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Thread: extraterrestrial biology

  1. #1 extraterrestrial biology 
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    I was wondering if another planet that contains life, the life could be different to ours. As in the fact that all life on our planet is carbon based and DNA is the genetic material. Is it be possible that on other planets the life has a different base element and genetic material?


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  3. #2 Re: extraterrestrial biology 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by mobc
    I was wondering if another planet that contains life, the life could be different to ours. As in the fact that all life on our planet is carbon based and DNA is the genetic material. Is it be possible that on other planets the life has a different base element and genetic material?
    It has been hypothesized that silicon might make a useful substitute for carbon. It's not quite as versatile in terms of the structures it can form and I have read that long silicon based polymers are not as stable as carbon ones. But there may be ways around this.

    There's a nice and fairly well-sourced article on alternate biochemistry on Wikipedia:

    http://en.wikipedia.org/wiki/Hypothe...f_biochemistry


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  4. #3  
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    Assuming it's carbon (objectively the best) it may still be fundamentally different. Because it's going to twist one way or the other. This is like the difference between nuts and bolts with left-hand threads or right hand threads. Incompatible!

    Waxing prophetic, we could see a fundamental war between sinister and righteous molecules, for "their seed is an abomination" yielding bitter fruit.

    I take the overwhelming left-handedness of our Earth life's amino acids as evidence life originated in the watery protoplanetary disc, where direct solar radiation is disproportionately hostile to the other kind. We also find a left-hand bias in the amino acids of meteors (and what's with all the organics in meteors?!).

    On the other hand >_< you could view the opposing spins of RNA and DNA as symbiotic. Maybe we're part alien?
    A pong by any other name is still a pong. -williampinn
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    Forum Cosmic Wizard icewendigo's Avatar
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    I dont know what life would be like on a planet very different from earth(ex: jovian gas giant) but I suspect that there might be somewhat frequent similarities with organisms that have live on earth on other earth-like or ocean planets.

    Theres great variety in shapes but occasional patterns emerge, a fish(shark), prehistoric reptile and mammal(dolphin) have evolved from different shapes to become somewhat similar in shape. The conditions in our environment that lead to life as we know it, might make similar patterns also more likely in similar environments.
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  6. #5  
    Forum Freshman Samuel P's Avatar
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    I've also heard about silicon being a base element for life on another planet.
    As it shares the same number of electrons in its outer shell as carbon it may be able to form the same sort of bonds, it's not as versatile though, as others have said.
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  7. #6  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by icewendigo
    Theres great variety in shapes but occasional patterns emerge, a fish(shark), prehistoric reptile and mammal(dolphin) have evolved from different shapes to become somewhat similar in shape.
    Certainly we'd expect some basic shapes that resemble life here, if there are similar environments. The basic "torpedo" shape we see in fish and aquatic mammals for example. That said, on Earth these species all started with some pretty crucial similarities that limited the extent to which they could adapt to a marine environment. All were tetrapodal vertebrates from the get-go for example. That basic body plan was simply modified so it is not all that surprising that we see similarities. Same holds for the 3 (that I know of) variants of flying animals- pterosaurs, birds and bats.

    Look at invertebrate species though, and the variety of solutions to the same "problems" that we observe when the gross morphology of the organism is less well defined.
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  8. #7  
    Universal Mind John Galt's Avatar
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    The most important thing to remember about alien life is that it will be alien. You really need to think carefully about what those words mean. In some instances it will take us quite a time to recognise that what we are looking at is actually alive.
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  9. #8  
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    Quote Originally Posted by Ophiolite
    The most important thing to remember about alien life is that it will be alien. You really need to think carefully about what those words mean. In some instances it will take us quite a time to recognise that what we are looking at is actually alive.
    Quite possibly so. Our definition of life is probably general enough to capture quite a diversity of types, but even then what we observe may not immediately seem to fit that. That's an exciting thought to me.

    There is every chance we'll find evidence of extraterrestrial life in the coming few decades, though it seems very unlikely to me that we'll have detailed enough evidence to answer questions on things like morphology. Perhaps within our solar system, but then that's all the more likely to have biochemistry reminiscent of ours, if not actually identical.
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  10. #9  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    I predict alien life will be mundane.
    "Kill them all and let God sort them out."

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  11. #10  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by spuriousmonkey
    I predict alien life will be mundane.
    In what way? Chemically similar to Earth life?
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  12. #11  
    Forum Freshman Samuel P's Avatar
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    Quote Originally Posted by spuriousmonkey
    I predict alien life will be mundane.
    Really? I've always though their evolution would be quite unique, making them look really different.
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  13. #12  
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    Alien is in the eye of the beholder.
    A pong by any other name is still a pong. -williampinn
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  14. #13  
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    If you look at life on Earth as our closest comparison to what might exist off Earth, an interesting point emerges.

    On Earth, life is 3.5 to 4 billion years old. For the first 3 billion years, that life consisted of very 'primitive' forms. Essentially life on Earth was layers of slime in the ocean. Only in the last few hundred million years has life evolved any real size and complexity.

    This would suggest that life off Earth would also be mostly very 'primitive', and like bacteria. It seems likely that we will have to investigate many worlds with life before we find any with complex life.
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  15. #14  
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    Possible lead is the odd self-stickiness of Martian subsoil.

    I'm still hoping for something motile, like worms even.
    A pong by any other name is still a pong. -williampinn
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  16. #15  
    Universal Mind John Galt's Avatar
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    Building somewhat on skeptic's point about complexity: we see things from a very human centered, multi-cellular viewpoint. The number of non-human cells in the human body is about ten times the number of human cells. The typical healthy human supports over five hundred species of bacteria. We aren't a complex organism, so much as a mini-biosphere.
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