How Did We Get Here?

from Through the Wormhole; Life is full of mysteries, but the most compelling mystery is life itself. Scientists are still trying to solve this age-old conundrum, how simple chemicals were somehow transformed into living molecules, molecules that eventually evolved into you and me. But the answers may at long last be close at hand, and more surprising than we could have ever imagined. Is this what happened on Earth billions of years ago? Did a spark turn inanimate matter into something that can grow, reproduce, and evolve, something we would define as alive? It's a puzzle that science has been struggling to piece together. We have a very good theory of life's evolution, but we have no agreed theory of life's origin. We don't know how a mix of nonliving chemicals turns itself into a living thing. That's a very good question. Because no one's actually experimentally converted the nonliving into living, we don't know precisely what we need. It's a question that may never find an answer. But the scientists who dare to probe our moment of creation are leading us on a fascinating journey to an unexpected destination. To solve the mystery of our genesis, we have to rewind evolution, go back to the time and the place where the first living things came to be our solar system more than 4 billion years ago. Geologist Stephen Mojzsis, from the University of Colorado, is traveling back in time to the Hadean, trying to discover evidence of life there. Stephen has developed a computer simulation to prove our planet could have remained hospitable to life even during the intense bombing campaign it endured in the Hadean 4 billion years ago. In 1953, two intrepid chemists try to answer this question. Stanley Miller and Harold Urey designed an experiment to simulate our planet soon after its birth.The results would turn out to be so groundbreaking that the apparatus has been preserved at the Scripps Institution in San Diego by their former student Dr. Jeffrey Bada. Jen Blank is sure of that because she believes life needed something else to get started on earth and it came from the sky at 20,000 miles per hour. We know that in the early history of the solar system, comets were slamming into the planets, and maybe this would have been a vehicle for delivering prebiotic materials to the early earth. In 1999, NASA sent a spacecraft called Stardust to snag a piece of a comet and bring it back to earth. When scientists analyzed the material, they discovered that it contained amino acids, the building blocks of protein, the very tissue of life.One of the big outstanding questions is whether or not organic compounds coming in on a comet and slamming into the earth could survive the harsh conditions of that delivery experience. Jen Blank works at SETI, the Search for Extraterrestrial Intelligence, but she's not interested in E.T. so much as alien molecules. So she's developed a computer simulation to see what happens to them on impact. Comets that hit earth head on are not very promising. The collision almost completely incinerates them. In this movie, the blue colors are cold, and as you go toward the red, it gets hotter and hotter. Jen's high-powered experiment suggests comets may have bludgeoned early Earth one step closer to life. They helped amino acids join together, perhaps even forming primitive proteins. We're actually harnessing the power of the impact to build larger biologically relevant molecules. At the top of the wanted list is DNA, the molecule that carries our genetic identity. Jack Szostak at Harvard Medical School is on a quest to solve one of life's biggest mysteries, how the earliest life-forms walled themselves in, defined "me" from "not me." At the University of Manchester in England, chemist John Sutherland is trying to discover how DNA came to be, the key to discovering how we came to be. For me, the really interesting point here is the transition between chemistry and biology. It's always been assumed that you need to have an informational molecule. Paul Davies is one of the world's leading cosmologists. He's the first to admit he's not a biologist, but he's not afraid to venture into their territory and ask questions no one else thought to ask. We don't know how a mix of nonliving chemicals turns itself into a living thing. We don't even know whether this is a very likely sequence of events or very unlikely sequence of events. But let's suppose it's very likely. Then shouldn't it have happened many times over right here on earth? Paul's term for possible homegrown alien life is "the shadow biosphere." And he has a plan for how we might discover it.

  How Did We Get Here? Find answers from scientists Stephen Mojzsis, Jeffrey Bada, Jen Blank, Jack Szostak, John Sutherland, Paul Davies, Felisa Wolfe-Simon, Ben Weiss
Spacecraft called Stardust to snag a piece of a comet

Spacecraft called Stardust to snag a piece of a comet

DNA came to be, the key to discovering how we came to be

DNA came to be, the key to discovering how we came to be

Mono Lake in California

Mono Lake in California

ALH84001 is a Martian meteorite

ALH84001 is a Martian meteorite
  We could look at places on earth where conditions are so extreme, so harsh, they're beyond the reach of life as we know it to see if there's some hardy alien type of microorganism living there. One of Paul's colleagues, Felisa Wolfe-Simon, is looking for a shadow biosphere by digging through the mud. So, the life that we might find in, let's say, this much mud, we could have billions of different microbes that are as different as you and I are to a mosquito. In fact, we are more closely related to mosquitoes than they are to each other. That's how different these microbes are. Felisa works at the U.S. Geological Survey in Menlo Park, California, but it's NASA's astrobiology program that pays her to study mud. So, one of the things I always do when I go to a new environment, regardless of where it is in the world, I take samples to set up a Winogradsky Column. A Winogradsky Column is like a potted history of the earth, a breeding ground for all kinds of strange microbes. You take your sample of mud and you just fill, say, a glass jar, and you put it in the window. Felisa was not disappointed when she dug in the mud of Mono Lake. She did, indeed, find bugs that could survive these highly toxic doses of arsenic. If Felisa's bugs are the offspring of a second genesis here on Earth, then life could be a cosmic norm. We would not be alone in the universe. But that leads us to an even more intriguing possibility, life on Earth may not be from Earth at all.     The scientific quest to discover the origin of life has revealed something totally unexpected. There might have been more than one genesis. Our planet might harbor not one, but two or more trees of life, each growing from a separate seed. Where did these seeds come from? That question is forcing us to reassess who we really are because the answer could be out of this world. Planetary scientist Ben Weiss has pieces of another world in his lab. They are rocks that have traveled from Mars to Earth, and he thinks microscopic Martians may have hitched a ride on some of them. About a ton of Martian rocks lands on earth every year, and over the history of the solar system, billions of tons of materials have been transferred. So it's possible that we, in fact, are Martians. 4 billion years ago, when Earth was being pounded by meteorites and comets, so was Mars. Shrapnel from those impacts was flying all over the early solar system. Scientists have found one Martian rock that dates back to those days of interplanetary violence. It's called ALH84001. You and I are the latest chapter of a story that's been unfolding for billions of years. How that story begins is still unknown. Did comets seed the Earth with the raw ingredients of life? Was Mars our original birthplace before we jumped to a new planet? Or are we the Earth's second or third incarnation of life? Aliens might be living among us. We might all be Martians.
List with pictures of the scientists, in order of their appearance in Through the Wormhole How Did We Get Here? documentary, who share us their knowledges:
Stephen Mojzsis

Stephen Mojzsis (geologist, University of Colorado)
  Jeffrey Bada

Jeffrey Bada (chemist, Scripps Institution in San Diego)
  Jen Blank

Jen Blank (scientist, Search for Extraterrestrial Intelligence)
  Jack Szostak

Jack Szostak (chemist, Harvard Medical School)
  John Sutherland

John Sutherland (chemist, University of Manchester)
  Paul Davies
Paul Davies (one of the world's leading cosmologists)
  Felisa Wolfe-Simon
Felisa Wolfe-Simon (Geological Survey, Menlo Park)
  Ben Weiss
Ben Weiss (planetary scientist)