Alien life, it turns out, is much closer than Mars
Driving out Highway 167 north of California's salty Mono Lake, you whiz by a jeep trail that heads for a crescent shore known as Ten Mile Beach. Few people find it, fewer still swim there. Once the bottom of the lake, this wide beach was gradually exposed as Los Angeles diverted the lake's tributaries, starting in 1941.
Mono dropped 45 feet in 40 years and, though some water now flows into the lake again, thanks to a precedent-setting California Supreme Court decision, it's only climbed 10 feet. Ten Mile Beach is mostly known for the alkali dust storms that billow off its surface.
But now it has a new claim to fame. In 2009, Felisa Wolfe-Simon, a NASA-funded geo-microbiologist, visited with her team and took mud cores from Ten Mile's shallows. She pipetted the samples into test tubes filled with a slightly arsenic solution, and waited for a cloudy culture of bacteria to grow. For months, she repeated the process, increasing the amount of the toxin in the solution each time, until what was left was a strain of Mono Lake "extremophile" -- not just tolerant of arsenic, but able to incorporate it into its most vital processes, in lieu of phosphorous. And this, you may have read, was unprecedented; therefore "alien."
Imagine if you were suddenly thrown into a chamber that contained only carbon dioxide, but found you could breathe anyway. In a manner of speaking, that's the kind of feat that the bacteria called "GFAJ-1" seems to have pulled off. Molecularly, arsenic very closely resembles phosphorous, which is why it's so poisonous. Cells take it up even though it then kills them.
Yet arsenic doesn't appear to stop the GFAJ-1 bacteria. Wolfe-Simon's team has detected arsenic in the bacteria's DNA, just where phosphorous -- previously thought fundamental to DNA -- should have been. No one knows why or how the GFAJ-1 accomplishes this trick, and some have criticized the study, arguing that the analyzed DNA wasn't adequately washed and that, in fact, there must have been some phosphorous in the solution. So the jury's still out.
But if ever such a remarkable discovery was to be made, it's not surprising that it would happen on Ten Mile's austere shore. In late-summer, great droves of green and beige brine shrimp wash in -- floating windrows that look like cereal. Algae-eating alkali flies -- the other visible denizen of Mono's harsh waters -- lie like a black carpet on the water's edge, their drone a steady hum. Some evenings, thousands upon thousands of phalaropes, a petite fly-eating shorebird, join together in whirring, serpentine flocks. The breathtaking landscape's not truly alien, or is it?
In some ways, Mono Lake simulates the chemical stew thought to have engendered life. At its lowest level in 1982, Mono Lake had an arsenic concentration of 17 parts per million. That may not seem like much unless you consider the EPA's standard for potable water is .01 ppm. Of course, Mono's water is undrinkable: It's roughly 2.5 times saltier than the ocean and full of sulfates, carbonates and borates. Slippery to the touch, bitter to the tongue, the lake has such high concentrations of minerals because it has no outlet. And it's as much as 2 million years old.
The view from Ten Mile Beach feels ancient. On all sides, mountains: to the east, the Whites, edging into Nevada; to the west, the Sierra, rising 7,000 feet above the lake; across its vast waters, the Mono Craters, the youngest mountain range in North America, a heap of volcanic cones and coulees that's erupted roughly every 500 years for the last 40,000, and is now overdue. This is a place over which the brutal elements rule. Most abundant on Ten Mile Beach are the countless quills from the 50,000 or so California gulls that nest on the lake each summer. Bleached white, they look like the discarded pens of all the scribes and poets who ever lived.
Yet now a microorganism may be Ten Mile Beach's grandest view, a glimpse, perhaps, of how the first cells survived, then thrived, in early Earth's caustic environment. If it holds up, Wolfe-Simon's discovery could suggest that there was no single origin to life. It shows, too, that while it makes a certain amount of sense to keep sifting through outer space for answers to the big questions about life, it also makes sense to search right here as well - to poke around some of Earth's strangest places - and thus to protect them, as we did at Mono Lake.
Nick Neely is a contributor to Writers on the Range, a service of High Country News (hcn.org). He is a freelance writer who recently spent two summers at Mono Lake.