Publishing Company Blog | If we're all Martians now, who are the aliens?

The idea that Earth was invaded by microbes from Mars challenges human beliefs about life, the universe and everything

"The evidence seems to be building that we are all actually Martians; that life started on Mars and came to Earth on a rock," Professor Steven Benner told the Goldschmidt meeting, this week's international scientific convention in Florence. The theory that microbes from Mars "infected" the Earth via meteorites, finding conditions here more conducive to their evolution, is nothing new – but Prof Benner's theory, that the minerals essential to life's formation were only readily available on Mars, is. Such a notion challenges almost every aspect of human culture, from biology to philosophy and faith – and practically every science fiction scenario in the book.

Long before HG Wells's War of the Worlds threatened the home counties with a Martian invasion, we humans were looking up at the red planet, coursed as it seemingly was by canals constructed by extraterrestrials, imagining the worst. From John Wyndham's scary triffids to Tim Burton's kitsch Mars Attacks!, dystopian science fiction has ever been predicated on the fearful alien other. How ironic to discover that we were the aliens all along.

There are serious questions here. For centuries philosophers have pondered the effect that the discovery of extraterrestrial life might have on human religions – could Christianity sustain itself in the light of evidence that we are not alone? After all, Genesis doesn't mention little green men. Yet the Vatican's chief astronomer, Gabriel Funes, recently announced that Catholics should actually welcome aliens as our extraterrestrial brothers, quoting Dante's Inferno as his mission statement: "Where we came forth, and once more saw the stars."

But the notion that the Earth really was invaded from outer space will surely undermine Ukip and its (even) less appealing European confreres. Perhaps Prof Benner's announcement means that all of us should be sent back as illegal immigrants.

One has to admire the sheer optimism of modern science: I love the fact that there is such a discipline as astrobiology, whose practitioners' task is to imagine what life might be like on other planets. Some have even populated "Goldilocks" planets (not too hot, not too cold), such as Kepler 22B, which may be an even more watery version of Earth, with giant "sky whales" that have evolved to "swim" through its fluid atmosphere. Yet here on the home planet we have profoundly strange aliens of our own. It is in the deepest undersea volcanic vents that we can look back into what life might have been like, at that moment of contamination. How odd that we see those bizarre creatures of the Stygian depths, with their eerie antennae and sightless eyes, and regard them as alien, when they are, after all, our distant ancestors.

And is it not part of our human hubris that we should presume all aliens to be weird versions of ourselves – somewhat ignoring the wonderful weirdness we ourselves represent? Hairless apes, pretty much inept at most things, increasingly reliant on the machines we have devised – and which in turn now threaten our own destruction.

In 1896, the American astronomer Percival Lowell hypothesised about "Mars as the abode of life". He presumed that an advanced civilisation had flourished on Mars, but was now dying, despite its desperate attempts to re-engineer its climate by using those canals to tap the planet's polar ice caps for water – and for all that it had sought to prevail over its environment: "What is found inconvenient or unnecessary to enslave, it would exterminate, as we have obliterated the bison and domesticated the dog." Lowell's vision inspired Wells's nightmare of technologically advanced but rapacious aliens invading Earth to appropriate our own resources. Doubly ironic, then, that we were the real Martians, and that many people – including quite a few scientists – believe that we're accomplishing that same doomsday scenario with equal rapacity. A century after Lowell, James Lovelock's Gaia theory posited that the planet would outlive its human infestation, shrugging it off as a temporary blight like a plague of greenfly, leaving barely a trace of our insignificent sway behind. As David Bowie, another alien who fell to Earth, sang in Life on Mars: "It's a Godawful small affair."