07-06-2019, 12:43 AM
(07-05-2019, 06:45 AM)stevebowers Wrote: I expect that every world that has an independently evolved biota will have a different set of codons. Assuming they use DNA, of course. But it is probably not completely arbitrary. Even if only one in a million genetic codes are viable, that still leaves untold billions of viable genetic codes. (A vast understatement).
Indeed. As an aside here, there are at least three possible homes for life other than Earth in the Sol system. (Mars probably underground, Europa, Enceladus.)
If we find life on one of them, what does it mean for prospects of life in the wider Galaxy? I submit that it depends on the details of its biochemistry.
If such life is just like Earthly life in all respects (chirality, genetic code, bases used) then it tells us nothing because it is possible for meteors to carry life-forms from one place to another within the Sol system. There are, after all, several meteorites on Earth known to be from Mars.
However, if such life is different from Earth's then the probability (as perceived by us) of life in other solar systems goes up. A lot.