Your DNA Is (Almost Certainly) From Outer Space

Summary

Highlights

• Many of us carry DNA from Neanderthals, and potentially outer space! 🌌
• The theory of panspermia suggests life may have arrived on Earth from space. 🚀
• Meteors with amino acids support the idea of life's building blocks having extraterrestrial origins. 🪨
• OSIRIS-REx's findings highlight the abundance of organic compounds in space. 🚀
• If life is common in the cosmos, maybe DNA-like systems are, too! 🌌

Key Takeaways

• Our DNA might have extraterrestrial origins, with life's coding systems possibly originating off-world. 🌌
• Panspermia suggests life traveled to Earth in simple forms, while pseudo-panspermia focuses on building blocks forming in space. 🚀
• Meteors containing amino acids and nucleobases lend credibility to life's extraterrestrial biochemical roots. 🪨
• Discoveries from missions like OSIRIS-REx bolster the idea of life's building blocks forming in space. 🚀
• Organic compounds are abundant in space, supporting the idea that life's ingredients are widespread across the universe. 🌌

Overview

Chapters

• 00:00 - 00:30: Introduction and Sponsorship Message The chapter opens with a sponsorship message thanking CyberGhost VPN for supporting PBS. The narrative then transitions into an intriguing discussion about human DNA, revealing that up to 4% of our DNA is inherited from Neanderthals. It further speculates that all humans may have DNA with origins beyond Earth, suggesting that the biochemistry underlying DNA coding systems could have extraterrestrial beginnings, potentially predating the existence of Earth itself.
• 00:30 - 01:00: Merchandise Promotion and Significance of Life This chapter introduces new merchandise available at the store, celebrating the 10th anniversary of Space Time. There is a limited edition anniversary design and some classic logo merchandise. Purchasing this gear not only enhances one's style but also supports the continuation of the show for another decade. The chapter concludes with a philosophical musing about life being the most remarkable occurrence in the universe, hinting at the intrigue of understanding its essence.
• 01:00 - 01:30: Challenges in Discovering Extraterrestrial Life This chapter addresses the challenges faced in discovering extraterrestrial life. The discussion begins with contemplating the possibility of life existing beyond Earth and highlights the importance of this discovery in understanding human impact on Earth. However, it acknowledges the lack of credible evidence of life on other planets and emphasizes our limited understanding of how life began on Earth itself, making it difficult to make definitive statements about life elsewhere in the universe. The chapter points out one positive note: the rapid emergence of life on Earth, as evidenced by the oldest fossils.
• 01:30 - 02:00: Panspermia and Early Life Theories The chapter discusses the theory of panspermia and its implications for the origins of life on Earth. It notes the rapid emergence of life shortly after the Earth's formation, suggesting that natural selection may not have had sufficient time to form the first single-celled organisms from basic elements. This has led some scientists to consider panspermia, the hypothesis that life originated elsewhere in the universe and was transported to Earth.
• 02:00 - 02:30: Pseudo-Panspermia Concept This chapter explores the concept of pseudo-panspermia, which suggests that while life may not have originated in space, its essential building blocks might have. The idea posits that complex molecules necessary for the origin of life (abiogenesis) could have been formed in space and arrived on Earth, potentially contributing to the development of life. It presents a middle ground to the theory that life, in the form of simple organisms, traveled to Earth from elsewhere in space, which lacks substantial evidence and is considered improbable.
• 02:30 - 03:00: OSIRIS-REx Mission Introduction The chapter introduces the OSIRIS-REx mission, highlighting the concept that fundamental building blocks for life may have originated in space rather than on Earth. It discusses the theory of pseudo-panspermia, suggesting these elements could have been delivered to Earth, expediting the path to life. The chapter also mentions the substantial evidence supporting this theory.
• 03:00 - 04:00: Early Earth and Organic Molecules The chapter titled 'Early Earth and Organic Molecules' begins by referencing the OSIRIS-REx mission and sets the stage by discussing the limited understanding of the origins of life on Earth. It highlights that life is fundamentally based on organic molecules such as nucleic acids, proteins, lipids, and carbohydrates, which function together in the complex systems of modern eukaryotic cells. The chapter acknowledges the simplicity of the first forms of life compared to contemporary organisms and suggests that even life’s precursors, like self-replicating RNA molecules, were simpler in the 'RNA-world'.
• 04:00 - 05:00: Amino Acids Formation and Space Evidence This chapter explores the hypothesis of amino acid formation as a critical step in the origin of life, focusing on how non-living chemicals can evolve into complex structures like RNA. It discusses the conditions of early Earth, where a primordial soup rich in energy and chemicals could have facilitated the combination of simple elements into organic molecules. These molecules then underwent numerous trials of combination and recombination, leading to increasingly complex compounds, forming a natural pathway toward the origin of life. This chapter also covers the evidence supporting these processes found in space.
• 05:00 - 06:00: Murchison Meteorite and Organic Compounds The chapter discusses the mysterious transition from organic molecules to complex, self-replicating RNA, despite recent advances in understanding. It highlights the known possibilities of pre-RNA developments dating back several decades. In 1952, scientists tried to mimic early Earth's conditions with liquid water and an atmosphere of hydrogen to explore the origins of organic molecules that could lead to RNA.
• 06:00 - 07:00: Chirality and Abiotic Origins Chirality and Abiotic Origins explores the origins of life, focusing on the potential for organic compounds such as amino acids to form under primitive Earth conditions. It delves into the Miller-Urey experiment, where a simulation of lightning in a primordial atmosphere resulted in the formation of organic building blocks, hinting at possible pathways to life's origins.
• 07:00 - 08:00: Space Missions for Organic Sample Collection The chapter discusses the prevalence of amino acids in the universe and their potential role in seeding Earth with the precursors to life. It highlights the Murchison meteorite as one of the first pieces of evidence that space rocks contain organic compounds.
• 08:00 - 09:00: OSIRIS-REx Mission Details and Challenges The chapter titled 'OSIRIS-REx Mission Details and Challenges' delves into the composition and significance of the Murchison meteorite discovered in Australia in 1969. This carbonaceous chondrite meteorite, primarily made of carbon, clay minerals, and water, is notable for containing over 90 different amino acids, some of which are uncommon on Earth. It also contains nucleobases like purine and pyrimidine, essential for DNA and RNA, and other organic molecules. Carbon dating has estimated the meteorite's age to be around 7 billion years, highlighting its importance in understanding the early solar system and the origins of life.
• 09:00 - 10:00: Return of OSIRIS-REx and Sample Analysis The chapter discusses the return of the OSIRIS-REx spacecraft and its sample analysis mission. It highlights the discovery that some components found are older than the Sun, suggesting complex organic chemistry in space predating life on Earth. The analysis adds to our understanding by comparing amino acids from the Murchison meteorite, noting their differences from Earth's typical amino acids, emphasizing the meteorite's extraterrestrial origins.
• 10:00 - 11:00: Sample Discoveries: Nucleobases and Amino Acids In the chapter titled 'Sample Discoveries: Nucleobases and Amino Acids,' the text discusses the significance of finding both left- and right-handed amino acids in a meteorite. On Earth, all life primarily uses left-handed amino acids, a feature that has persisted since the earliest DNA or RNA ancestors. The presence of both chiral forms in the Murchison meteorite suggests that these amino acids formed abiotically, before life began, supporting theories of their pre-life formation in space.
• 11:00 - 12:00: Bennu's Composition and Origin Chapter 'Bennu's Composition and Origin': This section discusses the importance of obtaining uncontaminated samples from space to understand celestial bodies better. It highlights efforts by international space agencies, mentioning NASA's Stardust mission that collected comet samples and Japan Space Agency's success in landing on asteroids and retrieving samples through its Hayabusa and Hayabusa2 missions. These efforts are key to ensuring no contamination from Earthly life in the samples collected from asteroids like Bennu.
• 12:00 - 13:00: Reconstructing Bennu's History The chapter delves into the exploration of the asteroid Bennu and examines its composition in the context of understanding prebiotic chemistry in space. It references the ESA's Rosetta mission and its success in landing a probe on a comet to collect samples. The primary question addressed is how advanced organic compounds can become in space, and the implications for panspermia theories, particularly the concept of pseudo-panspermia which suggests life on Earth might have been seeded from space. Some recent findings have shed light on these questions, improving our understanding of how life might have originated.
• 13:00 - 14:00: Pseudo-Panspermia and Life's Likelihood This chapter discusses NASA's OSIRIS-REx mission, an acronym for Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer. The mission focuses on the asteroid Bennu, a carbonaceous asteroid approximately 500 meters in diameter, which is part of the Apollo group that includes over 20,000 asteroids.
• 14:00 - 15:00: OSIRIS-APEX and Future Missions The chapter discusses asteroids with orbits that intersect Earth's, highlighting the potential threat they pose. It references past events, such as the asteroid explosion over Chelyabinsk in 2013, and mentions future possibilities, like the asteroid 2024 YR4, which has a tiny chance of impacting Earth in 2032. Although the asteroid Bennu currently poses no immediate threat, it makes close approaches to Earth, coming as near as 300,000 km (or 24 Earth diameters) every six years.
• 15:00 - 16:00: Conclusion and Sponsorship Message The chapter discusses the advantages of having potentially dangerous asteroid neighbors, emphasizing that they are easily accessible for exploration. It highlights the journey of the OSIRIS-REx spacecraft, which traveled from Earth's orbit to study and collect samples from the asteroid Bennu. After a thorough observational period to determine a safe landing site, the spacecraft successfully landed, collected samples, and easily departed Bennu due to its weak gravitational pull.

Your DNA Is (Almost Certainly) From Outer Space Transcription

• 00:00 - 00:30 Thank you to CyberGhost VPN for supporting PBS. Did you know that many of us have up to  4% of our DNA from neanderthals? And that 100% of us   may have DNA from outer space? No joke. At least  the biochemistry that defined the coding system   of your DNA may have happened off-world,  and perhaps even long before Earth existed.
• 00:30 - 01:00 Before we get started, just wanted to  let you know we have some new merch at   the merch store celebrating 10 years of  Space Time. We’ve got a limited edition   10 year anniversary design as well as some  classic logo merch. Having his gear doesn't   just make you incredibly cool, you also  helps us keep going for another decade. Life is the coolest thing to have happened in  our universe. It would be nice to know if it
• 01:00 - 01:30 happened anywhere else besides Earth—if nothing  else to know just how badly we’re screwing up   as we flirt with self-extinction. But  not only have we never found credible   evidence of life on or from other worlds, we  only have the sketchiest of ideas of how it   began on Earth. Makes it pretty difficult to say  much about what’s happening out there. But one   encouraging detail is just how quickly life got  started on Earth. The earliest fossils are dated
• 01:30 - 02:00 to within a few hundred million years of the Earth  first cooling from its early molten hell-ball   phase. And if you believe some of the more  tentative biosignatures, it could be much earlier. In fact, life got started so quickly on Earth  that some have argued that natural selection   just didn’t have the time to take raw elements  all the way to the first single-celled lifeform.   This difficulty led some scientists to propose  panspermia— the idea that life did not start
• 02:00 - 02:30 on Earth at all, but rather traveled here in  the form of extremely simple and presumably   extremely robust simple organisms. It’s a  fun story, and we’ve talked about it before,   but it’s not supported by evidence and  generally not considered particularly likely. But there is a middle road. Perhaps life didn’t  start in space, but maybe its building blocks did.   Pseudo-panspermia is the idea that many of the  complex molecules critical for abiogenesis—the
• 02:30 - 03:00 formation of life—were not formed on Earth, but  rather in the depths of space, in some cases   long before the formation of itself. If these  rained down on our planet in its early years,   that would allow our molecular ancestors to  skip many steps in their path to the first cell. The evidence for pseudo-panspermia is rather  strong. And the most compelling of that evidence
• 03:00 - 03:30 is just in, with the safe return of the OSIRIS-REx  mission. But before we get to those results, let's review what little we know  about the first formation of life. Life as we know it is based on a complex interplay  of organic molecules, primarily nucleic acids,   proteins, lipids, and carbohydrates. In  your body, these work together to form   the intricate machinery of the modern eukaryotic  cell. Of course, the first life was much simpler,   and life’s precursor simpler still—for example,  self-replicating RNA molecules of the RNA-world
• 03:30 - 04:00 hypothesis. But how did a bunch of non-living  chemicals even get to something as complex as   RNA? Extremely broadly, assume that in some  energy and chemical-rich primordial soup,   where simple elements combined into  organic molecules, when then combined   and recombined in a chain of trial and  error until this natural laboratory first
• 04:00 - 04:30 stumbled on self-catalyzing and  then self-replicating molecule. The step from organic molecules to complex,  self-replicating RNA is still pretty mysterious,   even if there have been recent advances. But  the pre-RNA part of the story? We’ve know that’s   possible for decades. Back in 1952, a pair of  scientists attempted to replicate the conditions   of the early Earth, with liquid water “ocean”  evaporating into an atmosphere of hydrogen,
• 04:30 - 05:00 methane and ammonia. An electrical spark  simulated primordial lightning powering   a chain or reactions that ultimately  led to a variety of organic compounds,   including five amino acids—the building  blocks of proteins. This was the famous   Miller-Urey experiment, and it was our first  hint at how the seeds of life may have formed. That experiment has now been repeated in  a variety of ways, and we now know that   amino acids can spontaneously form given the  right raw materials, an aqueous environment,
• 05:00 - 05:30 and an energy gradient. The apparent ease with  which amino acids form led scientists to wonder   just how ubiquitous these organic molecules  might be, not just on Earth, but through the   universe. For example, in the chunks of rock  and ice that rained down on the early Earth,   first building our planet and then perhaps  seeding it with the precursors to life. One of the first pieces of evidence that space   rocks are packed with organic compounds  was the Murchison meteorite, which fell
• 05:30 - 06:00 in Australia in 1969. This is a carbonaceous  chondrite meteorite, so, made mostly of carbon,   clay minerals, and water. But it was also  found to contain over 90 different amino acids,   including some that are not commonly found  on Earth, as well as the nucleobases purine   and pyrimidine which are critical components  of DNA and RNA, and other organic molecules. Carbon dating estimates that Murchison  is around 7 billion years old,
• 06:00 - 06:30 so a couple of billion years older than  even the Sun, meaning that complex organic   chemistry would have been occurring in  space long before life emerged on Earth. It’s hard to be 100% certain about the origin of  the molecules found in the Murchison meteorite   because the rock was in contact with Earth, which  we already know is infested with life. However,   the amino acids in the meteorite had one  distinct difference to those typically
• 06:30 - 07:00 found on Earth—they came in both left- and  right-handed varieties—both chiralities, both   mirror reflections. But all amino acids produced  by Earth life are left-handed—a chirality that   has been locked in since the first common DNA or  RNA ancestor of all life won that great molecular   war 3.5 to 4 billion years ago. The presence  of both chiralities in the Murchison meteor   tells us that these amino acids had an abiotic  origin—supporting their pre-life formation.
• 07:00 - 07:30 Pretty convincing, but the best  way to be sure there’s no cross   contamination from Earthly life is  to get samples directly from space. And there have been some incredible efforts to do  this. NASA’s stardust mission collected samples   from the coma of comet Wild 2 and returned them  to Earth. The Japan Space Agency was the first to   land on an asteroid and return samples—twice,  actually with Hayabusa and Hayabusa2. And
• 07:30 - 08:00 ESA’s Rosetta mission was the first to send a  lander to a comet where it analyzed samples on   location. These and other missions have shown that  organic compounds are abundant on space rocks. But how far along can this pre-biotic biochemistry  really advance in space? How much of a head start   might pseudo-panspermia have given to life on  Earth? Some of that has now been answered by
• 08:00 - 08:30 NASA’s OSIRIS-REx mission. In our long tradition  of unwieldy science acronyms, this stands for   Origins, Spectral Interpretation, Resource  Identification, and Security-Regolith Explorer. The spacecraft launched in 2016, with its sights on an asteroid by the name of Bennu. Bennu is a pretty ordinary  carbonaceous asteroid of middling size,   at around 500 m in diameter. It’s part of the  Apollo group—a collection of more than 20,000
• 08:30 - 09:00 asteroids with orbits that cross Earth’s.  That means they do sometimes slam into our   planet—like the one that exploded over Chelyabinsk  in 2013. Or as in 2024 YR4, which has a miniscule   chance of hitting Earth in 2032. Bennu has  no immediate chance of hitting us, but it   does make a close approach to Earth of around  300,000 km or 24 Earth diameters every 6 years.
• 09:00 - 09:30 The upside of these potentially cataclysmic  neighbors is that they’re quite easy to visit.   Which OSIRIS-REx did. It started that journey  in orbiting around the Earth, followed by a   mad dash to catch up to and orbit the asteroid.  Then after a few years of observation and analysis,   a suitable landing site was identified and the  spacecraft touched down. Samples were collected   before an easy escape from Bennu’s frankly  pathetic excuse for a gravitational field.
• 09:30 - 10:00 OSIRIS-REx rejoined Earth’s solar orbit  and dropped its sample capsule into our   atmosphere in September of 2023. And after  all of that, the capsule’s parachute failed.   Its first parachute failed. The second opened  just fine and the capsule landed right   on target in Utah. Since then, scientists  have been hard at work analyzing the sample,   and the first results of the findings were  finally published in January this year.
• 10:00 - 10:30 So, what did we find? Among the most exciting  discoveries in the sample are all five of the   nucleobases that serve as the code for DNA  and RNA. This is the first time we’ve found   five on the same space rock. The samples  also contained 14 of the 20 amino acids   that life on Earth harnesses to make proteins, These amino acids have both left- and right-handed   chirality, just like the Murchison molecules. Bennu sample has various other interesting
• 10:30 - 11:00 compounds, including a surprising richness  of ammonia—12 times higher than in the   Murchinson meteorite. Curiously, Bennu orbits  too close to the sun to preserve pure ammonia,   so its richness hints at a colder, more  distant origin. But more on that later. One of the most exciting finds were 11  different minerals that we know form when brines   slowly evaporate. That means Bennu, or the  stuff that formed it, was once in an aqueous,
• 11:00 - 11:30 salty environment. In fact, there were many signs  of the role of water in Bennu’s formation. Its   minerals match most water-altered meteorites ever  found on Earth, as well as the samples collected   from asteroid by JAXA. But, unlike most meteorite  samples, Bennu contains sodium rich salts,   which are rare in meteorites. Similar salts  are found here on Earth, like in Searles Lake,
• 11:30 - 12:00 California, confirming that Bennu once  contained pockets of sodium rich water. But normally we don’t find sodium rich  salts in meteorites because they react   strongly with our atmosphere. But because  Bennu’s samples were stored in pure nitrogen,   they maintained a pristine  suite of salts for analysis. With this analysis in, we’re able to  reconstruct a likely origin story for
• 12:00 - 12:30 this asteroid. And that origin is  probably a water-rich world that   existed for a time in the early solar  system, but has since been destroyed. Let me take you back 4.5 billion years  ago, on the icy fringes of the early solar   system beyond Jupiter’s orbit, a distant  protoplanet formed from a mixture of rock,   metal, and frozen water. As radioactive elements  created in an ancient supernova decayed within,
• 12:30 - 13:00 heat melted some of the ice, creating  mineral-rich reservoirs. These ancient   waters interact with ammonia and formaldehyde,  sparking the formation of complex organic   molecules. When the water eventually evaporates,  it leaves behind veins of brine-sourced minerals.  This protoplanet, however, is doomed. Before  it can grow to full planet-hood, a catastrophic   collision—perhaps with another similar  body—scattering its fragments into space. And
• 13:00 - 13:30 Bennu and many other asteroids pulled themselves  together from this debris. In the unsettled   early solar system with its wandering gas giants,  Bennu’s orbit was also fated to wander. Eventually   it settles into an orbit perilously close to  an inner-solar system planet. A planet that   would slowly turn blue-green and then twinkle  with night lights and then send a tiny visitor
• 13:30 - 14:00 of metal and silicon named OSIRIS-REx. Or at least, it seems like this is the most   likely story based on the bits of Bennu that we  brought back home. And if Bennu has the variety   of organic compounds that we discovered, so do  many asteroids, and probably comets. Many of these   peppered the early Earth—far more than today.  In fact, they are kind of what Earth is made of.   Like I said, pseudo-panspermia—the idea that the  chemistry of life got a head start from space
• 14:00 - 14:30 molecules—is pretty well supported. But does this tell us anything about the   likelihood of life elsewhere? We can be pretty  sure that there are watery worlds out there that   started out with an abundance of organic  compounds, all the way up to amino acids   and even nucleotides. It’s becoming harder  to imagine that simple life doesn’t form in
• 14:30 - 15:00 lots of places. But the observation of DNA and  RNA coding nucleobases could tell us something   pretty profound. If all planets start with  a similar chemical cocktail, maybe there’s   a pretty narrow path to life everywhere—one  that involves DNA-like molecules. Maybe the   system that codes Earth life—including your own  DNA—was set by extraterrestrial biochemistry.  And what about OSIRIS-REx? It delivered its  sample, but it stayed out there to continue
• 15:00 - 15:30 its adventure. NASA has renamed in OSIRIS-APEX,  and it’s now preparing to intercept the asteroid   Apophis. This time the mission isn’t  primarily to discover the origin of life,   but to help prevent its annihilation. Apophis  is one of the most hazardous Apollo asteroids.   It has a miniscule chance of hitting Earth  in 2036. OSIRIS-APEX will study any changes
• 15:30 - 16:00 to the asteroid that occur during its close  encounter with Earth in 2029. This will help us   track Apophis more precisely. It’ll also teach  us more about these close encounters, perhaps   allowing us to avert a future giant impact.  Well, thanks for looking out for us, little buddy,   and for helping us seek our chemical origins in  a protoplanetary, perhaps pre-solar spacetime. Thank you to CyberGhost VPN for supporting PBS.  If you’re looking to browse the web securely,
• 16:00 - 16:30 CyberGhost VPN is built to keep your online  activity safe and private, especially when   using public WiFi. They know online privacy  is challenging, and that “private” modes in   many browsers may not be as “private” as people  think. Just turn it on before you start browsing,   and with secure servers in over 100 countries,  CyberGhost VPN encrypts and reroutes all your   traffic to help prevent ISPs, workplaces, and  websites from tracking you. They help you stay
• 16:30 - 17:00 private and secure online, with service designed  to meet most customers’ needs. Plus, with over 38   million users worldwide, they are committed  to helping your information stay encrypted,   your IP hidden, and your online identity  anonymous. Use the link in the description   and get 4 extra months of service plus an 83%  discount and with 24/7 customer support, help   is always there if you need it. So click the link  in the description to learn about CyberGhost VPN.