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Message: <blockquote data-quote="LightPhoenix" data-source="post: 5394045" data-attributes="member: 115">I've been following this, and it's really cool.  Obviously, the big meaning behind this is that life can exist in phosphorous-poor conditions; ie, P isn't a prerequisite for life as we know it.  There's a more subtle meaning behind it as well.  It suggests that elements traditionally considered unstable (that is, they bond weakly) have the potential to be basic biological building blocks.However, there are a large number of biochemical caveats here.First and foremost, this only suggests that similar elements in a group can substitute.  Arsenic and P are very similar; in fact, that's what makes Ar so toxic - it substitutes for P and interferes with "downstream" reactions.  There's only one other substitution that is really feasible - selenium for sulfur (which we do see in bacterial amino acids such as selenocysteine).  On the non-essential side, the big difference I could see happening is bromine for chlorine; they're somewhat similar.  In contrast, silicon and carbon are fairly different chemically.This isn't to say life couldn't exist outside this schema (CHONP*S*); just that it would be vastly different biochemically to Earth-based life.</blockquote>