By advanced life, I don't mean per se intelligent, civilized life. I just mean things like complex, multicellular organisms such as plants and animals.
I am really curious about this, and I hope we some day get to see what alien life looks like. My own feeling is that it will look very much like life does on Earth. I don't say that because I lack an imagination. I say that because I believe organisms on this planet evolved the way they did for a reason. For example, all animals that I know of have the same tube design. That is, it eats, the food passes through a tube in which the nutrition is absorbed, and then it is excreted. That's the way animals get the energy they need in order to keep their genes going. All the other things like legs, tails, gills, and brains, and behaviors build on this tube scheme which is all about getting energy from the environment.
Those legs, tails, gills, and whatnot, are high-tech enhancements which are non-arbitrarily selected. Take the eye, for example. Nature non-arbitrarily created several different types of eye, such as the pin-hole camera eye, which solves the optical infinity problem with limiting the incoming light to a small point, which projects to a kind of folded-in retina. Then there's a simple light detector "eyes" (I guess you could call them eyes) that some protists have, as well as some types of worms, which cannot form images, but simply inform the organism as to whether it is light or dark. Then there's composite eyes, which lots of insects use. Then there's the more familiar camera eye, which is what we use, which, unlike the pin-hole eye, can see much darker environments more clearly, because the lenses can catch and bend more light toward the aperture, which sends it to the retina, whereas the pin-hole just passively gets whatever rogue photons happen to get trapped into its hole.
There are a number of other types of eyes, but they're all based on a few optical principles, like refraction and reflection. Human eyes are a little different from squid eyes (for invertebrates, the wires for the photoreceptors of the retina are behind from where the sensing cells collect light--the opposite is true for mammals), but it's really the same design. Light is focused with a big lens and projected to the retina.
From what I've read, this type of eye, as well as others, has evolved lots of times, independently. The reason for this, I think, is because there are only a few principles of optics available for nature to use, and because there aren't many designs that can work. Think about it. Is it a coincidence that our cell phone cameras are the same design as those of squid?
What about other things like sonar? Is it a coincidence that our own technology that we created is exactly the same as that which dolphins and bats use? No. This phenomenon, which we see in evolution time and time again, is called convergence. A litoptern, an extinct mammal which only ever lived in South America, has hind legs that look nearly identical to
those of horses, had an ancestral lineage which was completely independent of horses. I think the same principle applies: there are only a few designs that work, so you're going to see a lot of common themes among animals.
So if we do make it to another planet, I think it may look a bit different, but a lot of it is going to look the same. The differences might be minute, such as if it has a high oxygen (or oxygen equivalent) and high CO2 (or CO2 equivalent), you'll see big insects and flora, like what we saw in the Carboniferous period. So you might see different proportions, but on the large, things will be the same. We'll see legs, tails, gills, brains, and behaviors that will appear almost exactly as we see them on Earth.
That's one of the things that I look for when I watch Sci-fi flicks. Do the animals look realistic? I personally thought Avatar did a great job. They did indeed look alien, but at the same time, the animals absolutely had definable categories that you could precisely correlate with what we have. Starship troopers was a bit iffy. Giant bugs? Nahh, I don't think so. Insects like that design do not have complex circulatory systems like what mammals have, whose whole point is to create a large surface area to interface with the environmental air. Insects' oxygen-absorption works because they're small and don't need much oxygen. I'm not saying the Starship Troopers' bugs are bad, but to be workable, they'd need to be much smaller and less terrifying.
I am really curious about this, and I hope we some day get to see what alien life looks like. My own feeling is that it will look very much like life does on Earth. I don't say that because I lack an imagination. I say that because I believe organisms on this planet evolved the way they did for a reason. For example, all animals that I know of have the same tube design. That is, it eats, the food passes through a tube in which the nutrition is absorbed, and then it is excreted. That's the way animals get the energy they need in order to keep their genes going. All the other things like legs, tails, gills, and brains, and behaviors build on this tube scheme which is all about getting energy from the environment.
Those legs, tails, gills, and whatnot, are high-tech enhancements which are non-arbitrarily selected. Take the eye, for example. Nature non-arbitrarily created several different types of eye, such as the pin-hole camera eye, which solves the optical infinity problem with limiting the incoming light to a small point, which projects to a kind of folded-in retina. Then there's a simple light detector "eyes" (I guess you could call them eyes) that some protists have, as well as some types of worms, which cannot form images, but simply inform the organism as to whether it is light or dark. Then there's composite eyes, which lots of insects use. Then there's the more familiar camera eye, which is what we use, which, unlike the pin-hole eye, can see much darker environments more clearly, because the lenses can catch and bend more light toward the aperture, which sends it to the retina, whereas the pin-hole just passively gets whatever rogue photons happen to get trapped into its hole.
There are a number of other types of eyes, but they're all based on a few optical principles, like refraction and reflection. Human eyes are a little different from squid eyes (for invertebrates, the wires for the photoreceptors of the retina are behind from where the sensing cells collect light--the opposite is true for mammals), but it's really the same design. Light is focused with a big lens and projected to the retina.
From what I've read, this type of eye, as well as others, has evolved lots of times, independently. The reason for this, I think, is because there are only a few principles of optics available for nature to use, and because there aren't many designs that can work. Think about it. Is it a coincidence that our cell phone cameras are the same design as those of squid?
What about other things like sonar? Is it a coincidence that our own technology that we created is exactly the same as that which dolphins and bats use? No. This phenomenon, which we see in evolution time and time again, is called convergence. A litoptern, an extinct mammal which only ever lived in South America, has hind legs that look nearly identical to
those of horses, had an ancestral lineage which was completely independent of horses. I think the same principle applies: there are only a few designs that work, so you're going to see a lot of common themes among animals.
So if we do make it to another planet, I think it may look a bit different, but a lot of it is going to look the same. The differences might be minute, such as if it has a high oxygen (or oxygen equivalent) and high CO2 (or CO2 equivalent), you'll see big insects and flora, like what we saw in the Carboniferous period. So you might see different proportions, but on the large, things will be the same. We'll see legs, tails, gills, brains, and behaviors that will appear almost exactly as we see them on Earth.
That's one of the things that I look for when I watch Sci-fi flicks. Do the animals look realistic? I personally thought Avatar did a great job. They did indeed look alien, but at the same time, the animals absolutely had definable categories that you could precisely correlate with what we have. Starship troopers was a bit iffy. Giant bugs? Nahh, I don't think so. Insects like that design do not have complex circulatory systems like what mammals have, whose whole point is to create a large surface area to interface with the environmental air. Insects' oxygen-absorption works because they're small and don't need much oxygen. I'm not saying the Starship Troopers' bugs are bad, but to be workable, they'd need to be much smaller and less terrifying.
