Nat Geo_Birth of Life
Transcript
00:00How did life begin?
00:04It's one of the most fundamental and difficult questions, and has challenged us for eons.
00:12For years, scientists have been investigating this extraordinary puzzle, trying to figure
00:18out how non-living matter could have come together to form a living thing.
00:25It's a quest that drives scientists to look for clues at the very ends of the Earth, and
00:32even deep into space, searching for the secret of life.
00:57Our planet teems with life.
01:00From the highest mountain to the deepest ocean, life is everywhere.
01:07But how did it begin?
01:12How did life emerge on what was once a lifeless planet?
01:18I think it's just one of those big questions.
01:19I mean, people like to know where they're from and how they got there.
01:25Science now hopes to be able to answer this age-old question.
01:29Huge strides have been made, and extraordinary theories are now being investigated by some
01:34of the world's leading scientists.
01:38Some propose that life emerged from a warm volcanic pool.
01:42Some suggest it began deep on the ocean floor.
01:46And others believe that it developed out in the blackness of space.
01:51This is the time to be alive and working on this field of origin of life, because we
01:55now have the confidence that there are scientific ways of tackling the problem.
02:01But there's still so many unanswered questions.
02:05We want to know what's on our planet.
02:07We want to know what's out there in the universe.
02:09We can't help but be fascinated by it.
02:13A first step to understand how life began is to try to figure out where it began.
02:21For generations, it was assumed that life began on the Earth.
02:27Then in 1903, the Swedish chemist Svante Arrhenius came up with an outlandish idea, panspermia.
02:39His theory is that life was created in space or on another planet, and the seeds of life
02:46dispersed out into new worlds.
02:55NASA scientist Scott Sanford investigates the possibility that life may have started
03:00in space.
03:02Panspermia is not totally impossible.
03:04We know samples of Mars have made it to the Earth.
03:08So if you had life on Mars, maybe it could have been delivered to us in that way.
03:15Even if panspermia did explain life getting started on the Earth, it doesn't explain
03:19how life got started in the first place.
03:21Sanford is not convinced that life itself was delivered to the planet.
03:25But he does believe that some of the starting materials, the building blocks of life, came
03:30from outer space.
03:33And their delivery system was a comet.
03:37Comets are delivering building blocks, they're not delivering living systems.
03:41They're delivering the components from which you might be able to make living systems.
03:46Comets are made up mainly of water and dust, with traces of carbon dioxide, methanol and
03:51ammonia, all frozen into a giant, dirty snowball.
03:56Sanford believes that they also contain small numbers of organic compounds, some of the
04:01building blocks of life.
04:03But there's a problem.
04:04How did they get there?
04:07These building blocks are almost always put together by living things.
04:11They are complex carbon-based molecules like proteins, carbohydrates and nucleic acids.
04:17So how did building blocks end up on a comet?
04:20Unlocking this riddle is the first step to understanding this theory of the origin of
04:25life.
04:27Sanford suspects that the unusual conditions on comets might lead to the formation of these
04:32organic molecules.
04:35So he sets up an experiment to test his idea.
04:40His first task is to recreate temperature conditions found in space where the comets
04:44roam.
04:46He has to achieve temperatures approaching minus 450 degrees Fahrenheit.
04:53To get an idea just how cold that is, look at what happens to air when it is cooled to
04:58below minus 300 degrees Fahrenheit.
05:02This is liquid air, basically.
05:04And you can demonstrate this by taking, let's say, a balloon, which is simply air in a container.
05:10When Sanford places the balloon in the liquid nitrogen, the air inside it cools and some
05:16of the gases turn into liquid.
05:18And then when I remove it, you can see the balloon is flat, but as it warms up, it will
05:22return into a gas and blow the balloon back up.
05:27This only happens because the liquid nitrogen is at a very low temperature.
05:30So if we were to put this nitrogen in the machine back there, it would turn into a solid.
05:35So in fact, this liquid nitrogen, as cold as it is, is positively tropical compared
05:39to the kind of temperatures we normally work at when we're doing these simulation experiments.
05:45Whoops, we popped it.
05:52Sanford introduces substances found on comets, such as ammonia, carbon dioxide and methanol,
05:57into his comet simulator.
06:00They instantly freeze.
06:05The sample is then bombarded with radiation from a hydrogen lamp.
06:14This simulates what happens when the comet receives radiation, for example, cosmic rays
06:19and gamma rays, and then passes close to the sun.
06:26Radiation and heat can transform the simple molecules into an array of organic compounds,
06:33ranging from proteins to amino acids.
06:37And Sanford uncovers the secret of how this transformation occurs.
06:45Some comets pass around our sun in highly elliptical orbits.
06:50When they are far from the sun, the molecules that have been irradiated are tightly locked
06:54in place, frozen into a solid chunk of ice.
06:58But when they get closer to the sun, things warm up, and the molecules get a chance to
07:02make their move and react.
07:04If you start to warm that ice up so that things can move a little, then they start to find
07:08each other and they react.
07:10But they don't react with their preferred partner, the person who would make them the
07:12most stable.
07:13They react with whoever they're next to, so you have these marriages of convenience.
07:17And as a result, the chemistry is not the kind of chemistry you think of, you know,
07:21in your freshman chemistry laboratory.
07:23Sanford shows how the building blocks of life can be created on a comet.
07:27But how do they get down to the surface of the Earth?
07:30A comet can deliver material to the surface of a planet in several ways.
07:35Of course, the whole comet can run into the planet, but that's a rather destructive way
07:38to do it.
07:42But more elegantly is to have the comet shed dust, as we see in a comet's tail, and that
07:47dust can then hit the planet's upper atmosphere, slow down without burning up, and then settle
07:52down to the surface.
07:53We have comet dust raining down on us all the time, even now.
07:57It's an incredible theory, that comets can rain down the chemistry set needed to start
08:02life.
08:07So in February of 1999, NASA launches a bold mission to intercept a comet and return with
08:13a sample.
08:15It's a chance to test Sanford's theory.
08:27After five years of flight, the probe, codenamed Stardust, arrives at its target, just behind
08:34a comet known as Wild 2.
08:39Dust particles from the comet's tail stream into a honeycomb collector filled with a specially
08:44designed aerogel.
08:49The sample, trapped inside the aerogel, is now sealed inside the return capsule.
08:57Two years later, in 2006, it slams into the Earth's atmosphere and crash lands into the
09:04Utah desert.
09:06The Stardust capsule survives the journey, and a team of scientists open it to examine
09:12the contents.
09:14To their great relief, the mission is a success.
09:18The aerogel inside the collector is peppered with tiny particles of comet dust.
09:29When scientists at NASA analyze the dust, they discover a vast array of complex organic
09:34chemicals, including aminos and hydrocarbons.
09:45This confirms Sanford's theory that comets contain building blocks of life.
09:50When you want to make life on a planet, you don't necessarily have to start from scratch
09:53on that planet.
09:55But that delivered to the planet from outer space may be compounds that can play important
09:59roles in getting everything going.
10:02It's amazing to think that life could have been kick-started using organic building blocks
10:07delivered from space.
10:10But one British scientist thinks that life itself was created on board a comet.
10:16Does that mean we are all descended from an alien life form?
10:22The search to find out how and where life began has puzzled scientists for generations.
10:30Chandra Wickramsingha, professor of astronomy at the University of Cardiff, agrees that
10:36comets had a role in the birth of life.
10:39But he believes that life itself began on a comet.
10:44Comets are the best places for life to originate.
10:50Our planetary system is surrounded by 100 billion comets.
10:56So you are multiplying the odds in favor of life starting on any one of those comets
11:02over that on the Earth by a huge factor.
11:06Wickramsingha proposes that the organic molecules found inside comets came together to make
11:12the first single-celled life forms.
11:15It's a bold and controversial theory.
11:18At the beginning we were regarded as heretics, would have been perhaps burnt at the stake
11:22if we lived in medieval times.
11:25We were certainly mavericks, no question about it.
11:28Wickramsingha's radical claim is that cold icy comets not only contain complex organic
11:34compounds but also the other essential ingredient for starting life, liquid water.
11:41The water forms when radioactive isotopes decay, giving off heat, melting the ice at
11:47the center of the comet.
11:49In 2005, NASA engineers choose the comet Tempel 1 for a daring mission.
11:59They plan to smash a probe into the comet, exposing the inner core.
12:07The results of the mission could prove Wickramsingha's theory.
12:13This mission will test the engineers' abilities to the limit.
12:17The 820-pound payload will have to travel across space to intercept a comet traveling
12:23at ten times the speed of a bullet.
12:30After six years of meticulous planning, finally on January 12, 2005, the Delta rocket carrying
12:37the Deep Impact probe launches into space.
12:44After a 268,000-mile journey, the impactor, about the size of a school desk, separates
12:51from the mothership and hurdles toward the comet.
12:55It scores a direct hit.
13:05These images from space and Earth-based telescopes show the moment of impact.
13:14For the first time, the secrets of what lies inside a comet are exposed.
13:27From a lofty perch in space, the Spitzer Infrared Space Telescope analyzes the unique signals
13:34given off by the compounds contained in the plume of comet dust.
13:41An amazing array of ice and fine dust particles are seen.
13:48But to everyone's surprise, the data also shows that the comet contains clay, the same
13:54kind of clay that can be found on Earth.
13:57And it's thought the only way to make clay is with liquid water.
14:05Wickramsingha believes that this is proof that at some point in time, Temple I did have
14:10a gooey liquid water interior.
14:14With liquid water and organic molecules, comets could be incubators for life.
14:21Comets like Temple I could be packed with microorganisms ready to seed life throughout
14:27the galaxy.
14:28We here on the Earth are connected to a much, much bigger cosmos.
14:33Life on the Earth is part of a connected chain of being that extends to the remotest corners
14:39of the galaxy, maybe to the remotest corners of the universe.
14:43We have our cousins out there.
14:46But whether life began inside a comet or on the Earth, what is still completely unknown
14:53is how it happened.
14:56How non-living organic molecules combined to create the first living thing, this big
15:01birth is one of the big unanswered questions in science.
15:07The ancients used to believe that life could emerge spontaneously.
15:13A frog could emerge from stagnant water or flies from rotten food.
15:18In the 19th century, Charles Darwin proposed that perhaps life emerged only once, many
15:25millions of years ago.
15:27He suggested that this big birth then led to all life today through a process of evolution.
15:36Starting with the simplest possible life form, more and more complex creatures evolve.
15:43As each new species emerges, it forms a new branch on the tree of life, and working backward
15:49in time, we can see our ancestors.
15:54Scientists propose that all life on Earth is descended from a single microscopic organism,
16:00what's known as the last common ancestor.
16:05Understanding this ancient microorganism will help scientists uncover the secrets
16:09of the big birth.
16:12But how can you unpick over four billion years of evolution?
16:16A good place to start is with fossils.
16:24Martin van Cranendonk is a geologist with the good fortune to live in Australia, home
16:29to some of the oldest rocks in the world.
16:34And among these ancient rocks, van Cranendonk claims to have found fossil remains of an
16:39unusual organism that lived three and a half billion years ago.
16:47These are our great, great, great, great, great, great, great grandfathers and grandmothers.
16:52These are fossil stromatolites, about 3.5 billion years old, and they were deposited
16:58on the shoreline of an ancient ocean.
17:00They're the oldest evidence for life on Earth.
17:05Stromatolites are rock-like buildups of microbial mats clumped together in the ancient seawater.
17:12And they were composed of microbes that colonized the ancient seafloor on top of just wave-rippled
17:17sandstone.
17:19Their fossilized remains now show that life was already well underway three and a half
17:25billion years ago.
17:28What was it like?
17:29Well, after billions of years, the sea has changed, but modern stromatolites are still
17:35alive today.
17:37Van Cranendonk travels 600 miles across the Australian outback, here to Shark Bay.
17:45These are some of the largest stromatolites in the world, and they grow up to about a
17:49meter high.
17:51The stromatolite domes are formed by communities of microorganisms like bacteria and algae.
17:57They bind together with fine sediment to form layer upon layer of rock.
18:03Living on the mounds, the microorganisms carry out a process called photosynthesis.
18:09Using energy from sunlight, they turn carbon dioxide and water into energy, and in the
18:14process, they give off oxygen.
18:20But even though stromatolites date back at least three and a half billion years, scientists
18:25believe that they are still not the first step in the creation of life.
18:30To find that, we have to travel back even further in time.
18:37So far, there is no fossil record for this ancient period.
18:41But one scientist thinks she can discover what these first forms of life were like.
18:47It's a quest that will take her to one of the most remote places on Earth.
18:55There are estimated to be three billion separate species of microorganism on Earth, but less
19:00than one percent has so far been discovered.
19:04Hunting them down is NASA biologist Dr. Lynn Rothschild.
19:08All you have to do is look under a microscope, and they are so incredibly cool.
19:16When I was eight years old, I looked through a microscope and I just fell in love.
19:20I realized that they are absolutely at a crucial step to study evolution, and so that's the
19:25direction I went with my own research.
19:27So I get to have fun and get to study something important.
19:33Rothschild is traveling 14,000 feet above sea level to the Altiplano in southern Bolivia.
19:41It's a hostile landscape where temperatures regularly drop to minus four degrees Fahrenheit.
19:47It also has some of the highest recorded levels of ultraviolet radiation on Earth.
19:55But it could be the perfect place to find a close relation of the microbe that gave
20:00rise to all life on Earth, the last common ancestor.
20:07Getting up into the Bolivian Andes here seems like the last place on Earth we'd go to look
20:11for early life, but we found organisms up here that are probably like the earliest organisms
20:17on Earth.
20:18Hey, maybe we're even going to find ones that are similar to the last common ancestor of
20:23all of us.
20:27Rothschild scours the Earth, looking for microbes living in extreme conditions.
20:32It turns out that these microorganisms, called extremophiles, may be closely related to the
20:38most ancient forms of life.
20:41You have to really go to unusual environments to find ecosystems that are just microbial.
20:47I hope that those organisms prove to be extremely deep branch, in other words, organisms that
20:53seem to be much closer to our last common ancestor than you and me.
20:59The next stop for Rothschild is a landscape of boiling mud.
21:04Superheated steam, borne by shallow bodies of magma, shoots out of the ground.
21:10Hot geysers like this would have been present on early Earth, so Rothschild hopes to find
21:15life in these extreme conditions.
21:18The earliest common life form that we're all descended from lived in very high temperatures.
21:26Rothschild works meticulously, logging the exact temperature and position of each sample
21:31she takes.
21:33A great challenge for scientists trying to understand how life began is that even the
21:38most basic microorganisms alive today are still incredibly complex.
21:44When looked at on a microscopic scale, the intricate complexity of a cell is clear.
21:51From its ability to reproduce to the way it converts energy, every process in the cell
21:56is carried out by an extraordinary interplay of complex organic molecules.
22:02But the ancient microorganisms that Rothschild is tracking down in Bolivia could give us
22:08clues to the nature of the first organisms.
22:14As the sun dips below the horizon, the temperature plummets.
22:20Rothschild takes refuge from the harsh environment where these modern cousins thrive.
22:26Overnight, the temperature drops well below zero.
22:32Next morning, the vehicle won't start.
22:41Dr. Rothschild also feels the effects of the thin air 14,000 feet above sea level.
22:46It's not much fun for us when we drop our oxygen levels just a few percent, but on the
22:51early Earth there was no free oxygen whatsoever.
22:55So just to time travel back just a little bit is a huge price to pay for us humans.
23:02Rothschild's next hunting ground is the Laguna, Colorado.
23:07Its red color gives a clue about the very unusual type of microbe she hopes to find.
23:13This part of Bolivia boasts one of the highest UV counts of anywhere in the world.
23:18The thin atmosphere at this high altitude only partially blocks the sun's radiation,
23:23making living conditions here closer to those of the Earth four billion years ago.
23:29When life first arose, the level was incredibly high, vastly higher than we see today.
23:35And so by coming up here, even though we're not able to simulate the early Earth, because
23:40of course we couldn't live under those conditions, at least we can time travel a step backwards
23:45and get some idea what it would have been like for organisms in the past.
23:50Dr. Rothschild measures the levels of UV radiation.
24:01These readings are amazing.
24:03This is the middle of winter and already we've got extremely high UV readings, and I bet
24:08they're going to be even higher by noon.
24:10It's just amazing.
24:12Readings here can reach twice the average level of a California beach.
24:17And just as our skin is in danger from too much UV when we lie in the sun, the microbes
24:22that live here in Bolivia are at constant risk.
24:27Rothschild carries out a simple experiment to find out just what they are up against.
24:31What I'm doing now is looking at the effect of ultraviolet radiation from the sun on naked
24:36DNA.
24:38The naked DNA is a solution containing DNA molecules stripped of any protection from
24:44the cell that would normally surround it.
24:49And then what I'm going to do is seal it up and leave it out in the sun for a few hours.
24:55After just two hours of UV bombardment, the DNA molecules show severe damage.
25:01Levels of UV on the early Earth would have been around a hundred times higher.
25:06Many scientists think that our last common ancestor had to live in the dark depths of
25:11the ocean or buried under the ground for protection.
25:14But the microbes here manage to survive.
25:18Their red pigment helps protect their DNA.
25:23Just like we sun tan in the summer to protect ourselves, these organisms produce red pigment.
25:29But even though we know that UV radiation is very damaging to the DNA in all living
25:35organisms, there's also a flip side.
25:37UV radiation may have helped to drive evolution.
25:41It might even have had a role in kick-starting the big birth and the evolution of the last
25:46common ancestor.
25:48Ultraviolet radiation produces mutations.
25:51Now mutations aren't all bad.
25:54Without mutations we wouldn't have evolution.
25:56You need to have change in the genetic material to have change in the organisms.
26:02Our world, of course, would be very different if nothing had ever changed.
26:06We wouldn't be here.
26:08Dr. Rothschild's study of these microbes will help scientists understand how the first
26:14organisms survived the hostile conditions on the early Earth and give a clearer picture
26:20of what our last common ancestor was like.
26:23But another great mystery remains.
26:26How did the last common ancestor form?
26:29What is the link between the building blocks of life and the big birth?
26:34It turns out that some of the answers to that great puzzle may emerge from an extraordinary
26:38place in the depths of the ocean.
26:44The question of how life began has troubled scientists for centuries.
26:51Darwin's theory of evolution explains how species evolved, but we still do not understand
26:57how the first living thing was created, how evolution began.
27:03Creating life had been the stuff of science fiction.
27:16Then in 1953, a bold experiment began the modern scientific investigation into the origin
27:23of life.
27:26Stanley Miller tries to recreate the conditions of early Earth when scientists think life
27:31began.
27:33John Chalmers was an associate of Miller and now works in his lab.
27:38Stanley's was the first one to really have a research program directed towards the origin
27:43of life.
27:44It changed the ideas about the origin of life from mere speculation to a research program.
27:52Since Darwin's time, a lot has been learned about what the planet was like four billion
27:56years ago.
27:58It was an extraordinarily violent time.
28:01The Earth had only just formed and was continually bombarded by meteors, asteroids, and comets.
28:07And the atmosphere was very different to what we're used to today.
28:15Stanley Miller's experiment recreates these conditions in the lab.
28:19The flasks contain what Miller believed were the key components of the Earth's early atmosphere
28:25methane, ammonia, and hydrogen.
28:28The warm water represents the early ocean.
28:32But the key component was a Frankenstein-like bolt of lightning, a simulation of the electric
28:38storms that would have raged on the young planet.
28:42Miller started the experiment, and the next day, when he was in the lab, he discovered
28:48The liquid in one of the jars had changed color.
28:53And when he analyzed the substance, he found something remarkable.
28:58It was packed with chemicals called amino acids, what biologists and chemists call the
29:03building blocks of life.
29:06Of course, they're very important because all terrestrial life is made up of amino acids.
29:12Miller's experiment showed how simple molecules could be transformed into the building blocks
29:17of life.
29:20But these building blocks are still a long way from any kind of life.
29:25How do these so-called building blocks create life?
29:30One clue was to come from a very special package that was used to create life.
29:36In September 1969, the residents of Murchison in southern Australia were startled by a loud
29:42bang.
29:45A 200-pound meteorite fell into their village, showering it with rock.
29:51These small pieces of space rock have been the object of the experiment.
29:58Dave Deamer at the University of California, Santa Cruz, managed to get his hands on a sample.
30:04There was a flash of light in the sky and a rolling thunder, and a few minutes later, the stones of the
30:10meteorite just fell all over Murchison, Australia.
30:14And there was a strange aroma in the air.
30:18It was a very strange smell.
30:22Deamer extracts a compound from his small piece of the meteorite, which has the same aroma.
30:28So when I'm smelling this, I'm smelling an aroma that's 4.57 billion years old.
30:34That's the age of the solar system.
30:38Now, it's the oldest aroma on Earth, much older than the Earth's surface by about half a billion years.
30:44And I'm smelling it.
30:49It's got a kind of an old cigar butt smell or dirty sock smell.
30:55The smell gave Professor Deamer a clue that the liquid he had extracted from the meteorite was packed with
31:01organic chemicals.
31:05When he took this extract and put it under the microscope, he saw something extraordinary.
31:11We see beautiful little glowing vesicles that look just about the right size for a bacterial cell or larger cells.
31:19The extract from the meteorite contained molecules that were able to form tiny bubbles or vesicles.
31:27These vesicles looked just like the outer membrane of a small microbe.
31:33Some of the compounds were able to form membranous structures, beautiful little cell-like compartments.
31:39And we proposed then that this would be a way for the first cell membranes to have come about on the early Earth
31:45from these sorts of molecules.
31:49Perhaps these compounds, delivered from space, were the first steps on the road to life.
31:55But in order to form membranes, these molecules needed to have been in fresh water at just the right concentration.
32:03One idea of how this could happen is that they fell near a geyser in a warm volcanic pool.
32:09As the water droplets evaporate, the molecules start to become more concentrated and form tiny vesicles.
32:20Perhaps these self-assembling cell membranes, delivered from space, were the first steps on the road to life.
32:28The transformation of non-living chemicals into the first living cell.
32:34So I don't have any trouble imagining that this would be a common process,
32:38and this formation of compartments would have been the first step towards cellular life.
32:44But a simple bubble-like membrane is still a long way from being alive.
32:49Scientists still have to figure out how all the complex components that make up a cell
32:54came together to create the Big Birth.
32:58This time, the answer came from a lost world that had lain undiscovered for nearly 4 billion years.
33:06In 1977, a team from the Woods Hole Oceanographic Institution
33:11were looking for signs of volcanic activity on the seafloor, 8,000 feet under the surface of the ocean.
33:25The Big Birth
33:34Alongside these hydrothermal vents, they also found an incredible undersea world.
33:41Cut off from the light of the sun, it was thriving with species of plants and animals that had never been seen before.
33:49Until that moment, many scientists thought that all living ecosystems depended on photosynthesis.
33:56But here was a unique environment, completely cut off from sunlight.
34:02This strange underwater world captivated Carnegie Institute researcher Dr. Robert Hazen.
34:08Imagine how exciting it was to descend in the submarine into the black depths of the ocean,
34:13where people thought there was nothing.
34:15And they find these hydrothermal vents, these places where volcanic fluids are pouring out of the ocean floor,
34:22and not only that, because of all that energy, chemical energy, heat,
34:27there's living things, there's ecosystems, life abounds, microbes and tube worms and clams
34:32and all sorts of strange crabs and other things.
34:35After searching at these crushing depths, they found unexpected chimney-type stacks
34:41emitting plumes of scalding hot water.
34:44He had a hunch that these hot vents could be producing some interesting chemistry.
34:49Perhaps they could have produced the organic building blocks of life.
34:54He set up an experiment to find out.
35:01It's easy to do these experiments.
35:03You see, you just take a little bit of mineral, a little bit of chemicals, you put them in a gold tube and seal it up.
35:08You put that tube at high temperature and high pressure just for a few hours.
35:12Open it up, there's all this stuff inside.
35:16And the stuff he found turned out to be far more exciting than he'd ever imagined.
35:22When we did these experiments, we thought we'd find nothing really very interesting,
35:25just a few simple molecules that we could analyze and maybe write a little paper on.
35:29We were wrong.
35:31This stuff had the strongest aromatic smell.
35:34At lower temperature, it was like molasses.
35:36And at a little bit higher temperature, 350 degrees or so, it smelled exactly like Jack Daniel's whiskey.
35:42People would come by the lab and say, boy, you guys must be having fun.
35:45What are you doing?
35:47We were making the stuff of life.
35:49This strange aroma gave Hazen the clue that he, too, had created organic molecules.
35:56Once again, these molecules assembled into tiny membrane-like vesicles.
36:02They were behaving much like the molecules extracted from the Murchison meteorite.
36:07So Hazen had discovered that it might be possible to create these cell-like membranes close to the deep sea vents.
36:15But other researchers believe that this strange underwater world was capable of providing more than just a cell membrane.
36:23They believe that these warm vents were where all life's component parts came together.
36:30They claim the big birth happened here, at the bottom of a primordial ocean.
36:36In order for the big birth to occur, scientists believe that certain essential elements had to work together.
36:43For example, life needed a container, which came in the form of a membrane.
36:48It needed some way to reproduce.
36:51Today, this process is achieved through an extraordinary chain of organic molecules, DNA.
37:00Life also needed an engine, a chemical process called metabolism that converts fuel into usable energy.
37:09According to Dr. Michael Russell at NASA's Jet Propulsion Laboratory, it's metabolism that came first.
37:16Life has a job to do, basically.
37:19I could put it like this. You could have a modern car with an engine and a computer inside.
37:25But if you take the computer out, the car will still work.
37:28But if you take the engine out and just leave the computer, it won't.
37:31The computer is the kind of regulator, but the engine is what's really important.
37:35So that's why we think there has to be an engine first, and that engine is metabolism.
37:40Today, the engine of metabolism that powers every living thing is an extremely complex chemical reaction.
37:48But intriguingly, Russell thinks we all have traces of the first and simplest metabolic reaction buried within our cells,
37:57like living fossils that point to where life began.
38:01We can trace the kind of chemicals in the early Earth and see them even to this day.
38:07So, for example, there are iron sulfides in our skin, for example,
38:13and that's the little bit of rock that, to our mind, reminds us where we all come from.
38:17And according to Russell, this is where we come from.
38:21Deep sea vents made largely of iron sulfide.
38:25He believes that this and other compounds kick-started metabolism,
38:30acting as a catalyst to enable a reaction between hydrogen gas streaming out of the vents and carbon dioxide dissolved in the water.
38:40But eventually, this simple reaction evolved to become the complex chemical engine, metabolism.
38:48And eventually, the metabolism required DNA, because it did need a regulator, it did need a computer,
38:54but to start with, we just needed the engine.
38:57At some point, the metabolic engines acquired some bodywork, a membrane.
39:04Russell's theory gives one idea of how a simple chemical reaction
39:10could have driven the creation of more and more complex organic molecules
39:15and eventually created the first living cell and all life on the planet.
39:21There are still many gaps, but slowly the clues to the origin of life are beginning to emerge.
39:29But now a scientist claims that he might be able to put all these clues together using the latest laboratory techniques.
39:36He hopes to start life from scratch, something that hasn't happened on this planet for the past four billion years.
39:45Scientists are striving to answer the great question of how life began.
39:50It's a quest that has taken them to the remotest corners of the globe and deep into the inner workings of the cell.
39:58But as one group of researchers look back four billion years to the Big Birth,
40:03another group of scientists is looking for answers.
40:07But as one group of researchers look back four billion years to the Big Birth,
40:12another group of scientists is looking to the future.
40:17Around four billion years after nature first created life, scientists are now able to redesign it.
40:26The key to this extraordinary power is their understanding of one extraordinary chain of molecules, DNA.
40:35DNA is made up of four simple base molecules, adenine, guanine, cytosine, and thymine.
40:43The arrangement of these four molecules stores the information needed to create life.
40:48It's this natural technological innovation that's at the heart of all life on Earth today.
40:54And Tom Knight, a computer expert at MIT, wants to reprogram DNA to make new kinds of life.
41:01Fundamentally, there is one technology of life right now.
41:07And that technology, perhaps, was invented billions of years ago.
41:13And all we are doing is changing little bits and pieces of that technology.
41:20For thousands of years, mankind has harnessed nature, rearing livestock, and growing crops.
41:27Selective breeding has improved yields and created higher quality.
41:32But now bioengineers want to take a step further.
41:37Instead of just improving nature's original designs, some want to re-engineer life, creating so-called Life 2.0.
41:47We can now think about growing things which are not food.
41:53We could think about growing things like nanotechnology-level substrates for electronic circuits.
41:59I have a student who's looking at placing atoms precisely in patterned arrays on silicon surfaces.
42:10These new life forms might be able to manufacture products for us cheaply and easily.
42:16It's a little bit like going to the store and buying a cell phone.
42:19And what comes in the package with the cell phone is not just the cell phone, but also the factory which makes more cell phones.
42:26Re-engineering biology will bring a new era of exciting possibilities.
42:31But it will also bring new risks and responsibilities.
42:35And this is the shocking result.
42:37Any new biological factory released into the environment could have unforeseen consequences.
42:44A living factory with the ability to reproduce itself could be unstoppable.
42:50This town is in danger.
42:52But for the moment at least, this nightmare scenario is far away, because these new organisms are a long way from leaving the lab.
43:00As well as hoping to create new forms of life, bioengineering is now giving science a chance to explain the mystery of the big birth.
43:10Instead of having to attack the problem from the bottom up using basic chemistry, or from the top down by unraveling evolution,
43:18scientists can now use the technology of bioengineering to try and put the building blocks of life together themselves and create a living cell.
43:27Jack Szostak at the Harvard Medical School is a leader in the field.
43:32We're making the assumption that, OK, someday people will figure out how you make the building blocks you need.
43:38What happens if you have the building blocks?
43:42How do you put them together?
43:44How do you organize them so that they start acting like a cell?
43:48Szostak and his team at the Harvard Medical School have set themselves the task of building a living system in the lab.
43:57Well, we'd like to understand that transition from the chemistry of making molecules to the way that these molecules work together to give us life.
44:10So we would like to build a simple living system as a way of trying to understand that transition.
44:17Scientists believe life evolved over millions of years.
44:21Szostak is hoping to use the latest bioengineering techniques to do it in considerably less time.
44:28We want to make things go fast, as fast as possible.
44:32So we're making the building blocks ourselves and putting them together in just the right environment.
44:38We would like to get everything going in the timescale of a few years, which is speeding things up by a factor of, say, 100 million.
44:48Szostak hopes to create a working cell from simple building blocks.
44:53The only way he can do this is by boiling down a cell to its simplest possible components.
44:59One of the things that's made the origin of life very hard to think about for decades is the fact that all of the life we're used to seeing every day is so complicated.
45:11A big challenge is to create a simpler version of the complex DNA molecule.
45:16Szostak believes the answer is RNA.
45:19RNA is also made of four base molecules.
45:23But instead of being wound into a double helix, RNA has only one strand.
45:28Now, if you go back to thinking about really early simple cells, you could store some information in just RNA.
45:38You don't need to have DNA.
45:40Szostak's goal is to create a simple self-replicating RNA molecule.
45:46This, in theory, would eventually form a simple cell capable of duplicating itself.
45:52If successful, he may be able to start a process of evolution.
45:57We're interested in the beginnings of life, the transition from chemistry to the beginnings of biological behavior.
46:04And to me, the important thing that we have to think of in that transition is the beginning of evolution.
46:13And once evolution can begin, more and more complex cells will be created by the process of natural selection.
46:20Eventually, Szostak hopes to be able to evolve a simple self-supporting, self-replicating biological system.
46:28Some might call it life.
46:33Szostak's work might one day connect the dots between the building blocks of life and the last common ancestor.
46:40And show how inert chemicals can combine to create life.
46:46If he succeeds, it will be the crowning moment of over a century of research by some of science's greatest minds.
46:55Finally, we might solve the great riddle of how life began on our planet.