Did Ancient Civilizations Move Away From Earth? | Unveiled

Did Ancient Civilizations Move Away from Earth?

The idea that advanced extra-terrestrials have at one time visited Earth, or that they continue to visit Earth, has long been a popular line for alien enthusiasts. State-sponsored initiatives ranging from Project Blue Book in the 1950s and ‘60s, to the Advanced Aerospace Threat Identification Program in the twenty-first century, have now clocked up thousands of UFO and alien reports. The idea, though, is almost always that these unconfirmed, otherworldly creatures could be invading our planet… but what if the opposite was actually true?

This is Unveiled, and today we’re answering the extraordinary question; Did ancient civilizations move away from Earth?

For decades, there has been serious speculation - some credible, some not so credible - that humans may not have been the first intelligent life to evolve on our planet. Earth is more than 4.5 billion years old, and while we can chart various structural and sociological changes with a surprising degree of accuracy (particularly by analysing layers of rock), the suggestion that Earth might’ve hosted other advanced species billions of years before human beings has never truly gone away. It’s a favourite theme for science fiction writers, too, with “Doctor Who” being one of the first fictional works to feature it, with the introduction of the Silurians in 1970 - a race of humanoid beings with advanced intelligence which, crucially, predate man.

But is it really possible that creatures as intelligent or more intelligent than humans could have existed on Earth before us, before fleeing the planet for some reason? For Gavin Schmidt, director of the NASA Goddard Institute for Space Studies, and the physicist Adam Frank, it isn’t likely… but it is something we should definitely be asking ourselves! Together they developed the Silurian Hypothesis, an investigation into whether we - modern humans - would even be able to detect whether an industrial civilization could’ve existed before we did. If such a civilization did exist, then there aren’t any blatant signs on the Earth’s surface for us to follow up on today… But, for Schmidt, Frank and others, it’s much more complicated than all that!

One way to investigate evidence of previous civilizations is to consider their energy usage. Generally speaking, advanced beings need more energy as their population grows, and arguably one of the simplest ways to get that energy (that we know of) is to burn fossil fuels. When we use fossil fuels, we’re releasing carbon dioxide back out into the atmosphere, and scientists have various techniques to measure how much CO2 was or wasn’t present at any particular period in history. We can, therefore, chart carbon “spikes” in history, and debate what caused them.

In recent times, it’s thought that, as a result of human activity, our carbon levels have risen faster than ever before… so, were a future civilization ever to look back to now, there’d be compelling evidence that intelligent life did exist in our time period. The Silurian Hypothesis prompts us to ask whether we’ve seen something similar before, though, such as at the beginning of the Eocene Epoch about fifty-five million years ago. At that time, it appears as though a period of abrupt global warming also occurred - today called the Paleocene-Eocene Thermal Maximum - which, perhaps, would have created similar conditions to what we’re experiencing, or are on the verge of experiencing, today. It’s by no means proof that an advanced race existed at that time, more an indicator that something - natural or otherwise - was causing the Earth to change.

In the hypothetical event that ancient, unknown civilizations did once live here, however, a spike in global warming might well have been reason enough for them to leave. We only need to look at humanity’s various plans and efforts to spread out into the solar system right now, to imagine the thinking behind such a move. In the twenty-first century, we’re eyeing up Mars in particular, but also other nearby planets and their moons - including Jupiter’s Europa and Saturn’s Titan. For some ancient society living on an earlier Earth and in an earlier solar system, though, the destination of choice might’ve been different as well.

Some other (often fairly far-fetched) proposals in favour of pre-human civilizations also include that they may have been advanced enough to cover their tracks; that, in their latter stages, they deliberately chose to remove all traces of themselves, perhaps even anticipating that another civilization would develop on Earth after them. Either that or, in an earlier effort to tame their own climate change, they successfully developed carbon negative technologies - the like of which we’re trying to build today - thereby erasing their historical imprint, before switching planets just because they could. Importantly, though, while those motivations might seem valid enough, there’s still nothing by way of direct evidence that such a forward-thinking society actually did ever exist.

For now, all we really have to go on is that we can say with confidence that Earth has undergone climate change before, but we’re not certain what prompted past global warming spikes. We’re increasingly sure that today’s climate change is accelerated by humans, but that doesn’t automatically mean that previous temperature rises must have also been triggered by advanced civilizations. For now, that’s a leap for science fiction more than science fact.

In the meantime, though, it’s not as though humans should expect to be remembered forever. Yes, humanity’s impact on Earth has been considerable - we’ve built skyscrapers to the clouds and spaceships to get us to the moon - but it could all be quite temporary in the grand scheme of history. For Adam Frank, the chances are that after a couple million years; “any physical reminder of our civilization [will have] vanished”. Long term, direct evidence of our existence seemingly lies in the cities we’ve built, the roads we’ve laid, and the monuments we’ve constructed… but, were humans to for whatever reason disappear, then they’d all quickly start to crumble, before the vines, weeds, rivers and oceans gradually reclaim and eventually disintegrate them. When you consider, too, that despite it seeming as though we’ve conquered much of the Earth, only about one percent of the planet’s surface is actually considered to be urbanized... it might not even take that long! Regardless of any desire we might have to leave a legacy, Earth could be quickly wiped clean of humanity’s accomplishments… leaving it primed for another, far-future intelligent species to emerge, and to analyse rock samples wondering whether anything came before them.

Perhaps then, the same thing really did happen to some other advanced species; they forged a life on Earth, ran into problems, and either died off without a trace or relocated beyond our reach - their achievements now reduced to just a few layers of rock or ice, waiting for today’s scientists to truly decipher their meaning. In this way, it’s a hypothetical reality which conveys a real-world warning… that the Earth might not always be so hospitable to us.

But, in truth, it is still a hypothetical reality first and foremost. We cannot say with any certainty that an advanced civilization was here before us, or that they became advanced enough to move away.