Is that rock alive? If you're on another planet, new research suggests the answer could be yes.
Science fans should head over to the Telus World of Science this Saturday for a free talk on arsenic-based life and its implications for life on other planets.
The talk is part of the University of Alberta's annual space symposium and will examine last year's discovery of the first life form known to use poisonous arsenic in its DNA.
"The status quo of what life is has been changed a bit," says Frank Florian, science director at the Telus World of Science.
Life from poison?
Giving the talk is Ronald Oremland, a senior scientist with the U.S. Geological Survey, who has researched arsenic-eating life for decades.
All life is based on six different elements, says Oremland, speaking from his home in San Francisco: carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulphur. Phosphorous in particular is part of DNA and is considered essential for life.
Sci-fi fans have long fantasized about life forms based on elements outside these basic six. One of the more famous is the Horta, a silicon-based acidic blob from Star Trek that just happens to look like a guy wearing a rug.
Arsenic gets its killer reputation because it's right below (and thus similar to) phosphorous on the period table, Oremland says, which lets it sabotage energy and enzyme production.
About 30 years ago, while investigating selenium contamination in California's San Joaquin valley, Oremland's team found bacteria that could breathe and eat arsenic.
"[It's] essentially the inorganic version of bread for a certain type of bacteria," he says.
Some used it in a process like photosynthesis, while others used it to eat organic matter. These critters also lived in hot, salty, no-oxygen environments that you could find on other planets.
The team's latest discovery was announced last December. By searching California's Mono Lake, an ultra-salty lake, they found bacteria that could use arsenic instead of phosphorous in its DNA. "It's not a new form of life or anything like that," Oremland says, but it appears to be the first known creature capable of reproducing using something other than the six basic elements.
It was a provocative discovery that really got a lot of people ticked off, he says.
"It was like throwing meat to lions," he says.
Researchers around the world attacked his team's methods, while others praised their results, imagining a whole "shadow biosphere" of life based on elements outside the basic six.
Living rocks?
This discovery shows that life can live even under the harshest conditions, Florian says, and may be composed of elements previously unimagined. It's also good news for Horta fans, since it suggests that silicon could swap in for carbon — like arsenic and phosphorous, these elements are very similar.
"It opens the door to new possibilities," he says.
This discovery will be a big deal if other teams can confirm it, Oremland says.
"There might be other forms of life out there."
Unless you subscribe to certain philosophical beliefs, he says, rocks on Earth aren't alive.
"We don't encounter rocks going to the laundromat," he says, and we don't hear them talking about sexy girl rocks.
"Every other rock that I've seen that was moving on Earth was moving because of gravity," he says.
This discovery gets back to the age-old question of the nature of life, Florian says.
"What we know here on Earth may not be how things are elsewhere."
Oremland's talk is at 4 p.m. this Oct. 1. Call 780-451-3344 for details.
