Arsenic and life

Remember that movie a decade or so back with the non-carbon-based alien lifeforms? They were defeated by selenium poisoning, as chemically the selenium would react the same way arsenic reacts with us. A NASA news conference (due to start in 43 minutes) may tell us something about it. Gizmodo has already leaked the news (as did the BBC): NASA has found bacterial life (here on Earth, mind) with arsenic in place of the phosphorus in its DNA. Let me put it in simple terms: THIS IS HUGE.

All life on Earth - at least, as we knew it - has the same "building blocks" from which to begin: DNA (and RNA), comprised of carbon, oxygen, hydrogen, nitrogen, sulfur and phosphorus. But these bacteria, discovered in Mono Lake, California (a highly toxic environment), have no phosphorus in their DNA. None. It's all been replaced with arsenic. They are, in short, completely and fundamentally different from the rest of life on the planet. And that has tremendous implications. To everything.