Everything Everywhere Daily: History, Science, Geography & More - The Silurian Hypothesis (Encore)

Episode Date: August 16, 2024

The universe is billions of years old.  If, in the future, humanity were to explore the galaxy and visit other planets around other stars, we might be visiting places where at one time, an advanced civilization once existed.  However, if such a civilization existed, it might have been millions of years in the past. If that was the case, how would we even know that it existed?  Also, what if we ask that same question of Earth rather than of alien worlds? Learn more about the Silurian Hypothesis on this episode of Everything Everywhere Daily. Sponsors Sign up for ButcherBox today by going to Butcherbox.com/daily and use code daily at checkout to get $30 off your first box! Subscribe to the podcast!  https://link.chtbl.com/EverythingEverywhere?sid=ShowNotes -------------------------------- Executive Producer: Charles Daniel Associate Producers: Ben Long & Cameron Kieffer   Become a supporter on Patreon: https://www.patreon.com/everythingeverywhere Update your podcast app at newpodcastapps.com Discord Server: https://discord.gg/UkRUJFh Instagram: https://www.instagram.com/everythingeverywhere/ Facebook Group: https://www.facebook.com/groups/everythingeverywheredaily Twitter: https://twitter.com/everywheretrip Website: https://everything-everywhere.com/ Learn more about your ad choices. Visit megaphone.fm/adchoices

The following is an encore presentation of everything everywhere daily. The universe is billions of years old. If in the future humanity were to explore the galaxy and visit other planets around other stars, we might be visiting places where at one time an advanced civilization once existed. However, if such a civilization existed, it may have been millions of years in the past. And if that was the case, how would we even know that it existed? Also, what if we ask that same question of Earth, rather than of alien worlds.

Learn more about the Silurian hypothesis on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR.

This episode is going to be a bit different in that I'm not going to be covering a historical event or explaining the facts about something. This episode is going to be about questions. Questions that don't necessarily have any definitive answers, but questions that can get you thinking and questions that can help you understand how it is we know what we know about a great many things. The topic of this episode began with questions about intelligent life elsewhere in the universe. If we were to find intelligent life,

How would we even know that we found them? If there's some civilization on another distant planet, is there something in the atmosphere, perhaps, of that planet, that we could use to determine that there was a civilization there? Adam Frank, an astrophysicist at the University of Rochester, began wondering if every advanced civilization would do something to change their climate, similar to humans. In 2017, he took these questions to Gavin Schmidt,

the director of NASA's Goddard Institute for Space Studies. Schmidt is a climate scientist and a climate modeler. Schmidt, instead of answering the question directly, turn the question around and asked, how do we know there hasn't been some other advanced civilization here on Earth? At first, the question seems ridiculous. Humans are the only species on Earth that have ever created an advanced civilization, right? However, once you get past the initial incredulity,

you're faced with a serious question. How do we know that we aren't the only advanced civilization to have existed on Earth? Earth. That turns out to be a surprisingly difficult question to answer. Frank and Schmidt posed a thought experiment. If there was an industrial civilization on Earth, tens or hundreds of millions of years ago, what evidence would let us know of their existence? They dubbed this the Silurian hypothesis. They got the name from the race of lizard people from the Doctor Who television show. In the Doctor Who universe, the Silurians existed millions of years before humans, and their name was taken from the Silarian geologic period, which was about 443 to 419 million years ago.

Let me make it perfectly clear. The Silurian hypothesis is just a thought experiment. No one is actually claiming there was an advanced industrial lizard civilization on Earth over 400 million years ago. There is zero evidence of this. So don't go telling your friends about the podcast you listened to that said there were ancient lizard people on Earth. I'm sure such podcasts do exist, but that's the same.

this is not one of them. The thought experiment simply asks, if a civilization did exist, how would we know it? First of all, could such a civilization have even existed in the first place? It took about 500 million years from the rise of multicellular life to human beings. We like to think of evolution as one continuous path getting better and better, ultimately leading to the development of us, human beings. However, that is not at all how it works. While humans have, it wasn't destined to happen. We are not the end result of evolution. Every other species on the planet fits an ecological niche just fine. In fact, modern Homo sapiens have only existed for about 300,000 years, and the earliest things that we can point to as human ancestors dates back

about 2 million years. Our industrial civilization has only existed for 300 years. When you're looking at the time span that complex life has existed on Earth, there has been plenty of time for other intelligent species to have arisen. So, again, while no one's saying lizard people existed, it also isn't impossible to say that they could have existed. It's also believed that as early as 350 million years ago, there were already enough fossil fuels on Earth to have supported an industrial civilization. Coal, oil, and gas as energy sources would have been possible. So going back to the original question, if such an industrial lizard civilization existed, How would we know? Your first reaction is probably to say that we would just find their ancient

artifacts as we do with other ancient human civilizations. We'd find their fossilized remains as we do with other ancient creatures. There, however, is a problem with that. Almost nothing gets fossilized. The odds of any living thing becoming a fossil is extremely remote. Various species of dinosaurs roam the earth for tens of millions of years. During that time, there would have been not billions, but trillions of individual dinosaur creatures that existed at some point. From that enormous pool, we have only a few thousand complete dinosaur skeletons. There is a good chance, almost no living thing that you have ever encountered in your life will remain as a fossil in a hundred million years.

It's entirely possible, perhaps probable, that entire species are missing from the fossil record because no member of that species was ever fossilized. Moreover, even if the lizard people were fossilized, the odds of us finding those fossils are slim. Almost all fossil finds are discovered by accident, someone digging something when they encountered a bone. Maybe you think that even if we don't find fossils, maybe we'll discover their artifacts. We find stone structures all the time from ancient peoples. Golbeki Tempe and Turkey, on which I've done a previous episode, is almost 11,000 years old. Even if we can't find the remains of the actual people who built it, we can still find the evidence

of what they built. Maybe there could be some sort of Planet of the Apes type moment when we discover the lizard civilization equivalent of the lizard statue of liberty. The problem is that there's a huge difference between something surviving for thousands of years and something surviving for tens or hundreds of millions of years. The timescales we'd be talking about are geologic. Not only wouldn't buildings and roads survive, entire mountain chains and continents wouldn't even survive. It's easy to see with your own eyes how quickly concrete structures can decay after just a few decades. Skyscraper's made of steel will eventually corrode and collapse if not maintained, even if it took thousands of years for that to happen. Everything made of wood will eventually rot or burn if given enough time.

Natural disasters, even though they may only happen once a century, would be frequent enough to destroy most structures. earthquakes, floods, volcanic eruptions, fires, tornadoes, and even severe storms would take their toll over long periods. Structures that are buried would eventually become part of the sedimentary rock itself given enough time. So, once again, if an advanced industrial civilization did exist on Earth millions of years ago, how could we possibly know it? If there was evidence, it wouldn't be direct evidence.

It would have to be found somewhere in the geologic record. Franken Schmidt attempted to address this problem in a 2019 paper published in the International Journal of Astrobiology titled The Silurian Hypothesis. Would it be possible to detect an industrial civilization in the geological record? The key to finding evidence of a past civilization, or the key to a future civilization learning about us, would have to be found in the rocks themselves. One of the first things that could possibly be evidence of industrial civilization would be radioactive isotopes. Certain isotopes and elements do not appear naturally. A good example is plutonium 244, which has a half-life of 80.8 million years. If a civilization were to use nuclear weapons, then a concentration of unnatural isotopes could be evidence of an industrial civilization. Another more subtle clue could be stable isotopes. In particular, if you're an industrial civilization burning fossil fuels, those fuels would have had a biological origin, and the ratio of carbon 13 to carbon 12 would be.

be lower than normal. Carbon-based particulate matter, as well as CO2, which would be bound up in rocks, would create an anomalous layer where the carbon-13 to carbon-12 ratio changed. This could be a sign that fossil fuels were used, and they could be found in the geologic record. Another stable isotope that could signify the presence of a past industrial civilization would be nitrogen 15. The early 20th century saw the development of the Haber-Bosch process, which allowed for the artificial creation of nitrogen fertilizers. These, These fertilizers have skewed ratios of nitrogen 14 to 15 that you would find in natural biological processes.

As nitrogen is spread on farm fields that cover a large amount of area, this is a good candidate for discovery. Another more direct form of evidence would be discovering a layer of chemicals in the rock which are not produced naturally. Synthetic chemicals like chloral-floral carbons or per and polyfluoral alkylid substances, also known as forever chemicals, would also give a strong indication of industrial civilization. possibility would be the discovery of microplastics. There's now developing on Earth a layer of microplastics in ocean sediment. These are extremely small particles of plastic that are left as

plastics break down. They've actually been found all over the planet, so it's possible that a layer of plastics would be evidence of civilization. However, we have no clue if plastics could in fact survive that long. Pressure and temperatures involved with geologic processes could turn them into different molecules, and they could be digested by microbes before that ever gets a chance to happen. One problem with all of these signals that I've just mentioned is that if signs like this were found in the geologic record, they wouldn't necessarily be evidence of an advanced civilization. There are alternative theories for how many of these signs could appear without a civilization. Volcanism and meteor strikes could change stable isotope levels. If we search for evidence

of ancient civilizations on another planet, there is no guarantee that planet would have the same amount of radioactive elements that we have on Earth. Moreover, things like plastic and synthetic chemicals reflect what humans developed, and they might not represent what some other civilization would have developed. An industrial civilization could have existed, but never made any of those things, or may have only done so in very limited amounts. One of the best places to look for evidence of past civilization might not be on a planet at all. It would be up in space.

If a civilization became spacefaring, they would be able to put satellites in in high orbit or on neighboring moons. These would be able to sit, mostly unmolested, for millions of years. Cosmic rays and solar winds might bombard them, but they could basically stay there indefinitely without being subject to a planet's geologic processes. The entire Silurian hypothesis thought experiment shows just how tricky of a problem this is. Given enough time, almost all evidence of our civilization will disappear.

100 million years from now, any intelligent civilization, on Earth would have a hard time knowing that we were even here. So while we have no evidence of an ancient lizard civilization on Earth, and there's no reason to believe that they existed, we can't really prove that they didn't exist either. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Benji Long and Cameron Kiever. I want to give a big shout out to everyone who supports the show over on Patreon, including the show's producers.

Your support helps me put out a show every single day. And also, Patreon is currently the only place where Everything Everywhere Daily merchandise is available to the top tier of supporters. If you'd like to talk to other listeners of the show and members of the Completionist Club, you can join the Everything Everywhere Daily Facebook group or Discord server. Links to everything are in the show notes.