HomeEarthHow Future Archaeologists Will Study Human Civilisation Charles December 20, 2018 Earth, Sky From fossilised remnants of long-lost cities to technofossils to environmental catastrophe, how future archaeologists will study human civilisation By the beginning of the Cambrian Period, Earth’s oceans were teeming with life; exotic creatures typically baring little resemblance to those we know today. That was 541 million years ago when even the dinosaurs belonged to an unimaginably distant future. Modern humans have been around for a mere 300,000 years, but it wasn’t until about 6,000 years ago that the first civilisations started appearing. To describe our existence as fleeting would be a monumental understatement. While there’s no denying our current impact on the world’s ecosystems, it means practically nothing if we’re talking about timespans in the hundreds of millions of years. Given the dynamic nature of our geologically active world, very little survives over such lengths of time, so what are the odds of future archaeologists learning of our existence? It’s More than Just a Thought Experiment NASA Ames/SETI Institute/JPL-CaltechIf we ever want to find definitive evidence of the existence of extraterrestrial civilisations, we should probably start thinking like archaeologists, as well as spacefarers. For many of us, it’s an interesting thought experiment to imagine how a civilisation in the extremely distant future might view us. Chances are, we’ll be long gone millions of years from now, so any such civilisation is unlikely to be a human one either and, perhaps, might not even be of this world. However, rather than being purely theoretical, this line of thinking also has important implications for defining the longevity and scale of our impact on the environment around us. The ability to study the remnants of civilisations lost over vast geological timespans is also important in the search of extraterrestrial life. Given the volatile nature of human civilisation, it seems there’s a far higher chance of discovering the distant remnants of an alien civilisation that disappeared long ago than any that still survives. That’s why we we’ll need to start thinking like archaeologists in our search for alien civilisations. We can also apply the same hypothesis to our own planet. NASA climatologist Gavin Schmitt described this in 2018 as the Silurian Hypothesis, after a Doctor Who episode in which the time traveller encounters an advanced reptilian civilisation on Earth some 420-million years ago. Of course, that’s pure fiction, but even if there ever had been a civilisation before our own, how would we be able to tell? Fossilised Remnants of Ancient Civilisations PixabayEven the Great Pyramid of Giza will have eroded beyond recognition in a million years from now, but signs of its existence may persist for much longer. Fossils provide us with an insight into the past that allows us to visually recreate long-lost ecosystems to an outstanding degree of accuracy. Unfortunately, the chances of something getting fossilised are extremely small. It’s a process that requires exactly the right chemistry and environmental conditions, and then the fossil somehow has to survive, making them exponentially less likely to survive over much longer timespans. However, there’s a big difference between humans and every other organism known – we’ve constructed vast cities, transformed landscapes with farming and irrigation and built thousands of miles of underground tunnels to support our infrastructure. But, will any of this remain in say, a hundred million years from now? Or will great cities like New York and Tokyo have vanished without a trace. The Great Pyramid of Giza was constructed almost 4,600 years ago. It’s a true relic of humankind’s capability to build structures that can last for hundreds of generations. However, even this magnificent monument will have become unrecognisable within a million years from now according to the World Without Us by Alan Weisman. Even the footsteps of the first man on the moon will have eroded by then due to micrometeorites. After around 50 million years, even manmade materials such as plastic goods will also become unrecognizable. However, even in 100 million years from now, archaeologists may still be able to identify the fossilised remnants of large coastal cities in the form of an urban stratum. This theory was postulated by Jan Zalasiewicz in his book the Earth After Us, which discusses how our human legacy will fit into the fossil record. Naturally, some humans will also become fossilised, but that’s not likely to give away much of an indication of our civilisation. What is likely to raise eyebrows among future palaeologists, however, are disproportionately large numbers of a handful of species, most of which happen to be herbivorous. They’ll be the traces of domestication and mass livestock farming all over the world… except for Antarctica. Some scientists have even proposed chickens as a marker of our geological time (the anthropocene). Advanced Civilisations Revealed by Technofossils PixabayTechnofossils are imprints of our technology in the natural world. Our constantly increasing reliance on machines will ultimately be what identifies our civilisation in the distant future. Although our technology may also be our downfall, the machines and gadgets we take for granted every day of our lives will also be the legacy we end up leaving behind in the form of technofossils. For example, since we started mass-producing plastic in the 1950s, we’ve created almost enough to wrap the Earth in clingfilm. In other words, all the things that modern consumerism takes for granted and ultimately end up throwing away could become a treasure trove for archaeologists of the distant future. These so-called technofossils will ultimately redefine stratigraphy. By 2025, there will already be an estimated 75 billion internet-connected devices in the world. We’re also drawing ever closer to reaching a technological singularity, in which the growth of artificial intelligence will outpace our own capabilities as a species. Naturally, we can expect this to result in unfathomable changes to our civilisation by rendering us all but irrelevant. Google’s Ray Kurzweil believes the singularity is only three decades away. While the whole concept of technological singularity is still hypothetical at this point, it seems reasonable to expect that imprints of our technology will last much longer than we ourselves. As we’ve seen, fossilisation of organic matter is extremely rare, but the way we’ve impacted the Earth will leave an even greater mark. Consider, for example, the vast quantities of minerals we’ve mined to create all our technology. We’ve mined billions of tonnes of coal and iron alone, but these are relatively common materials. What would likely baffle any future civilisation is the prevalence of minerals in places they wouldn’t ordinarily be. One example is radioactive material locked away in ice cores and sediments left over from the nuclear tests of the mid-twentieth century. Moreover, modern civilisation has overseen the mass-mobilisation of trace elements, such as neodymium, lanthanum, cerium and yttrium, to produce our technology. One of the reasons we know about the impact catastrophe that ended the reign of the dinosaurs 66 million years ago is the unusually high traces of iridium in what remains of the Chicxulub crater. Iridium is extremely rare on Earth, but relatively common in asteroids. Just as today’s palaeontologists get insights into Earth’s past from the presence of iridium, future civilisations may learn about us from the disproportionately distributed amounts of rare-Earth elements. Warnings of an Environmental Catastrophe PixabayThough the environment would eventually recover without us, the extent of our impact on it could be revealed by air locked away in ice cores in millions of years from now. The human impact on the environment is obviously without doubt – it’s just the matter of degree that’s proven controversial. Right now, we’re living in the early stages of the world’s sixth major extinction event, which our species has had an undeniable role in. Current extinction rates are up to a thousand times higher than the natural background rate, putting us about two thirds of the way to an extinction-level event on-par with that of the Late Cretaceous (albeit not quite as sudden). Although the current Holocene extinction remains controversial, human civilisation has had a significant enough impact on the environment to leave its mark for millions of years. Since the beginning of the industrial revolution, atmospheric CO2 levels have risen from 280 to 400 ppm. That’s by far the highest in hundreds of thousands of years, and it could reach 1500 ppm over the next couple of centuries if we continue burning coal until it finally runs out. CO2 levels have fluctuated throughout Earth’s history from a high of around 7000 ppm during the Cambrian to a low of 180 during the Permian-Carboniferous ice age around 300 million years ago. However, these changes ordinarily happen over millions of years. Even if they do happen in a very short time span, this is usually down to a sudden upsurge of volcanic activity or some other natural catastrophe. Our mark on the Earth’s atmospheric composition will likely stand apart due to its discrepancies. Ancient Relics of Civilisation Lost Among the Stars PixabayFloating eternally through the emptiness of the universe, our space probes will outlive not only us, but also our very planet. Ever since the launch of Sputnik 1 on October 4, 1957, we’ve been sending things into orbit en-masse. Aside from the estimated half a million pieces space debris orbiting the Earth, we’ve sent hundreds of probes to explore the solar system over the past seven decades. Some of those have been travelling for so long that they’ve crossed the edge of the solar system and have now entered interstellar space. Space is, for the most part, empty. In the vast gulf between stars, it gets even emptier. With no weather and no atmospheric resistance, this hard vacuum is by far the best preserver of all. That’s why our space probes will not only outlast us, but quite possibly our very solar system as well. Voyager 1, which left the solar system in 2013, has nothing holding it back, aside from the vanishingly small amount of molecular hydrogen that would take billions of years to erode it. Indeed, the probe could one day enter the orbit of another star and, in theory, crash into something but again, chances of that happening are incredibly slim. The Voyager probes aren’t just hunks of metal floating eternally through space. They also carry with them the Voyager Golden Records, phonographs containing sounds and images portraying life and civilisation on Earth. Projected to last a billion years before the information on them becomes unreadable, these records are the ultimate time capsule; a testament to human civilisation built to survive even after all life on our planet has been extinguished by its natural fate. * Perhaps one day, in our relentless search for meaning and to prove that we’re not alone in the universe, we’ll eventually find definitive evidence of alien civilisations. But, given the fleeting nature of our own existence, it seems that any such discovery will instead come in the form of ancient remnants of a long-lost culture. For now, our mark on the universe awaits discovery perhaps tomorrow, perhaps in a billion years, or perhaps never. 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