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Alien Evolution
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Beylerbeyi View Drop Down
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Posts: 1355 		  Quote Beylerbeyi Quote  Post ReplyReply Direct Link To This Post Topic: Alien Evolution
    Posted: 23-Jul-2007 at 12:53
That alien is impossible. It is based on human design.
 
Five fingers and toes? We have five because the fish we are descended from had five bones in its fins. It was a justa chance. If that fish had four bones, we would have 4 fingers and use 8 based-maths.
 
Eyes, on the other hand, seem to be an evolutionary feature that can evolve independently. Our eyes and eyes of animals such as the octopus have evolved completely separately, but are remarkably similar to each other in principle. In fact Octopus eye is better than ours, because ours has a blind sopt due to a 'design' error.
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Posts: 1564 		  Quote DukeC Quote  Post ReplyReply Direct Link To This Post Posted: 24-Jul-2007 at 00:02
Originally posted by SearchAndDestroy

The Question wasn't whether we'd meet them, if they are out there, or what the possibilities of their existence are. The question was, do you believe evolution could have followed similar design, path, change, whatever you want to call it, as on earth and the way we always depict aliens. We give them a head, mouth, two eyes, and a nose, and we give them 5 digit fingers and make them primates.
 
Sure it could follow similar paths, look at some of the examples here on Earth. There's a remarkable similarity in shape and design between the paleolithic marine reptiles and modern cetaceans. There was also a marsupial predator that was almost identical to the Sabre-toothed tiger.
 
Water is the universal solvent and as far as we know provides one of the best environments for life to develope. Carbon is one of the most flexible structural elements appearing in forms as diverse as the hardest substance(diamond) and one of the softest(graphite). It forms complex molecules like nanotubes and buckyballs that may have played a role in the early development of life. Given these conditions, and the roles certain elements play in life I think it's likely that aliens would have something very similar to our DNA for geneitc coding. The reactivness of oxygen also allows a higher metabolic rate and the developement of complex multi-celluar life here on Earth, so it's a good candidate for the respiratory needs of an alien. It was anerobic bacteria that produced the oxygen rich atmosphere here on Earth, something that no doubt has occured on other planets.
 
Bilateral symmetry also gave advantages over early designs like sponges and cnidarians, so does grouping the sensory organs in a head. Given all this I think it's probable there will be similarities between humans and intelligent, tool using aliens.
 
Not sure I beleive there's aliens running around on Earth though, the distances between stars are just too vast and unless you start bringing in concepts like wormholes and warping space, are probably not brigable in less than many lifetimes.


Edited by DukeC - 24-Jul-2007 at 00:15
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edgewaters View Drop Down
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Posts: 2394 		  Quote edgewaters Quote  Post ReplyReply Direct Link To This Post Posted: 24-Jul-2007 at 05:27
Originally posted by DukeC

Not sure I beleive there's aliens running around on Earth though


I think micro-organisms are a possibility, and not just bacteria either.

There are several species of animal on Earth that could potentially survive alien environments, like the waterbear.
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Posts: 1551 		  Quote Dolphin Quote  Post ReplyReply Direct Link To This Post Posted: 24-Jul-2007 at 06:15
Whats a waterbear? Sounds like a disney character
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Posts: 1564 		  Quote DukeC Quote  Post ReplyReply Direct Link To This Post Posted: 24-Jul-2007 at 11:09
Originally posted by edgewaters


I think micro-organisms are a possibility, and not just bacteria either.

There are several species of animal on Earth that could potentially survive alien environments, like the waterbear.
 
How would they get here?
 
Panspermia from Mars is a possiblity, but it's yet to be determined that life developed there. It wouldn't be anything as complex as tardigrades which are related to arthropods, they developed only after billions of years here on Earth and Mars lost it's oceans and most of it's atmosphere after it's core froze early on.
 
Uni-cellular life travelling inter-stellar distances on ejected material is also possible, but the amount of such material that achieved escape velocity would be small. Even smaller would be the target presented by our solar system, then factor in how tiny the Earth is compared to that relatively small object.
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edgewaters View Drop Down
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Posts: 2394 		  Quote edgewaters Quote  Post ReplyReply Direct Link To This Post Posted: 24-Jul-2007 at 13:36
Originally posted by DukeC

How would they get here?


Comets, asteroids.

It wouldn't be anything as complex astardigrades whichare related to arthropods, they developed only after billions of years here on Earth and Mars lost it's oceans and most of it's atmosphere after it's core froze early on.


Right, but, what I'm saying is that we have animals that are a candidate for panspermia, so its possible other systems might as well.

Uni-cellular life travelling inter-stellar distances on ejected material is also possible


Why does it have to be unicellular? The tardigrade isn't (it has about 40 000 cells) and by all appearances seems to be perfectly capable of survival under the necessary conditions.

, but the amount of such material that achieved escape velocity would be small. Even smaller would be the target presented by our solar system, then factor in how tiny the Earth is compared to that relatively small object.


Well that's true, but we are hit by small amounts of extrasolar material on a fairly regular basis.
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Posts: 1564 		  Quote DukeC Quote  Post ReplyReply Direct Link To This Post Posted: 24-Jul-2007 at 13:55
Why does it have to be unicellular? The tardigrade isn't (it has about 40 000 cells) and by all appearances seems to be perfectly capable of survival under the necessary conditions.
 
It's true that tardigrades can survive extreme environments but they aren't invincible. A journey across inter-stellar distances would take 10s of thousands of years, water bears can go without water for only a couple of centuries at most. And while they're resistant to radiation, space is an extremely harsh environment. Amino acids can form there, but there's no evidence that life has ever evolved to survive in a hard vacuum full of cosmic radiation.
 
Any life would have to be kicked off it's home planet by a massive impact which would kill most organisms present. Then the material would need the energy to escape the gravity well of the system, travel across lightyears of vacuum and radiation and encounter a body that is infinitesimal in relation to it's environment. Any organism that can do that would be truly impressive, I'm not saying it isn't possible, just highly unlikely.
 


 
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Posts: 744 		  Quote TheARRGH Quote  Post ReplyReply Direct Link To This Post Posted: 13-Aug-2007 at 23:14
possible. Not likely. But, assuming that about 2% of the stars in our galaxy have planets (that's about 2 billion stars), and assuming that all those stars have about 3 planets on average (perhaps a conservative estimate), and assuming that perhaps 1% of that 6 billion planets have the conditions necessary to support life beyond the microbial stage, life that may, given enough time, gain sentience, That's about 60 million species that we could, in a a predictable world, come into contact with in our galaxy alone. If you have 60 million chances, it is quite possible that you may eventually come into contact with something that at least marginally or superficially resembles yourself. But i wouldn't bet on it, as the jury is, indeed, still out.

Edited by TheARRGH - 13-Aug-2007 at 23:16
Who is the great dragon whom the spirit will no longer call lord and god? "Thou shalt" is the name of the great dragon. But the spirit of the lion says, "I will." - Nietzsche

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