All language subtitles for Netflix - Alien Worlds 1x03 - Eden (2020)_Track04

The Earth, home to millions of species.

But what might live... beyond?

Astronomers have
discovered thousands of planets

outside our solar system.

They believe there are trillions more.

If life exists on only
a fraction of them,

then the universe must be... alive.

All living things have the same needs.

To feed...

reproduce...

and evolve.

By applying the laws of life on Earth

to the rest of the universe...

it's possible to imagine
what could live...

on alien worlds.

Planets beyond our solar system are
known to astronomers as exoplanets.

They are all trillions
of miles from Earth.

And yet, it might be possible
to detect a faint signature of life,

from the light of the stars they orbit.

Every star is sending to
us light of all different colors.

So, if we can catch
that light in our telescope

and put it through an instrument that
spreads the light out into a rainbow,

and we look in great
detail at that rainbow,

we will find the chemical fingerprints

of the elements in the
atmosphere of that star.

This is one of those rainbows captured
by the telescope of a distant star

about 12 light-years
away, the star Tau Ceti.

We can see these dark lines, like
from hydrogen in the star's atmosphere.

Down here, we see these three
characteristic lines of magnesium.

So, this is the atmosphere of the star,

but what we wanna do is catch light

that passes through the
atmosphere of an exoplanet,

to capture the chemical fingerprint of
that atmosphere in exactly the same way.

In 2012, this sort of fingerprint

was visible in our own solar system.

When Venus passed in front of the sun,

it was silhouetted against it.

For a moment, a tiny halo
appeared, the atmosphere of Venus.

It's this sliver of light
astronomers are looking for.

If they can analyze the
atmosphere of distant exoplanets

silhouetted against distant stars,

they might find proof of life.

We've thought very carefully
about what the signs of life will be.

So we look around and we
look at what's in the atmosphere

that could be remotely
detectable from light-years away.

And it always leads us
back to the same gas.

Oxygen.

50 to 70 percent of
oxygen in our atmosphere

is actually coming from the ocean...

which is the lungs of planet Earth.

The process that drives the growth
of the giant kelp in the oceans,

and, in fact, all the forests
that we see on the land,

is photosynthesis.

What interests me most
about photosynthesis

is the waste product
that gets tossed away,

and that's the oxygen that
goes into the atmosphere.

We think that almost all of
the oxygen in our atmosphere

is produced by photosynthesis,

by life here on planet Earth.

If you see it in abundance,

you know that the
planet is a living world.

Among trillions of worlds out there,

those with more oxygen
are more likely to sustain life.

Imagine... a planet like Earth

orbiting not one star...

but two.

This is Eden.

The light from its twin stars
powers photosynthesis...

pumping oxygen into the atmosphere...

allowing life to thrive.

Grazers feed on low-lying fungus...

but they're constantly alert to danger.

The canopy is home to predators...

perfectly evolved to
live among the trees...

waiting for their moment to strike.

On the ground, the grazer has the edge.

It's faster in a chase.

But the predator has
evolved a special weapon.

This time, the grazer escapes...

and the predator conserves its energy.

On any planet, energy is precious.

Starlight is a virtually
infinite source.

But the trick is to
turn that light into life.

We are in the tropical rainforest.

There are more types of plants and
animals here than anywhere else on Earth.

The trees and plants are
soaking up the sun's energy.

By the magic of photosynthesis, they
convert sunlight into glucose energy,

in other words, sugar.

You can see it and even taste it.

You can actually taste
the energy from the sun.

Plants act like batteries,

capturing the sun's energy as glucose.

Herbivores eat plants.

Carnivores eat herbivores.

Every link in the food chain

depends on the transfer
of this glucose energy.

And in this forest,

one animal can't get
enough of the stuff.

The hummingbird.

Hummingbirds can move their
wings over a hundred times a second.

You can feel how much energy
they are spending just by being there.

This frenzy of activity

is fueled by glucose-rich nectar.

This is a device that from
the front, it looks like a flower,

so a hummingbird
comes and it feeds from it.

And there is one.

It's going back and forth.
Come on, you can do it.

Uh... Okay, so now, he's drinking.

The device measures the
nectar the bird is drinking

and the oxygen it is breathing.

We calculate the energy
intake from the nectar

and the energy output from the oxygen

and we can calculate very accurately
how much energy the bird is using.

A hovering hummingbird consumes
oxygen at an incredible rate.

Ten times faster than
an Olympic sprinter.

The more oxygen it can get into its
cells, the faster it can burn glucose,

which unlocks the energy within.

On Earth, 21 percent of
the atmosphere is oxygen...

fueling the diversity of life around us.

On Eden, there's ten percent
more oxygen than on Earth...

so life here can be more diverse...

more energetic...

more competitive.

Summer is breeding season for grazers.

Always fearful of predators, they
don't spend time finding a mate.

Instead, they produce worm-like spawn.

Each needs to fuse with another

to create an embryo.

For protection, they form a cocoon.

Suspended above the
ground, the embryos can grow,

away from predators.

Here on Earth, the threat
of death is a huge factor

in the evolution of life.

Predation is everywhere.

There's not an organism out there

that doesn't run the risk of
being eaten by another organism.

The aspect that I'm interested in is
how predation shapes reproduction.

They're gonna be comin' in here.

This river is perfect
for studying guppy fish...

and their patterns of reproduction.

- Here. Here's another male.
- Yeah, yeah.

This is an easy neighborhood.

Here, guppies live with
only one other species of fish,

and it's a fish that rarely eats
guppies or harasses guppies.

They can swim wherever they want without
any risk of somebody trying to eat them.

- Oh, right. There you go. All right.
- Here we go.

Here we have some babies that we
just caught. We have five of them here.

They may look small to you, but that's
really big for a newborn baby guppy.

The guppies here invest a lot of effort

in relatively few offspring.

Downstream, it's a different story.

Okay!

Wow.

This boulder is a natural
barrier, dividing the river.

Below it lurks danger.

A guppy life down here is pretty
much like the life of a fugitive.

You're always on the run from predators.

If a guppy were to swim out here...

it wouldn't last a second.

The only defense the guppies have

is to produce lots of offspring,

in the hope that some
will survive to adulthood.

Okay, I've two babies from up there,
where guppies live without predators,

and four from down here,
where guppies live with predators.

There's a dramatic difference in size.

Those that are from here
are much, much smaller

than the ones that I
caught above the barrier.

Moms don't have a big prospect of living
to the future, no matter what they do.

So the best strategy down here
is to make many small babies.

The guppies have evolved
two different ways of breeding.

Having a few large babies...

or lots of small ones.

The deciding factor is
the threat from predators.

If you're one of the prey
items, you're gonna die young,

so you better live fast.

You better put a lot into having babies,
because if you don't, you'll go extinct.

Such a strategy would
apply on any planet

wherever one species preys on another.

On Eden, the grazers
have evolved to breed fast.

They produce as many
offspring as quickly as possible...

to ensure the survival of the species.

But in the forest,
they're never truly safe.

As summer ends, the fungi
grow orange-colored fruit...

which attract grazers.

Spores within the fruit
spread an infection.

Now, when predators attack,

infected grazers don't run.

They've lost their fear instinct.

It's an easy meal...

but a poisonous one.

The fungi have used the grazers
to infect and kill the predators.

Such complex relationships
between species exist on Earth...

but not all are so lethal.

The Hadza are hunter-gatherers,
living off the land.

My name is Palango.

As a man, my job is to hunt.

I always carry a bow and arrow

for protection...

because the bush

has many dangerous animals.

One high-calorie food
is prized above all else.

Honey.

But finding fresh honey is difficult.

The bees move their nests
from season to season.

So the Hadza call on help.

Honeyguides are very clever birds.

They know where honey is,
and they will take you there.

She makes a special cry...

and I whistle back.

If I follow her, she will lead
me directly to the honey.

The honeyguide has lived up to its name.

It's led them to a bees'
nest in a baobab tree.

The hunters need the
bird to find the bees.

And the bird needs the
hunters to access the honey.

The honeyguides take us to the bees.

But the bees are aggressive.

So she needs our help.

Climbing up a baobab tree...

is very hard and dangerous.

One day I fell.

We use smoke to get the bees drunk

and chase them out of the nest.

The risk is worth it.

Fresh, rich, honey.

Palango makes sure
the bird gets its share.

It's a win-win situation.

A complex relationship between species

is known as symbiosis.

The richer the ecosystem, the
more complex the relationship.

On Eden, a deadly three-way
symbiosis has evolved...

centered around the fungi.

First, they feed the grazers.

Then, they infect them...

to poison the predators.

And the fungi do all this to
grow their next generation...

which feeds on the bodies
of the dead predators.

On Earth, fungi play a
crucial, but invisible role

in the life of any forest,

behind the scenes.

So, I think most people think
the first complex life on our planet

was something like insects,
or maybe even the dinosaurs.

But, actually, hundreds of
millions of years before that,

really the first complex multicellular
organisms were these things.

Fungi.

We know of at least 140,000 species,

but that's likely to be less
than ten percent of the real total.

There's probably thousands
of different fungal species

just in this forest alone.

Okay, so we've actually
got three mushrooms here

and you can actually see these
dotted all throughout the forest.

But what's amazing is
that these mushrooms

are really just the tip of the iceberg.

When we look below the surface,

most of the fungus is actually
in these little... tiny little threads,

that go all throughout the soil.

And this is called the mycelium,

and it connects all of the
other mushrooms in this area.

There can be tens of kilometers
of these tiny microscopic fungi

spreading throughout the entire soil.

The tree needs those fibers to survive,

because the tree can capture
carbon from the atmosphere,

and it provides that
carbon to the fungus.

In contrast, the fungi access
nitrogen and phosphorus from the soil,

which they give in
exchange for that carbon.

So, really, it's a mutualism that
benefits both of the organisms.

Possibly the most extraordinary thing

about this mycelial system

is just how connected it is.

So, the fungi that are
attached to the roots of this tree

will also be attached
to the roots of that tree,

and that tree over there,

and they will also be
connected to their neighbors

via the same mycelial system

that is really going
tree to tree to tree.

The mycelial network is like
a circuit of wires and nodes

through which information can flow.

And with it, fungi can
maintain the forest.

So, if we have one tree
over there that's dying,

it might reallocate more
nutrients towards that tree,

so that the tree can do better

and, as a result, the
fungal system does better.

Similarly, if there's disturbance
at some part of the fungal network,

it will remove nutrients away

so that it can minimize the
impact of that disturbance.

It's these invisible ecosystem engineers

that are keeping the entire system
functioning in a really healthy way.

This system has become
known as the Wood Wide Web,

and it sounds like a bit of a joke,

but, really, it doesn't function
so differently from the internet,

keeping all of the organisms
connected in the forest system.

This process is happening
all across the planet,

in every ecosystem we can imagine.

So, if we're gonna get a lush
ecosystem on some alien planet out there,

I bet you that it's underpinned

by something like this
massive mycelial system.

Life in the forests
of Eden is a trade-off

between fungi, grazers and predators.

But there are greater
celestial forces at play.

Eden has stronger seasons than on Earth,

greater fluctuations of light
and warmth from its twin stars.

As winter approaches,

the remaining predators migrate...

chasing the light.

The remaining grazers die.

It's the same every winter.

Nothing grows in the dark forest...

except the embryos in their cocoons.

Just as the season starts to change...

the grazers hatch...

taking their cue from the
return of the twin stars.

On Earth, life does the same thing,

using the seasons as a clock.

It's midsummer,

the longest day of the year.

There's a lot of fly
fishermen out this time of year

because this is the time of
year that the fish are biting,

because there is an abundant
food source in the river,

and that food source are all
these guys, the mayfly nymph.

So, we think of mayflies as
flying around on the land with us,

but they spend the vast majority
of their life cycle living down

on the bottom of the
river, developing, growing,

and it's all really building
up to this one time in the year

where they're all going to emerge.

Yellow Breeches River

feeds the Susquehanna.

Beneath these waters,

millions of mayflies are
primed and ready to go.

And when the sun sets, they emerge...

en masse.

There are just so many insects
that seemingly came out of nowhere.

It really almost feels
like an alien invasion.

Mayflies live, at most, for two days.

In that time, they must find a
mate to pass on their genes.

They have one shot, they have
one chance, and if they miss it,

it's game over for that mayfly.

Once they've mated,

the females return to
the river to lay their eggs,

and then die.

Each of these little
white dots is a mayfly

that successfully made it back
to the water and has laid eggs.

They are floating down by the
thousands, by the hundreds of thousands.

They have started the next generation

that will continue on and
do this again next year

in this really precisely timed event.

The rhythm of the
seasons is always dictated

by the tilt of a planet
towards its star.

Earth is tilted at an angle
of 23-and-a-half degrees.

On Eden, that angle is 40 degrees,

so more light spreads across
more of the planet's surface.

And more light means more life.

It's spring, and there's food to eat...

but the new grazers need
to grow as fast as possible...

before the predators return...

and the life cycle repeats.

Wondrous creatures...

fed by glucose...

powered by oxygen...

nourished by starlight.

What is true on Eden may be
true throughout the universe...

that all life depends
on the flow of energy.

How might life adapt
on a different world,

inhabited by intelligent beings,

intelligent enough to make a new home...

among the stars?