habitat, on different islands,

look so similar?

Why do the ones near
the ground have long legs,

and the ones up in the
trees have short legs?

Why up in the tree do they have big toe
pads and they're often green, and the ones

down in the ground have smaller toe pads
and are brown in color?

Jonathan suspected that each
ecomorph's anatomical features

helped it survive in a
particular part of the forest.

He hatched an ingenious plan to put this
idea to the test.

The way we test that is basically by
having the lizard Olympics.

Jonathan captured 15 different anole
species in Puerto Rico and Jamaica.

And he brought them into the lab to
measure their sprinting speed,

jumping ability, and toe pad cleaning
power.

The species that live high in the trees,
the trunk crowns and crown giants,

have the biggest toe pads.

These toe pads help them
stick to smooth surfaces

like leaves so they
don't fall out of the trees.

Trunk grounder anoles
have long legs, which help

them jump far and
run fast on flat surfaces.

Trunk grounder anoles are
critical skills for a lizard that

has to capture prey and
escape predators on the ground.

Jonathan's lizard Olympics confirmed what
he suspected.

But each ecomorph has
adaptations that help it

move through a
different part of the forest.

We did find one interesting twist we
didn't expect.

We thought that lizards with short legs
would be faster on narrow surfaces.

Turns out they're not faster at all.

They may not be fast, but
the short-legged anoles of

the twig ecomorph do have
an advantage on thin branches.

They hardly ever fall.

In contrast, long-legged anoles have real
trouble maneuvering on twigs.

They reach around to get
the twig, and sometimes

they just miss and
they just fall off the twig.

For an anole, being able to
move quickly and confidently

through the forest turns between
a full belly and an empty one.

Or even between life and death.

Imagine an anole species living down near
the ground.

Just by chance, some have genes that give
them longer legs than others.

These long-legged lizards can run fast.

So they're great at catching prey and
escaping predators on the ground.

On average, long-legged anoles will
produce more offspring than short-legged

anoles, passing more of their genes onto
the next generation.

So over many generations, the whole
species will evolve longer legs.

That's exactly
how Charles Darwin

envisioned the process
of natural selection.

So to Jonathan, natural selection in
different parts of the forest could

explain why each ecomorph evolved its
distinctive traits.

The problem was, no one was there to see
evolution happen.

I always compare studying evolution to
being like a detective story.

We've got a whodunit.

What happened in the past?

Why did it happen?

We can't go back in time, so we have to
use whatever clues we have to piece it all

together to figure out what happened in
the past.

Since each island has different species
but the same ecomorphs, the big question

is whether these ecomorphs
evolved once and then spread to

the different islands or evolved
separately on each island.

To distinguish between these
possibilities, we need to reconstruct the

evolutionary history of anoles in the
Caribbean.

An evolutionary tree is
a diagram that illustrates

the evolutionary
relationships of species.

Like a real tree, an evolutionary tree
begins with a single ancestor species.

When that one species splits into two,
the stem branches.

As the tree grows, some branches die back
as species go extinct.

But others keep growing and branching.

For a group like anoles, with
hundreds of living species,

figuring out the evolutionary
tree is a daunting task.

One type of evidence that helps scientists
build evolutionary trees is something you

can find inside every plant and animal on
earth.

DNA.

DNA changes over time, it evolves.

The longer two species have
been diverging separately,

the greater the difference
will be in their DNA.

So by sequencing the DNA of many species,
you can build an evolutionary tree.

The shape of that tree, its
pattern of branching, can help

us understand how anoles
evolved and spread across islands.

At one extreme, all the
ecomorphs could have evolved

just once, then spread
from island to island.

At the other extreme, anoles could have
spread to different islands first,

then to the ecomorphs separately on each
of the four islands.

Jonathan and his colleagues collected DNA
samples from 55 species of anoles to build

an evolutionary tree that encompassed
every ecomorph on all four islands.

Had the ecomorphs truly evolved
independently on different islands,

well the DNA should tell us.

The tree gave them an astonishing answer.

Despite all the variation among them,
anoles living on the same island were more

closely related to each
other than to species on other

islands, even the ones
that looked strikingly similar.

This meant that anoles had colonized the
different islands first, and then evolved

on each island into a virtually identical
community of ecomorphs.

No one could ever tell the difference They
evolved independently on each island.

These scientists had revealed another law
of the lizard.

When they live in the same type of
environment, different species evolve

similar traits to survive again and again
and again.

Well people were very excited when this
result came out because it showed that

evolution does repeat itself, that there
are rules to evolution.

Many scientists thought that nature was so
complex and evolution unfolded over such

long timescales that you rarely see the
same outcome twice.

They suggested if you could
somehow replay the tape

of life, you would get a
different outcome every time.

But here you got the same outcome four
times in a row on different islands.

Jonathan decided
to dig deeper into this

intriguing idea that
evolution was predictable.

It would be great to actually do an
experiment to test the hypothesis that

natural selection drives the evolution of
these features.

Jonathan was about to venture into new
scientific territory and discover

something that Darwin never would have
imagined.

It's a little known fact that Charles
Darwin was a great experimenter,

but he never did an experiment
about his most important

idea, the theory of
evolution by natural selection.

And the reason he didn't do an experiment
is obvious.

He thought that evolution moved incredibly
slowly, glacially slowly.

He thought it would take thousands of years
to lead to changes that we could detect.

Well, Darwin was right about

which he was wrong.

It turns out that anoles
can show us something

that Darwin never
could have imagined.

What evolution looks like as it's
happening.

To see it for ourselves, we're heading to
the Bahamas.

On the four biggest islands
of the Caribbean, anoles

have evolved to thrive in
different parts of the forest.

And their DNA reveals that they did so
independently on each island.

These events took millions of years.

But what if you could watch evolution
happen?

Charles Darwin thought that the Earth
changed gradually over eons.

And since plants and animals
adapt to their environments,

he thought the process of
evolution had to be slow as well.

But some environments are much more
dynamic than Darwin imagined.

The Bahamas have hundreds of tiny islands
that often get hit by hurricanes.

Here, species colonize and go extinct from
year to year.

That makes them the perfect laboratory to
study survival and adaptation.

And that's what brought ecologist Rob
Pringle here.

If you do your best male
lizard impersonation,

you might get the females
to come check you out.

Oh yeah, should I get down and do some
pushups?

I was helping Rob catch a knolls for a
massive experiment on a knoll evolution.

Easiest and best way to catch a knoll is
to noose it.

Which is basically, it's land fishing for
lizards.

So you take a fishing pole and you tie a
little slip knot at the end of it.

And you try to loop that around the head
of a lizard.

And then you pull.

And hopefully you have a lizard on the end
of your stick.

Oh, look at this guy.

Bring him to your face.

Oh, right?

But I gotta say, that was the worst lizard
catch in history.

So I got the lizard and I also fell thigh
deep into a hole in the limestone.

But me and the lizard are okay.

Oh, there we go.

I'll leave it to the professionals from
now on.

Well, you know.

Rob and his colleagues bring the knolls
back to their portable lab to sample their

DNA and take x-rays to measure the
lizard's bones with precision.

They're looking for signs of
evolution taking place not over

millennia but during an
experiment lasting just a few years.

After you x-ray her and
take her measurements,

then she's going to
come right back to this.

That's exactly right.

She'll probably just think it was a really
weird dream.

It'll just be a weird dream, something
she'll tell her friends about,

like you guys wouldn't
believe what happened

to me and that none
of them will believe her.

Knoll researchers have been
coming to the Bahamas for decades

because it's a perfect place
to study lizard evolution.

If you get a small enough island that you
can study the whole population and yet big

enough that they can
survive and adapt, it's

almost the equivalent
of a laboratory test tube.

In the 1970s, ecologist Tom Shainer found
small islands without a knolls and he

added a knolls to study how populations
grow, shrink, and eventually go extinct.

Some populations defied the odds and
continued to thrive year after year.

These survivors gave Jonathan an
intriguing idea.

Would the lizards adapt to their new
island homes?

They had inadvertently set up an evolution
experiment because these islands differed

in their characteristics.

Tom Shainer had moved brown and knolls
from a larger island, Staniel Key,

where the lizards lived
on large trees, to these

tiny little islands
that didn't have trees.

They had narrow bushes and narrow stem
vegetation.

Just like twig and knolls having short
legs on narrow vegetation, we predicted

that the brown and knolls
would move from a broad

surface to a narrow surface,
would evolve shorter legs.

Did the same rules that
made evolution predictable

on the large islands
operate in the Bahamas too?

And if so, could we witness evolution
happen in just 14 years?

Few biologists would have asked this
question because most of them still

thought that animals evolved too slowly to
observe in a human lifetime.

But Jonathan saw an opportunity to put
this conventional wisdom to the test.

A big part of biology
is about creativity and

about understanding
what is the right question.

There's an artistry there and if that's an
art, then Jonathan's a Picasso.

Jonathan returned to Tom Shainer's islands
in the 1990s with a new plan to compare

the anatomy of the new island populations
and the original source population.

If the knolls were different,
that would show that

these populations had
evolved in just 14 years.

And the results flashed on the screen.

The populations were different.

They had evolved.

Well, needless to say, this is incredibly
exciting.

The knolls differed in just the way
Jonathan expected.

On the islands with slender branches,
the knolls had evolved shorter legs.

And they did so in just 14 years.

Even for knolls, which can reproduce at
one year old, 14 years is incredibly fast.

Of course, we should have been very
surprised.

He thought that evolution
occurred so slowly that you

couldn't possibly see it until a
thousand years had elapsed.

Once we realized that knolls
would adapt rapidly to new

conditions, that opened our eyes
to other experiments we could do.

Knoll researchers could
now ask new questions,

like how do predators
affect evolution?

And they could answer those questions not
just by doing detective work about the

ancient past, but by doing experiments and
watching evolution unfold in the present.

That's what Rob Pringle and Jason Colby
are doing in the Bahamas right now.

So, it's a good place to be if you're a
brown or knoll.

Let's go paint some lizards.

Let's go paint some lizards.

Rob showed me how to
mark knolls with non-toxic,

water-soluble paint
for his experiment.

Yeah, there's a ton of lizards on this
island.

It's also fun.

Yeah, it's a lot of fun.

It's like shooting lizards in a barrel.

Shooting lizards in a tree.

Yeah, it's kind of exactly like that.

The lizards will lose these paint marks
the next time they shed their skins.

But the paint doesn't need to last long.

By marking all the knolls we can find one
day and returning to count the marked and

unmarked knolls the
next day, we can estimate

the total number of
knolls on an island.

Last year we had upwards of 400 lizards on
this island.

This population census
helps the researchers monitor

how the knolls are
doing on different islands.

And on some islands, the
knolls are in real danger because

Rob and Jason have added
another lizard into the mix.

One of the brown knoll's enemies.

The curly-tailed lizard.

It turns out that
curly-tailed lizards don't

just impact the numbers
of knolls on islands.

They actually cause natural selection.

Within the first six months
of the curly-tails being

there, knolls with longer
hind limbs have better survival.

And presumably that's because
they're faster at running on

the ground to escape predation
from the curly-tailed lizard.

Gradually, the knolls begin to move up.

They spend less time on the ground and
more time in the slender branches.

Once they're out of
danger from the predator,

natural selection
has a different effect.

During that period, selection reverses and
favors brown knolls with shorter hind

limbs because they're occupying
these narrower branches and

knolls with shorter limbs can
move better in that environment.

These experiments reveal another law of
the lizard.

Natural selection is happening all the
time.

And it's driven not only by the
environment, but also by other species.

One species more than any other is shaping
the next era of lizard evolution.

How are knolls adapting to the age of
humans?

To find out, Nate and I are heading to my
backyard, Miami, to discover the

astonishing adaptations of these little
lizards in the big city.

Our journey has already
shown us that knolls

are evolving to survive
in a changing world.

But never in their history
have knolls faced a more

perilous or uncertain environment
than the world of humans.

Living in Miami, I see knolls around me
every day.

But a lot of the knolls I see in Miami
didn't actually originate there.

They come from islands all over the
Caribbean.

Southern Florida is a melting pot of knoll
immigrants.

Florida has only one
native species of knoll, but

eight other species have
established populations here.

They got to Miami either through the pet
trade or accidentally in shipments of

produce and other goods coming from the
Caribbean.

Humans don't just bring them to the city.

As we convert wild forests into concrete
jungles, we also bring the city to knolls.

When knolls arrive in a new area, they
encounter novel types of environments.

And so there are new predators,
there are new competitors.

Most knolls live on the trunks of trees,
branches of trees, higher up in the canopy.

But in the urban environment,
much of this vegetation

has been replaced by
buildings and walls, lamp posts.

Those surfaces can be smoother and harder
to climb than trees and rocks.

And that's not the only challenge of city
life.

By replacing natural
vegetation with concrete,

asphalt, they change
the thermal environment.

They're much hotter than a comparable
natural area.

Since lizards can't regulate
their body temperatures internally,

the heat of the city could
also threaten their survival.

In some cases, the challenges are too
overwhelming.

They just can't do it.

But sometimes they're able to survive and
perhaps even adapt to these new conditions.

One of these survivors is
the Puerto Rican Crested

Anole, which thrives in
cities throughout Puerto Rico.

Researchers Kristen Winchell and Shane
Campbell-Staten want to understand how

this species is coping with life in the
city.

The overarching question
my research is trying to

tackle is can humans influence
the course of evolution?

How fast can these animals change?

And can they keep pace with human-mediated
changes in the environment?

I think a lot of people do get confused
when I'm walking around in urban areas.

I am walking around with a fishing pole
which is very strange.

I'm sticking my fishing pole up trees and
on their walls which is even stranger.

So we get a lot of questions.

To understand whether lizards are adapting
to city life, Kristen and Shane collect

anoles from urban and natural sites and
take them back to their field lab to

compare their anatomy and physical
performance.

Kristen found that
compared to forest lizards,

urban lizards had longer
legs and larger toe pads.

The question is do these traits make a
difference?

To find out, Kristen planned
a new Lizard Olympics to

test the anoles performance
in the urban environment.

The first event in this
competition, urban and forest

lizards sprinted on racetracks
with three different surfaces.

We're running them on painted concrete,
on bark, and on unpainted metal.

We're very interested to
see if the forest lizards can run

as fast as the urban lizards
on these other substrates.

While Kristen's lizards sprinted on
miniature racetracks, Shane set up a less

traditional Olympic event to test how urban
anoles cope with the heat of the city.

Reptiles are cold-blooded
animals and a lot of

aspects of their biology
are linked to temperature.

To figure out how hot a lizard can get
before it stops working, we gradually warm

that lizard and we periodically flip it
onto its back.

Shane isn't hurting the lizards.

As he slowly heats them up, they
eventually get too hot to respond.

The riding reflex is
such a good test because

a lizard always
wants to be on its feet.

Shane records the temperature at which they
can no longer turn themselves back over.

And then he quickly helps the lizards cool
back down.

After capturing and testing hundreds of
anoles, it was time for Shane and Kristen

to compare the lizards from the forest and
the city.

On average, urban lizards
were able to tolerate temperatures

that were one degree Celsius
hotter compared to forest lizards.

A difference of one degree Celsius might
not seem like a lot, but for a lizard,

this is a difference of being able to be
active all day long and have access to all

of those mates and all of that food that
you otherwise would have to give up

because you're hiding in the shade trying
to cool down.

The urban lizards also have
an advantage running on

the slick surfaces found
in the city environment.

The urban lizards run faster on all
substrates, and these differences are most

pronounced on the very
smooth vertical substrates

on the metal and on
the painted concrete.

The ability to perform well
on these substrates has

real implications for their
survival in this habitat.

These little lizards continue to surprise
scientists with their powers of

adaptation, even in fast-changing
environments.

Kristen and Shane and Shane's discoveries
show that the anole's ancient evolutionary

playbook still helps them survive and
adapt, even in the modern world.

Just when we thought our
journey was over, we heard

about a new discovery in
the Dominican Republic.

A new anole species.

A truly bizarre lizard that had caught
scientists completely off guard.

We had to see it.

One of the few people
who knew where to find

it was a scientist
who first described it.

It's an unexpected discovery.

This is a giant anole that lives high in
the trees, but it's strikingly similar to

a group of lizards previously only known
from Cuba.

So this anole potentially represents a new
ecomorph.

So we're here to look for it.

Luke took us to the place where he first
saw this mysterious anole.

You get this sort of neat
spot where the trees are dry

forest trees but then you
start getting this Spanish moss.

Lots of lichen.

I've never seen any place like this.

This is a totally bizarre, unique,
cool place.

I'm liking this environment.

Oh, that's good.

I'm liking this environment.

Luke told us that our best
chance of finding these lizards

was to search for them at
night while they were sleeping.

Is that a guarantee?

Is that a promise?

Promise.

Awesome.

I can't wait.

This new species was one of the most
mysterious lizards in the world.

And we wanted to be the first film crew to
find it.

Easier said than done.

Gotta be in the right spot.

Get lucky and be looking for the right
thing.

From Luke's description we knew what to
look for.

A grayish, mossy looking lizard sleeping
on a gray mossy branch.

I've never seen so many tarantulas.

Welcome to my world.

After spending five hours
looking at twigs in the

dark he starts seeing
things that aren't there.

I'm pretty sleepy.

It's been a long, unsuccessful night.

Other than a few hundred tarantulas and a
ton of bug bites we had nothing.

I think we're going to find it.

Just... not tonight.

We still had one more night in the
Dominican Republic.

One last chance to be the first film crew
to capture footage of this new species.

But it was starting to feel like a long
shot.

It was our last night in this remote
corner of the Dominican Republic.

Our last chance to find and film a lizard
that was brand new to science.

We were all a little nervous.

So the goal here is if you see a lizard
and it doesn't see you look away from it.

Don't scare it with your lights.

Flag it.

Radio over.

Let everybody know.

A few hours go by and Luke gets a call
over the radio.

So we got Ananol up here.

Alright, I'll be right over.

Which tree?

Yep, that's Ananolus landistoiae.

Hello guys.

Okay, we got one.

Baby?

We got one.

Where is it?

I'll show you.

So we're going to be careful not to spook
it.

You see there's that white spot.

Oh yeah.

That's it.

It's a little juvie hanging head down.

How did you see that?

Totally different looking from everything
else we've seen.

First Ananolus landistoiae, man.

Yeah.

Alright.

Seeing this lizard for the first time was
amazing.

But then reality hit.

It was dangling from a branch 30 feet off
the ground.

Way too high for us to film.

Our only chance was to
wait until sunrise and hope

that it moved low enough
that we could catch it.

I got an idea.

I got a great idea.

Let's pull the car over here and noose him
from on top of the car.

We both get on the roof.

Nate's looking through
the camera so that he

can guide me because I
can't see what I'm doing.

No.

He's lost it.

Yes, yes, yes, yes, yes.

Oh!

You got him!

F♪♪♪!

You got him!

Got him!

Yes!

Neil!

Hands down, the best lizard catch that
I've ever seen.

One of the rarest anoles in the world.

Oh, he's like a little dinosaur.

What?

He's trying to bite me.

Oh my god.

I'm pretty stoked.

This is like the whole trip we've been
looking for this guy.

Very, very few people who are interested
in anoles have seen this lizard.

It's super special to get to home.

As we held this new species and filmed it
climb back into the tree, we couldn't help

but remember the first law of the lizard
we learned on this journey.

Expect surprises.

Even on Hispaniola, an island where
biologists have worked for decades,

here was a strange anole
totally unlike anything else

that no one had even
noticed until a few years ago.

It really drove home how little we still
know in many ways about anoles.

But even some of the most common species,
the ones that scientists have studied for

decades, there are still things about
their lives that we just don't know.

When I graduated from
college, I said to myself, I'm

never going to study anoles
again because we know it all.

Of course that was naive.

Far from knowing it all, we barely
scratched the surface.

Neil and I had followed the anole story
for more than a year.

From Caribbean rainforests to university
laboratories.

From tiny Bahamian islands to the city of
Miami.

We started this quest thinking we
understood why anoles were special.

But our journey left us with something
more profound.

Going and seeing the diversity of anoles
in an island like Puerto Rico,

it's like going to the Louvre in Paris and
appreciating the dirt in there.

It's something that's
beautiful and complex

and fascinating completely
of its own accord.

When I was a scientist
studying lizards, people

would always ask me, why
are you studying lizards?

And I think that it's normal to be
skeptical.

It's hard to understand why it could
possibly be important to dedicate all this

effort into understanding how these
lizards live their lives.

But life on Earth is incredibly
complicated.

And understanding the rules that generated
that diversity is fundamental to

understanding where we fit into the bigger
picture.

And very few other organisms have taught
us as much about those rules as anoles.