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Thread: How Would We Know If Intelligent Life Existed on Earth Before Humans?

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    United States Avalon Member Skywizard's Avatar
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    Default How Would We Know If Intelligent Life Existed on Earth Before Humans?

    Could there have existed an intelligent race on planet earth before us? What if they were so
    intelligent and evolved that we couldn't see evidence of their existence?



    Did someone inhabit our planet before us? To find out we need to examine our own carbon footprint, claim scientists



    Reptilian menaces called Silurians evolved on Earth before humankind — at least in the "Doctor Who" rendition of the universe. But science fiction aside, how would we know if some advanced civilization existed on our home planet millions of years before brainy humans showed up?

    This is a serious question, and serious scientists are speculating about what traces these potential predecessors might have left behind. And they're calling this possibility the Silurian hypothesis.

    When it comes to the hunt for advanced extraterrestrial civilizations that might exist across the cosmos, one must reckon with the knowledge that the universe is about 13.8 billion years old. In contrast, complex life has existed on Earth's surface for only about 400 million years, and humans have only developed industrial civilizations in the last 300 years. This raises the possibility that industrial civilizations might have been around long before human ones ever existed — not just around other stars, but even on Earth itself.

    "Now, I don't believe an industrial civilization existed on Earth before our own — I don't think there was a dinosaur civilization or a giant tree sloth civilization," said study co-author Adam Frank, an astrophysicist at the University of Rochester in New York. "But the question of what one would look like if it did [exist] is important. How do you know there hasn't been one? The whole point of science is to ask a question and see where it leads. That's the essence of what makes science so exciting."

    Artifacts of human or other industrial civilizations are unlikely to be found on a planet's surface after about 4 million years, said Frank and study co-author Gavin Schmidt, director of NASA's Goddard Institute for Space Studies in New York. For instance, they noted that urban areas currently take up less than 1 percent of Earth's surface, and that complex items, even from early human technology, are very rarely found. A machine as complex as the Antikythera mechanism — which is considered to be the world's first computer from ancient Greece — remained unknown until the development of elaborate clocks in RenaissanceEurope.

    One may also find it difficult to unearth fossils of any beings who might have lived in industrial civilizations, the scientists added. The fraction of life that gets fossilized is always extremely small: Of all the many dinosaurs that ever lived, for example, only a few thousand nearly complete fossil specimens of the "terrible lizards" have been discovered. Given that the oldest known fossils of Homo sapiens are only about 300,000 years old, there is no certainty that our species might even appear in the fossil record in the long run, they added.

    Instead, the researchers suggested looking for more subtle evidence of industrial civilizations in the geological records of Earth or other planets. The scientists focused on looking at the signs of civilization that humans might create during the Anthropocene, the geological age characterized by humans' influence on the planet.

    "After a few million years, any physical reminder of your civilization may be gone, so you have to look for sedimentary anomalies, things like different chemical balances that just look wacky," Frank said.

    One sign of industrial civilization may have to do with isotopes of elements such as carbon. (Isotopes of an element vary in how many neutrons they possess in their atomic nuclei — for example, carbon-12 has six neutrons, while carbon-13 has seven.)

    For instance, humans living in industrial civilizations have burned an extraordinary amount of fossil fuels, releasing more than 500 billion tons of carbon from coal, oil and natural gas into the atmosphere. Fossil fuels ultimately derive from plant life, which preferentially absorb more of the lighter isotope carbon-12 than the heavier isotope carbon-13. When fossil fuels get burned, they alter the ratio of carbon-12 to carbon-13 normally found in the atmosphere, ocean and soils — an effect that could later be detected in sediments as hints of an industrial civilization.

    In addition, human industrial civilizations have also discovered ways to artificially "fix nitrogen" — that is, to break the powerful chemical bonds that hold nitrogen atoms together in pairs in the atmosphere, using the resulting single nitrogen atoms to create biologically useful molecules. The large-scale application of nitrogenous fertilizers generated via nitrogen fixing is already detectable in sediments remote from civilization, the scientists noted.

    The Anthropocene is also triggering a mass extinction of a wide variety of species that's likely visible in the fossil record. Human industrial activity may also prove to be visible in the geological record in the form of long-lived synthetic molecules from plastics and other products, or radioactive fallout from nuclear weapons.

    One wild idea the Silurian hypothesis raises is that the end of one civilization could sow the seeds for another. Industrial civilizations may trigger dead zones in oceans, causing organic material (from the corpses of organisms in the zones) to get buried that could, down the line, become fossil fuels that could support a new industrial civilization. "You could end up seeing these cycles in the geological record," Frank said.

    All in all, thinking about the impact that a previous civilization has on Earth "could help us think about what effects one might see on other planets, or about what is happening now on Earth," Frank said.





    Source: https://www.livescience.com/62338-in...re-humans.html


    I truly believe there was a lot more advanced civilizations before our's today.

    peace...
    ~~ One foot in the Ancient World and the other in the Now ~~

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    Avalon Member Star Tsar's Avatar
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    Default Re: How Would We Know If Intelligent Life Existed on Earth Before Humans?

    A recent presentation from Dr Frank...

    Quote Posted by Star Tsar (here)
    Harvard-Smithsonian Center For Astrophysics

    Adam Frank | What Astrobiology Tells Us About The Antropocene

    Streamed & Published 5th April 2018

    Adam Frank delivers his presentation on why it is resonable to the ask the question of alien life in terms of what humanity's & Earth's evolutionary path.
    Adam calls it "Climate change for aliens".

    In this talk I present new results exploring how questions related to developing a sustainable human civilization can be cast in terms of astrobiology. We begin by presenting a classification scheme for planets based on the degree of chemical disequilibrium generated by the coupled planetary systems. In this context we discuss the role of biospheric feedbacks in the presence of a global energy-harvesting species. We explore how Earth System Science frames the thermodynamics of successful species and their interaction with biospheres including those species that develop energy-intensive civilizations. We then focus on the most import factor for sustainability in an astrobiological context: the mean lifetime L of an ensemble of species with energy-intensive technology. We cast the problem into the language of dynamical system theory and discuss how astrobiological results usefully inform the creation of dynamical equations, their constraints and initial conditions. We present solutions to an initial set of equations showing different trajectories of development of the couple civilization-planetary system. Finally we use Kepler data to set an empirical limit on the probability that we are the only time in cosmic history that an energy intensive technological species has evolved.

    I for one will join in with anyone, I don't care what color you are as long as you want to change this miserable condition that exists on this Earth - Malcolm X / Tsar Of The Star

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    Default Re: How Would We Know If Intelligent Life Existed on Earth Before Humans?

    Interesting, trying to figure out whether prior civilized species existed on Earth. Well, looking at physical artifacts, especially long lasting ones such as those made from stone, if one looks objectively, the traces are there to be found. These traces may predate homo sapiens, so this doesnot preclude another species:

    Megalithic structures point to civilizations dating back over possibly millions of years:

    http://earthbeforeflood.com/who_and_...c_complex.html

    Giant megaliths of the Ural Mountains:


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    Default Re: How Would We Know If Intelligent Life Existed on Earth Before Humans?

    Joe Scott ("Answers with Joe") — who is (a) very mainstream, (b) very bright, and (c) quite arrogant (or maybe just presents himself as a smartass to be entertaining) — wades in to this topic with this interesting new video. It's the last third of the 22 minutes that most viewers might find thought-provoking.


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    UK Avalon Founder Bill Ryan's Avatar
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    Default Re: How Would We Know If Intelligent Life Existed on Earth Before Humans?

    Some more, from Dr Jason T. Wright, a mainstream astrophysicist with an admirably open mind.

    Start at 28:50:


    Here's his 2017 paper:


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