Sea Camp: Did Life Start In Hydrothermal Vents?

How did life start on Earth? The answer is a big scientific mystery scientists are actively investigating. After talking with many scientists, host Regina G. Barber found that an abundance of water on Earth is most likely key, in some way, to the origin of life — specifically, in either deep sea hydrothermal vents or in tide pools. It's for this reason some scientists are also exploring the potential for life in so-called "water worlds" elsewhere in the solar system, like some of the moons of Jupiter and Saturn. This episode, Regina digs into two water-related hypotheses for the origin on life on Earth — and what that might mean for possible alien life. Have another scientific mystery you want us to cover on a future episode? Email us at [email protected] mailto:[email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave https://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  This message comes from Capella University. That spark you feel? That's your drive for more. Capella University's FlexPath learning format lets you earn your degree at your pace without putting life on pause. Learn more at capella.edu. You're listening to Short Wave from NPR.

• 0:20Emily Kwong?

  Hey, Short Wavers. Emily Kwong here with my favorite astrophysicist Regina G. Barber.

• 0:26Regina Barber?

  Thank you, Em. I'm glad I'm your favorite. Am I the only astrophysicist?

• 0:29Emily Kwong?

  You're the only astrophysicist I know, so as long as I don't meet another one. We are back with our next installment of Sea Camp, our summer series that dives deeper each week into the wonders and mysteries of the ocean.

• 0:40Regina Barber?

  Yes, so many mysteries.

• 0:42Emily Kwong?

  It's been such an incredible series, honestly. You, last week, and producer Hannah Chin, were hanging out in the midnight zone with deep-sea giants. Where are we going today?

• 0:52Regina Barber?

  So today, we're exploring this really cool phenomenon that happens in both the midnight zone, that's the one we just visited, and the zone below it, the abyssopelagic.

• 1:01Speaker 03

  This is what we would call the abyss. Very interesting, very eerie.

• 1:07Emily Kwong?

  I'm ready to go to the abyss.

• 1:08Regina Barber?

  Yeah.

• 1:09Emily Kwong?

  And this sounds like our Sea Camp tour guide, Noelle Bolin, yes? A marine biologist from the National Oceanic and Atmospheric Administration.

• 1:16Regina Barber?

  Yeah, she says the abyssal zone is interesting because, as we learned in the last episode, the average depth of the ocean floor is 4,000 meters, and that's where this zone starts, which means...

• 1:27Speaker 03

  It's only in certain places of the ocean around the world that you get into the abyssopelagic.

• 1:32Regina Barber?

  Hmm. Those lucky places are 4,000 to 6,000 meters underwater, and they're the home to today's topic. I'm so excited. Hydrothermal vents.

• 1:42Emily Kwong?

  Oh, these are these underwater mini volcano-looking things that spew hot water, and all these extremophiles, all these critters that are adopted to live there will live on them.

• 1:51Regina Barber?

  Yes, exactly. They were first discovered in the 70s when scientists dragged a probe across the ocean floor, and they detected these huge temperature differences, and they were really surprised. Since then, we've learned a lot about them. Some of them are really hot, over 700 degrees Fahrenheit, and they come in all sorts of sizes. Some are really... Really small, some are huge, like up to 180 feet. That's 18 stories tall.

• 2:16Emily Kwong?

  Wait, there's vents as tall as buildings?

• 2:18Regina Barber?

  Yes, yeah, they're these underwater chimneys, basically. Except instead of smoke, they're spewing minerals, gases, and hot water. Sometimes those minerals contain iron, copper, and zinc. And they're spewing like black stuff, so like scientists call them black smokers. There are white smokers too, that have like different elements.

• 2:38Emily Kwong?

  Wow, okay.

• 2:39Regina Barber?

  Yeah, and Emily, that warmth and mineral richness, that makes them really good spots for some ocean animals to thrive.

• 2:46Speaker 04

  The giant tube worm, I think, is one of the weirdest looking animals. It can grow to be over six feet tall, but it is a worm. And it has like a kind of hard shell that it lives in, which is the same material that fingernails are made out of. And they are everywhere.

• 3:06Regina Barber?

  That's Heather Fullerton, a microbiologist at the College of Charleston, and she studies hydrothermal vents. She said that there are fish and crabs, mussels, there are loads of shrimp, so much life. In fact, some scientists think that life in its earliest forms could have started there.

• 3:22Emily Kwong?

  Really?

• 3:22Regina Barber?

  Yeah.

• 3:23Speaker 04

  When Earth was first forming, or had just first formed, the atmosphere we had was not protected from UV radiation. And it has been studied that some of the kind of small building blocks of life can be formed at vents.

• 3:40Emily Kwong?

  My stomach just did a flip flop.

• 3:41Regina Barber?

  Okay, this is why I'm reporting on it.

• 3:43Emily Kwong?

  Cool.

• 3:44Regina Barber?

  So when she's talking about like building blocks, she means like nucleotides, amino acids. Heather says that DNA and RNA, for example, are extremely vulnerable to like UV light. So maybe they first form deep in the ocean where they'd be protected from those rays.

• 3:58Emily Kwong?

  That's amazing. Wow, okay.

• 3:59Regina Barber?

  Yeah, so Em, it turns out that hydrothermal vents, they could exist on other moons and planets too.

• 4:06Emily Kwong?

  What?

• 4:06Regina Barber?

  Including my favorite, one of Jupiter's moons like covered in water and ice, Europa.

• 4:11Emily Kwong?

  As if you couldn't love Europa more. Now you have even more reasons to love it.

• 4:14Regina Barber?

  I mean, this is why.

• 4:15Emily Kwong?

  So if the building blocks of life on Earth started at Earth's vents, and there could be vents on other worlds like Europa, could there be life all the way out there?

• 4:25Regina Barber?

  That's what I'm trying to find out with my reporting.

• 4:28Emily Kwong?

  I see why we're here today. So today on the show, Gina dives into a big question. How did life really begin on Earth?

• 4:35Regina Barber?

  And could the answer lead us to life in alien oceans elsewhere in our solar system?

• 4:40Emily Kwong?

  You're listening to Short Wave, the science podcast from NPR.

• 4:51Speaker 00

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• 6:11Emily Kwong?

  All right, Gina, I know you have been cooking on this question for a long time, even though it seems really simple at face value. How life started on Earth, what did you find?

• 6:21Regina Barber?

  Yeah, it's actually something I've been thinking about since I was like 16. And after talking to many scientists, I'm pleased to give you a very simple answer.

• 6:31Speaker 06

  There is no consensus.

• 6:33Regina Barber?

  Oh, great. That's Mike Wong, friend of the show and an astrobiologist.

• 6:38Speaker 06

  One of the greatest outstanding mysteries of science is how does life begin? We really don't know yet, but that hasn't stopped us from theorizing.

• 6:49Emily Kwong?

  Mike Wong has turned my mood around. Okay, what are the theories?

• 6:53Regina Barber?

  Well, there's multiple competing ideas on how and where life began. Like, two of the big ones have to do with water.

• 7:00Speaker 07

  All of life's origins, every single group of animals you can think of, every single group of even plants, it all comes from the oceans ultimately.

• 7:08Regina Barber?

  That's Karma Nangalu, a paleontologist and a postdoctoral fellow at Harvard University. And he studies ocean fossils so old, they're from before there was life on land.

• 7:17Emily Kwong?

  Yeah, I mean, it is true. Even before dinosaurs walked on land, we had animals in the sea.

• 7:22Speaker 07

  It's an incredible thing. If you think about the ocean, it's very much a nurturing environment in many ways. You know, the burden of gravity has taken off you in many ways. So many animals become very large in the ocean as a result.

• 7:32Regina Barber?

  Like whale sharks, which can be up to like 12 meters or 40 feet.

• 7:37Emily Kwong?

  Or giant manta rays.

• 7:38Regina Barber?

  Yeah, so big. Those are over 15 feet wide or about like 4.5 meters for like metric levers out there.

• 7:45Speaker 07

  Oh, there's also things like temperature stability because of, you know, obviously water's thermal properties. Then you consider land and being in the open air. It's way harsher by comparison.

• 7:55Emily Kwong?

  But vents are harsh.

• 7:56Regina Barber?

  Yeah.

• 7:57Emily Kwong?

  They're hot and there's obviously no sunlight down there.

• 7:59Regina Barber?

  Yes, these are great points, Em. And it turns out that heat is actually one of the reasons some life thrives down there. Like, it's where they get their energy.

• 8:08Emily Kwong?

  Yeah.

• 8:08Regina Barber?

  Karma says life around these hydrothermal vents is unique because like a lot of food chains on Earth get their energy from sunlight. But these animals and bacteria are so far down in the deep, dark ocean that their food chain is built on something else.

• 8:21Speaker 07

  They have to kind of like base the food web on something that's not based on photosynthesis. And so many of these animals undergo a process called chemosynthesis, which is basically building up energy and building up usable, you might colloquially say, food stores by synthesizing chemicals rather than requiring light energy.

• 8:38Regina Barber?

  Yeah, so in this scenario, it's possible early life didn't need much, if any, sunlight.

• 8:44Emily Kwong?

  Okay, so that's the first idea for how life could have begun in the oceans. What's the other idea?

• 8:52Regina Barber?

  So the second leading hypothesis deals with shallow water, specifically like tide pools. And researchers who are in this like second hypothesis of origins of life camp, they basically think oceans are too wet all the time for life to have emerged there.

• 9:07Emily Kwong?

  I mean, wetness is a signature trait of oceans.

• 9:09Regina Barber?

  Yeah, but that's potentially like a problem. Some scientists think for complex molecules to build up, you need these like wetting and drying cycles to bond molecules together.

• 9:18Emily Kwong?

  Oh, wetting drying cycles?

• 9:21Regina Barber?

  Yeah.

• 9:21Emily Kwong?

  So because the material in tide pools is only submerged in water some of the time.

• 9:27Regina Barber?

  Yeah.

• 9:27Emily Kwong?

  That's why they're a good alternate candidate for life on Earth.

• 9:31Regina Barber?

  Yeah, so like the tide pools you were just talking about that you've encountered, those were like on a beach. These tide pools could also exist like in the middle of oceans. Like think of like a volcanic mount, like the tippy top of a volcano that like shot up. I'm going to bring back Mike Wong to explain this like tide pool theory a little more. He says that this bit of volcano maybe pops out of the water. It's probably sloped, so when it rains.

• 9:56Speaker 06

  A pool will fill up, and if no rain comes for quite some time, then it'll dry up. And this is important because in order to link up the pieces of RNA, that chemistry has to go through what's called a dehydration reaction, which means it has to get rid of a water, it has to spit out a water molecule in order to make that link.

• 10:14Regina Barber?

  Yeah, and Mike is talking about like RNA because scientists generally think it's one of those like fundamental molecules that early life could have been based around.

• 10:23Emily Kwong?

  So between these two scenarios, the all ocean, all the time scenario and the tide pools everywhere scenario, which is it?

• 10:30Regina Barber?

  Yeah, so here's the thing. The more I talk to all of these different scientists, the more I realized I had to like rethink my questions. Like across these two ideas, we've been talking about location a lot.

• 10:42Emily Kwong?

  Yeah.

• 10:42Regina Barber?

  And maybe we shouldn't.

• 10:44Emily Kwong?

  Wait, what do you mean?

• 10:45Regina Barber?

  Well, I talked to Lori Barge, another astrobiologist and geochemist, this time at NASA's Jet Propulsion Lab. And she added this layer of nuance to my search.

• 10:54Speaker 08

  So I think that the right question is less, which environment did life originate in? And more, what conditions were required for the origin of life?

• 11:02Regina Barber?

  Like, it's more about the process.

• 11:04Emily Kwong?

  Yeah.

• 11:05Regina Barber?

  So environment matters, but different conditions can exist in the same environment.

• 11:10Speaker 08

  And so I think the discoveries that we need are to know what reactions were necessary for the origin of life? And then what environments had those conditions? And there might be more than one answer, is the thing. Because early Earth was a very big place. And was there only one origin of life? I don't know if there was.

• 11:27Regina Barber?

  Her lab focuses on chemistry, really like testing to see if they can figure out how primordial matter and chemical reactions might have been affected by things like other minerals or ions in seawater.

• 11:38Emily Kwong?

  Yeah.

• 11:39Regina Barber?

  Or by molecules in the atmosphere.

• 11:41Emily Kwong?

  This makes sense. Like, how can we know where to look for something if we don't know what we're looking for? If we haven't defined that? Exactly.

• 11:49Regina Barber?

  Right. And some of those conditions scientists are looking for could be around some hydrothermal vents. So Lori and other researchers are taking samples from the Earth's oceans and trying to simulate in their lab what they think some vents in early Earth would be like.

• 12:05Speaker 08

  So in our experiments, we make little chimneys. And we put organics in them sometimes.

• 12:11Emily Kwong?

  So she's making her own little hydrothermal vent?

• 12:14Regina Barber?

  Yeah. Yeah, yeah. Her and her team make these like small hydrothermal vents. You know, remember those black and white smokers from the beginning of the story?

• 12:21Emily Kwong?

  Yeah.

• 12:21Speaker 08

  And we're trying to look at, first of all, where do the organics go? And then we also look at the energy that the chimneys can generate. So if you put, let's say, electrical leads in the chimney and in the ocean, you can measure the potential, the electrical potential they generate. So in that sense, it's kind of like a battery. So you have all these different properties. So you can, depending on the experiment, it's designed for different reasons.

• 12:42Emily Kwong?

  So what have they found? What, like, what conditions lead to life on Earth? And maybe on other planets?

• 12:49Regina Barber?

  Right, so they are still working on that.

• 12:52Emily Kwong?

  I was gonna say this.

• 12:53Regina Barber?

  But the fact that there could be the right conditions in some vents brings us back to these icy moons in our solar system, like Enceladus and Europa. They are wet all the time. No tide pools, no drying and wetting cycles.

• 13:05Emily Kwong?

  So... Do you think there could be vents on Enceladus and Europa? Is that where you're going with this, based on what she's saying?

• 13:13Regina Barber?

  Yeah, maybe, like a big maybe.

• 13:15Emily Kwong?

  Yeah.

• 13:15Regina Barber?

  But Mike, and I admit, me too, are part of this optimistic scientist club, inspired and enthralled by this idea that ingredients of life could exist elsewhere in our universe, like in these vents.

• 13:28Speaker 06

  Hydrothermal systems are just infused with all of this rich chemical and thermal energy that could have helped spark metabolic systems into existence. And because we think that there are similar hydrothermal systems at the bottom of these oceans of the icy ocean worlds, Europa and Enceladus, maybe you would get another origin of life.

• 13:54Regina Barber?

  But like, obviously Europa and Enceladus, they're not the same as Earth.

• 13:57Speaker 08

  No. You'd have to take, you know, an organic reaction that we think we understand on Earth and say, what if, what if the ocean was alkaline like Enceladus? Or what if minerals were present like on Europa? And would it be different? And if so, how?

• 14:09Regina Barber?

  If life could happen there, it might look a little different than life here on Earth. But what's cool about Enceladus in particular is we've actually gotten a glimpse of what it's like already. Like NASA's already gotten direct data of its like ocean through a geyser shooting water into space.

• 14:25Emily Kwong?

  I love that Enceladus just spews water into space.

• 14:27Regina Barber?

  It does.

• 14:28Emily Kwong?

  And it doesn't seem like, at the end of the day, there is a lot of resolution, though there is a lot of interesting science.

• 14:35Regina Barber?

  Yeah. And so we end this episode the way we end so many of these episodes. To answer the big questions, we need more data, more research, like, needs to be done.

• 14:44Speaker 08

  That seems to be a theme on Shore Wave.

• 14:46Regina Barber?

  Yeah. But like, I don't know, it's kind of like beautiful and like humbling that there's still so many big questions out there.

• 14:53Speaker 08

  We don't know exactly yet how life emerged on Earth. And so there is this question of, could it have emerged more than once and only one survived to be the tree of life that we know? Could it happen multiple ways and it just didn't happen on Earth? We don't really know. And so when we go out to look for life elsewhere, we have to consider, first of all, could an Earth-like origin of life have happened? But also, could other things have happened that may not have happened on the Earth? We really don't know.

• 15:18Regina Barber?

  So there you go, Emily. After all this reporting, no answer, but I've learned more. And I still have hope that these like little chimneys may be on the bottom of Europa's ocean.

• 15:30Emily Kwong?

  I hope that for you, too. And that there's a hydrothermic alien Santa Claus that'll come out of them.

• 15:36Regina Barber?

  Oh, my god. Maybe. I just want a little shrimp. I just want you a little rope of shrimp.

• 15:41Emily Kwong?

  Gina, thank you for bringing us this story that you are clearly very passionate about.

• 15:46Regina Barber?

  I am. Thank you.

• 15:49Regina Barber?

  This episode was produced by Hannah Chen. It was edited by showrunner Rebecca Ramirez and Tyler Jones checked the facts. The audio engineer was Robert Rodriguez.

• 15:57Emily Kwong?

  Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy.

• 16:02Regina Barber?

  Special thanks to Max Barnhart for his biology expertise.

• 16:05Emily Kwong?

  Thanks, Max. I'm Emily Kwong.

• 16:07Regina Barber?

  I'm Regina Barber.

• 16:08Emily Kwong?

  And thanks to you, short wavers, for listening to Short Wave from NPR.