The Origin Of Our Genetic Code | How the Universe Works | Science Channel

We find the microcosmos in every feature of Earth. But where did this strange kingdom of the very small come from? Some of its members are so weird, they look like aliens. Could they have come from space? There's this idea that microbes could have hitched a ride on a chunk of an asteroid that would fall to Earth. They could form on a different planet, something hits that planet, the rock that they're sitting on gets lifted and then hits the Earth as a meteorite. The idea of hitchhiking bugs sounds a bit wild. But we have found chunks of Mars on Earth. Perhaps these space rocks brought life. It's not completely ridiculous. We know that rocks, for example, could come from Mars and land on Earth. A giant asteroid impact on Mars could blow shrapnel into space that could land on Earth. To learn how, we must return to the early solar system, 4.5 billion years ago. Many infant planets orbit a new star, our sun. This infant solar system is chaotic. Collisions between planets are inevitable. The early solar system was like a pinball machine. Stuff was hitting, knocking stuff off. That would land somewhere, knock stuff off. The young Mars is in the line of fire. It already has primitive oceans and perhaps primitive life. A huge space rock smashes into the surface. We call the event the Borealis impact. It blows quadrillion tons of rock into space. It's not crazy to think that one of these chunks of rock traveling through our solar system has some hitchhikers on board. If there's some microbe riding on an asteroid that got blasted off of Mars, kind of feel sorry for it, right? It's just living there on Mars, doing whatever little Martian microbes do. And then a giant impact ejects this thing into space. In order to get from one planet to another, a cell would have to run a gauntlet. It's almost like winning a survival game show. You've got to survive being blasted off your homeworld. You've then got to survive the interplanetary journey inside a small lump of rock, being exposed to the vacuum of outer space, to cosmic rays, to UV radiation, being dried out and frozen. So the idea of moving life around the solar system or around the galaxy on asteroids poses a lot of different challenges. Events like the Borealis impact ejected so much rock from Mars, there were lots of opportunities for hitchhiking bugs to run the gauntlet of space. But could they survive the journey? To find out, astronauts on the International Space Station grew simple bacteria outside in space. After a year of being in open space, miraculously, some of these microbes survived. It's incredible. These microbes just could not be killed, even though they were in the worst possible environment for life. The mission therefore shows us that life can survive the environment and outer space. Life can be transferred between planets. Maybe life did get started on Mars, on our next-door-neighbor planet, and then was transferred here inside a meteorite. Maybe we are immigrants from Mars. Hitchhiking bugs may have arrived on Earth and kick-started the microcosmos. But now, recent studies of meteorites suggest that even if living microbes didn't make the journey, the building blocks that made them did. In November 2019, an international research team found an organic molecule called ribose in meteorites that had crashed on Earth. Ribose is a sugar. It's a simple sugar, but it is a sugar that is absolutely crucial to all life on Earth. Ribose is the sugar that makes up RNA. And RNA sits right in the linchpin of every cell. RNA is a simple form of genetic material that controls cellular function. It's found in most primitive creatures. Finding ribose on a meteorite is so important for us to understand the origins of the microcosmos, because these are the building blocks. These are the things that it needs to get started. So understanding where these building blocks come from allows us to understand how the microcosmos might have evolved and started. The Rosetta mission found another building block for life out in space, a form of phosphorus on the comet 67P. This was astounding. Comet 67P was formed at the birth of the solar system, 4.67 billion years ago. And it hasn't changed since then. It's a time capsule from the birth of the sun and the planets. And it's been in the deep freeze ever since. So these forms of phosphorus that we found on comet 67P tell us what was available at the time the Earth was forming and then when life was getting started on primordial Earth. The early solar system contained many chemicals needed for life. It's an important discovery because it means that these compounds were around when the solar system was forming. So they would have been readily available for life to tap into and use to start forming cellular structure. These discoveries not only show that essential chemicals came to Earth, but that they exist throughout the solar system. We tend to think of the microcosmos as only existing on Earth in the sense that only Earth has these building blocks. But now these new observations suggest that a microcosmos, at least the building blocks for one, could exist beyond Earth and throughout the solar system. Comets and asteroids may have brought chemicals to kick-start the microcosmos. Now, explosive new research suggests that space rocks hitting Earth did even more. Could the violent impacts themselves have helped life get started? How did the microcosmos and life on Earth start? Did asteroids and comets deliver the building blocks? Phosphorus, ribose and other organic compounds? Or did they start life in other ways? New research suggests the impact of crashing space rocks could have provided the spark for life. The force of the impact actually triggered the creation of these molecules that are the building blocks of life. The energy from the impact breaks down and reforms molecules into new compounds. You can actually strip apart atoms and molecules, recombine them in more complex ways and make the stuff of life in an impact. Over millions of years, complex organic materials fill Earth's oceans. Then, around 3.5 billion years ago, the process that kick-started life began. Going back to the origins of life on Earth, it was a process. You began with large molecules that almost accidentally began to make copies of themselves. These became the first genetic material. Some of these larger molecules bound together and became the first sort of protocells. A protocell could represent this earliest pre-life stage of evolution. Protocells lack the full chemical machinery of modern cells. They're a simple cell membrane surrounding a glob of genetic material like RNA built from ribose and phosphorus. Now you have a barrier. Now you can actually control which chemicals come into the cell and which go out. And you protect the genetic code intact inside the cell. Once that happened, evolution began to run with it.