On December 2, 2010, NASA held a press conference to “discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life”. The announcement was important and revolutionary, going so far as to redefine the chemical definition of life.
However, the announcement and scientific article have become the centre of a debate that has rippled through the global scientific community.
What was the discovery?
A research team led by Dr. Felisa Wolfe-Simon discovered a unique bacterium hidden in California’s Mono Lake. They found that arsenic (a metallic element that forms a number of highly poisonous compounds) had replaced phosphorus within the organism’s DNA.
Prior to this discovery, all known forms of life were made up of six essential building blocks: carbon; hydrogen; nitrogen; oxygen; sulfur and phosphorus, which led to reasonable assumption that all life in the universe must require these six key elements.
So why is this important, and why is NASA involved?
Finding out that these six elements are not an absolute requirement for life to exist and thrive widens the search for planets and environments that would potentially support extraterrestrial life. A discovery this important led to its publication in the journal Science.
Why are the findings now being debated?
One of the first, and most rigorous, arguments against the finding was written by Dr. Rosie Redfield, a microbiologist at the University of British Columbia. Essentially, she claimed that poor experimental controls (the design of the experiment) could have accounted for most of the observed results. Following her criticism of the findings, more scientists, reporters and bloggers began to question the results.
In response to such strong criticism, Dr. Wolfe-Simon has invited her critics to write letters to Science so that they can be peer reviewed and published.
While we wait for a decisive answer to emerge from the debate, we can take away a few very important ideas. Neither science nor scientists are perfect and the scientific process is a constant give and take of competing ideas. Scientists typically reach an agreement on specific ideas through experimenting over and over again, and arguing their “case” to others. The very essence of science is the notion that we draw the best conclusions we can with the data we have in front of us.
Science has been “corrected” in the past and many of our current theories will likely be proven wrong in the future.
While this is an exciting discovery to follow in the news, it is important to always ask questions and listen to both sides of the story before drawing your own conclusion.
Carl Zimmer has written an excellent compilation of the opinions of the scientific community surrounding this discovery.
Article first published on December 10, 2010.