SETI should be STI

SETI should be STI ››: Paul Davies, in the New York Times, has a nice article about the possibility of serial terrestrial geneses:

[W]e may not need to go all the way to Mars to find another sample of life. It could be lurking under our very noses. No planet is more Earth-like than Earth itself, so if life started here once, it could actually have started many times over
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Thus, microbes from another genesis - alien bugs, if you will - could conceivably have survived on Earth until today. The chances are that we wouldn't have noticed. Under a microscope, many microbes appear similar even if they are as genetically distinct as humans are from starfish. So you probably couldn't tell just by looking whether a micro-organism is "our" life or alien life. Genetic sequencing is used to position unknown microbes on the tree of life, but this technique employs known biochemistry. It wouldn't work for organisms on a different tree using different biochemical machinery. If such organisms exist, they would be eliminated from the analysis and ignored. Our planet could be seething with alien bugs without anyone suspecting it.

Yep, I like it. It's not that they are forever out of sight; we just haven't looked in all the places they could be yet[6]. One bit galled me though: he mentions that we may be able to identify these aliens among us if they happen to have opted for right-handed amino acids (our "genesis" uses the other chirality) but this is surely space-fill for the article. We don't know whether the chirality thing was truly a chance event or if there was some selection in play, and we should also avoid such DNA- or protein- or carbon-chauvinism when contemplating other forms of life.; [Permalink…18-Apr-05…Deserving memes……Comments (0)]

SETI should be STI

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