Thanks to scorching temperatures and a choking atmosphere, it’s known as Earth’s evil
twin… but was Venus always so hostile?
This is Unveiled, and today we’re answering the extraordinary question; did humans live
on Venus before Earth?
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In September 2020, news broke of a ground-breaking study of Venus.
Led by scientists from Cardiff University in the UK, it found that in the Venusian clouds,
high above the surface of the planet itself, there are traces of phosphine - a molecule
that’s one part phosphorous and three parts hydrogen.
Back here on Earth, phosphine is a marker of life, usually found in anaerobic (or, low
oxygen) environments.
The discovery, then, sparks all new debate about whether there’s alien life elsewhere
in the solar system… and whether Venus - Earth’s hellish, uncompromising neighbour so often
overlooked when it comes to potential alien homes - could be the place to find it.
Importantly, the team behind the phosphine discovery haven’t even begun to claim that
their work should stand as proof that life exists on Venus.
In fact, they’ve openly invited other scientists, astronomers and researchers to find another
explanation for it.
And we are dealing with a pretty tiny signature here… with only about ten to twenty phosphine
molecules per billion.
Still, even at such a low concentration, and even discovered where it has been (about thirty
miles above the surface of Venus), analysts all over the world are scratching their heads
as to how it got there.
And the presence of life, either now or in the past, remains a very active line of enquiry.
The idea that life could’ve existed on Venus in the distant past isn’t a totally new
one.
While Mars usually steals most of the headlines when it comes to planetary exploration, we’ve
been quietly looking the other way to study Venus over recent decades, too, and the theories
about the second-closest planet to the sun are mounting up.
In terms of the here and now, Venus doesn’t have much going for it.
Extreme temperatures more than 450 degrees Celsius, crushing pressure, and a ninety-six
percent carbon dioxide atmosphere mean that it ranks as one of the least hospitable places
we’ve ever tried to get close to.
And we have tried.
In the 1970s and ‘80s, various Soviet Union probes attempted the perilous descent onto
Venus… with varying success.
But even those that did actually land on the surface, only lasted for a short while before
they were destroyed - with the still-record time on the ground set by the Venera 13 probe
in 1982, which endured 127 minutes before it succumbed.
NASA has also landed on Venus, with the Pioneer Project in 1978, but most of everything else
we’ve tried with the planet has been limited to orbiters and flybys.
The Soviet spacecrafts Venera 15 and 16 orbited in the mid-80s, relaying back vital information
to suggest a total lack of plate tectonics on the planet.
Then, NASA’s Magellan mission (in the early ‘90s) more extensively mapped Venus, helping
us to determine that its surface was relatively young, probably between 500 million and 800
million years old.
By now, we were forming a picture of Venus as a dead planet… but also as somewhere
that might’ve once been more alive.
In more recent years, that picture has become more detailed.
The Venus Express was a European Space Agency mission operating for more than nine years,
between late-2005 and early-2015.
Again, it studied Venus from afar, but this time with something else in mind, as well
- climate change.
As we’ve come to realise that Venus (as we know it) has been choked with carbon dioxide,
showing a runaway greenhouse effect, soaring temperature extremes, and generally nightmarish
conditions… there’s an argument that it is what Earth could become if global warming
continues here unchecked.
A key finding of the Venus Express mission, however, was further reported evidence of
past oceans on the planet.
Today, it’s a scorched and poisonous place, but long ago it really might not have been.
As the excitement surrounding Venus grows, then, there is a dedicated mission moving
around the planet as we speak, with the JAXA probe, Akatsuki, in orbit since 2015.
So, it’s very much a case of watch this space in terms of more news coming from this
particular region of the solar system!
Nevertheless, it remains a big leap from suspecting that life of any kind might exist (or might
have at one time existed) on Venus, to saying that human beings might’ve lived there before
they lived here.
And yet, the suggestion has been made before now.
In September 2019, almost exactly one year before the 2020 discovery of phosphine, a
team from NASA’s Goddard Institute released details of a study wherein five simulations
showed how Venus might’ve evolved with different degrees of water coverage.
These sims built on what was, by 2019, our fairly solid belief that Venus did once host
oceans… only it imagined that those oceans could’ve continued to thrive.
In real life, we know that they didn’t; we know that something happened around 700
million years ago to trigger what’s been called an outgassing of CO2, and thus the
runaway greenhouse effect we know has now taken hold.
Take that outgassing event away, though, and all five of the Goddard Institute simulations
suggested that Venus would’ve been able to maintain safe, suitable temperatures for
life to exist.
No one’s too sure what caused Venus to become clogged with CO2, but if it hadn’t then
it really might’ve been like a twin world to Earth - a place very much like it, with
only slightly higher temperatures (on account of its closer proximity to the sun).
When scientists and astronomers analyse far off star systems today, they often speak of
the Venus Zone, meaning a close band around a star where the planets inside are suspected
to be unsuitable for life.
But if Venus is only so inhospitable because of a chance event - the outgassing that no-one’s
really sure on a reason for - then perhaps we shouldn’t be so quick to write off Venus
Zone objects in our search for alien life.
One key aspect when analysing an alien world is, can it maintain liquid water?
And, according to the Goddard Institute, if history had played out differently, then Venus
might well have.
So, what are the chances that human beings could’ve evolved there as they have here?
On the one hand, the human species can be seen as simply the result of the right chemicals
and conditions and elements being present at just the right time.
Modern humans have only been on Earth for 300,000 years or so, although our evolutionary
ancestors had been around for much, much longer before then.
Regardless, even 300,000 years is but a blip in the grand scheme of the universe… and
it only represents a very small percentage of the time that Venus has been around for
(which is about 4.5 billion years).
If then, there’s an argument that the conditions on Venus now are what Earth is en route to
experiencing, then there could also be an argument that Venus might’ve previously
hosted the same (or very similar) conditions as Earth does today.
In which case, what’s to say that humans wouldn’t have developed, too?
Well, there’s one main argument against that having happened; it’s just so incredibly,
incredibly unlikely.
Developments including the 2020 phosphine discovery continue to show that the prospects
of life in general existing elsewhere are high, with the majority scientific consensus
being that there is alien life out there - we just haven’t found it yet.
Venus has never really been at the forefront of our search for life because it’s so hostile,
but that view is slowly changing.
Now, it no longer feels beyond belief that alien life of some type could’ve at one
time survived there… but carbon copy human beings?
Probably not.
Even if the Venusian conditions were once closer to Earth’s, the planet’s entire
timeline will’ve had to have mimicked Earth’s almost perfectly… which it can’t have
done because all of this will’ve had to have happened at least a few hundred million
years ago, sometime before the carbon dioxide-inducing outgassing that cast the planet into ruin.
Just as most theories indicate that alien life anywhere isn’t likely to look all that
human (despite what the movies suggest), if alien life was found on Venus (or found to
have existed in Venus’ history), there’s really no telling what it would be like.
The chances of walking, talking, recognisable humans just so happening to evolve on the
planet next to ours (out of the billions of other planets out there) are, then, absurdly
low - with or without phosphine molecules being discovered in the Venusian clouds of
today.
What do you think?
Is there anything we missed?
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