[Question] Origins of life - Many times

[Sashatheman]

I always heard that all the living things are related on earth and that we can trace it all back. We might not have all the pieces of the puzzle but its beleived thats how it works.

 

My thought is this. Could life arise many times in differnt places on earth and in suttle differnt ways, which still allows it to become more complex over time.

 

That would mean that not all living things can be traced back to a single organism, but many similar but slightly differnt ones.

 

Maybe theres a fundemental natural force that allows life to evolve past a certain complexity with only DNA, but with this natural force, is it possible that different types of organisms arose from non-living organisms many different times, and in different places?

[Airmid]

That's exactly the question astrobiologists ask themselves.

Personally, I'd answer this question with "yes", but of course there's no evidence (yet). It will be really hard to find any evidence on Earth, though. Life on Earth is quite old, and in the old days resources that could sustain life were probably pretty rare. Competition must therefore have been fierce, so only the best adapted organisms would have been able to survive.

If a second attempt to create life has been made later in the history of Earth, it would have had very little chance to survive, since it would have to compete with the already well-established and evolved life on Earth.

So prospects to find any evidence of Earth are bleak. There's two tiny sparks of hope left. First, 80% of the microbial life in sea has never been cultured, and so has never been studied genetically. Second, there's Lake Vostok, a lake that lies underneath kilometers of ice on Antarctica, and that has been sealed off from the rest of the world for millions of years. It will be very interesting indeed to see what kind of organisms can be found there!

Still, I think the best chance to find other life forms will be on other planets.

[Sashatheman]

hmm, thanks for yuor reply. yeh i was reading about Lake vostok before, and they were comparing it to , the seas on Europa, a moon of a planet which i forgot.

 

but yeh if life on another planet is found, could it possly not use DNA like life on earth done, and use something similar to it, or completely different? makes me wonder

[AzurePhoenix]

Europa orbits Jupiter. I'm constantly torn between the idea that life will arise in a plethora of bizarre ways unique to each origin, vs the idea that certain aspects of chemistry and anatomical effectiveness will lead to convergence by way of "the road of least resistance." Maybe it will be a limited version of both. Of course, it'll be utterly impossible to know until we can actually examine and compare/contrast life from multiple sources of origin, so probably not in our lifetimes.

[Airmid]

but yeh if life on another planet is found' date=' could it possly not use DNA like life on earth done, and use something similar to it, or completely different? makes me wonder[/quote']

 

Yep, I'm asking myself the same question. I'm putting myself in some constraints though, since my starting hypothesis is that the building blocks of life originate from space. Following that thought, life on other planets should be built from the same building blocks too. We have amino acids in space, so there's something to work with. Polymerizing doesn't seem to be much of a problem, given some favourable conditions. That's only a first step, but it might lead to RNA/DNA-like structures anywhere to store genetic information.

I haven't been reading up in depth yet about RNA/DNA and potential alternatives, but I will need to do so soon. There's some questions nagging my brains though, and those are: why only 20 (or actually 22) amino acids are used in Earth life; why are only a few bases used in RNA/DNA; why can't life do without RNA/DNA; what exactly is the role of RNA/DNA for Earth life; and, why is RNA/DNA so well fitted to carry out this task.

 

How nice it would be to get those questions answered! The last 2 questions seem to me the ones that might actually be answerable, so that's what I'll focus on for a start. Any suggestions are appreciated!

 

Airmid.

[Airmid]

Today I found this article on my favorite science news site. You're not the only one who thinks that there's more than one kind of life on earth, Sashatheman!

 

Airmid.