Transcription
[Music] I'm going to tell you about the most incredible place we think we know, our home. But once you've seen it from space, it hits you. It might be the weirdest place in the whole universe. Eight astronauts, with over a thousand days in space between them, can tell us how being up there helped them to truly understand what goes on down here.
I've been a stargazer ever since I was a kid. My grandmother even gave me a compass to make it easier to find the North Star. I love looking out into space and imagining, are there other worlds out there? Is anything living on them? You know, every day you're finding a new planetary system that looks pretty similar to Earth. The possibilities of life somewhere else other than Earth, I think, are very hot. I like to think that there's other life out there. If there is life out there, I mean, what would it be like? Could we talk to it? I mean, is it going to want to fight, or will it like romantic movies? Is there anything out there like you and me? To find out, we can't just look into space. We also need to look down here. I'm going to tell you how clues to alien life are hidden on our strange [Music] rock.
May Jemison was the first African-American woman in space, but Earth's orbit was not enough for her. She's now head of a Starship initiative. It's a 100-year mission to boldly go where no one has gone before. Growing up, science fiction was my go-to storytelling. As a little girl, as I watched Star Trek, I was fascinated because science was one of the characters. It was right in the middle of it. And so my love for science really met an incredibly interesting vision. I was fortunate enough to meet Nichelle Nichols, who played Lieutenant Uhura, at a Star Trek convention. She was really instrumental in the recruitment of some of the first women astronauts and the first minority astronauts in the U.S. Space Program. I wasn't one of her recruits, but I'm really happy to say that she's one of my best friends now.
I think we're done. I think we're done. Andoran, huh? Yeah. People are always asking me, "Will we find aliens on other worlds?" And I know they really mean, "Will we find Vulcans or Klingons?" Well, to know how likely that is, we really have to understand how we got diverse, complex life on this planet. Scientists believe, believe that somewhere around 4 billion years ago, life emerged on Earth. One might imagine that once we get life out of this primordial soup, the road to complex creatures like flowers and humans is pretty straightforward. But hold on, it's not quite that easy. There was no rule that life had to get bigger. There was no rule that life had to become more complex. Life could have stayed simple and small, but it didn't. Today, we live on a planet inhabited by over 8 million different species. And for that to happen is so unlikely that it makes you wonder if it could happen anywhere [Music] else.
As you look down at the Earth from space, you see the ocean, the desert, the grasslands. You know that life exists in every one of those locations. And the type of life that's there, well, that depends on what food is available for [Music] it.
The caves have no light source. When you're away from the entrance, it's as dark as dark things get. The creatures that choose to live in a cave, they do it for a reason. In a totally dark place, any light is incredibly effective.
The glow-worms glow when they are hungry. The bugs have no idea. I think, oh, light instinctively fly towards it. All of a sudden, they're stuck. The glow-worm is a deceptive creature. The more you know, the more you see, the more disgusting and ferocious do you realize these caves [Music] are. When the glow-worm's got its bag, it will bite or puncture into the wall of the insect and suck out the inside. [Applause] [Music] [Applause] [Music] [Applause] [Music] [Applause] [Music]
Surely, it's a law of nature that life evolves to fit its surroundings. If we find life on other planets, it's likely that it was the best suited to prosper in the conditions there. An extraterrestrial Darwinian evolution, if you [Applause] please.
As human beings, we are constantly asking questions: Who am I? Why are we here? What is the meaning of existence? But it turns out the big question for life is, what are we having for dinner? Food is energy. Everything living needs it. And it's a big reason why creatures live, act, and look the way they [Music] do. The complexity of life here is staggering. Just imagine how peculiar a camel might appear if you'd never seen one before. You might think it was a creature from another planet, but its strange design makes perfect sense for the way it gets and uses energy. Like its wide, flat teeth for chewing tough plants, or a hump of fat stored energy that allows it to survive months in a harsh environment without eating. To sustain a complex creature like a camel requires vast amounts of energy. Even something like a fly, with millions of complex cells, is breathtakingly complicated and requires a steady flow of energy. [Music]
But even if you're a tiny microbe, smaller than a pinhead, you still have energy [Music] demands. When we think about life, we usually think of the big stuff, you know, plants and animals. But the majority of life on Earth are small, single-celled organisms, bacteria. And they have evolved to eat almost [Music] anything.
So I think, yeah, and go down the king mast, and then you jump into the third hole. Okay, well, you, I've done the checklist. I've got the coms ready. So, good luck. [Music]
This is one of the biggest graveyards of ships in the world. Around 50 Japanese boats and over 250 aircraft were sunk here by American forces during the Second World War. [Music] Some were blown up with torpedoes, others were bombed. It might seem like useless junk now, but for some kinds of life, it's a perfect home. All that energy that was poured in to make the vessels of the war is there, waiting to be released. Rusticles look like stalactites, and they are part metal and part microbes. Microbes extract the chemical energy from the metal, using it to grow and reproduce. To us, iron is just a metal, but for these microbes, it's food. The rusticle is crawling with billions of happy bacteria, all chomping on an all-you-can-eat iron underwater buffet. [Music]
The first creatures on Earth were microbes. And in the future, when all human life is gone, the bacteria will still be there, doing their business. I love my food, but, but I mean, I'm a little picky. And that's because I'm not a microbe. They will eat anything: metal, rocks, oil, plastic, even human flesh. But having a big palate like that comes in handy. Bacteria can survive up on mountaintops. They can survive in deserts. They're in the soil. They're thousands of feet up in the atmosphere. They're everywhere. So it doesn't matter what a planet is made of, or how poisonous its atmosphere. Even if there's just a tiny bit of energy to extract, simple microbes will work out a way to get it out. In the universe, there, there's got to be that stuff. There's got to be these single-cell organisms that are living in environments that life as we know it here on Earth could probably never tolerate. Given an unlimited number of planets and an unlimited amount of time, it's a little bit delusional to think that this is the only place life could have ever evolved. Maybe there are microbes on other planets, but there's a big leap between them and something I can talk to here on Earth. That leap couldn't have happened without a visitor from 93 million miles away.
Over the years, I've had many encounters with aliens, and this may come as a shock to you, but they weren't real. But if Hollywood is right and there are aliens, they're going to have needs, and it's going to be all about energy. Up to a point in Earth's history, energy came from heat, from volcanic vents, from lightning strikes. This energy was readily around. But as the Earth started to cool and to change, the weather changed. A new source of energy was needed. Some bacteria came up with a new mechanism: "Let's use the energy from the sun," which is readily available. It was a really pivotal moment in the history of life on [Music] Earth.
On the space station, we have this vast array of solar cells that collect and harness the solar energy from the sun, and we use this to run all the systems, to sustain life. If things don't work the way they're supposed to, that can get very tricky, very fast. When you look out the window, you see these solar panels that extend the length of a football field, and these eight ginormous solar arrays. They would go from blue to gold to copper color, just beautiful. So I'm out doing a spacewalk, and one of the things you're worried about is the solar panel, trying to maneuver my way around those solar panels, and looking down at Planet Earth and the greenery down there, and I realize, "Hey, Planet Earth is really one big solar panel." Also, plants have been converting solar energy and storing it effectively for billions of years. This, this biological magic trick means that even when there's only the faintest trickle of sunlight, plants can grow. [Music]
Photosynthesis, we've all heard about it, right? But have you ever really considered what it means? What plants do is eat sunlight streaming from our sun, 93 million miles away, and they use it to make carbon dioxide into starch granules of stored energy, which plants use to power their [Music] [Applause] growth. When I see a live plant, their green makes me know life is possible. Plants make a place feel welcoming, like home. Every leaf on every plant is like a tiny battery. Photosynthesis from plants worldwide generates around 100 terawatts of power each year. To put that into perspective, it's enough to match the energy demand of the modern world nearly six times over. Running a planet packed with life takes a lot of energy. Kudos to the big ball of fire in the sky. Plants dying out on it. Once they started, they spread all over the world, but those first plants were missing something, which meant there was one place they couldn't go: up. [Music]
Very big project. Miracle gifts from God. Speed, flexibility, external scaffolding ability. [Music] [Music]
Bamboo can grow so high because it contains a molecule called lignin. It's the bamboo's own internal scaffolding. Lignin evolved around 400 million years ago, and it changed the world. It provides structural strength for plants, and they get to grow tall. From the outside, plants and trees are beautiful, but it's the inside that reveals their dynamic, intricate structure. These mesmerizing patterns are the storybook of its [Music] life. Because of lignin, plants have given our rock a solar-powered skin that harvests energy from the cosmos, and that harvest supports almost all life here on Earth. The truth is, money doesn't make the world go 'round. Energy does. Plants store [Music] energy, so it didn't take long for something to evolve to take [Music] advantage. When an animal eats a plant, it gains the energy that a plant captured from sunlight. Animals could not exist without [Music] plants. If another planet evolved creatures like goats or like us, I'm almost certain it would have plants as well. But plants on this other planet may not be green. Plants here are only green because our sun is green. [Music]
The majority of light emitted from the sun is in the blue-green wavelength. It doesn't look green to us because it has light emitted in other areas too, in red and blue. And so when you blend all those together, they look white. Most plants here on Earth have evolved to use primarily red and blue light for photosynthesis. They reflect back the green light, which is why they look green. On an alien planet, if there's complex life, there'll be something like plants and something like animals that eat them. But it probably wouldn't stop there, because here on Earth, that's not the last link in the food chain. How do we begin to imagine what aliens might be like? Well, if animals have evolved on another planet, they might not have arms, but they'll still be looking over their shoulders, because chances are, there are predators out there. [Music]
There are two ways to load up on the energy you [Music] need. You can be like a fish and spend all day nibbling and nibbling on your ocean green, or you can be like a man of [Music] war and snatch up in an instant all the energy the fish picked up from days of nibbling. [Music]
Plants consume sunlight, animals eat the plants, and other animals eat those animals. It's the circle of [Music] lunch. Every creature on Earth has evolved its own body shape to maximize its chances of getting a meal without being eaten. Take cats. I love cats, particularly house cats. Cats have a very good sense of themselves. They're very confident. Cats are fairly pleased with themselves, and cats have good reason to be pleased with [Music] themselves. Cats are all around the world, from the desert to the Arctic to temperate climates. For me, cats represent one of the pinnacles of evolution. [Music]
Cheetahs, for instance, have evolved into perfect hunting machines, but even they may find it hard to catch their prey. Shoh is the cocky one, that she's very independent and on her own. And as a cub, she was the one that was the strongest. Odyssey, the male, he's just, yeah, he doesn't have a care in the world. And as a baby, I lost him. Almost, I had to keep him in my bed for two weeks. He was on, on drip because he was so dehydrated, and he was just the weakest of the three. [Music]
I raise them, and I give them their names, so they're like my kids. They call Mariska van Vuuren the Cheetah Whisperer. She rescues abandoned cubs on the plains of Namibia. Going and helps them learn how to eat. When they're babies, and they're around about six, seven months old, they need to chew. Then they need to learn what taste of meat they like. Where there's a juicy hunk of energy, some creature is going to work out a way to try and get a taste. The springbok is the ultimate fast food. If you look at the springbok, they've kind of developed into a smaller species, light-boned, nothing extra. They got these long legs that gives them that acceleration and jump to catch the springbok. The cheetah needs to be even faster. Go, come, Babas. So Mariska helps the cubs keep in shape. Go, go. The lure is a pulley system, just connected to a battery, a car battery. We just tie a piece of string to it, and you let them just chase it. It's like a kid. You have to make them fit. By the time they have to really run 100 meters and catch a springbok, they're going to be dead if they do it for the first time. So it's getting them ready for a proper hunt. They can get from 0 to 100 kilometers an hour in a blink of an eye. Everything is just modified and made for speed. They have a light bone structure. They've got long nails. It's like an athlete using [Applause] spikes. It's got a very long tail in comparison to the other carnivores, so it can cut a corner very quickly without flipping or falling. [Music]
They normally spot the springbok way before me. We need to be at least 100, 120 meters from a springbok for the springbok not to outrun them. The surprise element is crucial to them. He [Music] almost 90% of the times they get [Music] away. It's rough being a predator. Cheetahs are living on a knife's edge. They use almost as many calories catching their food as they get from eating it. But there's other ways to get food besides catching it. If you can't outrun them, outthink them. Oh, [Music] [Music] [Music] D [Music] Hey!
These wise guys have worked out an angle: trading sunglasses for food. It brings in the maximum amount of calories for the minimum amount of [Music] effort. Monkeys are smart, but we've got a bigger racket. We've hacked the entire planet to feed over 7 billion of [Music] us.
Hello, I'm Mae Jemison. Right now, I'm aboard the Space Shuttle Endeavor, over 300 kilometers above the Earth and traveling at over 7,000 meters per second. My first view from space was the city of Chicago, no kidding, my hometown, and it looked just like the map I learned when I was a child, because the concrete of the city seemed to be separated from the grain of the farms that surrounded Chicago. Chicago prospered because of its ability to transfer food from the place that it was grown to humans that were far removed from that local. The Chicago stock market, the agriculture around Chicago, the corn fields, all of that is about a manipulation of the food web. It's something we humans do really well. Our eating skills are epic. [Music] [Music]
Our brains are so big and complex that we have managed to figure out all sorts of clever ways to get our food: chemicals to fertilize crops, genetic manipulation to modify them, nourishment to make animals grow up big and fast, and even robotics to process them. Here on Earth, there are over 8 million different types of complex life, all feeding 24 hours a day, every day of every year, including over 7 billion human beings. [Music]
If it's edible, it's going to get [Music] eaten. Plants eat sunlight, animals eat plants, and other animals eat animals. But there wouldn't be anything larger than a microbe to eat. No cucumbers, no fish, no steak and fries. None of this food chain would exist without a freaky event we think only happened once in the whole of Earth's history. [Music]
Our planet is like a huge restaurant where everything is eating everything else. Humans are at the best table, just eating, eating, and eating. But is this joint a franchise? Are there other branches out there in the universe? The answer to that revolves around the strangest meal that ever happened. Every complex life form on this planet, including you and me, has relied on the same solution for what seemed like an insurmountable hurdle: getting enough energy. Around 2 billion years ago, when nothing lived on Earth except microbes, we think one microb ingested [Music] another. Nothing particularly remarkable happened all the time, but this time, the microbe was engulfed but not digested. It actually survived in the host and became a part of [Music] it. This remarkable microb had a superpower: [Music] it generated energy using [Music] oxygen, allowing it to extract 15 times more energy from its [Music] food.
This is the moment when life as we know it really began. The microbe that survived led to what we now call mitochondria. It lived on in its host, and together they started a new life form: a big, complex cell that could connect with other cells to make big creatures. All of them using oxygen to break down their food. Mitochondria inhabit every single cell of every complex life form on this planet. That means they power everything from flies to trees to cheetahs and us. Think about it: we all carry the same machinery in us, and we wouldn't be the complex, complicated organisms that we are today without mitochondria. If we didn't have that one moment, Earth would have no plants, no plant-eaters, no meat-eaters, no us. Life on Earth would be just bacteria chewing on rock and each other. It took trillions of bacteria swallowing trillions of bacteria for more than 2 billion years before that one failed meal, which suggests it's kind of rare. How rare? Maybe Earth is only rare for an alien planet out there to evolve over those billions of years and to be exactly like it evolved here on Earth. Well, that's like rolling those dice and hitting a one, you know, a billion times in a row. The overwhelming probability, if you find a planet with life on it, it's probably going to be very simple life. You know, we're not going to, I always say, see Mr. Spock. You know, we're not going to necessarily find, uh, the, the bipedal character that looks very humanoid just walking through the door and saying, "Hey, I evolved on a different planet, and there's a whole bunch of us around." But do I think simple life exists in other places? Absolutely. Looking up at all those points of light, we'll always wonder, is there life out there somewhere? Maybe there is, maybe even a lot of it. But there's a good chance that as we gaze up at those stars, there'll be nothing remotely like us looking back. Next time, the greatest mystery in the universe could be right between our ears. [Music] [Music]