So Look at the alien here on the right. Aliens are supposed to have evolved on other planets with an entirely different ecosystem. Sure I have heard the argument that similar forms would evolve on different planets because the forms are so useful. But look at the alien here. The Ears, eyes, nose and mouth are nearly identical to a human. This thing has eyebrow ridges, cheek bones, and a little dent above the lip. Look at its neck, it has that same hollow point where several tendons meet the shoulder assembly. This picture isn’t an alien, its a human with makeup on. (or animatronic).
Facing reality here, for TV there were budgets back in the 50s and 60s and aliens had to be produced cheap enough that a profit could be made. Look at star trek. Vulcan = human with ears. Klingon = human with forehead. Andorian = human with wigs and makeup and antennae. maybe movies could have done better, and many have. H.R. Giger created a really nifty alien for the 1970s movie Alien. It was sorta humanoid but also very alien in its shape (And biology and movement) but for story purposes its behavior had to be understandable to the audience, at least as far as a horror movie monster goes.
But I think the TV sci-fi has taken us a bit too far. So many NASA scientists admit they were were inspired to go into space science because of star trek. It is causing a mental blockage. For instance, many scientists who are quoted on tv about looking for alien worlds tend to focus on planets in the “Goldilocks” zone. That is planets with liquid water and an oxygen atmosphere. This may make sense, after all, the only life we have ever known is us, right? What about all the strange ecosystems here on earth. the crabs and womrs that live at 500 degrees F under the sea? or the anaerobic bacteria that live deep in the earth’s crust? We keep finding life where we never knew it could be. We need to expand our definition of what is habitable to fit reality, not our pre-conceived notions.
Take humans for example. What are we? We are the product of 500 million years of evolution. Our distant ancestors arose in the sea (unless they were seeded by comet or some such stellar vehicle) and developed into an array of life forms suited for the sea. Look at modern sea life variety. Biology has stripped the plant kingdom of its seaborn members, but there still are photosynthesizing creatures in the sea. Plus Mollusks, Arthropods, and Endopods. That is no bones, bones on the outside, and bones on the inside. Our human ancestors were the Endopods (in fact we are still endopods). Some time about 250 million years ago an animal developed a bone shell around its nervous system, a backbone formed. Over time that backbone turned into a skeleton. Much of its rivals developed hard shells, the mollusks like clams, squid, snails, muscles, Or they developed a linkage of bony armor, the arthropods, like insects, crabs, spiders, trilobites. Our endopod ancestors had a problem of defense, But had a much more adaptable body type. They could grow faster with out having to shed its previous skeleton. They had a lot more structure than the Mollusks and could survive harder hits. Over time they became equals in the sea. some where around 175 million years ago photosynthetic life moved to land followed by the bugs and then the other creatures. Then the reptiles and protomammals came, Then the dinosaurs, birds, and full mammals. Then monkeys, apes, humans, and so on and so forth.
Our human form, both physical and mental is a result of where our ancestors lived. The apes lived in the forest where having hands for tree climbing came in handy. A bunch of our ancestors were kicked out of a shrinking forest (rain forests have been shrinking for 8 million years, so don’t freak out if they are still shrinking.) and having those hands were useful for picking up sticks to beat up lions and hyenas. Standing erect to see over grass helped. All of this stimulated our group nature and our cognitive abilities.
What does all this have to do with aliens? ok, lets look around. On earth we have 2 general broad categories of land life, Plants and Animals (this is vernacular not scientific which has 6 or 7 kingdoms depending on the biologist you talk to). We think thats how it “should be”. so we design alien ecosystems to be like that. Doesn’t have to be. Why should it? Some where 176 million years ago plants rooted themselves to use resources in 1 place, and animals stayed mobile. Costs more energy to be mobile, but you can escape predators. Why would an alien ecosystem evolve the same way?
What we have to look at is how life works really. On earth chemicals are gathered and chemical reactions release energy allowing life. generally if done with the help of oxygen its called aerobic. lacking that oxygen its anaerobic. Aerobic life produces much more energy with the same chemicals than anaerobic life does. This is on earth. Earth also has a strong electromagnetic field around it blocking high energy particles from space. Imagine an alien species not needing oxygen for energy release because they absorb energy from cosmic sources. Oxygen and water are toxic, we use them, so we tolerate them, but water will dissolve most things and oxygen can kill you if you get too much.
This alien that drinks cosmic rays would have to evolve on a world lacking an EM field. Since they don’t need light, they could be much farther away from their star than we are, living in a colder environment. The atmosphere could be much thinner or filled with gases we find toxic or corrosive. As a result our hypothetical alien does not live in the Goldilocks zone and has little to no oxygen in its atmosphere. It is by definition anaerobic life but it is very efficient at thriving on cosmic background radiation. Also this ecosystem doesn’t need the plant/animal division to cycle gases, just a food chain to cycle nutrients. They might have many kingdoms, but we would not understand them as plant animal, although some creatures might be rooted as it does offer some advantage.
So which species on this alien world would achieve sapience? who knows. That really depends on how their neurology works. We store our thoughts chemically in the brain. Why do we have a brain? because our fish ancestors developed a knob of neural tissue at the head of their spinal column. Why would these aliens do the same? They don’t have to. they could have a decentralized nervous system, much more like bugs. (not alien bug analogies! quiet, it wont be alien bugs). Perhaps they could store chemical chains, or make chains of cells (for this experiment I’m assuming they have cells, which we don’t have to do) that store data in random places throughout the nervous system. We are assuming they have locomotion because it’s no fun if they don’t.
But what kind of locomotion? Life is more easily evolved in a fluid environment, an ocean of liquid or gas. For this experiment we are assuming liquid, but not necessarily water. We have said they live in a colder place, so we need something that is liquid in colder temps, Maybe carbon dioxide. I can’t say, I don’t have enough chemistry background to know what liquids can diffuse enough stuff to make life. What ever that liquid is, its fluid so the life would evolve to either walk on the bottom or swim through it. Or both. lets go with both. A distributed nervous system and a need for locomotion, lets go with tenticles. They are easy enoguh to evolve. they are just outcroppings that grow larger and more complex. They can double for hands, feet, flippers, and tongues. So we have this blob of tentacles swimming and walking around our alien ocean. they ingest nutrients floating around and avoid being eaten by larger such creatures, or shelled creatures, or what ever.
Do they have to live on land? not really (but what about fire and metal… what about it? dont need that stuff for space travel…. gfaw!) they can stay liquid environment based. For our thought experiment we are going to say they are social, because we are talking about alien society. They get more complex, they gain more ability with their tentacles. they learn to manipulate their environment. But how to they form technology? Well they are on a planet farther away from their star, which, from what we know of stellar cosmology, suggests it would likely have less metal. (this could be wildly wrong) But nothing stops them from developing plastics. mixing chemicals to make polymers isn’t out of the question. They need materials to build things like tools that let them hunt better. maybe nets since they are aquatic. After a while some of them figure out aquaculture. It becomes easier for them to raise food rather than hunt it. So they stop being nomadic and start picking up real-estate to defend. (also assuming tribal nature of these beings which we don’t have to do) They find ways to defend and fortify their areas, develop some kind of society which doesn’t have to be hierarchical so lets make it collective. They agree on a path and all follow it without much direction from leaders, which they don’t have.
Over time they improve their tools and their production and those polymers come along. Stronger armor, better weapons, better tools for farming and building. After a long time they develop methods for exploring the land. They find its a potent source of energy but with out the liquid they can’t survive there unaided. They bring the sea with them when they go on land, like submarines that go on land and carry an aquatic environment with them. Eventually they make their way into space after getting to land and seeing the night sky with all those stars.
They get into space and look for other worlds and are very excited to see earth, until they realize some deadly facts. 1) It’s just too damned hot, the liquid is all vaporized, nothing can live there. 2) It has an electromagnetic field, it would block off the radiation that is required for life. 3) it’s atmosphere is full of oxygen which would burn cause living things to get chemical burns. It clearly doesn’t have any life on it, it can’t sustain it.
So the aliens and humans never meet each other. Because they don’t have an electromagnetic field their radio communications and ours are radically different. we can’t distinguish eachother from background radiation. we never meet and both think we are alone.