What Shape Would Intelligent Extraterrestrials Be?

 
   

Ever since I was young and interested in science fiction and in evolution, I often scoffed at the big-headed people that were supposed to man flying saucers - why, I said, would billions of years of evolution, a long series of random and chaotic events, have produced creatures that were recognizably humanoid on another planet?

But recently I've been giving it a bit more thought.  You might be surprised at how likely it is for an intelligent species to be at least vaguely humanoid...

We'll take it step by step.

First, we have to agree that the sort of life under discussion would have developed in some sort of water environment (not absolutely necessary, but it's hard to get the complex chemistry to work in the atmosphere of a gas giant planet, and other possible liquids don't dissolve things well enough to get an appropriate complex chemistry going - I wouldn't discount the possibility at all, but we'll just avoid the long list of unknowns by sticking with aqueous-based systems). You also need lots of energy input for high-level biological organization, probably sunlight on an Earth-like planet...  Again, other energy sources are possible (our distant ancestors may have organized using geothermal energy) but have limitations that would probably keep life too simple.

First, on a pathway to intelligence, you're going to have to go through nervous systems.  That sort of quick-response system gives you some animalistic form of life.  Intelligent plants are an interesting science-fiction idea, but evolving them would be tricky - animal-plant types could get you there, I suppose, but it's hard to see a big advantage for intelligence if you can get most of your nutrients just basking in the light.

Next, movable life forms  (animals) that have a preferred movement direction evolve a front end with most of the senses and processors there (an evolutionary process called cephalization), and a bilaterally symmetrical (with "matching" right-and-left-side structures) form behind it for efficient locomotion.  Animals that don't move this way shouldn't develop the central processors necessary for intelligence.   That gives us animals with a head end, complete with brain and a lot of front-loaded sense organs, and pair-matched limbs...

Life may have evolved in water, but living in water is unlikely to lead to what we consider intelligence in a science fiction universe - that is, technology or advanced manipulation of tools. You could make a case for cephalopods (octopus, etc.) being smart, and potentially highly intelligent, but there probably are limitations to what sort of advanced technology could be derived while living in a salt- water environment. Electricity as we know it is pretty much out. Marine life would have many other materials-based technological disadvantages as well.  You may want to look at whales as a form of intelligent life, but they barely qualify as science-fiction "sentient life" (and there are better explanations for their brain size than smarts). So we need animals adapted to land and atmosphere, and they need...

Land animals need legs. How many legs? It seems like more legs could bear more weight, but what you actually see in fossil history on Earth is a reduction in leg numbers in groups like insects and spiders (whose construction materials and organization - skeleton on the outside - limits their potential size and, unless you're going for a hive-mind, their intelligence levels too). Is four legs a good number? That's the most unpredictable aspect - our fishy ancestors, and their first land-living descendants, had four, pretty much across the board, but it's unclear whether that would be a functional preference rather than luck-of-the-draw. Eventually, to get intelligent animals you need to get at least one set of legs free of weight-bearing responsibility - this leads to the manipulation abilities (hands) that, in humans, led to vast development of our brain abilities after birth (being carried reduced immediate sensory and coordination needs in infants and allowed their brains a longer time to develop), as well as our being able to carry tools around.  Carrying the same tools around for a while puts a premium on design efficiency and durability (technology), as well as instructional communication - although early human communication probably had more social underpinnings than technological ones (social organization, though, seems like another "must have" in our evolving thinkers). Our likely candidates for smarts would have internal skeletons (greater size possible, so bigger brains) and jointed legs, a trait which shows up in wildly different groups as a natural answer to the challenge of moving quickly around on land. You could make a guess about joint number and limb placement that would probably get you something similar to what you find on our planet's animals.

What's on a land animal's head? The pertinent senses from way back when are sight, sometimes in a flat facial plane to facilitate depth perception (can you manipulate tools efficiently without depth perception?), found often in predators and active tree-climbers;  hearing, with binocular detectors well separated to localize sound (that could be located someplace other than the head, though);  taste somewhere near the mouth (but in animals with a long history of hands, they could be there), which would be on the head, and probably smell (a powerful component of taste) in the vicinity. Neither of these last two is too well served with bilateral structures, so something central is more likely. The really complex level of communication skill you'd need for intelligence would probably be at least somewhat sound-based, although visual (as in squid skin-pattern shifting) is possible, and you could go with telepathic although it's hard to support it from a physics standpoint (sort of - you can support pretty much anything if you dig far enough into quantum mechanics, though).

What do we get? Something at least partly upright, with jointed limbs matched right-to-left, some sort of grasping/manipulating hands and a head probably moved more above than in front of the body. A couple of eyes (single lens, which is a better system than multiple lenses [compound eyes] if you've got the room), a mouth, some sort of nose, possibly ears. Humanoid? Maybe. If velociraptors had had a chance to keep evolving, would their intelligent descendants be humanoid? Depends on how you define "humanoid."

Should intelligent, technological aliens be "Star Trek"-style humanoid, like earth people with minor variations? Not without some religious implications, I would think. Could they be humanoid within a modern TV budget? Definitely.

 
     

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