The NASA press conference today was about the discovery of a new life form on Earth - a bacterial strain known as GFAJ-1 found in mud taken from Mono Lake in California, that is able to use arsenic (instead of phosphorus) to make its DNA and proteins. This is the first ever organism ever found that appears to thrive in the absence of an element thought be to be critical to life as has long been defined. Life on Earth and the chemistry of life is dominated by Carbon, Hydrogen, Oxygen, and Nitrogen with Phosphorus and Sulfur. These are the six elements of life that are essential to life: life as we know it cannot exist without them. But Dr. Felisa Wolfe-Simon and colleagues found an organism on Earth that can utilize arsenic in place of phosphorus. OK, why is this such a big deal? Well, the DNA molecule is shaped like a spiral ladder with the rungs of the ladder comprising of pairs of nucleotides which spell out the genetic instructions of life. The sides of the ladder which are referred to as the backbone are long chains of alternating sugar and phosphate molecules. A phosphate molecule contains five atoms, one phosphorus and four oxygen atoms. Thus no phosphorus, no phosphate. No phosphate, no backbone. No backbone, no DNA. No DNA, No life. Yet, GFAJ-1 substituted arsenic for phosphorus to build DNA, RNA and other critical molecules to life. No such lifeform has ever been discovered to date. A lifeform that does not belong in our life tree.
What does this mean? It means that we need to relook at our definition of "Life" and how to search for it; on Earth, in our solar system and in the universe. To summarize the research of Dr. Wolfe-Simon and colleagues: "The research appears to expand the range of possibilities of habitable environments on Earth and on other planets and moons. On a more fundamental level, the findings may indicate the very definition of what is required for life to exist and may need to be to broadened to encompass a wider rang of possibilities."
A detailed analysis of the biochemistry to follow that will better explain this most profound discovery. I must say this Dr. Wolfe-Simon, today because of your work and your tenacity to push limits and boundaries I now live in a different universe than than the one I awoke in. Please push the limits of our understanding of "life" and the universe we are a part of. What a great day or all of humanity. An exceptional day. Thank you!