In 2010 NASA announced the discovery of microorganisms that, after being treated in laboratory, could keep growing only using arsenic, instead of the (though very small amount of) phosphate they also had in nature. However, this was confuted by further studies in the following two years. Has there been success in finding "alien" life on Earth, somewhere else, since then?

Edit: the NASA article from back then says what gilleain sais below. I naively hoped a couple of articles from different (not scientific, but not bad) journals were not modifying the facts. Thus the question actually is if non-carbon-based life has been found.

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    $\begingroup$ Wait...You tag this organic-chemistry and exclude Carbon explicitly from your question? $\endgroup$
    – M.A.R.
    Jun 12, 2015 at 17:16
  • $\begingroup$ @M.A.Ramezani Oops. I thought I could call it still organic, since we're dealing with life. Like unconventional organic chemistry, rather than inorganic. Though I've removed the tag. $\endgroup$ Jun 12, 2015 at 17:21
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    $\begingroup$ Not only was it refuted, but the original claim did not go so far as to say that it was 'non-carbon-based' life, only that the arsenic was used in place of phosphate in the DNA backbone. $\endgroup$
    – gilleain
    Jun 12, 2015 at 17:26
  • $\begingroup$ @gilleain Correct, the NASA article from back then says what you say. I naively hoped a couple of articles from different (not scientific, but not bad) journals. $\endgroup$ Jun 12, 2015 at 17:39
  • $\begingroup$ @M.A.Ramezani Would it have to be called inorganic, then? $\endgroup$ Jun 12, 2015 at 18:06

1 Answer 1


Just because an organism might need a nutrient, whether arsenic or cobalt (which homo sapiens needs for making RBC's) does not mean that the organism is not carbon-based. What had been announced was that an organism used arsenic to replace phosphorus, not carbon, which has since been amended.

There is also the question whether the GFAJ-1 microbe is a facultative or obligate user of arsenic, or simply excludes arsenic. Though the organism can survive high concentrations of arsenic, it appears to do so by discriminating between As and P and using the phosphorus in its metabolism.

There are organisms such as Sulfurospirillum arsenophilum and S. barnesii that are at least facultative As users, deriving energy from oxidation or reduction of arsenic compounds, but the arsenic is not replacing carbon, much less phosphorus, in their biochemistry.

  • $\begingroup$ Yes, your answer and gilleain's comment made me understand what some not scientific articles didn't. I meant to rephrase the question: has non-carbon-based life ever been found on Earth? Thank you. $\endgroup$ Jun 12, 2015 at 17:50
  • $\begingroup$ No... however,, when we finally create self-constructing, self-repairing machines (with additional qualities we use to define "life"), will we have created non-carbon-based life? See en.wikipedia.org/wiki/Artificial_life and en.wikipedia.org/wiki/Golem for example. $\endgroup$ Jun 12, 2015 at 17:57
  • $\begingroup$ Indeed I had thought of that. But that's not even chemistry, is it? :D $\endgroup$ Jun 12, 2015 at 18:02
  • $\begingroup$ Not necessarily, as I can see. Gratitude. $\endgroup$ Jun 12, 2015 at 18:17
  • $\begingroup$ Possibly silicon "chemistry"... both for IC's and aluminosilicate clay ;) $\endgroup$ Jun 14, 2015 at 4:03

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