On Alien Physiology

A human, cleverly disguised as an alien.

A human, cleverly disguised as an alien.

It’s taken as a given by many people that that the entertainment industry makes aliens look fairly human because of budgetary reasons. There is truth in this. There’s also the fact that since humans have two arms and two legs it’s tough to make them look anything other than essentially human. But “true” sci-fi fans know that aliens would likely look nothing like us! They’d probably be so alien we couldn’t even conceive of how bizarre they look, we’re told. They could be so alien we’d never even recognize them as intelligent life!


I contend that there’s a few basic things that every life form capable of rising to at least our level of technological progress has to have. Without those things, you can’t have a viable species that’s capable of reaching even the most basic technological level, much less getting to our own level or beyond. When you consider these basic things, you’re left with a species that must, by logical reason, look at least somewhat like we do. Let’s get started.


Humans have five basic senses; touch, taste, smell, hearing and sight. There’re others, too, like time sense, but we’ll leave those aside for the moment and concentrate on the traditional five.

For the purposes of this article, I’m going to create a species called the Vlorps. The Vlorps, from Vlorpia, naturally, evolved on a planet with other species and competed for space and resources with those other species. In order to do so, the Vlorps had to have ways of experiencing sensory input. Unless Vlorpia is a night world, they likely have predator species that can see. Ergo, it’s probable that the Vlorps could see, otherwise how would they evade their sighted enemies or hunt down prey?

It is likely that the Vlorps would have sight, and would have only two eyes. Two eyes gives you stereoscopic vision, which is very useful when trying to evade predators. More than two eyes serve no useful purpose and require more brain power, so two make evolutionary sense. It is possible two have two eyes positioned in a way that doesn’t allow for stereoscopic sight, like with horses and cows, but meat-eating species tend to have forward-facing eyes that allow for stereoscopic vision. I would imagine that the Vlorps would likely originate from a meat-eating species, since we know that at least with humans, access to proteins from meat helped us to evolve. Stereoscopic eyes are also necessary for other advances that we’ll see later, such as blacksmithing, so I think, at least at this point, it’s reasonable to assume the Vlorps would have such a thing.

Moving on, unless Vlorpia has no atmosphere, which doesn’t make any sense at all, sounds exist. Any species that can exploit those sounds has an advantage over species that can’t. Therefore it’s likely that the Vlorps would have the ability to hear.

Now it is possible that a species could exist with “sonar” type hearing that would render sight unnecessary, but I think that’s unlikely in a sentient species. It’s also very likely that the Vlorps would have stereo hearing. That provides an advantage when eluding predators, since you can pinpoint where noises are coming from. Having more than two ears is excessive and requires more brain power for processing the input with no real advantage, so it is likely that the Vlorps can hear and have two ears positioned at different points that allow them to do so.

So at this point we’ve established that the Vlorps have two eyes facing forward and two ears positioned at opposite sides of their bodies. These could be located at waist level, I suppose, but I imagine that putting them near the brain makes more sense, so they’re likely located on the head, as are the eyes, since that minimizes the potential for problems with the optic nerves.

Please note that I’m not saying that the Vlorps see in the same light spectrum we do. Let’s assume their species evolved in a place with a different kind of sun, so perhaps they see further into the red range than we do. We can assume that their eyes can adapt, at least somewhat, to different levels of light and darkness, as well.

Now, then. Taste and smell are both very connected. At least in humans, you can’t really have one without the other. If you doubt this, try to eat something flavorful when you have a very stuffed-up nose. A sense of smell is very useful. With it, you can tell if something might be spoiled. You can sense if a predator might be in the area. You can sense if prey might be in the area. I don’t know that it’s as required for a highly-evolved species, but we’ll give the Vlorps a nose, with two nostrils (since redundancy in your breathing systems is a good thing), in the middle of their faces, right below the eyes. Why there? Because that gives us an easy place to put the sinus cavity, and again, it means a shorter path for input to reach the brain.

And if you’re reading carefully, you’ll notice a pattern here. All the sensory organs so far are located near the brain. That makes sense, if you think about it. All the input they provide goes to the brain, and having them near it makes that journey faster. Putting ears down on the feet and eyes in the palms of the hands might look interesting, but it doesn’t serve any real purpose. So since we need a container for the brain, which I’ll think of as a head, we put the ears, eyes and nose on the head as well.

And speaking of the nose, we’ll give them a basic sense of taste to go along with the smell, since that’s also useful on an evolutionary level. The sense of taste must, of course, go with the mouth, and I think, again, it needs to be near the brain. Our sense of taste works in conjunction with our sense of smell, so putting it near the sinus cavity makes sense.

While we’re in the mouth area, let me point out that the Vlorps would almost certainly have a spoken language. Why wouldn’t they? Speech is very efficient and a good way to communicate information (well, unless it’s based entirely on metaphors and mythology, because come on). It’s better than something like a color based language, or something that involves nothing but non-verbal communications. I can’t really see that an alien species would be able to build a civilization without such a language. How else would they communicate? Telepathy? Show me any scientific way that would be possible and I might give in there.

Moving on. We have a Vlorp with a recognizable head containing the brain, two forward-facing eyes, two ears on either side of the head, a nose between the eyes and a mouth below that. This is a mostly human pattern so far, and that makes sense, I think. I’m also putting the head on the top of the body, since if it’s up high, it takes the ears and eyes up with it, and that’s an advantage since it provides a wider range for hearing and seeing.

Then we get to the sense of touch. Again, this is something that helps in the tracking of prey and the evading of predators. Being able to sense subtle changes in the wind, for example, could alert a Vlorp that the dreadful predator species, poetica creatura is nearby. Having nerve endings spread out over the body and processed by the brain makes sense, but it doesn’t create any visible change to our little Vlorp.

So that’s the senses covered. What’s next?

Basic anatomy

Humans, and most other large land species, have four limbs. In our case, and in the case of a few others, that’s two for locomotion and two for manipulation. Vlorps will likely be the same. Having more than four limbs requires more brain power that can be better used for other things, like learning to make fire (more on this later). Vlorps would likely need to stand upright to avoid predators and to do other things that we need them to do later on to reach our level of tech. So let’s assume they have two legs that end in feet. We’ll assume that they can use these legs to run as well as walk, because otherwise hunting prey and/or escaping predators would be very difficult.

Likewise we’ll assume that they have two arms that end in something at least approximating a hand that has digits capable of moving independently. I don’t think that more than, say, six fingers (counting a thumb, which isn’t necessary if the fingers are positioned right), on each hand are needed. I also think that less than four on each hand would be too limiting. So I’m going to go off the human design slightly and say that the Vlorps have four fingers and no thumb. The fingers are positioned across from each other in groups of two. This allows for gripping and manipulation of items.

Now, on to sex. The Vlorps will need to have a basic method of reproduction, and here is some room for creativity. There’s no reason to assume the Vlorps evolved from a mammalian-type species. I’m going to say they evolved from something similar to, but not quite the same, as dinosaurs. I’m going to give them warm blood, but I’ll have them lay eggs. This means that the female and males alike have cloacas. I’ll further assume that like many reptile eggs, the shells are soft, so the parents have a motivation to remain and watch over them until they hatch.

I’m not going to give the Vlorps scales, since I don’t think they need them, but I will give them very roughly textured skin and some very minor level of feathers on their heads and down their spine. No tails, since that’s an extra limb that isn’t really needed and, like an extra arm or leg, would require more brain power to process.

Now we move on to why some of these things are necessary for a species to evolve even to our own level of advancement.

Why these things?

This is where I come to what I call the Caveman Theory of Alien Design. I want you to picture a human caveman trying to survive in the dawn of time. One day he’s climbing a rock face and one bit of rock detaches, falls, and strikes another bit causing a spark. This caveman is very fascinated by this, and learns that, as the newsreader says, the secret is to bang the rocks together, guys. This he does, causing more sparks, and before you know it, he’s mastered fire.

Now I want you to imagine a proto-Klingon doing this same sort of thing. Pretty easy, right? Now picture a proto-Ferengi doing it, and charging you in beads for the lesson. What about a cave-Wookie? What about some long lost Cardasian precursor race? How about…well, I was going to throw in a Doctor Who race, but since they mostly look like Time Lords, and the ones that don’t (Daleks, for example), are usually engineered that way, there isn’t much point.

I think you’ll agree that picturing those various species muddling about in the…well, mud…learning how to make fire seems plausible. Now to pick on Doctor Who for a moment, can you picture a Rutan making fire? What about a cave Macra, trying his best to not end up as crab-cakes in the process? What about a more basic form of a Horta? Or how about a Hooloovoo trying to make…well, really anything. It just doesn’t work. Come to that, can anyone picture primitive cave elves?

Exactly how does something someone sneezed up build a civilization?

Exactly how does something someone sneezed up build a civilization?

That’s the thing, really. If you can’t picture a very basic, proto-version of your alien species mastering fire, then your species does not work. Fire provides light, heat and a way of cooking food. In its more advanced form, it provides a way of making tools and weapons, and even now it’s the basis of much of what we do. If you can’t picture an alien making fire, then that alien is a design failure.

The Vlorps come from a fairly warm world, so they don’t really need fire for heat. But they do need it for light and they discover that cooking meat makes it taste about a billion times better. It also releases certain enzymes and makes proteins easier to break down and digest.

Now picture Vlorps a million years after fire. Now they’ve developed agriculture and started forging metals. Doing these things, especially forging, requires as body that is capable of beating and heating metal. I think it’s also pretty easy to picture a Vlorp rancher, tending to his flock of herbivore animals known as prandium in cruribus. Moving further down the line, one can imagine, with relative ease, a Vlorp mastering gunpowder, operating an early computer, developing an airplane, and eventually traveling into space to visit one of Vlorpia’s two moons.

These things are all imaginable, and all doable by a Vlorp, because they have a physiology that allows for them to do so. One arm wouldn’t allow them to advance as a species. Three arms would take up too much brain power. Some sort of sentient, land-dwelling squid with eight limbs would be a nightmare, since all they could do would be to move about. Their brains wouldn’t be able to process much other than controlling their arms. And as for something like an intelligent ooze, well, exactly how would that work in the real world?

It’s possible, I submit, that alien life might develop their technology along completely different lines from our own, and do so in a way that doesn’t require them to look even remotely humanoid. But I think I’ve shown here that if you have to get from developing fire to having spaceflight, you really do need something that’s a basically humanoid body.

So remember this the next time you watch some sci-fi film set on a far distant world and feel tempted to roll your eyes at how human the CGI aliens look. Ask yourself, how else should they appear?


3 Responses to “On Alien Physiology”

  1. bogleech Says:

    I know this is rather old, but….octopuses, squids, cuttlefish and other cephalopods are actually extremely intelligent. Their brains do much more than just moving all their limbs. They demonstrate problem solving and learning on the level of a human toddler, almost. They exhibit play behavior, they can learn to remember individual HUMANS by their faces (we can’t even tell two chimps apart at a glance most of the time!), and the sophistication of their brains implies a vaster learning capacity cut short only by their 1-2 year lifespan.

    • bogleech Says:

      Wait, why did I think this was old? I got a little muddled by the recent month switch I guess.

    • Chris Says:

      I considered the case of the squids and the like. But I still doubt strongly that they can reach actual sentience and build up a civilization. I could be wrong, and a creature that evolved from them, moved onto land and likely developed fewer limbs would be quite possible.

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