Answering Mark on Astrobiogeography
A person named Mark stopped by and left this comment on my post about astrobiogeography. He writes
If life is found somewhere else in this vast universe and it works just like life on earth what would that mean?
It’s an interesting question and I’m glad he asked it. I think it’s so interesting that I thought I’d give my answer in it’s own post (just so more people see it) than leaving a comment.
If life was found elsewhere that worked just like life on earth, it would cause the biggest uproar in the scientific community ever seen. Briefly, here are some imaginable scenarios I have off the top of my head.
- An exact replica of earth is found. The continents and the geology are the same. The fossils are the same. The exact same species exist with the same distributions, etc.
Conclusion — special creation starts looking a whole lot more appealing.
Let’s even go a step further. The people are the same, the religions are the same… I become a creationist. It doesn’t solve any problems about who the creator is, but it’s just about impossible to imagine a scenario like this happening, and if it did, I’m not sure you could explain it scientifically.
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Life is found that works just like life on earth. DNA, genetic code, etc. But the proteins being used to build everything, and the organisms themselves are completely different. Life may work the same way, but it looks nothing like what we’ve seen before.
Conclusion — Couple of options here. The scientific one is that this completely overthrows our ideas about origins of life and how they happened. Perhaps life really can only exist this way. Under the right conditions, life evolves to work like it does on earth. Evolution then takes a different course in reponse to different environmental conditions.
Metaphysically, you can decide that a creator set things up more than once to let them play out…
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Life works totally different. This is the overwhelming prediction based on what we know about life today. It could be as minor as a genetic code that’s just built differently. For example, you don’t have to have the same bases in DNA. For example, we use uracil in our RNA. It’s conceivable to imagine a genetic code built of different molecules. Or life could work completely different. Something so different that the rules are just unlike anything we’ve seen on earth.
Conclusion — life evolved seperately at another location.
Number three is definitely the scientific prediction about what life would look like elsewhere. It would be something else if it turned out to be wrong.
Thanks for the response.
If life is ever found other places it will be very interesting to see how it all plays out.
Mark
I suspect that if life gets far enough along on another world, that there will be creatures that can fly (after all, flight evolved here separately for insects, birds, dinosaurs, and mammals); creatures that can swim; creatures that will be landlubbers; creatures that can “see” using more or less what we know as the visible spectrum; creatures that can detect sonic waves (they can hear); creatures that can feel; etc. This will be true whether or not their DNA base pairs are the same and whether or not they are carbon based.
I expect pretty much analogues to earth creatures though appearance and details will be different.
And that would certainly be logical if the environment was the same. But something tells me there might be a possibility that life could exist in a totally different way. Something we haven’t even envisioned. For example, evolution as we know it happens because of very specific conditions with how our genetic code works. I think it’s conceivable that life elsewhere might have different conditions.
Yep you are right.
but since evolution by natural selection works because of the tendancy of genes/DNA/organisms to replicate themselves, with those replicating themselves better eventually “pushing out” less fit genes/DNA/organisms, couldn’t a system of life NOT based on our genetic code evolve using different rules? Or not at all? Basically, I guess I am suggesting that natural selection works here because of the specific nature of our genetics and self-replication. A system based on something else (whatever else that may be) will not necessarily play by the same rules.
Precisely Jim, and that was exactly what I was talking about with this statement from point #3.
Just realized that I more or less reiterated what Jay mentioned above. I should read everything more closely before commenting….
…but an interesting debate on this type of subject would be whether or not our system of genetics and replication is the only way life could originate. I believe our ideas about the very origins of life involve some kind of autocatalytic, selfreplicating molecule (a la RNA). If this is so, perhaps life on any kind must originate in a similar way, setting up a system where natural selection comes into play. Thus, evolution by natural selection may be a universal law for life of any kind even if the details differ. I like this idea – the Law of Natural Selection.
Jay – you beat me to the punch