Microbe That Eats Meteorites Might Hint at Our Alien Origins

A meteorite from the NWA 869 strewn field. H. Raab [CC 3.0 license]/Wikimedia Commons

There are those who believe that we're born of aliens, and not all of them wear tin foil hats.

In fact, it's a topic of serious scientific investigation. The idea is sometimes called the "panspermia hypothesis," which proposes that life on Earth did not originate here, but rather was seeded by meteorites carrying alien microorganisms that arose on some other rock in the far-flung universe.

Of course, without any known evidence of alien microbes from elsewhere, it's a difficult hypothesis to test. But new research recently published in the journal Scientific Reports might offer a boost to this much-debated idea.

The study authors, led by astrobiologist Tetyana Milojevic from the University of Vienna, looked at a peculiar microbe by the name of Metallosphaera sedula, which is known for its voracious metal-hungry appetite. Because meteorites are filled with lots of the food that these microbes crave, researchers wanted to see how well the bugs adapted to a steady diet of extraterrestrial rock.

What they found was quite remarkable. Not only did the M. sedula heartedly chomp on the meteorites, but they actually harvested food from the space debris more efficiently than they could from Earth stones.

"M. sedula was capable of autotrophic growth on stony meteorite NWA 1172, utilizing metals trapped within it as the sole energy source," wrote the authors. "When grown in the presence of NWA 1172, cells of M. sedula were characterized by intensive vivid motility."

In other words, nom nom nom.

The meteorites clearly produced healthier, fitter microorganisms. Scientists guessed that this might have to do with the diverse content of tasty minerals found on the space rocks. Some of the meteorite material contained around 30 different types of metals, which gave M. sedula a very balanced diet.

While this research is hardly proof of panspermia, it does offer a model for how the idea could have worked. Imagine hardy M. sedula-like organisms thriving on some metal-rich alien world in a galaxy far, far away. Then, suddenly, a catastrophe: a collision with another planet. Such a collision could have sent the organisms flying through space, clinging to debris from the world-shattering event.

But this was an intergalactic voyage that they could survive, because they had all the food they needed for the journey: the meteor that would become their transport.

Imagine next that this microbe-carrying meteor found itself on a collision course with a newly-formed planet Earth. Maybe these were the kinds of organisms that first landed on our barren world, eventually evolving into life as we know it today. At the very least, this new research on M. sedula paints a pretty picture as to how this story could have been possible.

It's weird to think that an organism like M. sedula could have been our primordial Adam-and-Eve. Though if you ever find yourself with an odd, unexplained craving for a metal snack, perhaps you'll know why.