Terrestrial life, extinct and past; or alive and present is amazingly diverse – in appearance anyway, but also in the environments they inhabit and the abilities they have to survive and thrive. But under the skin, our fundamental biochemistry, be you T-Rex, or be you a maple tree, or be you a bacteria, or be you, you, well you’re all as closely related as makes no odds. Extraterrestrial life will also be amazingly diverse – in appearance. However, the fundamental biochemistry that makes them, them, might be equally diverse relative to what makes you, you.
Traditional Hollywood fare, when it comes to envisioning aliens, tends to take the cost-friendly option and place actors in strange looking, but humanoid form costumes and associated makeup. Or, forget the costumes, maybe they just give the actors pointed ears or paint a few dots on them or wrinkle their noses! The question remains, will real, as opposed to Hollywood
Appearance: This isn’t so much an exercise as in a general ‘design an alien life form’ but what might a technologically advanced intelligent life form look like – inevitably humanoid, or perhaps not? Let’s start with the general humanoid form as likely – or maybe not. If you were designing an intelligent alien being from scratch, say our technological equals or better, what would you have to include?
Well, you’ll need sensory organs. No life form that has developed technology will be blind and/or deaf; touch has obvious survival value, as does taste and smell, but these are secondary to vision and hearing. You don’t have to have external ears to hear though, so the one essential feature will be eyes. Eyes have evolved independently many times in terrestrial biology, so vision is as close to essential as makes no odds. The eyes could be unusual in that they might have evolved to detect different areas of the electromagnetic spectrum than just visible light. The one other point about vision is that the higher up the eyes are placed the better in order to see farther. I mean if your eyes were located at the tips of your big toes you’d be visually handicapped relative to a being with eyes much higher up. Two eyes are better than one in order to achieve stereoscopic vision, and give some redundancy protection. Compound eyes work too, as any fly adequately demonstrates, but in order to see the really fine print, compound eyes are lacking.
You need to get around, so that means some form of locomotion equipment. Fins and flippers are okay if you’re a water creature, but spending your life in water isn’t conducive to developing technology. Scratch fins and flippers. Okay, so I assume you’re land-based, at least some of the time. One locomotion appendage will get you around if you hop, but two, four, six, or eight, etc. work too, and again, provide some redundancy backup. An odd number of limbs isn’t unknown, say a starfish; and some four footed animals can survive even with the loss of a limb. You might think that too many limbs might be selected against since you’d think the extra neuron power need for coordination would reach the point of diminishing returns. However, centipedes/millipedes, etc. put the lie to that. The number of limbs (tentacles are cool too) aren’t critical; what’s critical, if you’re to develop technology, is that you have to have appendages (even tentacles) that can manipulate the objects in your environment.
Now scallops can move about without having limbs, but it’s hard to visualize a scallop type life form developing technology, primarily because that form of locomotion only tends to be effective in a liquid environment, and a liquid environment isn’t conducive to achieving high technology.
If you have technology then it’s fairly obvious you have the ability to manipulate objects with some sort of appendage(s). The minimum required is one. Humans who have lost the use of a hand can still function and manipulate objects with the other. A tail might suffice. Then there are tentacles!
You probably need a central processing unit (CPU) – a brain of some sort – but it wouldn’t of necessity have to be up top.
Then there’s the topic of whether you have internal or external support – some structure to support the innards or insides of a life form. Housing support could come in the form of a simple sack – an external membrane holding in the innards, like a cellular wall. Or, that external wall could be tougher, like an external hard shell, say like a clam, snail or insect tends to have. Or, even though every life form has to have some sort of external ‘skin’, the actual job of keeping the innards, inside could be more the function of an internal skeleton, the kind vertebrates like us have and to which the bits and pieces are housed in and supported by. Remove your bones and you’d be one sloppy mess!
Admittedly, you need less rigid internal and/or external support if you’re environment is a liquid. An octopus or squid or jellyfish is pretty helpless out of water. A liquid medium also allows you to grow to bigger sizes than would otherwise be the case. Whales do very nicely supported in water, but if beached, find themselves in some quite considerable life-threatening strife.
Finally, there’s a tradeoff between locomotion and your support structure. You can’t really have an entirely near-rigid support structure since that would tend to hinder locomotion. Trees don’t walk around! Triffids are great sci-fi fare, but it’s hard to see that concept work in the real world. A ‘tree’ might have appendages that could manipulate objects in their environment, but their ‘legs’ would have to be really something else in order to move the ‘tree’ from A to B.
As to overall size, that in part is going to be a function of the gravity field you’re in. Presumably there’s a minimum size you have to be in order to have enough complexity to come to terms with being an intelligent species. There’s also a maximum size. Life forms are subject to the same sorts of engineering limiting factors as bridges and buildings. If you double your area (say your leg cross section), you triple your volume (your mass), so sooner or later something has to give as more and more mass needs to be supported by relatively less and less area. You can only grow so much in whatever gravity field limits that growth based on the materials you’re composed and constructed out of. Still, that’s going to cover a very wide range of possible sizes.
Sex: It’s hard to envision any complex life form undergoing asexual reproduction, say via splitting in half – down the middle – like relatively ‘simple’ cells do. There could be self-fertilization, but that limits genetic diversity so needed for relative rapid evolution. One assumes other life forms on other planets have a biological evolutionary process in place given how near essential diversity assists in overall survival.
Other bits and pieces can vary. External coloration is variable; smooth skin, scales, feathers, and fur/hair – no matter. Horns, tails, tusks or other adornments can be as many and varied as you’d like.
Essentials checklist:
*Eyes topside, minimum two.
*Ears somewhere; topside is better but not of necessity where ours are; two is better for determining direction, but three or more just creates confusion.
*Locomotion appendages, minimum one; more is better.
*Manipulative appendages, minimum one; more is better.
*A CPU brain – somewhere within.
*Size: Not too large; not too small.
*Genders: At least two to achieve genetic diversity, but not too many least things get too complicated.
*Support structure(s): Both internal and external appear to work, so that might be a tossup.
Juggling all those essentials, with open slather on the majority of traits that are of little near mandatory consequence, well just say you could come up with a massive variety of life forms, from humanoid to quite unlike anything humanoid. Alien beings that are alien solely due to having pointed ears, facial dots, or wrinkled noses, while in the realm of plausibility, show a rather lack of imagination on the part of Hollywood bigwig writers, produces and directors.
To be continued...
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