3 ms·

I feel like the detection of e.g. amino acids on mars is just wishful thinking. That either points to panspermia (either mars->earth or earth->mars or, uhh, ali

by duaneb 14y ago

I feel like the detection of e.g. amino acids on mars is just wishful thinking. That either points to panspermia (either mars->earth or earth->mars or, uhh, alien-> both?) or concurrent development of extremely similar forms of life. Both scenarios strike me (irrationally) as extremely unlikely. I'm guessing it will discover a biproduct of biological processes, e.g. high levels of methane.

jlgreco 14y ago
It seems to me that the probability of life independently developing along similar routes is hard to really peg a probability on. We only have one example of abiogenesis to study right now, but evolution of earth-life could give us some basis to reason about independent instances of abiogenesis. Certain "features" just make sense for life on Earth, and have evolved numerous times independently. Flight is a classic example, having evolved four completely separate times (bugs, (extinct) pterosaurs, birds, and bats). Complex eyes also seem to have independently developed many times. Similarly, it seems fairly reasonable that certain "life chemistries" "make more sense" than others. The extent to which that may be the case could also be up in the air I think. Maybe 'carbon with a water solvent' is particularly common, but amino acid based is less so. Or maybe amino acid based life tends to naturally follow from an also likely carbon based chemistry. It will be exciting to see what we uncover in the future. I think either two cases of abiogenesis or a solid case of panspermia would be pretty wild, for their own reasons.
maaku 14y ago
Speak to a(n astro)biologist. It is exceedingly likely that independently developed extraterrestrial life will use amino acids in some way, shape, or form. It is exceedingly unlikely that it would use the exact same 20 amino acids, however, which would give a way of detecting panspermia. For that matter, any chemically unlikely preponderance of a subset of amino acids would be very strong evidence for life.
jerf 14y ago
Intra-solar-system panspermia is far more mundane than the galactic-sized versions. It is well known that pieces of all the planets end up on other planets due to being ejected during meteor impacts and eventually landing on the other ones. We know this, because we have found some of the ones that have landed on Earth. It is a reasonable hypothesis that certain hardy bacteria could conceivably survive the trip. If Mars was ever hospitable to live, there is a plausible path for simple Earth life to get there. So in the event Martian life is discovered, there's still some work to be done; is it "just" Earth life that got there, albeit presumably heavily-adapted, or can it be established that it is not from the same line as Earth? The second one is the real jackpot question that has profound implications for our place in the universe. The first one, less so. Not zero, but definitely less so. And if it is the first one, it's going to be a real bear trying to explain that it isn't the second one to a press that is mostly incapable of understanding the difference, let alone explaining it to the public....

by duaneb 14y ago

jlgreco 14y ago

It seems to me that the probability of life independently developing along similar routes is hard to really peg a probability on. We only have one example of abiogenesis to study right now, but evolution of earth-life could give us some basis to reason about independent instances of abiogenesis. Certain "features" just make sense for life on Earth, and have evolved numerous times independently. Flight is a classic example, having evolved four completely separate times (bugs, (extinct) pterosaurs, birds, and bats). Complex eyes also seem to have independently developed many times. Similarly, it seems fairly reasonable that certain "life chemistries" "make more sense" than others. The extent to which that may be the case could also be up in the air I think. Maybe 'carbon with a water solvent' is particularly common, but amino acid based is less so. Or maybe amino acid based life tends to naturally follow from an also likely carbon based chemistry. It will be exciting to see what we uncover in the future. I think either two cases of abiogenesis or a solid case of panspermia would be pretty wild, for their own reasons.

maaku 14y ago

Speak to a(n astro)biologist. It is exceedingly likely that independently developed extraterrestrial life will use amino acids in some way, shape, or form. It is exceedingly unlikely that it would use the exact same 20 amino acids, however, which would give a way of detecting panspermia. For that matter, any chemically unlikely preponderance of a subset of amino acids would be very strong evidence for life.

jerf 14y ago

Intra-solar-system panspermia is far more mundane than the galactic-sized versions. It is well known that pieces of all the planets end up on other planets due to being ejected during meteor impacts and eventually landing on the other ones. We know this, because we have found some of the ones that have landed on Earth. It is a reasonable hypothesis that certain hardy bacteria could conceivably survive the trip. If Mars was ever hospitable to live, there is a plausible path for simple Earth life to get there. So in the event Martian life is discovered, there's still some work to be done; is it "just" Earth life that got there, albeit presumably heavily-adapted, or can it be established that it is not from the same line as Earth? The second one is the real jackpot question that has profound implications for our place in the universe. The first one, less so. Not zero, but definitely less so. And if it is the first one, it's going to be a real bear trying to explain that it isn't the second one to a press that is mostly incapable of understanding the difference, let alone explaining it to the public....