User blog:Mr.Robbo/Human Chauvinism 1

To help with originality, I've decided to start compiling a list of features present in humans that may not be present in extraterrestrial species and civilizations. Some features may be more antrocentric than others, while some may actually be the only plausible candidate for a feature of an extraterrestrial species or civilization. Nevertheless, most are commonly found in science fiction.

Before I start, I should mention that there is always 'convergent evolution', which says that the human situation (planetary environment, body type, structure of civilization) will be the one that is most common in the universe, simply because it is the most optimal or the most conductive to an advanced technological civilization.

There are some pretty good arguments for this, such as that four limbs are naturally the best number for a creature of bilateral symmetry (like the four corners of a rectangle, with no limbs sitting in the middle not pulling their weight), along with a sensory organ (head) at the front (where the action is); the brain would be inside this sensory organ to be closest to the main senses, and would probably be protected by a hard shell (skull). The natural next step of this would be for the limbs closest to the head to evolve to manipulate the environment (arms), with the rest of the body becoming vertical to deal with the shift in load.

The aliens in settings such as Star Trek are so blatantly humanlike that they can't even be explained using convergent evolution. Anyway, the theory assumes that all extraterrestrials will evolve on a very similar environment to Earth, in almost exactly the same way. I don't like it. A variety of unique aliens is much more fun!

Humanoids
There is no reason why the most common alien body shape should be humanoid. There are many popular science fiction settings that are guilty of this (such as Star Wars and Star Trek), though usually it's for budget reasons (humanoid aliens are usually less common in written settings). Usually all an intelligent alien needs is a means of sensing its environment, a means of manipulating its environment and a means of communicating with other members of its species (though this is highly simpliefied and a whole host of other factors should be considered aswell).

Think of the variety of body shapes on Earth (where there are few humanoid species). You could have squid-like aliens or insect-like aliens or even bird-like aliens that manipulate their environment primarily using their beaks. Even then, you could design an alien nothing like any creature seen on Earth (though I admit that's a more difficult one) to inhabit some really wierd environment with unique evolutionary challenges.

Four Limbs
Billions of years ago, some of the first large animals crawled onto land from the sea and they just happened to have four limbs... and so it continued. Why should this also happen on an alien planet? The seas of early Earth had fish with up to twelve limbs! The makers of Avatar made the creative decision of giving their aliens six limbs (I commend them!), but then spoiled it slightly by making the Na'vi humanoid (well, they had tails, which is technically a fifth limb, and I expect it's a lot easier to find human actors to play the movements for the Na'vi these days).

I think it's likely that an alien (with bilateral symmetry, at least) would still have limbs in pairs, though as I just mentioned, something like a tail could count as a limb, and perhaps some unique evolutionary situation could result in a strange combination of limbs? Why not no limbs? That would be tough; how would they use tools? For aliens without bilateral symmetry, there's a lot more freedom. Just think of starfish! Actually, speaking of that...

Bilateral Symmetry
Bilateral symmetry (creatures that have roughly the same body plan on both sides) seems to be quite common in large-scale Earth animals, so there're obviously some big evolutionary advantages in bilateral symmetry (such as, well, it's easier to run!). However, I don't want to rule out the possibility of aliens with, for example, radial symmetry (perhaps some sort of octopus-thing, for example). There could be environments that make (for example) radial symmetry more evolutionarily advantageous than bilateral symmetry. Perhaps they have science fiction stories that mostly feature aliens with a radial symmetry? Regardless, I think that the bilateral symmetry of animals on Earth will be most common, though not universal, in the galactic community.