The notion that life on Earth has extra-terrestrial origins has provided fertile ground for scientists and science fiction writers alike. With one key difference.

It’s the greatest story ever told. But any decent publisher would most likely reject even the latest draft of the complete chronological Book of Life. The problem isn’t the slow-paced character development, the convoluted plot or even the seemingly random way some of the leads get killed off. (I mean, a meteor wiping out the dinosaurs – who saw that coming?)

No, the script’s Achilles’ heel is its opening pages. The first chapter should set the scene with a description of how life on Earth got going, yet none of the available narratives are particularly convincing. For all the theories on offer, there’s still no scientific consensus on how living things arose from non-living chemicals.

New evidence presented at a recent geochemistry conference in Florence has breathed new life into the old, and previously rejected notion that life may have only begun here after first starting on Mars. The formation of RNA, a vital precursor to life as we know it on Earth, at least, requires the presence of certain forms of the elements boron and molybdenum. Professor Steven Benner from the Westheimer Institute for Science and Technology, in Gainesville, Florida, argued life was likely to have started out as Martian because the required forms of these particular chemicals are unlikely to have been present on early Earth but probably were on the young Mars.

It’s an interesting theory, but shifting the origin of life to another world means having to explain how primitive life managed interplanetary travel. Given that over 100 meteorites found on Earth have been identified as Martian, it is within the bounds of possibility that some key molecules or even very simple organisms could have hitched a ride.

However even if Mars did offer more favourable conditions a few billion years back, achieving abiogenesis – something living somehow assembling itself from just the right set of chemical building blocks – still seems like the longest of longshots. Perhaps it seems so unlikely simply because it is. From microbe to mankind maybe we are all phenomenally lucky to be alive.

Or perhaps despite the many theories as to where life began – including in the primordial soup of Earth’s early atmosphere, in volcanoes, in deep sea hydrothermal vents, in shoreline foam, on radioactive beaches, and in some way-or-other elsewhere in space – we are still missing some pieces in the puzzle.

Either way, the notion of life on Earth having extra-terrestrial origins has provided fertile ground for science fiction writers. With one key difference. Where scientific explanations are inevitably complex, fictional accounts tend to trade detail for sweeping grandeur, focusing less on the specifics in favour of carving out a distinct origin for humankind.  

Kick-start life

In some cases – most famously 2001: A Space Odyssey – something unfathomably alien chooses, for unfathomably alien reasons, to give our ape-like ancestors an intellectual leg up so we can become the planet-dominating, planet-threatening species we are today. Star Trek is also fond of this tack. From original series episodes like Return to Tomorrow to the Next Generation’s The Chase, they’ve had various permutations of extra-terrestrials seeding the galaxy with humanoid species. I’d like to think this was a deep comment on cosmological connectedness, but I suspect it was more to help justify why in a pre-CGI era of television everywhere the Enterprise’s crew boldly went they ran into life-forms who, barring the odd stuck on rubbery bit and some face paint, looked uncannily similar.

Last year’s disappointing film Prometheus also falls into this category. The opening scene appears to show an alien sacrificing himself so his DNA can kick-start life on Earth. Both versions of Battlestar Galactica took this even further with the original 1978 series’ credits beginning with the voice of Patrick MacNee (yes, Steed in The Avengers) declaring: “There are those who believe that life here...began out there. Far across the universe with tribes of humans”, and the recent remake (SPOILER ALERT) climaxing with the revelation that all of us today are partly descended from both the human crew of the Battlestar convoy and some of their cybernetic Cylon enemies.

There are plenty more examples. The recurring theme is that humanity is not merely the product of abiogenesis plus three-and-a-half billion years of evolution, and that at some stage we’ve had extra help from extra-terrestrials to make us special and by implication superior to other living things on the planet. That seems, to little old me at least, to be the product of self-aggrandising, anthropocentric arrogance. Can we not accept that we are one species among many?

There is at least one TV series, later remade as a film, which bucks the trend by seeing the alien influence on human development as making us worse rather than special or better. In Quatermass & The Pit, first transmitted by the BBC in the late 1950s and still among the greatest science fiction series ever, has our destructive tendencies having been implanted millions of years ago by violent aliens from a nearby world to make us more like them. The serial ends with a speech from lead character Professor Bernard Quatermass. His final words are: “Every war crisis, witch-hunt, race riot and purge is a reminder and warning. We are the Martians. If we cannot control the inheritance within us, this will be their second dead planet.”

Given the latest evidence, perhaps he was on to something.

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