If you want to see some of the toughest, most hardy organisms on the planet, you’re going to need a microscope. Microbes – bacteria, amoebas, archaea, and so on – can live just about anywhere, from the bottom of the ocean to the top of the tallest mountain. There’s trillions of them in your body right now and they can even survive in the cold void of space.
So you can imagine what a surprise it must have been for Noah Fierer and his team of microbial ecologists to find somewhere with no microbial life at all.
“Viable microbes have been detected in even the most inhospitable environments and it is widely assumed that all environments on Earth should contain detectable microorganisms,” wrote the team in their study published last month in the Journal of Geophysical Research: Biogeosciences. “This assumption is likely incorrect.”
Given how ubiquitous microbes are across the planet, it was no mean feat to find somewhere they hadn’t already colonized. In fact, the researchers had to take themselves all the way to the Shackleton Glacier in Antarctica, where the unique mix of cold, dry, and salty conditions combine to make one of the least hospitable environments on Earth.
“It’s the combination of multiple very challenging environmental conditions that restricts life more than just one acting by itself,” study co-author Nicholas Dragone explained in Science News. “It’s a very different sort of restriction than, say, just high temperature.”
Using a range of tests, the researchers analyzed more than 200 soil samples from the region looking for evidence of microscopic life. And while the vast majority contained enough microbes for the team to detect and classify the various species, a good 20 percent turned up no microbial DNA at all.
“We are not suggesting that we have found ‘lifeless’ or ‘sterile’ soils, nor have we identified the low temperature threshold for life,” cautions the paper. “However, our inability to detect microbes or microbial activity in certain soils suggests that these surface soils represent a limit to microbial activity and survival driven by the cold, dry, and salty environmental conditions.”
Now, the discovery of, essentially, nothing may not seem like a big deal, but it really is. You see, microbes are one of our best bets in the search for extraterrestrial life, and a lot of astrobiologists have got pretty excited recently about the prospect of a bunch of the microscopic creatures burping on Mars. But if there are places on Earth where no microbes can be found, Fierer and his team say, it’s probably not going to be easy to find them on Mars.
“The combination of conditions found in the surface soils of the Shackleton Glacier … are similar to those found on the surface of Mars,” the paper explains. “Given that Martian soils are much older, experience similar or even harsher conditions, and contain even higher concentrations of the same salts … our results suggest that searching for active life in surface soils on Mars is unlikely to return positive results.”
On the other hand, maybe we shouldn’t lose hope. Finding life on Mars may be a long shot, but finding life on Earth is generally pretty easy – which is why some in the scientific community think the results of the study must be a simple false-negative.
“Certainly, there were things there,” Jeff Bowman of the Scripps Institution of Oceanography, who was not involved in the research, told Science News “This is Earth.”
“This is an environment that is massively contaminated with life.”