Arsenic Instead Of Phosphorus

NASA researcher Felise Wolf-Simon has discovered a strain of bacteria that can replace phosphorus-- which heretofore biologists have thought was essential for life-- with arsenic and continue to thrive. Yes, arsenic-- Agatha Christie's favorite poison. Phosphorus and arsenic are closely related chemically, which likely accounts for the bacteria's ability to switch them, but the discovery is still a game changer.

This discovery once again widens the parameters of life, a process that has been continuing for the past couple decades at least. When life was found around volcanic vents deep in the ocean, it became obvious life could exist over a wider range of environments than scientists had imagined. Since then, life has been found in various supposedly inhospitable places on Earth, including deep inside nuclear power plants, bathed in what should be lethal radiation. As that is not a natural environment, and has in fact existed for only a few decades, bacteria inside nuclear facilities might tell us something about how quickly evolution can move.

Wolf-Simon's discovery clearly has major implications for the search for alien life, as well. Life-as-we-know-it may be a woefully inadequate yardstick. Why wouldn't it be? If we assume life evolves according to local conditions, assuming further that life elsewhere would be built on the same base as Earth life seems a bit odd. Arsenic instead of phosphorus is likely one more step towards realizing the infinite complexity of the universe.