NOVA scienceNOW w/ Neil deGrasse Tyson: Where did we come from?

Summary

In this captivating episode of NOVA scienceNOW, host Neil deGrasse Tyson takes us on a journey to uncover the origins of our planet, life, and our own species. The program delves into the formation of the solar system, the genesis of life through groundbreaking experiments, and the evolution of humans, including the peculiar role lice play in our history. Join the adventure and discover how cosmic events, chemical processes, and even tiny parasites have shaped our existence.

Highlights

• Neil deGrasse Tyson embarks on a meteorite hunt in Arizona's deserts. 🪨
• Scientific insights suggest a supernova could be behind the formation of our solar system. 🌟
• The fascinating story of RNA and its implications for life's origins is unveiled. 🧬
• Lice are used as evolutionary tools to track human history and adaptation. 🐜
• Discover the potential to erase memories and its implications for identity! 🧠

Key Takeaways

• Discover how a supernova might have triggered the formation of our solar system! 🌟
• Learn about the groundbreaking experiment that could explain the origins of life! 🧪
• Explore how lice have played a surprising role in tracking human evolution! 🐜
• Find out about the brain's ability to erase memories and its impact on identity! 🧠
• Uncover the scientific quest to understand our cosmic and biological origins! 🌌

Overview

The episode kicks off with Neil deGrasse Tyson exploring the Arizona deserts on a mission to find meteorites. This treasure hunt not only aims to collect these ancient rocks but also uncovers the cosmic narrative of our solar system's dramatic beginnings, potentially linked to a supernova explosion.

From the cosmic to the microscopic, we shift focus to the origins of life on Earth with groundbreaking research on RNA, one of the building blocks of life. Scientists replicate early Earth conditions in the lab and reveal a possible recipe for life's genesis, providing a new understanding of our biological roots.

Rounding out the episode, the program takes an unexpected turn with the exploration of human evolution through the lens of, surprisingly, lice. These tiny parasites offer insights into our past, such as when we started wearing clothes, and contribute to answering profound questions about our identity and memory's role in defining who we are.

Chapters

• 00:00 - 00:30: Introduction In the introduction of the Nova science now series hosted by Neil deGrasse Tyson, the season is centered around exploring six big questions. This specific episode focuses on the question: 'Where did we come from?' It delves into the origins of the Sun, the planets, and Earth, investigating the events that triggered their creation. The journey involves searching for rare discoveries that shed light on this cosmic mystery.
• 00:30 - 08:00: Searching for Meteorites The chapter 'Searching for Meteorites' discusses the exploration and discovery of meteorites which have descended from the sky, providing evidence of cosmic events. It suggests a more violent cosmic birth than previously thought, and delves into the origins of life on Earth. It metaphorically compares the creation of life to cooking, emphasizing the challenge of recreating the building blocks of life in a laboratory to understand how life began billions of years ago.
• 08:00 - 26:00: Chemical Origins of Life The chapter explores the possible chemical origins of life, hinting at groundbreaking research that may have retraced a critical step in the emergence of life. It emphasizes the significance of looking at problems from different perspectives, suggesting that new insights into our origins and evolution can be discovered through innovative approaches. The chapter also touches on unresolved questions in human evolution, which these new perspectives might help address.
• 26:00 - 45:00: Lice and Human Evolution The chapter opens with a provocative statement about lice, suggesting that simply mentioning them causes alarm in schools.
• 45:00 - 80:00: Memory and Identity The chapter explores the concept of memory and identity, emphasizing the alarming notion that erasing someone's memory can effectively erase their identity. This idea raises significant questions about the essence of who we are and how much of that is tied to our memories. Furthermore, the chapter hints at broader discussions regarding our origins and existence, supported by scientific exploration and inquiry, as featured in the Nova science program.
• 80:00 - 83:00: Conclusion The conclusion chapter takes a reflective glance at the journey of human existence, emphasizing the significance of various historical and cosmic events that have shaped us. It highlights the seemingly trivial and grand events that were crucial in bringing humanity to its current point in history. The chapter underscores the unique and peaceful position of Earth in the cosmos, orbiting the sun in a near-perfect circle, which has allowed life to evolve and thrive over billions of years.

NOVA scienceNOW w/ Neil deGrasse Tyson: Where did we come from? Transcription

• 00:00 - 00:30 hi I'm Neil degrass Tyson your host of Nova science now where this season we're asking six big questions on this episode where did we come from the Sun the planets our home the Earth what triggered their creation I went on the hunt for rare
• 00:30 - 01:00 evidence where are we that's been dropping from the sky got something it sounds really big and it's pointing to a cosmic birth more violent than we ever imagined also life it's been around for billions of years but how did it begin you know what you want to make but you don't have a recipe for decades we've been trying to cook up the building blocks of life in the lab and recreate the origins of it all but the parts
• 01:00 - 01:30 didn't seem to fit together until now we were the guys who stood back and looked at it in a different way one team may have retraced a key step in the birth of life itself how did they do it and what about us and our Origins they say some of the hairiest questions in human evolution could be solved by these guys headlight Li have been with us and evolving with us for as long as we have existed see right there that comes
• 01:30 - 02:00 straight out oh my goodness oh my good if you want to hit the red alarm button in school all you have to say is the word life these tiny blood suckers are rewriting human history we cannot neglect the lies also where does your identity come from your memory of course my memories Define me this brain researcher made a major discovery about how memories are formed and even how they can be
• 02:00 - 02:30 erased you can wipe out who you are and that's an alarming thing all that and more on this episode of Nova science now funding for Nova science now is provided by where did we come from how
• 02:30 - 03:00 did we get here our history in the cosmos and on planet Earth was shaped by countless events some obviously epic some seemingly trivial yet all vital in getting us to this point here and now the people we are today one of the reasons we're here that we exist at all is that Earth cosmically speaking is in a relatively peaceful place orbiting our sun in a near Perfect Circle our Cosmic neighborhood has granted life billions
• 03:00 - 03:30 of years to evolve mostly undisturbed but where did this stable piece of real estate come from we know that stars and planets Once Upon a Time all started out like this with enormous clouds of gas and dust how we got from here to here we haven't exactly figured out yet but lately we found some intriguing new evidence that tells us our peaceful solar system may have started with a violent event
• 03:30 - 04:00 [Music] if we want to unlock the secret behind the origin of our sun and its planets it would be helpful to find some remnants from the birth itself an event that took place about 4 and 1/2 billion years ago luckily there are some rocks left over from our earliest days asteroids formed during our Solar System's [Music] birth occasionally some of them drop in
• 04:00 - 04:30 on Earth and when they do they're called [Music] meteorites I've come to the deserts of Arizona to try to track down some rare space rocks
• 04:30 - 05:00 where are we perfect place for hunting for meteorites Southern Arizona look at this couldn't ask for a better place open desert it's an old Lake Bed and so the sand is being blown away like right now and it's exposing the rocks that are on the ground and it just so you just looking for something that looks a little bit different and you'll know it when you see it well I'm from the city so all this looks different I'll be hauling everything back for you so how do you spot a meteorite well sometimes the signs are hard to miss
• 05:00 - 05:30 some leave deep impacts in Earth like one that blasted Arizona's baringer crater 50,000 years ago but most leave less obvious traces they can be as small as dice reduced to a rocky Cinder then they have to be distinguished from Earth's rocks one trait stands out in nearly all meteorites metal they've got it so the best way to find a meteorite is to hear
• 05:30 - 06:00 it [Music] first no question about that one and we can pick far out Reuben Garcia brought along some samples and showed me why a metal detector is the meteorite Hunter's best friend it's what meteorite Hunters call a Halo you don't have to swing over the meteorite you get in that Halo area and you hear the sound going up you get in the zone we like that
• 06:00 - 06:30 this is very typical as meteorites go this is called an ordinary condite and and about 82% of all meteorites that fall are going to be of that variety condres are rocky meteorites that haven't melted completely that's what we want to find there's more we've actually got what we call meteorite canes and this is where these are golf clubs I know this is a go this is a golf club with a very strong in this case two very strong magnets
• 06:30 - 07:00 attached go ahead and test it with the can and see what you got yes music to my ear I have found a meteorite you certainly have I keep this one we found it are you guys ready to find some meteorites let's go find some go do it hunting for meteorites is like trying to find a pebble on miles of beach one of The Graduate students has found something watch the cactus oh
• 07:00 - 07:30 thank [Music] you it sounds really big oh there it is piece of farm equipment that is your first metor wrong congratulations meteor wrong meteor wrong but I wanted meteor right so all we do is fan out now and just fan out and just this is a whole area here it could be anywhere it's got
• 07:30 - 08:00 something this has no characteristics of a meteorite H this meteorite hunting is a lot harder than it looks and some days you don't find any so they told me this was the remains of a meteorite hunter that came out unprepared this is one of those days don't tell them what you find out here luckily over the years Hunters have turned up more than 30,000 speci
• 08:00 - 08:30 the largest at around 60 tons landed in Africa 880,000 years ago some of the rarest are pieces of the Moon blasted here after impacts there but one of the coolest things about meteorites is that most were formed 42 billion years ago during the birth of our solar system when for reasons not yet known a cloud of gas and dust
• 08:30 - 09:00 transformed into a sun with circling planets so can these space rocks tell us what triggered the event here at Arizona State's Center for meteorite studies its director Minnie wad come on in is trying to decipher our Cosmic past here you will gown up to go into the clean land protective clothing prevents contamination from foreign
• 09:00 - 09:30 particles inside wadwa breaks down meteorites in search of their chemical birth certificate after crushing and dissolving them in acid she can identify the atoms and molecules inside the results this 4 and2 billion year old meteorite is laced with a special kind of atom called nickel 60 nickel 60 is interesting for us because
• 09:30 - 10:00 it is the Decay product the daughter of iron 60 and iron 60 is really what we're after nickel 60 is created with another atom iron 60 decays through radioactivity that number 60 tells you how many protons and neutrons are in an atom's nucleus so when this rock formed 42 billion years ago it was originally infused with iron
• 10:00 - 10:30 60 and iron 60 is created in only one place a supernova a supernova is the violent destructive explosion that marks the death of a massive star so that means when these meteorites were forming from a gas cloud during the birth of our solar system the gas cloud had been sprinkled with iron 60 from an exploding Supernova we're interested in Iron 60 because it
• 10:30 - 11:00 may be injected by a supernova nearby right before we were all right before the solar system was born but wait a minute a supernova is one of the most powerful explosions in the universe it's so luminous it can be seen across billions of light gear it releases as much energy in an instant as our sun will produce over its 10 billion year lifetime so how could baby solar system
• 11:00 - 11:30 survive such a violent destructive event Well turns out some researchers think the reason we survived is that the Supernova explosion was actually the trigger that created our solar system in the first place the one question that we're trying to understand right now is could such a supernova actually have been involved in the formation of our own solar system Alan boss is one astrophysicist convinced that we owe our existence to a supernova
• 11:30 - 12:00 he thinks it happened like this like everything else in the universe we started out as a cloud of gas and dust then a distant massive star died and went supernova sending a shock wave toward us when the wave of pressure hit the cloud it collapsed and condensed starting a chain of events that led to the formation of our sun
• 12:00 - 12:30 you can think of it kind of like a snowplow you can create mounds of snow or destroy them we can do either or so you are the Supernova of the skis slope that's for sure as the plow pushes through a parking lot of light fluffy snow the snow clumps together in bigger and bigger chunks [Music]
• 12:30 - 13:00 out in space pressure hitting a gas cloud has a similar effect except instead of snowballs you get [Music] Stars once you've got the makings of a star gravity draws leftover gas and dust into a giant swirling disc the dust continues to stick together clumping into Rocky [Music] asteroids which eventually become orbiting Rock rocky
• 13:00 - 13:30 planets and voila a solar system so is this where we came from well not everybody's buying the Supernova as a Creator Theory what remains a little bit controversial about that idea is that you can't have that fluffy Cloud near the Supernova when that shock wave is just coming out of the Supernova explosion it's super strong for Steve Dash a supernova hit a gas cloud is more likely to do
• 13:30 - 14:00 this like a snowplow in overdrive a supernova shock wave might sweep away any gas clouds in its [Music] path Dash thinks something gentler triggered the collapse a shock driven by radiation from a massive star but Alan boss has crunched the numbers and insists that at the right distance a supernova shock wave would be
• 14:00 - 14:30 transformed from a destroyer into a Creator we believe that our own solar system was a cloud sitting there in space more or less mining its own business when a supernova shock wave struck the cloud and have it collaps down and form a new star system we still don't know for sure what the trigger was but since we've discovered meteorites with Supernova dust we do know know that a violent
• 14:30 - 15:00 explosion rocked our Cosmic neighborhood at the time of our birth and it's quite possible that without it our stable stately solar system would never exist at all [Music]
• 15:00 - 15:30 one of the most significant events in
• 15:30 - 16:00 our distant past is still perhaps the greatest mystery the origins of life itself how did it all get started if you look down the evolutionary tree of life you'll see that we mammals branched from reptiles which branched from fish and so on and so on all the way down to the base of the tree a common ancestor some single cell organism billions of years ago but what
• 16:00 - 16:30 came before that and where did the very first living thing come from correspondent Chad Cohen digs down deep into the roots of the tree and uncovers some groundbreaking Research into how life first began everything on Earth that has ever lived came from an ancient ancestor billions of years ago perhaps a simple single celled organism like this but from where did it come from where did
• 16:30 - 17:00 the first life emerge life emerged from chemistry it's then it's after that it's just details right so at the root of the tree of life it appears is chemistry simple elements like carbon hydrogen oxygen and nitrogen but how did they get cooked together into the complex molecules of life we're here on the planet and we must be here as a result of organic chemistry John Southerland from the University of
• 17:00 - 17:30 Manchester England along with co-authors Matt poer and Beatrice Geron Bon Geron okay he and his team took on the task of looking for the Holy Grail of life you know what you want to make but you don't have a rescue we can all imagine what this is like in the kitchen we bring together different ingredients all the time to make all kinds of different things it's the recipe though that makes it all work take for example the cream puff oh yeah
• 17:30 - 18:00 pesu okay pesu as it's known in French in this case I know the ingredients flour eggs milk water butter what I don't know is the recipe so I might just try mixing all these things together and baking them I could try different orders different combinations different
• 18:00 - 18:30 amounts but what you get is not pesu too brittle too hard too well I have no idea attempts to find the recipe for early life were unsuccessful too even though researchers knew the basic ingredients yeah exactly Nobel laurat Jack shc and his team at Massachusetts General Hospital say that early life needed two things
• 18:30 - 19:00 you need the cell membrane a something to live in and keep other things out and you need some genetic material something that can allow the inheritance of information every modern creature uses DNA to do that it's an organism's instruction manual genetic code spelled out in chemicals inside this twisty double helix DNA has long been held as the fundamental molecule of life we also have RNA as well usually described as
• 19:00 - 19:30 DNA's Helper but now it turns out RNA has a starring role years ago RNA was kind of a a bit player in the cell now our picture is completely inverted and we think RNA is really the important thing RNA has a genetic code also written with chemicals a c g and U they're used to help build the proteins that make up the cells in our our bodies skin hair brain cells the
• 19:30 - 20:00 heart RNA helps make them all so what's the recipe for RNA it's made from three parts a sugar a phosphate and a single letter of the genetic code a base each of these parts is made up of simple chemicals that existed on the early Earth but nobody has been able to put them together that is until John Southerland came along we were the guys who stood
• 20:00 - 20:30 back and and looked at it in a different way it's one thing to make chemicals in the lab but there were no Labs on the early Earth so southernland tried to replicate the conditions in some ways simulate what that Earth would have been like simulate the actual chemistry that took place starting with their version of what Charles Darwin suggested as the perfect spot for the source of Life a warm Little Pond the pond itself is actually the little round bottom flask and because it was a warm Little Pond
• 20:30 - 21:00 it's around about the temperature of a a cup of English tea sounds nice and so they tackled the problem at hand trying to make RNA knowing what chemicals it would take the question was how to cook them together people have known the ingredients for some time now but the recipe has not been really working out you actually have to be the person that writes the recipe book so that means we have to go back to the kitchen and try to combine our ingredients or pot a shoe in a new way remember the ingredients
• 21:00 - 21:30 eggs milk flour water and butter we combined them before with no luck but now we have a real Chef to help us well you had the right ingredients right you forgot one very important step it's that intermediate step Chef Richard copage of The Culinary Institute of America explains that I was missing an all important intermediate step you didn't pre-cook the mixture I can't just mix these things together and bake it no
• 21:30 - 22:00 because that's why you have this so pre-cooked what does it mean to precook something some of the ingredients need to be cooked together first this is the intermediate step that you didn't do earlier yeah I first cook the water milk butter and flour together no eggs then take it to the mixer now you can add the eggs okay now finally okay and you get just the right mixture all right that's ready to to be
• 22:00 - 22:30 baked the result wow they look perfect without that intermediate step of pre-cooking you really don't have P too it's not much of anything without that intermediate pre-cooking step great and apparently that was the problem scientists were having with RNA trying to all the parts together and that's not the way to do it no it's not so southerland's team took their own intermediate step first they created a
• 22:30 - 23:00 hybrid made of a sugar and only half of the base the part that holds the genetic code this intermediate substance came together in the flask through the simple process of evaporation it looks like a smear or smudge on the inside of the flask on the early Earth the intermediate would have formed through evaporation made its way up into the atmosphere and then fallen from the sky and so this would come down in rain or if the temperature was cold it would precipitate out of solid particles and fall to the ground almost
• 23:00 - 23:30 like a kind of organic snow and as in the lab meeting up with the remaining chemicals in perhaps another warm Little Pond and attaching together in the final step and it worked for the first time scientists created a building block of RNA what's called a ribonucleotide containing the base C in hindsight pretty simple it never occurred to me to try putting them together in a different order so it was
• 23:30 - 24:00 not obvious it was in fact an amazing accomplishment because if you take the the right mix of ingredients in the right order with the right set of conditions you can cook a nice piece of pastry I can make arri a nuclear tide and it came together in simple steps that could have taken place on their own on the early Earth my team and I have recreated an early Earth scenario and let it run and the chemistry just does it on its own but that wasn't all they took their piece of RNA and subjected it
• 24:00 - 24:30 to something else easy to come by on the early Earth Light yes sunlight and so if you hit the switch you'll see what happens when the sun shines something amazing happens the light shining upon their sample turns some of the SE bases the bit that makes up the genetic code into use so two for the price of one just by just by having the sunshine they had discovered a natural pathway to two of the four letters of RNA letters
• 24:30 - 25:00 that code for the proteins that build all living things we were pretty happy actually understatement or no they were happy I would never say the contrary but in an English way we might have had a trip to a local pub and so while we're a long way from figuring out exactly how life got started they've really I think solved one of the central hard questions in Prebiotic chemistry they filled in a
• 25:00 - 25:30 piece of that mysterious Underside to the tree of life because as we Trace our Origins by looking down chemists like Sutherland are seeing things in a different way what you see looking down from biology is what we see looking up from chemistry and we can actually establish a link between the two a pathway from simple to more complex chemicals until chemistry becomes biology they've given us a glimpse of where we come from
• 25:30 - 26:00 [Music] [Music] [Music] [Music]
• 26:00 - 26:30 life existed on Earth for nearly 4 billion years before anything remotely resembling a human being showed up and even then when we started to Branch off
• 26:30 - 27:00 from other Apes about 10 million years ago our ancestors looked pretty different for one thing they were a lot hairier then at some point hair mostly disappeared from parts of our bodies and remained in a few others including the head without body fur we had to figure out how to make clothes to keep us warm since hair and clothes don't turn up much in the fossil record figuring out when and why all this happened has stumped palale ologists but recently we
• 27:00 - 27:30 discovered a witness to our hairy history correspondent zaton combed through the evidence to find the stealthy diminutive creature who's now revealing some new Clues to our Origins and defining key steps on our path to Being [Music] Human these little creatures might not be pretty but scientists are just now discovering how much lice can reveal about our
• 27:30 - 28:00 past presumably lights have been with us and evolving with us and adapting with us for as long as we have existed as a separate species and even before the origin of humans most parents are horrified to hear their child might have headlight but when evolutionary biologist Mark stoning got the news he was just curious my son came home from school with a note from the teacher saying that a child in his class had come to the class with lies and in the pamphlet there were some facts about lice two facts caught his eye headlice
• 28:00 - 28:30 only live on the human scalp and they cannot go more than a day without drinking our blood but then when I actually started to look into this in more detail I discovered that it was potentially even more interesting ston King discovered that the story of lice contains clues about our ancient history dating all the way back to the dawn of humanity itself most of what we know about human
• 28:30 - 29:00 evolution comes from these the fossilized bones of our ancestors with their help we've traced our Evolution from small furry creatures to the big brain beings we become today but bones can't tell us everything one mystery that stumped the fossil Hunters is when we started wearing [Music] clothes we're not talking about these kinds of clothes but something more more basic we don't have any direct evidence
• 29:00 - 29:30 to answer the question when the first uh closing develop and it's a very important question important because it'll help us get a handle on when we left Africa our ancestral home and spread out into colder regions the earliest Clues are bone sewing needles dating as far back as 40,000 years ago but we know early humans were World Travelers long before that their fossil remains have been found across the globe they were
• 29:30 - 30:00 tropical creatures and they had to adapt to this new environment and it's really some kind of puzzling question to figure out how they were able to cope with this kind of environment at some point our ancestors figured out how to bundle up but when lice May hold the answer it's really fascinating to me that we can use these parasites to study so many different aspects of human evolutionary history Z you are not going
• 30:00 - 30:30 to believe the things we can learn David Reed is now the world's foremost expert on the evolution of Li he thinks the pest can solve all kinds of mysteries about our past like when we started wearing clothes he's bringing me to a local strip mall in Florida to see if I've got what it takes to be a professional [Music] nitpicker Z this is Katie from Life Solutions good to meet you Katie nice to meet you too and what's your your name Kylie hello Kylie so what are we going
• 30:30 - 31:00 to be looking for today we're going to see if Kylie has head lights Katie is going to teach me to remove lice the age-old way by hand initially I like to part the hair here see right there right there okay I just go straight you got it absolutely now come straight out all the way out oh my goodness oh my goodness so I got you some samples so what are we going to do with these guys well we're going to take them back to the lab and we're going to study their DNA back in the lab Reed studies the DNA
• 31:00 - 31:30 of not only the head louse but also of this little guy pediculus humanus humanus the body or clothing louse to the naked eye it looks identical to the Head louse but there are a few key differences it lives and lays its eggs only in clothes and bedding and unlike the head louse the clothing louse can kill you that it carries three different deadly diseases that have killed millions of humans over recent history there are epidemic typhus transen fever
• 31:30 - 32:00 and relapsing fever because of these diseases that they carry they were partly responsible for absolutely decimating Napoleon's Grand Army through its famous wintered March as dangerous as they might be for Reed clothing lights are fascinating because they must have evolved from headlight and they could only do that after we started wearing clothes clothing lice wouldn't have had a niche to live live in until humans started wearing clothing so if we can learn when
• 32:00 - 32:30 they first started to emerge from headlice populations we can learn when humans began to wear clothing for the first time Reed set out to determine when the head louse and the clothing louse split into two separate species to do that he used a genetic dating technique called the molecular clock here's how it works DNA is made out of a sequence of four chemicals known by their initials a c g and T the
• 32:30 - 33:00 DNA sequence mutates or changes randomly but at a known rate DNA sequences Changed by mutations and the idea behind the molecular clock is that those changes are occurring at more or less a constant rate over time when Reed compared the DNA from Modern clothing lights to human headlight he discovered that the two species split over 170,000 years ago and this read says is when we started to wear clothes 170,000 years is important
• 33:00 - 33:30 because that tells us that modern humans had the technology to use clothing while they were still in Africa and that then allowed them to successfully colonize other parts of the world scientists believe that the invention of clothing in Africa was a key factor in allowing our ancestors to migrate into colder climates and to spread across the glob the invention of clothing is just one of the Mysteries that light are helping us all they also hold crucial Clues to the big event that made
• 33:30 - 34:00 clothing necessary in the first place the loss of our fur the loss of body hair is interesting to anthropologists because it is a feature that distinguishes us from our nearest living relatives chimpanzees they have body hair we don't the problem is no one has been able to determine when our ancestors took this big evolutionary step it turns out that the answer May lie with another another kind of lice even less welcome
• 34:00 - 34:30 than headlice the crab or pubic L lives only in the human pubic region and has large claws designed to grab on to the thicker hair we know pubic lice didn't evolve from headlice they're a completely different species so different we must have caught them from another animal human pubic Li are more closely related to gorilla lies than they are to other human lies actually scientists don't know exactly
• 34:30 - 35:00 how light jump from gorillas to our human ancestors they speculate we may have eaten them or perhaps slept in their nests but they do know that in order for crab Li to survive on our something had to give we lost our body here and that basically created a if you will a geographical barrier between the pubic region and the head region that the lice could not Crist so both headlice and crab lice were able to thrive on our bodies thanks to this no light land the expansive skin on our
• 35:00 - 35:30 torso so if we can figure out when crab lice appeared as a separate species that should tell us when we started showing all that skin to find the answer David Reed compared the DNA of gorilla lice and human crab life he found that the two species split about 3 million years ago and that's when David Reed believes we lost our body hair when we were still small chimp likee creatures with few of the qualities we consider human most estimates don't go beyond a million
• 35:30 - 36:00 years and suggest that we lost our hair around that time these lights are telling us a very different story that we might have lost our body hair as long as 3 million years ago and that's a milestone in human evolution because losing their fur enabled our ancestors to regulate their body heat by sweating more efficiently eventually they could run long distances and hunt wild animals the protein this provided was essential to the development of a big brain the Hallmark of becoming human
• 36:00 - 36:30 piecing together the details of our human journey is a challenging task it's ironic that some of the most mysterious gaps are being filled in by a creature we never really liked we cannot neglect any piece of evidence and if the lies teach us something uh it's very important so we cannot neglect the lies a
• 36:30 - 37:00 [Music] [Music]
• 37:00 - 37:30 [Applause] [Music] All Humans all living creatures have common Origins but what about our individual Origins our own personal history where does that come from who you are where you've been and what you've done it's all up here captured and preserved in your memories
• 37:30 - 38:00 if you lost that the story of your own Origins you'd lose your identity your sense of self in this episode's profile we meet a researcher whose fascination with how memory and identity work led him to discover a chemical that has the power to erase memories and make our sense of where we come from [Music] disappear as a new father Andre Fenton loves capturing memories of his baby
• 38:00 - 38:30 daughter Zora and wife Lisa that's Zora's first Halloween Andre thinks of all his memories as living in a dynamic set of file cabinets in his [Music] mind where they're stored and add up to a life memory defines a person my memories in many ways Define me as a neurobiologist at Sunni
• 38:30 - 39:00 downstate in Brooklyn Andre has become famous as the guy who with a simple injection can wipe away a memory forever scientists have thought it was impossible to erase a memory so that was like a shock to the whole Community you can wipe out who you are and that's an alarming thing Andre's cuttingedge ideas tap into our deepest hopes and fears something we've seen in the movies there's Eternal Sunshine of the Spotless
• 39:00 - 39:30 Mind that deliberately investigates what would happen if you could erase painful Amorous memories I'm erasing you and I'm happy the conclusion is it's not good except what Andre is doing is real his fascination with the inner workings of the Mind dates back to his childhood born in Guyana Andre had to adapt to a strange new world at a young age age when I was six or seven I moved
• 39:30 - 40:00 to Toronto Canada what was essentially a new culture so I learned to skate immediately and at home Andre had to cope with the tumultuous relationship between his mother and stepfather they must have separated I don't know 10 times or so uh during the course of their their marriage they were divorced twice I have Painful memories and if you'd asked me right after my stepfather had packed his suitcase would you like
• 40:00 - 40:30 to get rid of this memory the answer might probably have been yes when I was in high school I became deeply interested in understanding who are you in this world what is the nature of my experience at Montreal's McGill University Andre searched for answers he tried meditation and philosophy then a movie suggested that the key piece of this puzzle might lie
• 40:30 - 41:00 inside his own head I had seen Altered States where a psychologist goes into a sensory deprivation tank and he has experiences that come from his brain and he's seduced by this beautiful so Andre tracked down a sensory deprivation tank to try himself and it was like instant meditation and the thing that fascinated me was
• 41:00 - 41:30 that my mind would construct images I could move rather fast at times I warp speed fast and at other times very very slowly there was nothing I was really experiencing that was outside of me his time in the tank convinced Andre that to understand his experiences he must first learn how the brain works that's when he turned to
• 41:30 - 42:00 Neuroscience one of the first challenges in the lab was to create a device that would force a rat to acquire a specific memory a kind of memory making machine so Andre ran an electric current that would send a harmless shock whenever the rat entered the invisible triangle in the future the rat should remember to avoid this area the device was called the place ofo voidance task but because Andre was only
• 42:00 - 42:30 interested in spatial memory he needed to make sure the rat was not cheating by using sight sound or smell to navigate the arena surface to outsmart the rat Andre began obsessively looking for a solution well Andre is an incredible multitasker you know I think a typical moment with Andre is that he's walking the dog and her Baby Bjorn talking on a cell phone in a conference call and taking money out of the bank
• 42:30 - 43:00 kind of all at the same time argument but many of his best ideas surface in one unusual place I spend a lot of time in the shower thinking about things which my family is very unhappy about cuz we only have one shower it's like a pieces of a puzzle that he needs to fit together and he kind of works on it works on it until it clicks that's when he had a breakthrough
• 43:00 - 43:30 with his memory making machine I let the rat step up onto my hands which I kept just above the arena surface and benedetto physically turned the disc and I let the rat crawl off my hand and we watched to see where the rat avoided by constantly rotating the floor Andre had taken away all the clues for finding the shock Zone and that's how the rotating Arena developed now Andre had a machine that
• 43:30 - 44:00 could quickly create long-term spatial memories but what to do with it enter Todd saer a fellow neuroscientist whose lab coincidentally was just one story up from Andre at Sunni down state Todd was one of many researchers struggling to discover the mechanisms the brain used to lock in some memories for a lifetime While others faded away neuroscientists believed that a long-term memory occurred when a specific pattern of connections between
• 44:00 - 44:30 a group of neurons were strengthened and maintained over time after two decades of research Todd suspected that many of those connections were maintained by a single enzyme in the brain called PKM Zeta in a sense I love PKM Zeta the clearest way to demonstrate its power would be to block PKM Zeta and see if a long-term memory would be erased so I walked down one flight into Andre's
• 44:30 - 45:00 office and he said think we're ready to find out if PKM Zeta is actually the mechanism for maintaining memories so I said Andre what's the best task to test the hypothesis that PKM Zeta is important for maintaining long-term memory Todd suggested several memory experiments to use with PKM Zeta but Andre saw flaws in all of them then he suggested another apparatus and I said no now I see this problem with that he eventually said what would you use I
• 45:00 - 45:30 said well I would use the place avoidance task the experiment was simple they placed a rat in the rotating Arena and let it learn to avoid the shockone a nice thing about the place avoidance task is that where the rat goes gives you a pattern that looks like a scribble when the rat is avoiding it's a scribble that avoids a triangle once the rat consistently avoided the triangle
• 45:30 - 46:00 the memory had been learned then they injected a chemical which would stop PKM Zeta from working in the brain If you inhibit PKM Zeta then you should be able to erase a memory Todd was sure it would work I was certain it would not work but once we injected the inhibitor you could see that the rats went everywhere and the scribble just went all over the arena
• 46:00 - 46:30 like when the animals put There For the First Time The Rat's memory of the shock Zone was Gone with PKM Zeta disabled the strength of the connections among the brain cells that formed the memory seemed to weaken we came to the very simple conclusion PKM Zeta is crucial for maintaining long-term Memories the kind that lasts forever the kind that make you who you are Todd came down with some sort of bubbly thing sort of poured it
• 46:30 - 47:00 around and we cheered to that Andre realized he was just scratching the surface of how PKM Zeta and long-term memory work but the Press swarmed over the story of memory erasing scientists in Brooklyn seeing Andre's face on the from page of the New York Times was a surprise to all of us while Andre's experiment only applied to rats his research touched on a darker current in the public psyche I received emails from a variety of people who were interested
• 47:00 - 47:30 in having their memories erased I'm seeing therapists and psychiatrists two years now but to no avail if I could get at least three year Amnesia somehow I would do it in a minute happily trade in all my memories even the good ones if it would erase this I am living in hell and would try anything to please please keep me in mind if any clinical Tri sorry if I inconvenienced you in any way I really did have a lot of accomplishments in life and had a lot of future
• 47:30 - 48:00 potential I really hope I never get to make the decision of whether we reboot a mind or not I'm convinced that it's a bad idea imagine you're an adult person and you spent a lot of time accumulating an identity you might not like that identity but the very notion that you could literally remove all of it I don't
• 48:00 - 48:30 know what you would be I'm not sure you'd be human and I wouldn't know how to put it back [Music] [Music]
• 48:30 - 49:00 and now for some final thoughts on where
• 49:00 - 49:30 we came from we only recently figured out the origin of our own Moon and we have some idea of how the Sun and Earth formed but that's only because modern telescopes Empower us to see other stars and planets freshly hatched within gas clouds across the Galaxy as for the origin of life itself the transition from inanimate molecules to what any of us would call Life remains one of the great frontiers of biology since life on Earth is so far the only
• 49:30 - 50:00 known example of life in the universe our dilemma May simply be that we have no other examples to compare us with if we did then the life non-life transition might look downright simple to us no doubt the most challenging class of questions in science is the origin of things so much of what we understand comes from knowing what something is and what that something used to be which allow us to figure out or at least imagine what happened in
• 50:00 - 50:30 between okay so where did it all come from we're quite happy with our big bang description of cosmic Origins but actually the Big Bang accounts for what happened only after the beginning the beginning itself and especially what happened before Remains the biggest mystery of all why because our universe is the only known example of a universe in the universe and that is the cosmic
• 50:30 - 51:00 perspective and now we'd like to hear your perspective on this episode of Nova science Now log on to our website and tell us what you think you can watch any of these stories Again download additional audio and video explore interactives hear from experts and watch revealing profiles from our web only series The Secret Life of scientists and Engineers here's a sneak peek scientists have some amazing lines that you would never [Music]
• 51:00 - 51:30 guess I like to push limits it is me but to a big extreme I play in a band called Harry and the Potters with my brother ice skating is nothing but applied Newtonian physics I started cheering completely by accident fire it up so if you're waving left you must use your right hand you don't want people to get a full view of your armpit never a pretty
• 51:30 - 52:00 [Music] thing I'd go with the Olympic gold medal but only cuz there's no Nobel Prize for mechanical [Music] engineering the butt glue it's a special sort of glue that you apply to your rear end that actually holds your swimsuit in place I scared my undergrads with that find it all on
• 52:00 - 52:30 pbs.org that's our show and we'll see you next time on Nova science now what's the next big thing will our cars be so smart they drive themselves I just press this button and it will come and pick me up can we power our cars with fuel grown in a field Advanced biofuels this is the future of energy for the US and will intelligent machines take over the world don't worry I'll keep you warm and safe
• 52:30 - 53:00 in my people's Zoo next time on Nova science now see a hidden side of science on Nova's web exclusive Series where we challenge experts to explain their work in less than 30 seconds I'm a neuroscientist and I work on two basic problems one is how does the Brain Store the experiences that you have as you go through the day and the second is how does the brain extract those experiences
• 53:00 - 53:30 so that you can use those memories and that information judiciously to get through the day and in particular how you organize your thoughts that's the subject that I work on this Nova science now program is available on DVD at shoppbs.org hi I'm Neil degrass Tyson your host of
• 53:30 - 54:00 Nova science now where this season we're asking six big questions on this episode where did we come from the Sun the planets our home the Earth what triggered their creation I went on the hunt for rare evidence where are we that's been dropping from the sky got something it sounds really big and it's pointing to a
• 54:00 - 54:30 cosmic birth more violent than we ever imagined also life it's been around for billions of years but how did it begin you know what you want to make but you don't have a recipe for decades we've been trying to cook up the building blocks of life in the lab and recreate the origins of it all but the parts didn't seem to fit together until now were the guys who stood back and looked at it in a different way one team may
• 54:30 - 55:00 have retraced a key step in the birth of life itself how did they do it and what about us and our Origins they say some of the hairiest questions in human evolution could be solved by these guys headlight Li have been with us and evolving with us for as long as we have existed see right there that comes straight out oh my goodness oh my good you want to hit the red alarm button at school all you have to say is the word
• 55:00 - 55:30 lice these tiny blood suckers are rewriting human history we cannot neglect the lies also where does your identity come from your memory of course my memories Define me this brain researcher made a major discovery about how memories are formed and even how they can be erased you can wipe out who you are and that's an alarming thing all that and
• 55:30 - 56:00 more on this episode of Nova science now funding for Nova science now is provided by where did we come from how did we get here are history in the cosmos and on planet Earth was shaped by countless events some obviously epic
• 56:00 - 56:30 some seemingly trivial yet all vital in getting us to this point here and now the people we are today one of the reasons we're here that we exist at all is that Earth cosmically speaking is in a relatively peaceful place orbiting our sun in a near Perfect Circle our Cosmic neighborhood has granted life billions of years to evolve mostly Disturbed but where did this stable piece of real estate come from we know that stars and
• 56:30 - 57:00 planets Once Upon a Time all started out like this with enormous clouds of gas and dust how we got from here to here we haven't exactly figured out yet but lately we found some intriguing new evidence that tells us our peaceful solar system may have started with a violent event if we want to unlock the secet behind the origin of our sun and its planets it would be helpful to find some
• 57:00 - 57:30 remnants from the birth itself an event that took place about 4 and 1/2 billion years ago luckily there are some rocks left over from our earliest days asteroids formed during our Solar System's [Music] birth occasionally some of them drop in on Earth and when they do they're called
• 57:30 - 58:00 [Music] meteorites I've come to the deserts of Arizona to try to track down some rare space rocks where are we perfect place for hunting for meteorit Southern Arizona look at this couldn't ask for a better
• 58:00 - 58:30 place it's open desert it's an old Lake Bed and so the sand is being blown away like right now and it's exposing the rocks that are on the ground and it's just so you're just looking for something that looks a little bit different and you'll know it when you see it well I'm from the city so all this looks different I'll be hauling everything back for you so how do you spot a meteorite well sometimes the signs are hard to miss some leave deep impacts in Earth like one that blasted Arizona's baringer crater 50,000 years
• 58:30 - 59:00 ago but most leave less obvious traces they can be as small as dice reduced to a rocky Cinder then they have to be distinguished from Earth's rocks one trait stands out in nearly all meteorites metal they've got it so the best way to find a meteorite is to hear it first [Music]
• 59:00 - 59:30 no question about that one and we can pick far out Ruben Garcia brought along some samples and showed me why a metal detector is the meteorite Hunter's best friend it's what meteorite Hunters call a Halo you don't have to swing over the meteorite you get in that Halo area and you hear the sound going up you get in the zone we like that this is very typical as meteorites go this is called an ordinary condite and and about 82% of all meteorites that
• 59:30 - 60:00 fall are going to be of that variety condres are rocky meteorites that haven't melted completely that's what we want to find there's more we've actually got what we call meteorite canes and this is these are golf clubs I know this this is a go this is a golf club with a very strong in this case two very strong magnets attached go ahead and test it with the can and see what you got that yes music to my ears I have found a
• 60:00 - 60:30 meteorite you certainly have I keep this one we found it are you guys ready to find some meteorites let's go find some do it hunting for meteorites is like trying to find a pebble on miles of beach one of The Graduate students has found something watch the cactus oh thank you it sounds really
• 60:30 - 61:00 big oh there it is piece of farm equipment that is your first meteor wrong congratulations meteor wrong meteor wrong but I wanted metor right so all we do is fan out now and just fan out just this is a whole area here it could be anywhere you got something has no characteristics of a meteorite H this meteorite hunting is a
• 61:00 - 61:30 lot harder than it looks and some days you don't find any so they told me this was the remains of a meteorite hunter that came out unprepared this is one of those days they'll tell them what you find out here luckily over the years Hunters have turned up more than 30,000 specimens the largest at around 60 tons landed in Africa 880,000 years
• 61:30 - 62:00 ago some of the rarest are pieces of the Moon blasted here after impacts there but one of the coolest things about meteorites is that most were formed 4 and2 billion years ago during the birth of our solar system when for reasons not yet known a cloud of gas and dust transformed into a sun with circling planets so can these space rocks tell us
• 62:00 - 62:30 what triggered the event here at Arizona State's Center for meteorite studies its director mini wad on in is trying to decipher our Cosmic past here you will gown up to go into the clean lab protective clothing prevents contamination from foreign particles the inside wadwa breaks down meteorites in search of their chemical birth
• 62:30 - 63:00 certificate after crushing and dissolving them in acid she can identify the atoms and molecules inside the results this 4 and2 billion year old meteorite is laced with a special kind of atom called nickel 60 nickel 60 is interesting for us because it is the K product the daughter of iron 60 and iron 60 is really what we're
• 63:00 - 63:30 after nickel 60 is created with another atom iron 60 decays through radioactivity that number 60 tells you how many protons and neutrons are in an atom's nucleus so when this rock formed 4 and2 billion years ago it was originally infused with iron 60 and iron 60 is created in only one place a
• 63:30 - 64:00 supernova a supernova is the violent destructive explosion that marks the death of a massive star so that means when these meteorites were forming from a gas cloud during the birth of our solar system the gas cloud had been sprinkled with iron 60 from an exploding Supernova we're interested in IR 60 because it may be injected by a supernova nearby right before we were all born before the solar system was born but wait a minute a supernova is
• 64:00 - 64:30 one of the most powerful explosions in the universe it's so luminous it can be seen across billions of light years it releases as much energy in an instant as our sun will produce over its 10 billion year lifetime so how could a baby solar system survive such a violent destructive event event Well turns out some researchers think the reason we
• 64:30 - 65:00 survived is that the Supernova explosion was actually the trigger that created our solar system in the first place the one question that we're trying to understand right now is could such a supernova actually have been involved in the formation of our own solar system Alan boss is one astrophysicist convinced that we owe our existence to a supernova he thinks it happened like this [Music] like everything else in the universe we started out as a cloud of gas and
• 65:00 - 65:30 dust then a distant massive star died and went supernova sending a shock wave toward us when the wave of pressure hit the cloud it collapsed and condensed starting a chain of events that led to the formation of our sun you can think of it kind of like a snowplow you can create mounds of snow or destroy
• 65:30 - 66:00 them we can do either or so you are the Supernova of the ski slope that's for sure as the plow pushes through a parking lot of light fluffy snow the snow clumps together in bigger and bigger [Music] chunks out in space pressure hitting a gas gas cloud has a similar effect except instead of
• 66:00 - 66:30 snowballs you get [Music] Stars once you've got the makings of a star gravity draws leftover gas and dust into a giant swirling disc the dust continues to stick together clumping into Rocky [Music] asteroids which eventually become orbiting rocky planets and voila a solar system so is this where we came
• 66:30 - 67:00 from well not everybody's buying the Supernova as a Creator Theory what remains a little bit controversial about that idea is that you can't have that fluffy Cloud near the Supernova when that shock wave is just coming out of the Supernova explosion it's super strong for Steve Dash a supernova hitting a gas cloud is more likely to do this like a snowplow in overdrive a supernova shock wave might
• 67:00 - 67:30 sweep away any gas clouds in its [Music] path Dash thinks something gentler triggered the collapse a shock driven by radiation from a massive star but Alan boss has crunched the numbers and insists that at the right distance a supernova shock wave would be transformed from a Destroyer into a Creator we believe that our own solar
• 67:30 - 68:00 system was a cloud sitting there in space more or less mining its own business when a supernova shock wave struck the cloud and have it collapse down and form a new star system we still don't know for sure what the trigger was but since we've discovered meteorites with Supernova dust we do know that a violent explosion rocked our Cosmic neighborhood at the time of our birth and it's quite possible that without it our stable stately solar
• 68:00 - 68:30 system would never exist at all [Music]
• 68:30 - 69:00 one of the most significant events in our distant past is still perhaps the greatest mystery the origins of life
• 69:00 - 69:30 itself how did it all get started if you look down the evolutionary tree of life you'll see that we mammals branched from reptiles which branched from fish and so on and so on all the way down to the base of the tree a common ancestor some single celled organism billions of years ago but what came before that and where did the very first living thing come from correspondent Chad Cohen digs down deep
• 69:30 - 70:00 into the roots of the tree and uncovers some groundbreaking Research into how life first began everything on Earth that has ever lived came from an ancient ancestor billions of years ago perhaps a simple single celled organism like this but from where did it come from where did the first life emerge life emerged from chemistry it's then it's after that it's
• 70:00 - 70:30 just details right so at the root of the tree of life it appears is chemistry simple elements like carbon hydrogen oxygen and nitrogen but how did they get cooked together into the complex molecules of life we're here on the planet and we must be here as a result of organic chemistry John Southerland from the University of Manchester England along with co-authors Matt poer and Beatrice gerand Beatrice Geron okay he
• 70:30 - 71:00 and his team took on the task of looking for the Holy Grail of life you know what you want to make but you don't have a rescue we can all imagine what this is like in the kitchen we bring together different ingredients all the time to make all kinds of different things it's the recipe though that makes it all work take for example the cream puff oh yeah pesu okay pesu as it's known in French in this case I know the ingredients
• 71:00 - 71:30 flour eggs milk water butter what I don't know is the recipe so I might just try mixing all these things together and baking them I could try different orders different combinations different amounts but what you get is not pesu too
• 71:30 - 72:00 brittle too hard to well I have no idea attempts to find the recipe for early life were unsuccessful too even though researchers knew the basic ingredients yeah exactly Nobel laurat Jack shc and his team at Massachusetts General Hospital say that early life needed two things you need the cell membrane a contain something to live in and keep other things
• 72:00 - 72:30 out and you need some genetic material something that can allow the inheritance of information every modern creature uses DNA to do that it's an organisms instruction manual genetic code spelled out in chemicals inside this twisty double helix DNA has long been held as the fundamental molecule of life we also have RNA as well usually described as DNA's Helper but now it turns out RNA has a starring role years ago RNA was
• 72:30 - 73:00 kind of a a bit player in the cell now our picture is completely inverted and we think RNA is really the important thing RNA has a genetic code also written with chemicals a c g and U they're used to help build the proteins that make up the cells in our bodies skin hair brain cells heart RNA helps make them all so what's the recipe for RNA it's made from three parts a
• 73:00 - 73:30 sugar a phosphate and a single letter of the genetic code a base each of these parts is made up of simple chemicals that existed on the early Earth but nobody has been able to put them together that is until John Southerland came along we were the guys who stood back and and looked at it in the different way it's one thing to make chemicals in the lab but there were no Labs on the early Earth so Sutherland
• 73:30 - 74:00 tried to replicate the conditions in some ways simulate what that Earth would have been like simulate the actual chemistry that took place starting with their version of what Charles Darwin suggested as the perfect spot for the source of Life a warm Little Pond the pond itself is actually the little round bottom flask and because it was a warm Little Pond about the temperature of a a cup of English tea sounds nice and so they tackled the problem at hand trying
• 74:00 - 74:30 to make RNA knowing what chemicals it would take the question was how to cook them together people have known the ingredients for some time now but the recipe has not been really working out you actually have to be the person that writes the recipe book so that means we have to go back to the kitchen and try to combine our ingredients or pot of shoe in a new way remember the ingredients eggs milk flour water and butter we combined them before with no
• 74:30 - 75:00 luck but now we have a real Chef to help us well you had the right ingredients right but you forgot one very important step it's that intermediate step Chef Richard copage of The Culinary Institute of America explains that I was missing an all-important intermediate step you didn't pre-cook the mixture I can't just mix these things together and bake it no because that's why you have this so pre-cooked what does it mean to precook something some of the ingredients need
• 75:00 - 75:30 to be cooked together first this is the intermediate step that you didn't do earlier yeah I first cook the water milk butter and flour together no eggs then take it to the mixer now you can add the eggs okay now finally okay and you get just the right mixture all right that's ready to be baked the result wow they look perfect without that intermediate step of pre-cooking you
• 75:30 - 76:00 really don't have PW of shoe it's not much of anything without that intermediate pre-cooking step great and apparently that was the problem scientists were having with RNA trying to all the parts together and that's not the way to do it no it's not so southerland's team took their own intermediate step first they created a hybrid made of a sugar and only half of the base the part that holds the genetic code this intermediate substance came
• 76:00 - 76:30 together in the flask through the simple process of evaporation it looks like a smear or a smudge on the inside of the flask on the early Earth the intermediate would have formed through evaporation made its way up into the atmosphere and then fallen from the sky and so this would come down in rain or if the temperature was cold it would precipitate out as solid particles and fall to the ground almost like it kind organic snow and as in the lab meeting up with the remaining chemicals in perhaps another warm Little
• 76:30 - 77:00 Pond and attaching together in the final step and it worked for the first time scientists created a building block of RNA what's called a ribo nucleotide containing the base C in hindsight pretty simple it never occurred to me to try putting them together in a different order so it was not obvious it was in fact an amazing accomplishment because if you take the the right mix of ingredients in the right order with the
• 77:00 - 77:30 right set of conditions you can cook a nice piece of pastry I can make a r a nuclear tide and it came together in simple steps that could have taken place on their own on the early Earth my team and I have recreated an early Earth scenario and let it run and the chemistry just does it on its own but that wasn't all they took their piece of RNA and subjected it to something else easy to come by on the early Earth Light yes sunlight so if you hit the switch
• 77:30 - 78:00 you'll see what happens when the sunshines something amazing happens the light shining upon their sample turns some of the seab bases the bit that makes up the genetic code into use so two for the price of one just by just by having the sunshine they had discovered a natural Pathway to two of the four letters of RNA let letters that code for the proteins that build all living things we were pretty
• 78:00 - 78:30 happy actually understatement or no they were happy I would never say the contrary but in an English way we might have had a trip to a local pub and so while we're a long way from figuring out exactly how life got started they've really I think solved one of the central hard questions in Prebiotic chemistry they filled a piece of that mysterious Underside to the tree of life because as we Trace our Origins
• 78:30 - 79:00 by looking down chemist like southernland are seeing things in a different way what you see looking down from biology is what we see looking up from chemistry and we can actually establish a link between the two a pathway from simple to more complex chemicals until chemistry becomes biology they've given us a glimpse of where we come from [Music]
• 79:00 - 79:30 [Music] [Music] he [Music]
• 79:30 - 80:00 life existed on Earth for nearly 4 billion years before anything remotely resembling a human being showed up and even then when we started to Branch off from other Apes about 10 million years ago our ancestors looked pretty different for one thing they were a lot
• 80:00 - 80:30 hairier then at some point hair mostly disappeared from parts of our bodies and remained in a few others including the head without body fur we had to figure out how to make clothes to keep us warm since hair and clothes don't turn up much in the fossil record figuring out when and why all this happened has stumped paleontologists but recently we discovered a witness our hairy history correspondent zong combed through the evidence to find the stealthy diminutive
• 80:30 - 81:00 creature who's now revealing some new Clues to our Origins and defining key steps on our path to Being [Music] Human these little creatures might not be pretty but scientists are just now discovering how much lice can reveal about our past presumably light have been with us and evolving with us and adapting with us for as long as we have existed as a separate species and even before the
• 81:00 - 81:30 origin of humans most parents are horrified to hear their child might have headlight but when evolutionary biologist Mark stoning got the news he was just curious my son came home from school with a note from the teacher saying that a child in his class had come to the class with lies and in the pamphlet there were some facts about lice two facts is eye headlight only live on the human scalp and they cannot go more than a day without drinking our
• 81:30 - 82:00 blood but then when I actually started to look into this in more detail I discovered that it was potentially even more interesting Stone King discovered that the story of lice contains clues about our ancient history dating all the way back to the dawn of humanity itself most of what we know about human evolution comes from the the fossilized bones of our ancestors with their help we've traced
• 82:00 - 82:30 our Evolution from small furry creatures to the big brain beings we become today but bones can't tell us everything one mystery that stumped the fossil Hunters is when we started wearing [Music] clothes we're not talking about these kinds of clothes but something more basic we don't have any direct evidence to answer the question when the first uh closing developed and it's a very
• 82:30 - 83:00 important question important because it'll help us get a handle on when we left Africa our ancestral home and spread out into colder regions the earliest Clues are bone sewing needles dating as far back as 40,000 years ago but we know early humans were World Travelers long before that their fossil remains have been found across the globe they were tropical creatures and they had to adapt to this new environment and it's really
• 83:00 - 83:30 some kind of puzzling question to figure out how they were able to cope with this kind of environment at some point our ancestors figured out how to bundle up but when lice May hold the answer it's really fascinating to me that we can use these parasites to study so many different aspects of human evolutionary history Z you are not going to believe the things we can learn David Reed is now the world's foremost expert on the evolution of lice he thinks the
• 83:30 - 84:00 pest can solve all kinds of mysteries about our past like when we started wearing clothes he's bringing me to a local strip mall in Florida to see if I've got what it takes to be a professional [Music] nitpicker Z this is Katie from Life solution good to meet you Katie nice to meet you too and what's your name Kylie hello Kylie so what are we going to be looking for today we're going to see if Kylie has head lice Katie is going to teach me to remove lice the ageold way by hand
• 84:00 - 84:30 initially I like to part the hair here see right there right there okay and I just go straight like you got it absolutely now com straight out all the way out oh my goodness oh my goodness so I got you some samples so what are we going to do with these guys well we're going to take them back to the lab and we're going to study their DNA back in the lab lab Reed studies the DNA of not only the head louse but also of this little guy pediculus humanus
• 84:30 - 85:00 humanus the body or clothing louse to the naked eye it looks identical to the Head louse but there are a few key differences it lives and lays its eggs only in clothes and bedding and unlike the head louse the clothing louse can kill you that it carries three different deadly diseases that have killed millions of humans over recent history there are epidemic typhus trench fever and relapsing fever because of these diseases that they carry they were partly responsible for absolutely
• 85:00 - 85:30 decimating Napoleon's Grand Army through its famous winter March as dangerous as they might be fed clothing lights are fascinating because they must have evolved from headlice and they could only do that after we started wearing clothes clothing lice wouldn't have had a niche to live in until humans started wearing clothing so if we can learned when they first started to emerge from headlice populations we can learn when humans began to wear clothing
• 85:30 - 86:00 for the first time Reed set out to determine when the head louse and the clothing louse split into two separate species to do that he used a genetic dating technique called the molecular clock here's how it works DNA is made out of a sequence of four chemicals known by their initials a c g and t a DNA sequence mutates or changes randomly but at a known rate DNA sequences Changed by mutations
• 86:00 - 86:30 and the idea behind the molecular clock is that those changes are occurring at more or less a constant rate over time when Reed compared the DNA from Modern clothing lice to human headlice he discovered that the two species split over 170,000 years ago and this read says is when we started to wear clothes 170,000 years is important because that tells us that modern humans had the technology to use clothing while they were still in Africa and that then
• 86:30 - 87:00 allowed them to successfully colonize other parts of the world scientists believe that the invention of clothing in Africa was a key factor in allowing our ancestors to migrate into colder climates and to spread across the globe the invention of clothing is just one of the Mysteries that lice are helping to solve they also hold crucial Clues to the big event that made made clothing necessary in the first place the loss of our
• 87:00 - 87:30 fur the loss of body hair is interesting to anthropologists because it is a feature that distinguishes us from our nearest living relatives chimpanzees they have body here we don't the problem is no one has been able to determine when our ancestors took this big evolutionary step it turns out that the answer May lie with another kind of lice even less welcome than headlice the crab or pubic L lives only in the human pubic region and has large claws
• 87:30 - 88:00 designed to grab on to the thicker hair we know pubic lice didn't evolve from headlice they're a completely different species so different we must have caught them from another animal human pubic Li are more closely related to gorilla lice than they are to other human lies actually scientists don't know exactly how light jump from gorillas to our human ancestors they speculate we may have eaten them or perhaps slept in their nests but they do know that in
• 88:00 - 88:30 order for crab lice to survive on our something had to give we lost our body here and that basically created it if you will a geographical barrier between the pubic region and the head region that the lice could not cross so both head lice and crab lice were able to thrive on our bodies thanks to this no LIC land the expanse of skin on our torso so if we can figure out when crab lice appeared as a separate species that should tell us when we started showing all that
• 88:30 - 89:00 skin to find the answer David Reed compared the DNA of gorilla lice and human crab lice he found that the two species split about 3 million years ago and that's when David Reed believes we lost our body hair when we were still small chimp likee creatures with few of the qualities we consider human most estimates don't go beyond a million years and suggest that we lost our hair around that time these lights are telling us a very different story that we might have lost our body hair as
• 89:00 - 89:30 long as 3 million years ago and that's a milestone in human evolution because losing their fur enabled our ancestors to regulate their body heat by sweating more efficiently eventually they could run long distances and hunt wild animals the protein this provided was essential to the development of a big brain the Hallmark of becoming human piecing together the details of our human journey is a challenging task it's
• 89:30 - 90:00 ironic that some of the most mysterious gaps are being filled in by a creature we never really liked we cannot neglect any piece of evidence and if the lies teach us something uh it's very important so we cannot neglect the lies [Music] [Music]