Science Opinions

There’s been a lot of controversy surrounding the “discovery” of supposedly arsenic-based bacteria that NASA published in early December. Even respectable media outlets have touted the find as a “redefinition” of what constitutes life as we know it. Discussion about the existence of extraterrestrial alien life or simply alien life on Earth has been sparked. The problem is that the media, in a frenzy to publish the article, overlooked many facts — perhaps by not being familiar with the science, or perhaps by being misled by scientists attempting to gain notoriety.
For those unfamiliar with the experiment, the New York Times offers a very accessible rundown and summarizes the findings. They write: “Scientists said Thursday [Nov. 25] that they had trained a bacterium to eat and grow on a diet of arsenic, in place of phosphorus — one of six elements considered essential for life.” The bacteria were taken from Mono Lake in California, which has naturally higher levels of arsenic. The scientists reasoned that bacteria already adapted to an environment containing arsenic could be grown in a medium containing progressively more arsenic, eventually incorporating arsenic into its DNA.
If this were true, it would most definitely force us to redefine the concept of life as we understand it, since, as astronomer Dimitar Sasselov explained to the New York Times: “Nature only uses a restrictive set of molecules and chemical reactions out of many thousands available. This is our first glimmer that maybe there are other options.” The “other options” opens the door for the existence of extraterrestrial life — if life can exist without the need for Earth-based elements, than there is no reason that it could not have evolved on other planets. This fantastic possibility captured the imagination of readers and journalists alike and is responsible for a flurry of space-based reports following the study’s publication.
Arguments for life not of Earth were given further weight with the announcement that NASA has found alien amino acids on meteorites found in Sudan. These two discoveries attempted to change the way we think about life and amino acids. The Sudanese meteorites should have been free of any organic compounds, as they are normally destroyed by the extreme temperatures meteorites reach as they hurtle through our atmosphere. The reports helped fuel a science media frenzy, with years of old reports being re-posted and circulated across the web, as long as they concerned extraterrestrial life. However, the asteroid findings seem a lot less exciting once a closer examination of the arsenic bacteria study was conducted, so don’t get excited just yet.
The arsenic bacteria study claims that the bacteria are violating the rules that govern life — specifically that they are substituting arsenic for phosphorous in their DNA and RNA. The six elements that are generally accepted as being necessary for life on our planet are phosphorus, carbon, oxygen, hydrogen, nitrogen and sulfur. Without these elements, living things simply cannot create the molecules necessary to function. If the bacteria were substituting arsenic for phosphorus, it would mean that there has been a dramatic shift in the operation of life, and many scientific findings — especially tests for life in harsh or extraterrestrial environments — would have to be called into question.
The study was surrounded by a flurry of media attention, with a variety of outlets reporting exaggerated claims about extraterrestrial life. Headlines such as “Is this the lake that provides the clue to extra-terrestrial life?” and “Life as we don’t know it . . . on Earth?” topped articles with dubious interpretations of the findings. NASA dismissed criticisms concerning the study as most were posted to blogs and Internet sites, even though some of the bloggers and commentators were researchers well equipped to review the findings.
One biologist, Rosie Redfield, who runs a microbiology research lab at the University of British Columbia, provides a very detailed criticism of the experiment. She points out several flaws in the data and draws attention to overlooked details in the scientific process.
According to Redfield there are multiple instances of dubious science in the study, for example: the growth rates of arsenic-fed bacteria are plotted on a graph in logarithmic scale (where the vertical axis is represented by exponentially increasing numbers, as opposed to linear ones. i.e. 1, 10, 100, 1,000, 10,000 . . . versus 1, 2, 3, 4, 5 . . . ) and compared to grow rates of phosphorus-fed bacteria that are plotted on a linear scale. The graphs superficially resemble each other, and the distinction is invisible to the uninformed. Tests for arsenic content in DNA were not carried out or carried out poorly, and there was a failure to distinguish between various cell elements that may have contaminated the DNA sample with arsenic.
The most damning evidence, however, comes from a calculation Redfield did. The scientists attempting to prove that the bacteria were substituting arsenic for phosphorus claimed that the cell’s volume relative to phosphorous content made it impossible to create phosphorus-based DNA. In simpler terms, the finding implies that the amount of phosphorous relative to the overall mass of the cell was simply not sufficient to create all of the needed DNA, therefore another element must have substituted in its place. Arsenic is chemically similar enough to phosphorous that is can theoretically be substituted into the phosphorous-requiring chemical reactions. The NASA scientists therefore claim that since the bacteria’s environment contained no phosphorous and the bacteria continued to survive, they must have been substituting arsenic for phosphorous.
Redfield points out that the scientists failed to take into account the large “granules” and “empty spaces” in the mutated arsenic-fed bacteria. These spaces accounted for a large portion of the cell’s volume and would not significantly affect the size of the cell’s genome. The mutated cells, though physically larger, were still genetically very similar to the cells in the control group. If these factors are taken into consideration, the bacteria appear to have a normal phosphorus level, and are not living “without” phosphorus, but rather using bare minimums — possibly scavenging the molecules from their dead brethren, says Redfield. Critical tests that would have provided a definite answer as to whether the DNA actually contained phosphorous were not carried out. Redfield also points out that standard cleaning procedures were not carried out — or at least they were not mentioned in the paper. She hypothesizes that the arsenic found inside the bacteria is not from the DNA, but from other arsenic containing portions of the cell that contaminated the DNA samples during testing. The blog leaves off with a call for more rigorous testing procedures and more attention paid to cleaning and verifying results.
Other scientists also offer criticisms, most of which are centered around the media response and the validity of the scientific methods used in the paper. Discover Magazine assembled a list of scientists who voiced their opinions, with concerns including: “All of the extraction assays are remarkably crude and do nothing to separate any contaminating arsenic from the samples — surely a must if you are trying to argue that arsenic is part of the molecular structure of your DNA and not simply associated.” Another researcher writes: “I think this paper should not have been published. What I’m seeing in the media is that people understand this paper as showing that all of the [phosphorus] in the DNA of this bacterium is replaced by [arsenic], and that this is a new form of life. It’s being vastly over-hyped.”
The finding points to deeper problems present with the scientific community as a whole, especially the current “publish or perish” culture.
As it stands, scientists are pressured to publish as much material as possible, regardless of the importance of the findings. The website puts it succinctly: “Career advancement hinges on publications. But data generation requires dollars.” Money is the driving factor behind the rush to publish findings, and possibly explains why the scientists involved in the arsenic study were quick to report their findings to the mainstream media while asking that complaints and criticisms only be brought up in specialist publications. By the time the scientific community’s backlash manifests itself, the findings have already been disseminated into the public consciousness and the lab has gained notoriety.
It’s easier to exclaim “eureka” and fuel society’s collective imagination than it is to meticulously inform them of some contextually important findings. The autism vaccine debate is a perfect example of this system in action, with the media and public falling into hysteria at the drop of an (ill-informed and irreputable) hat, and the truth taking months and even years to make its way into society.
The arsenic bacteria findings have been an intensely misguided media event, with the general unfamiliarity of science being to blame, at least on the side of the journalists. There were few critical reviews of the paper in the media, and many reports were prone to fantasizing and aggrandizing the findings, carrying on flights of fancy about extraterrestrial life. The debate reminds us that science is not about shocking discoveries, but about testing, repeatable experiments and above all, peer review.
If NASA wants criticisms to appear solely in scientific publications, it should not send findings that are hard to interpret and sound sensationalist to the general public. They should use the correct avenues of peer-reviewed journals and wait for the findings to be repeated and confirmed. The problem shows a greater issue with the scientific community as a whole — the substitution of fame and glory for valid scientific progress.
Now, if you’ll excuse me, I have some ground breaking findings regarding perpetual motion and zero-point energy that I need to publish.