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The Earth, home to millions of species.

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But what might live beyond?

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There are countless planets throughout the universe.

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If life exists on only a fraction of them, then the universe must be alive.

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All living things have the same needs to feed, reproduce and evolve.

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By applying the laws of life on Earth to the rest of the universe, it's possible to imagine

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what could live on alien worlds.

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All life forms need a planet to live on. But how many planets are there in the universe?

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Think about our star, the sun, with Earth, Mars, Jupiter orbiting it.

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For centuries, people have asked themselves, what about the other stars?

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Do they have planets as well?

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And 24 years ago, I found one.

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Didier Quellos is a superstar astrophysicist.

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He has won the Nobel Prize for discovering the first planet beyond our solar system.

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I was 28 years old when I found the planet.

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I was about to finish my PhD and my PhD advisor gave me the key of the equipment.

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And after observing a couple of times, the star Fifty One Peg, I realized that something was going on on that star.

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And frankly, I just panicked at that time.

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I thought something was really wrong with my equipment.

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And the more I wanted to understand this, the least it made sense.

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Until the point I got convinced, it must be a planet.

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That's likely to be a planet over there.

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Could be Jupiter over there. It's pretty cool.

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Distant planets are invisible to telescopes because they don't emit any light.

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But if a planet passes in front of a star, it casts a tiny shadow.

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And there's a minuscule dimming of the star's brightness.

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When astronomers detect this dip in light level, they have found a new planet.

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Hello guys. Here is what the telescope is looking at.

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This is a picture of the telescope right now.

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In the middle you have the target we are observing.

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So you analyze this whole field, you process the data, and if you're lucky enough, you detect this.

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It's a little bit of a decrease of the flux.

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And this tells me that there is a planet orbiting that star.

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We know there are a huge number of planets in the universe.

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There must be zillions of different lives.

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Let's imagine that this is the Earth here.

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Right? So imagine that one meter is 20 light years.

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So I make two meters is 40 light years. This is where you have 51 pegs, where the first planet was detected.

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Each of these tiny lights represents a star where a planet has been found.

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Over the next few years, planets were turning out everywhere.

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Planet, planet, everywhere.

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It looks pretty cool right now.

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Horizon of star on planet. All around.

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Planets beyond our solar system are called exoplanets.

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Astronomers have found over 4,000 of them, and they keep finding more.

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They now believe there's at least one planet for every star in the universe.

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That means over a million, billion, trillion exoplanets.

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More than all the grains of sand on Earth.

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A vast canvas for the evolution of life.

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The distances are mind-boggling.

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The nearest exoplanets are trillions of miles from us.

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But they're all subject to the same force that holds the Earth in place.

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Gravity.

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Imagine a world double the size of Earth with twice as much gravity.

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This is Atlas.

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How would life adapt on such a world?

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Gravity pulls vegetation to the planet's surface.

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And yet, seeds can float in the sky.

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That's because gravity here is so strong.

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Air molecules are densely packed together,

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creating a thick buoyant atmosphere for seeds to drift through.

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And where there are seeds, there are sky-grazes.

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Giant herbivores with six wings to ride on the dense pillow of air.

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Because of the extra gravity, they weigh twice as much as they would on Earth.

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But they don't fall from the sky.

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The atmosphere is thick enough to keep them airborne.

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Whether on Atlas or on Earth, flying is always a battle to overcome gravity.

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You might say you have a pretty complicated relationship with gravity.

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And you can really feel that gravity is a force pulling you down as you struggle your way up.

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But ultimately, my dream has always been to be able to fly.

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The thing I love most about paragliding is that it's so simple and intuitive.

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It's just you and the air.

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Like the sky-grazes on Atlas, paragliders use their wings to generate lift.

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But the atmosphere is less dense on Earth.

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So it takes more effort to stay airborne.

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Most people don't see air as a substance.

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But for me, when I'm flying, I really see it as a fluid that's moving up and down the valleys and along the ridges.

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It would be really weird to fly in a very dense atmosphere.

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You could just be gliding around the whole time effortlessly.

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The best way to gain altitude is to find an updraft known as a thermal.

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When you hit the thermal, it's very similar to when you're in an elevator and it starts.

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You feel the push upwards.

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Just the power of nature to pull me up.

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When I'm flying and I see a bird circling up, it means there must be a thermal there.

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We're always constantly looking at them.

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You can really feel the balance between the gravity pulling you down and the air lifting you up.

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You can then use your body weight to gain speed and use that speed to generate more energy and feel that you're moving through the air.

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The gravity may be weaker on Earth than on Atlas, but the thinner atmosphere means there's less buoyancy.

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So eventually, everything falls.

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The sky is the only way to get there.

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On Atlas, the sky grazers never need to land.

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Their front and back wings are for direction and thrust.

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Their long middle wings are for catching thermals.

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Despite their weight, the air is thick enough for them to live a life in the sky.

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But it's not always a peaceful life.

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As on Earth, grazers attract predators.

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Using hydrogen-producing bacteria to inflate their air sacs, they take to the skies.

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Alone, there's no match for their prey.

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So they hunt in a pack, waiting for a sky grazer to stray from the group.

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Target sighted. They expel their gas and attack from above.

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The fastest predator on Earth uses the same tactic.

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My interest in flying falcons is their predatory instinct coupled with the speed factor.

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And how they use that speed to their advantage.

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But just watching a top predator do its thing is perfection.

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I probably have 30-some birds at this moment. Each bird is a different personality.

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What I love about falcons is how evolution has made the most perfect specimen.

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I do have a relationship with these guys. Certainly from my end I do.

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I don't think the falcons see it that way, but they certainly see me as part of the team.

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Vahe Alavurdian trains captive bred falcons how to hunt.

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These birds are already genetically programmed to be the top-notch avian predators that they are.

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What we do as falconers is to try to awaken that predatory nature in the bird.

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Lure training is the very first step.

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I want to put that lure in front of the bird and get the falcon to coordinate eye to foot

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and throw its feet out as if it's going to grab it.

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As that happens I try to pull that away from the falcon to get it to shoot up in the air and repeat this process again.

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I want to see that bird drop down as vertical as it can.

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That's something that they later on will apply to hunting game.

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When the falcons are ready, Vahe introduces a prey target, a racing pigeon.

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The falcon can't keep up with the pigeon in a chase, so its best bet is to drop on it using gravity.

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When the bird thinks that he's got the advantage, that's when the wings will get tucked in.

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They stoop into a little teardrop shape coming down from the heavens.

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The kinetic energy of a falcon hitting a pigeon would be as if you were hit by a cannon ball.

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In training, the pigeon invariably gets away because the falcon is made to stoop from less than a thousand feet.

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When hunting for real, it'll drop from a greater height to lethal effect.

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The predators make their move.

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They deploy their wings to create drag,

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destabilizing the sky grazer to devour it on the ground.

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The falcon is too small to take down such a large beast.

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Today, they'll go hungry.

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The sky grazer climbs to a safe height to recuperate.

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But as a fertile female, she has company.

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Male grazers competing to be chosen as a mate.

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Their oversized tails are a handicap, making it harder to fly.

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But to the female, they're a sign of vitality.

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The first to reach her gets to mate and pass on his genes.

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The same principle applies on Earth,

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whether up in the sky or down in the dirt.

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Males compete for the right to mate.

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I think when people sit at home watching insects on top of a tree,

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they imagine a cameraman sitting in the jungle in a river or in a hedge

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waiting for this beetle to come across and reproduce

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or have a fight in front of the camera.

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It doesn't work that way.

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This is a ramshackle-old shed which is attached to my parents' place,

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which is just there.

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Huge advantages to having a place attached to your mum and dad's.

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You get good dinners in the evening and teas arriving during the day.

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Come and have a look and see what we're doing.

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Oh, gosh. What an after-day.

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They are rhinoceros beetles.

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The male's got these big horns. The female doesn't.

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It's a form of sexual selection because the females like males with big horns.

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So every time they mate, they'll mate with a beetle that has a slightly bigger horn

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than the one they last seen before, and therefore that male passes its genes on.

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So over generations, the horns will get bigger.

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Anywhere particular?

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Just on the log facing the other male.

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Right, here they go. They're going straight away.

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The horns of a male rhinoceros beetle

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are like the tail of a male sky grazer.

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They've evolved for sexual competition.

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Going straight down to the right.

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Try and walk the lead.

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Yes.

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れ massacre.

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Yeah.

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One, two, three.

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Is that all right? Yeah.

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Can I put this in? Yes.

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Male insects don't always fight to snare a mate.

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Sometimes it's enough just to show off their physical prowess.

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Right, I'm going to bring the male in front of you.

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He's coming in from your right.

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Now it's flown off.

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These are stalk-eyed flies.

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Stalk-eyed fly is an amazing little thing.

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It looks a little bit like an ant with massive eyes on the ends of stalks.

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Both the male and the female have eyes on the end of stalks,

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but the male has much longer eyes stalks than the female.

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The males with the long stalks will come up to one another

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and they will kind of have a little dance.

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And they will try and judge which of the two of them has the biggest stalks.

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There they are. That's the standoff.

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The winner of that will remain where they are and the loser will then toddle off.

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That winner then will gain access to the female and be able to reproduce with her,

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and that way can pass on the genetics that he has,

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which will include that of a longer eye stalk.

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Yes. Are you on it? Got it.

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Oh, it's fantastic.

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Normally it's a second and they're gone. This is fantastic.

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Why would the male stalk-eyed fly go to the effort of having these enormous eye stalks?

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Well, the idea is that you are conspicuously signaling to the female

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that you can have this incredible investment of energy into this resource

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that is completely needless.

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And if you can still survive, if you can carry on flying and living

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and not getting predated upon, and still have this wasteful extravagance

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coming out of your head, then you're going to be a pretty good bet to reproduce with.

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On Atlas, the long tail of the male sky grazer shows his ideal choice.

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To father the next generation.

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But the mother can't lay her eggs in the sky.

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So she's come down to land.

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Because of the gravity, she's too heavy to launch herself back into the sky.

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To create new life, she must surrender her own.

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The babies grow up close to where their mothers died.

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Now they need to get off the ground and into the air.

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But scavengers lie in wait.

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A bone-laying, a body-laying, a body-laying, a body-laying, a body-laying,

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boneless creatures with no skeleton to give them form.

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They kill by enveloping and dissolving their prey.

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The sky grazers have only just hatched, but already they're in grave danger.

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And now, there's no going back.

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The End

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Every day on Earth, young animals have to overcome terrible odds if they're to survive.

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60% of meerkats don't make it to their first birthday.

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For a young meerkat in their early life, there's a lot of danger here.

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They're vulnerable for many months after they're born.

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But particularly in the first month or two after they emerge from the burrow.

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Predators are everywhere and a constant danger.

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There are snakes in this area that will eat a young meerkat.

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A young meerkat is safe within a group, but if it lags behind, it's vulnerable.

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Scorpions are a constant threat.

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The young are really completely incompetent and totally ignorant when it comes to dealing with scorpions initially.

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But they can't avoid this danger forever.

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They're going to eventually have to learn how to neutralize the threat.

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The first time that a young meerkat faces a scorpion and it has to deal with it itself,

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is probably a terrifying encounter.

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This is a real moment of truth.

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It's a real rite of passage because once they've managed to do that themselves,

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then they really are at a stage where they can start to forage by themselves and become independent and be a useful group member.

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So they've really managed to escape the vulnerability of being a pop and made that transition into being an adult.

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It's one step on the road to adulthood, but it's by no means plain sailing after that.

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There are a lot of threats out there and it will have to continue to learn.

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It's a real moment of truth.

234
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It's a real moment of truth.

235
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It's a real moment of truth.

236
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It's a real moment of truth after all of this.

237
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It doesn't matter how much it's new or how long it lasts but you should be willing to let it grow.

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They have no choice.

239
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It's time to fly.

240
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I'm not safe.

241
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Even in the air, they're still not safe.

242
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On Atlas, survival is a game of chance.

243
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Life goes on, from one generation to the next.

244
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At least for now.

245
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The strong gravity of Atlas pulls asteroids onto a collision course.

246
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The Earth is a place where the gravity of the collision is lost.

247
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Most burn up in the atmosphere.

248
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But there's a constant threat something big will get through.

249
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And reset the course of life on the planet.

250
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Because gravity is weaker on Earth than Atlas,

251
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asteroid strikes are less frequent.

252
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But when they do occur, they can be catastrophic.

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This is the Yucatan Peninsula.

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27,000 square miles of tropical jungle.

255
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But hidden within the jungle are numerous sinkholes called cenotes.

256
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These are entrances to vast underground cave systems.

257
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There's no surface rivers or streams in the peninsula.

258
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So the only source of water is underground in caves.

259
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But the really interesting thing is the location of these cenotes.

260
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Although there's probably 10,000 or more cenotes across the peninsula,

261
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in the northwest corner,

262
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they occur in a very well-defined semicircle.

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If we follow that semicircle out into the Gulf of Mexico,

264
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we now have a complete circle that marks what one would expect

265
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from the edge of an asteroid impact crater.

266
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65 million years ago, gravity pulled an asteroid into our solar system.

267
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It smashed into our planet, causing the extinction of 75% of life on Earth.

268
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The asteroid strike generated enough debris to block out sunlight for two years.

269
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A world plunged into darkness.

270
00:36:38,200 --> 00:36:42,200
Nothing could grow.

271
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This would happen on Atlas if a big enough asteroid hit the planet.

272
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Cenotes are difficult places to survive.

273
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Just like the Earth was 65 million years ago.

274
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The Earth is a very large planet.

275
00:37:07,200 --> 00:37:12,200
The Earth was 65 million years ago.

276
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What are the characteristics that a species needs to survive an extinction?

277
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Somebody hid here.

278
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So crocodiles are very resilient animals.

279
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They live both in the water and on land.

280
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They're generalists. They don't require a specific diet.

281
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They'll eat almost anything.

282
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Whatever is available is good enough. They'll take it.

283
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Here in this Cenote, once fallen in, gotten trapped, no way out,

284
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somehow, someway, it succeeded.

285
00:38:21,200 --> 00:38:26,200
They're survivors.

286
00:38:26,200 --> 00:38:32,200
In a changing world, it pays to be a generalist, not a specialist.

287
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If a big enough asteroid hits Atlas, the sky grazes and predators would be doomed.

288
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They're too specialized to cope with change.

289
00:38:59,200 --> 00:39:04,200
The generalists are the boneless scavengers.

290
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Like crocodiles, they eat anything and live anywhere.

291
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On this imagined high-gravity world, they could be the only ones left.

292
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On this imagined high-gravity world, they could be the great survivors.

293
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How might life adapt on a different world, where creatures are trapped

294
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between a searing desert and a frozen shadow land?

295
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A world of extremes.