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?
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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.
What do you think?
Is there anything we missed?
Let us know in the comments, check out these
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