Something’s amiss with aliens and arsenic
The stage was set by a coy news release from NASA that hinted at a discovery tied to the search for extraterrestrial life. The blogosphere went wild: Had bacteria been found on one of Saturn’s moons, or life of some sort on Mars?
FOR THE RECORD:
Mono Lake bacteria: A Dec. 23 article in Section A about a bacteria from Mono Lake that may be able to survive on the toxic element arsenic quoted Harry Collins, who studies the sociology of scientific knowledge at the University of Cardiff, and said that the university is in England. It is in Wales, another part of Britain. —
Instead, it was revealed this month in the journal Science that a strange bacterium lurking in the mud of California’s Mono Lake had an uncanny ability to live off the poisonous chemical arsenic and even build it into its DNA.
News reports were dewy-eyed with wonderment over the study, which challenged conventional notions of what life on Earth — or elsewhere — could look like. Then, in short measure, came the scientific trash talk.
“Flim-flam.” “Naive.” “Fraudulent.”
An embarrassing PR gaffe? Mediocre science that got undue attention because the buildup was too sexy to resist? A case of the peer-review process gone horribly wrong?
All played a role. But mostly, the wrangling is just a turbo-charged version of the kind of debate researchers have engaged in for centuries.
“The mythology of science is that you look down the microscope and you know what’s what,” said Harry Collins, who studies the sociology of scientific knowledge at the University of Cardiff in England. “But it’s a matter of scientists slowly coming to a consensus, and it often takes a very, very long time to reach.”
It started with a far-fetched question: Could an organism survive without phosphorus, one of the six elements considered essential to all living things?
Felisa Wolfe-Simon, a young biochemist, suspected it was possible that some creatures could — if they replaced the phosphorus with arsenic, a close chemical relative that is usually toxic. (She declined requests to discuss the controversy.)
“I thought it was crazy,” said Ronald Oremland, who studies how microbes metabolize toxic elements for the U.S. Geological Survey in Menlo Park, Calif. But he agreed to help test her hypothesis.
Their research team collected bacteria from arsenic-rich Mono Lake. When they brought the bugs back to the lab, they grew some of them in a broth with only trace amounts of phosphorus and increasingly higher concentrations of arsenic. Tests strongly suggested that the bacteria not only survived, but had incorporated the arsenic into their DNA and other cellular machinery, where it appeared to be standing in for phosphorus.
“We couldn’t believe it, but it worked,” Oremland said last week at a geophysics conference in San Francisco.
The organisms could survive under conditions long assumed to be incompatible with life. And if it was true in this case, then other such creatures might exist on this planet — or in worlds beyond.
That prospect tickled NASA, which studies the origins of life and searches for evidence of it elsewhere in the universe. The space agency’s astrobiology program funded Wolfe-Simon’s long-shot inquiry.
But perhaps it went overboard in teasing the results.
“I believe in the field of astrobiology … but I think this was overhyped,” said Rocco Mancinelli, a member of the NASA Astrobiology Institute based in Mountain View, Calif. “NASA should have known better.”
Editors at Science did a cursory review of NASA’s news release, but with work piling up before Thanksgiving, they didn’t give it a thorough read, said spokeswoman Ginger Pinholster. “In hindsight, I surely wish that we had,” she said.
Dwayne Brown, the NASA public affairs officer who wrote the release, defended it as a “factual statement.” “Clearly ‘extraterrestrial’ is a buzzword, but there was no intent to hype anything,” he said.
It didn’t take long for skeptical scientists to dig into the report to see if all the hoopla was justified.
“I don’t know whether the authors are just bad scientists or whether they’re unscrupulously pushing NASA’s ‘There’s life in outer space!’ agenda,” Rosie Redfield, a professor of cell and developmental biology at the University of British Columbia in Vancouver, wrote in her blog “RRResearch.”
University of Colorado microbiologist Norman Pace, who helped pioneer the study of unusual organisms and co-wrote a 2007 report commissioned by NASA on the potential for extraterrestrial life, called the study borderline fraudulent.
“It should not have been published,” he said in an interview.
One of Pace’s primary objections is that the bacteria weren’t completely deprived of phosphorus. The broth contained more phosphorus than some parts of the ocean that are known to support life.
He and other critics added that if the microbes had incorporated arsenic into their DNA, those molecules should have been too unstable to stick together when researchers washed them with water.
In a statement released last week, Wolfe-Simon and Oremland said that large pieces of DNA made with arsenic would not necessarily be so fragile. They also reiterated that the bacteria weren’t getting by on the minuscule amount of phosphorus — they didn’t grow in a broth with the same amount of phosphorus and no added arsenic.
It is not the first time NASA has made questionable claims about alien life.
In 1996, researchers at the Johnson Space Center in Houston said they had discovered what appeared to be fossilized remains of tiny bacteria in a meteorite from Mars that landed in Antarctica about 13,000 years ago. The clincher, they said, was tiny crystals of magnetite inside the fossils, similar to magnetite produced by bacteria on Earth.
Critics scoffed. The magnetite, they said, was caused by the shock of entering the Earth’s atmosphere.
NASA scientists continue to study the rock; others remain unconvinced.
“NASA’s shameful analysis of the alleged bacteria in the Mars meteorite made me very suspicious of their microbiology,” Redfield wrote on her blog.
But the Mono Lake project, Oremland said, had to jump through hoops at the U.S. Geological Survey, at NASA and finally at Science, where editors sent the report to three anonymous reviewers for thorough vetting before deciding it was worthy of the world’s top journals.
“At what stage do you say the criteria are enough?” he said. “The peer review was done.”
Researchers rely on peer review to determine which findings have true merit. Many wondered: How could this study slip through?
The irony is that peer review is quite subjective.
The system began more than 300 years ago with amateur scientists in Europe when it was possible to gather all of them in one room to hash things out. In the 19th century, the number of scientific papers grew and journals convened committees of nine or 10 people to vote on which studies should be published.
That evolved into a system in which editors sent articles out for review. The process became more standardized after World War II, as public funding for scientific research exploded.
“Peer review became a stamp of scientific authenticity,” said Harvard researcher Alex Csiszar, who studies the history of science.
But the process has obvious flaws. Among them: In a world of sub-sub-specialties, sometimes reviewers don’t have the expertise to identify mistakes.
Dr. Michael Callaham, who edits the Annals of Emergency Medicine, is one of a handful who study peer review to see if the process can be improved. His findings aren’t exactly uplifting.
A study this year tracked 1,499 referees over 14 years and found that 92% experienced a “very slow but steady deterioration” in the quality of their reviews.
Another study found that reviewers didn’t get any better after training designed to boost their skills.
In a third paper, Callaham sent an error-filled manuscript to more than 200 experienced reviewers, who missed most of the mistakes.
In physics and math, researchers share their studies online and solicit feedback from the wider community before publishing their results. As a result, papers are vetted by hundreds of experts instead of just a handful, Callaham said. But that approach doesn’t lend itself to fields such as medicine and biology; to test a series of mathematical equations, you don’t have to recruit hundreds of people for a clinical trial.
“Peer review is like democracy — it’s a lousy system, but there isn’t anything better,” he said.
Ultimately, the verdict on arsenic-eating bacteria will come in as other research groups conduct their own experiments. Wolfe-Simon told Science on Monday that dozens of labs have requested bacteria samples so far.
“Within a few months,” Oremland said, “we’ll either be vindicated or we’ll have a lot of pie in our faces.”
Times staff writer Thomas H. Maugh II contributed to this report.
