Dispute Continues Over NASA's Arsenic Life Discovery

Dispute Continues Over NASA's Arsenic Life Discovery

Heated debate over “arsenic life” that began five months ago (see our story) continues this week with the formal publication of the team’s findings in the journal Science (subscription required). The debate began after a team of scientists announced discovery of a life-form that seemed to dispute one of the fundamental truths of life — a microbe that could thrive on arsenic.

Last December, National Aeronautics and Space Administration (NASA) research fellow Felisa Wolfe-Simon and her team published results of an experiment involving a microbe found in Mono Lake in Northern California. When placed into conditions lacking phosphorous – one of the building blocks of life – and rich in arsenic, the organism, dubbed GFAJ-1, was able to replace the necessary element with the chemically similar, yet ordinarily toxic, one and live, they claimed. NASA hinted at the finding in a press release preceding the press conference that announced a finding that would have implications for astrobiology — the search for life elsewhere in the universe. Although the discovery is here on Earth, the implications of the finding question the most basic assumptions of life and offers new considerations for NASA’s astrobiology program.

Even when the announcement was made, other scientists were wary of giving too much weight to this one experiment. Steven Benner, Distinguished Fellow at the Foundation for Applied Molecular Evolution, who participated in NASA’s December press conference, warned that chemists would need “exceptional evidence” to support the findings and described it as an “exceptional claim.”

The sentiment proved to be true not only for chemists, but for other scientists who were “sharply critical of the paper” as reported in Science’s blog, ScienceInsider, on Friday. Technical comments on the Wolfe-Simon team’s conclusions quoted by ScienceInsider show concerns over the possibility of phosphorous contamination when the arsenic-rich environment was created in the laboratory. Benner, a molecular biochemist, authored one of the Technical Comments and questioned the basic hypothesis of the research on the basis of the instability of the arsenic compound. “Their hypothesis…would, if true, set aside nearly a century of chemical data concerning arsenate and phosphate molecules,” he wrote.

The team’s initial reticence in December to respond to comments and its desire to have “that discourse in the scientific community” prompted many of the Technical Comments. ScienceInsider also summarizes the team’s response to the criticisms. The team stands by its initial results and points to its acknowledgement in the original paper that while trace amounts of phosphorous were detected in the experiment, these would not account for the bacterial growth measured.

The debate suggests that NASA astrobiologists, while keeping close watch of the research that comes out in the next couple of years over this issue, should perhaps not rush to hone in on arsenic-rich environments on other planets in the quest for life. Here on Earth at least, the question remains open.

User Comments

SpacePolicyOnline.com has the right (but not the obligation) to monitor the comments and to remove any materials it deems inappropriate.  We do not post comments that include links to other websites since we have no control over that content nor can we verify the security of such links.