"Low levels of phosphate in growth media, naive investigators and bad reviewers are the stories here," said Norman Pace of the University of Colorado, a pioneer of identifying exotic microbes by analyzing their DNA, who was another co-author on the weird-life report.
I asked two of the authors of the study if they wanted to respond to the criticism of their paper. Both politely declined by email.
"We cannot indiscriminately wade into a media forum for debate at this time," declared senior author Ronald Oremland of the U.S. Geological Survey. "If we are wrong, then other scientists should be motivated to reproduce our findings. If we are right (and I am strongly convinced that we are) our competitors will agree and help to advance our understanding of this phenomenon. I am eager for them to do so."
"Any discourse will have to be peer-reviewed in the same manner as our paper was, and go through a vetting process so that all discussion is properly moderated," wrote Felisa Wolfe-Simon of the NASA Astrobiology Institute. "The items you are presenting do not represent the proper way to engage in a scientific discourse and we will not respond in this manner."
While Redfield considers Wolfe-Simon's research "flim-flam," she thinks it's fine for the NASA scientists to hold off responding to their critics. She is working on a formal letter to Science detailing her objections. But Jonathan Eisen of UC-Davis doesn't let the scientists off so easily. "If they say they will not address the responses except in journals, that is absurd," he said. "They carried out science by press release and press conference. Whether they were right or not in their claims, they are now hypocritical if they say that the only response should be in the scientific literature."
Some scientists are left wondering why NASA made such a big deal over a paper with so many flaws. "I suspect that NASA may be so desperate for a positive story that they didn't look for any serious advice from DNA or even microbiology people," says John Roth of UC-Davis. The experience reminded some of another press conference NASA held in 1996. Scientists unveiled a meteorite from Mars in which they said there were microscopic fossils. A number of critics condemned the report (also published in Science) for making claims it couldn't back up. And today many scientists think that all of the alleged signs of life in the rocks could have just as easily been made on a lifeless planet.
The controversy over the Martian meteorite still sputters on today because they contain only a few alleged fossils, rather than living bacteria. There are only a limited number of tests that scientists can run on the rocks, and their results remain murky. Fortunately, that's not the case for GFAJ-1. Critics say that a few straightforward tests on the bacteria would show whether they really do have arsenic-based DNA once and for all. And the NASA scientists say they're ready to hand out GFAJ-1 to researchers who want to study it. This controversy may be burning brightly at the moment, but it probably won't burn for long.