They haven't actually found any "alien" life at all, despite what the teen-oriented gee-whiz "news" web sites have said. They claim to have discovered a previously unknown type of terrestrial bacterium which, they allege, uses arsenic instead of being restricted to carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur.* They believe it substitutes arsenic for phosphorous in the phosphate backbone of its DNA. They found it because they were wondering if such a chemistry was possible so they looked in a lake where the mud has a very high arsenic content. If they are right then it is the only earthly life form of this type known so far, sure, but they have just started looking. The scientists have said there might be many more. So no green men. The "alien" link, if you can call it that, is simply that if it is true then it widens the range of conditions in which we know life can exist, so that there will be more places off the earth where life might exist than we thought before. This happens every time another extremophile bacterium is found. Is the US Govt trying to distract people from Wikileaks?
Also there has been criticism of the lab methods used. Steven A. Benner (a big expert in this kind of stuff) has expressed doubts that arsenate has replaced phosphate in the DNA of this organism. He suggested that the trace contaminants in the growth medium used in the lab cultures are sufficient to supply the phosphorus needed for the cells' DNA. So it might all be another "cold fusion" type of "discovery".
*I spell "sulphur" the British way.
