Possible Alien Life

[Boerseun]

I've watched a couple of "Alien"-type movies recently, and it occurred to me how the popular image of an alien has dictated how we envision aliens to look like.

 

So, I was thinking that using our common sense we could hypothesise about what they would actually look like, ignoring everything Hollywood came up with (mostly because Tormod said we need something new and fun to talk about!:hyper: )

 

So - firstly, I should state what I believe:

 

1) We have incredibly weird animals and plants on this planet.

2) Animals and plants evolve to fill niches. The specific demands of these niches dictate what the animal/plant would look like.

3) I think life would come up with roughly similar solutions for similar problems on similar planets.

4) I think that given two possible solutions for a specific problem, life would tend to go with the least complex, most energy-efficient solution.

 

So - I'm sure there's a lot more to add to the above, but let's begin:

[Boerseun]

To begin with, I'd say two eyes is probably the norm. It's the simplest and easiest way to achieve stereoscopic vision. To illustrate, just think of all the unrelated animals (insects, reptiles, mammals etc.) who've adopted this solution.

 

I'd also say that a head is a fairly common feature, with the eyes attached to the mobile head so that the animal can see around itself without actually having to turn the body. And the brain should be close to the eyes to speed up reflexes. As is the solution on Earth!

 

It seems as if we're a pretty common lot on Earth!

 

Any more ideas?

[pie]

It's a good bet that if there were any advanced civilizations in our universe, they would have had to evolve in a similar way as we are doing.

 

I suspect that there may be oceans on these life Bering planets with sharks in the oceans, and Jurassic forms of life. - One reason is that the sharks we have on planet earth are very efficient on body design. - Once a species adapts to its environment, evolution stops.

 

In the case of the sharks, these animals stopped evolving before the dinosaurs walked on the earth.

 

So, it may be a good guess that if there were advance civilizations in our universe, there home planets would have oceans with sharks that look similar to ours. - Beyond that, life must take a similar path as on earth.

 

I often thought that advanced civilizations might be more like a "star wars" space bar where all sorts of animals evolved into higher thinking beings.

[Boerseun]

Sure - but I'm talking more about life in general.

 

There's a couple of evolutionary dead-ends found on Earth, that might have been taken further on an alien planet because the environment would demand it. I think one thing that would definitely be inevitable would be the 'predator/prey' type scenario, like we see in the jungles on Earth. The reason for this, of course, is that an animal (say, a grazer) is a handy concentration of available energy for any other animal that woul want to become a carnivore.

So, in that respect, it seems as if Earth also took a relatively common or inevitable approach!

[HydrogenBond]

The evolution of the life on earth was influenced by the environment, which was changing and evolving over time. Alien life would probably contain DNA since the laws of physics and chemistry should be the same everywhere. But a different environ and different changing environ would change the natural selection process. If the sun of the alien world was always much hotter and the oxygen and ozone always lower, the humanoids at the top of this alien evolutionary chain may have tough skin like a reptile. Being cold blooded may also be better to keep the body cool during the hot days. They may be better able to conserve water and have learn to hybernate during the hottest months of the year, etc., . The keyboards on their laptops may also be metallic due to their spiney claws.

[UncleAl]

1) Oxidative metabolism with pumped gas flow. If you want to kick butt you need the power output. Gills, lungs on the outside, are fragile plumbing. Water does not carry enough oxygen/volume.

 

2) Endoskeleton. Exoskeletons (insects, arachnids) don't host much intelligence and don't allow much size. Absence of skeletons (octopus) host good intelligence but requires a dense support medium. No fire, folks, and no technology therefrom.

 

3) Sensory cluster up front and forward. It doesn't do you much good to know you are going to die after it happens. At least one near-field high spatial resolution sense and one far-field distance sense. It's gonna have eyes, sound, and chemical sensors. Stereolocation is important to survival. Some of the sensors will be at least paired.

 

4) Coarse and fine manipulation of the near-field environment. Something manipulable sticks out the center or on both sides, and it terminates in specialized anatomy. Ya gotta get a grip if you wish to evolve intelligence.

 

5) Symmetry. Evolution may diddle with that, but considerations of balance during locomotion argue for it overall. Ya gotta flee and pursue if you hope to survive as a species.

 

6) Accomodations for local gravity and lifestyle therein.

 

7) Odd chemistries? I think not. We are star tar. Life will pretty much run like stuff we have here. Fine points of metabolism will be altered.

 

Intelligent alien life will not look especially alien compared to the variety of local products. Customization may be interesting, espcailly if they invest in vigorous gene-gineering of their species. They may smell and sound severely alien - or be good to eat. I'd worry about reciprocal indulgences of that last possiblity.

[pgrmdave]

I think that how they look would be largely determined by their environment. Consider what would have evolved differently if earth had a different mass, and had twice, or half the gravity that it has. If there was much less gravity, then it would be less necessary to have as much muscle to move, and more mass could be dedicated to other activities - thought, metabolism, disease fighting. In a lower oxygen environment, things would live longer but, assuming they still need oxygen, they would need to develop a way to either efficient use or gather the oxygen. In a higher oxygen environment, things would die quicker, but may not need such specialized organs as lungs and gills to obtain oxygen, instead absorbing it directly into the body.

[pie]

Hyderogenbond - You stated: "Alien life would probably contain DNA since the laws of physics and chemistry should be the same everywhere." - Yes, and the size of the home planet should dictate the surface gravity and ocean pressures on the planet. - So as you suggested that an alien world that was hotter with the oxygen and ozone lower, may select for humanoids with reptile skin and sleeping in the day.

 

I don't know if this type of world could exist. If it were hotter, the oceans may evaporate on an earth-sized planet such as Venus. If on the other hand the alien planet was larger than earth the surface pressures would be greater, so smaller animals might evolve.

 

Again, these higher pressures would not allow brain expansion on these larger planets, and would be unlikely to develop advanced civilizations.

 

I suspect that if there are any advanced civilizations in our universe, there home planet is similar size to earth, either being a littler larger, or smaller, but not much difference.

 

The oceans would have sharks similar to ours with some of sea sloath evolution similar to human. - It might be a scary thought to think our earth is common to all like in the universe with jurassic worlds being the norm.

[HydrogenBond]

The discovery of life deep in the oceans at tremendous pressure or bateria near hot mineral springs shows how adaptive life can be. Animals live high in the mountains, in the deserts, in the artic. These all show that a variety of environments can support life. It may come down to an optimum environ for fastest evolution. The earth seems to have served the purpose.

 

The need for liquid water is probably one of the basic criteria. More water moderates the surface temperature, while more pressure allows for more water. There is probably critical gravity that keeps the water from going to space even with high surface temp. if gravity gets too high life may remained in the water where one can feel weighless.

[Tormod]

And don't forget that for an extremely long period of time, our planet was ruled by dinosaurs - much, much longer than humanoids have been around, and a lot earlier, too.

[CraigD]

I’m strongly skeptical that any of our more definite speculations about alien life, interesting, thoughtful and informed thought they may be, are likely to be correct.

 

In contrast to Physics, most of what we know to be true of terrestrial biochemistry is due to empirical discovery, not theoretical prediction, explanation rather than hypothesis. The common statement belief that “Extraterrestrial life will likely have DNA, because we are unable to propose an alternate biochemistry as effective as it” implies that we deduced the existence and structure of DNA from first principles, and failure to deduce an attractive alternate model is informative.

 

The only speculation I feel confident making is very general: Extraterrestrial life will be surprising.

 

On a gross anatomical level, I think Arthur Clarke’s recent speculation about ET Life is interesting. This idea suggest that life may be very common, existing on nearly any planet even remotely able to sustain it, but may be predominantly terribly boring, conmsisting of very simple organisms competing on the basis of metabolic efficiency and little else, such as worlds dominated by photophilic ozzes and slimes. The evolution of complex life may be very unusual.

[lindagarrette]

Did anyone see "Alien Planet?" I just turned in the DVD and don't recall the source but I thought it was imaginative and worth an hour or so of entertainment. Fortunately it assumed the laws of physics apply universally and there were a lot of other assumptions, such as that life evolves, and that it requires a stable environment like the earth.

 

I suppose its possible that another form of DNA could lead to completely different life forms assuming evolution is part of the definition of life. ;There could even be one life form on a planet, an individual, living alone without growing or replicating, but then how could it survive? I think if we find anyone out there or if it finds us, it will have a face.

[HydrogenBond]

The laws of physics are assumed to be the same throughout the universe. With the longest life subparticle composites of the universe everywhere in the universe, i.e., electrons, protons and neutrons, it follows that chemistry is also universal. The environment will determine which equilbrium chemistry is available. An acid planet will be different than a basic planet but both will follow the laws of chemistry. The heavy planet may cause crystals to form differently than on a light planet but the same laws of chemistry should apply.

 

The carbon atom and DNA, RNA which is the basis of life on earth is probably the only chemistry that can support rapidly evolving life. The only other atom core that may have a shot is Si. It is below C on the periodic table and does a lot of what carbon does. The problem with silcone based life is that silcone macromolecules are very stable and not easily broken down. That is why they are used for breast implants, low temperature break fliud, superballs, carwax, etc.. The molecules of life need to be able to change more easily so that evolution can pertubate to the future.

 

DNA, RNA on earth provides for amazing diversity, where various critters are uniquely suited to that environment. Alien life could also be a odd diversity based on their environment to which they have become suited. Superfiscial diversity is what we see, but underneith the skin we are very anatomically uniform. All aminals have a heart and brain even though one crawls and the other flies.

[HydrogenBond]

Here is an interesting angle on aliens. Let us reverse engineer our image of aliens and deduce its home environment. The aliens of sci fi, tabloids, and witness account have big eyes, big heads and frails bodies. The big eyes migth tell us that there is low light level on their planet. Evolution would create bigger visual sensory systems to pull in the lower light level or light at higher wavelength such as IR. This would explain sitings being more common at night and why they hide during the day. Thier frail bodies might mean low gravity on their planet causing their muscle mass not to develop. Or could be an artifact of long space travel. This would be a reason to stay inside their space craft. Their puny bodies might imply small lungs suggesting their planet or space craft having a higher concentration of oxygen in its atmosphere. Their big head implies bigger brains or thicker skulls. The bigger brains could mean higher intelligence while their thicker skulls might be need to protect a more frail brain configuration. Maybe less gray matter and more white matter. This would make them good con artist and less law abiding (another forum). Maybe they are not explorers but escaped criminals or maybe visionaries. The criminal visionary angle is more conisitent with their shy and cautious behavior

[BlameTheEx]

Before assuming that alien life will be much like earth life it is a good idea to consider earth life. All of it, including prehistoric.

 

2 eyes are not inevitable. Look at the spider. My guess is that out in the universe forward facing vision is an oddity. An animal with all round vision has the advantage.

 

Bilateral symmetry is probably popular but not inevitable. We have had a fair number of 5 sided species like the starfish. Think of an alien with say, 3 eyes, legs, and arms. No reason that it have total symmetry any more than we have out hearts in the centre. The mouth might have migrated to one side and the internal organs to wherever is practical. A modified 3 way symmetry.

 

Most evolution has occurred underwater on earth. The starting point would probably be the same as on earth - the development of weapons. Flint can just as easily be shaped under water. Farming and group hunting would develop just as easily along with the domestication of animals. I question the idea that fire is necessary to develop intelligence. Assuming volcanic activity (Probably necessary for a viable planet) there should be plenty of heat to power an industrial revolution. Research powered by volcanic vents! All told air breathing intelligence is probably the exception rather than the rule. Think intelligent octopi.

 

Finally we could consider a creature, or plant, with intelligent control of its body. Organs grown at will. Biological rather than flint weapons starting the push to intelligence. A civilisation based on regulating, developing and trading genes. How is that for intelligently adapting to a changing environment? Of course such a creature probably wouldn't define us as intelligent!

[HydrogenBond]

If humans evolved from apes we were vegatarians at one time. Fire helped the early humanoid veg gatherers become carnivores. Fire changes the texture of animal flesh making it easier to digest. Becoming omnivoros allowed human to survive the ice, because the sparse twigs and berrys were eatened by the herding animals. The fire also kept them warm. Maybe one of the cavemen looking to keep their fire going decided to threw in a dead refridgerated animal into the fire, figuring it would burn like wood. When it began to smell good enough to eat; the rest is barbeque.

 

As far as aliens anything is possible considering the variety here on earth. Evolving from water is makes sense but higher evolution would face certain problems. The first being dissolved oxygen for brain development. Whales have large brains but require a lot of bulk. Space travel would be difficult to develop because the having to carry around all that water weight.

[CraigD]

If humans evolved from apes we were vegatarians at one time.

Modern apes aren't vegitarians. It's unlikely ancient ones were much different.

 

Virtualy all primates suppliment a primarily fruit and leaf diet with insects and other small animals. Chimps hunt and eat animals only a few times smaller than themselves (eg: monkeys). Depending on their habitat, baboons may get more of their calories from meat than the average human, and have been known to prey on animals as large as domestic sheep and goats.

 

Although humans digestive systems are significantly different than other living primates, the difference is not so great as was once thought. For instance, when I last attended a biology class that covered the subject, I was taught that humans are digestively incapable of subsisting on a chimp-like diet where leaves are a staple. In the 1980s, however, this assumption was tested by the simple expedient of having a bunch of grad students eat leaves for a couple of weeks, revealing that, while less optimally than chimps and gorillas, humans can in fact obtain adequate calories from leaves, via the same mechanism as these other primates (fermentation-like activity in the large intestine).

 

:surprise: Grad students are great. Privileged are those who have them.