Our erect backbone distinguishes us from almost every other species on Earth, and is a very rare feature. If any aliens we meet are without an erect backbone (which seems very likely), they will not seem very similar to us physically.
I think it is worse than that. There may be a small subset of intelligent aliens that do have vaguely humanoid bodyplans, but they will almost certainly be different to us in many other ways; these ‘almost-human’ types might be more difficult to relate to than types that are completely non-human. The closer a non-human gets to human features, the closer it gets to the ‘uncanny valley’, where we start projecting human traits onto them which are not really there.
A human-like alien without recognisable facial signals (such as smiling or frowning) might resemble a living corpse, like those appalling human-robot dolls.
Would a large-brained bird with heavy front-facing arm-analogues necessarily develop a heavy tail? Perhaps not. Here is the skeleton of a Gastornis, a flightless predator bird similar in lifestyle to a theropod.
Note that the tail is relatively short, but the pelvis has extended backwards in a remarkable fashion, to counterbalance the heavy head.
Note that I did not say that birds were cantilevered, just that they are balanced similarly; apart from the penguin, this seems consistently true.
“What are the odds an alien species would be similar to us physiologically”
I’m thinking you are talking about an intelligent technology wielding species and not just any old lifeform, correct? You should also distinguish between physiology and anatomy.
I would say the odds of a tech wielding species to have a general anatomy (humanoid) to humans is… very high. Some of the other posts have already given many reasons for this, I will make it simpler and say that under the same natural laws with the same chemical building blocks present, there really isn’t that many ways to make a working metabolism. Despite what scifi claims there really aren’t any ‘rock monsters’ or ‘crystal entities’ or ‘hyper intelligent shades of blue’ or any other ‘life but not like we know it Jim’ around.
If it arises, alien life will do so from a pool of the same chemicals we have down on Earth, and mutations and evolution will still take place following the same evolutionary rules and natural laws we have down here. And a basic humanoid shape is simply a very efficient one for a tech wielding species. Look around: is there ANY land based lifeform on Earth which has the general anatomy for developing industry that ISN’T humanoid? I certainly don’t see dolphins discovering fire or elephants building spaceships with their trunks. You need a hand, you need strong bones and backs to lift things in the early phase of development. That will likely mean bipedal (2 arms repurposed for tool use), erect, with arms and hands. Put a head on top (where else?) and you got a humanoid.
That said, I don’t expect them to look human. Arms may be longer or shorter, perhaps they have more or fewer fingers, more joints, some external vestigial features, a tail, eyes further apart, larger or smaller. Bony plates on abdomen, some horns, why not. Unlike the absence of a brain, eyes, hands and bones for leverage, none of these changes would make it more difficult to develop technology and build a spaceship.
But scifi shows need to save on special effects you know? They can hardly break the actors legs in a few places just to make it more realistic.
Many millions of years ago a superficially elephantine extraterrestrial race came down to Earth and looked around. Were monkeys discovering fire or building space ships? Hands must be a dead end, since they’ve existed a hundred of million years and were only fit for brachiating and manipulating small objects. The aliens could teach the monkeys cute tricks, like getting them to paint, but it didn’t go anywhere. You need the combination of strength and dexterity of a trunk to build a celestial empire. Obviously.
Roboticists have been hyping up what amounts to soft robo-tentacles for a long time. They’re strong, flexible, resistant to compression, and they don’t get stuck because they have to worry about stupid bones.
About the only thing I would bet on for alien intelligence is that it probably has bilateral symmetry. And that just might be bilateral chauvinism. Even if it’s more efficient or makes bio-mechanical sense that doesn’t mean a radial or barrel symmetrical animal couldn’t come to dominate a planet out of historical happenstance. If it then underwent cephalization or tried to rework their body plan because they’re motile on land they could look super funky.
Our intellectual evolution was allowed for by our (utilitarian) physical evolution.
I don’t quite grasp how an amorphous blob could develop advanced technology, but that’s the thing about our universe: it’s amazingly unpredictable what is possible.
An amorphous blob implies that there’s no or little differentiation between cells and organs. Without differentiation, you’re probably right.
But if you allow that thing to have a specialized brain and some eyes, and let it form tentacles/pseudopods to manipulate the environment… I think that’s quite possible as an intelligent life form. On the other hand, it’s pretty unlikely that amorphous blobs could outcompete species with limbs and bones, so if we’re talking about evolution on a hypothetical alien world, then it doesn’t seem likely that blobs would last long enough to get around to evolving brains.
(That said, I once wrote a short story around an amorphous blob intelligence that photosynthesized and covered its planet a meter deep in “goop.” Being so large, it thought at glacial speeds, so it didn’t even realize that humans had landed until thousands of years after they looked around, found nothing intelligent, and left. The goop concluded that they couldn’t be intelligent, since they didn’t hang around long enough to have a thought.)
Tentacles are NOT useful for lifting heavy objects. They are great for small critters and aquatic lifeforms, not for a species which has to build city’s out of stone and mine ore and do every other type of heavy manual labour for literally hundreds of thousands of years till machinery gets invented.
Those ‘stupid bones’ provide leverage, giving an organism actual strength and not just dexterity.
Um… you are aware that tamed elephants are used for heavy lifting?
Also, evolution doesn’t make optimum solutions, it makes adequate solutions. Given what elephants can do with their trunks I could conceive of an intelligent species using a trunk - which is essentially a sort of tentacle - to manipulate objects. Yes, the elephant’s trunk is attached to a bony skull, but the trunk itself has no bones in it.
I may be wrong, but my impression was that elephants curl their trunks around a heavy object and then let their neck muscles do the lifting, the trunk simply holding on through tension. I don’t know how heavy something can be that they actually manipulate on the end of their trunks.
Still, an animal could evolve that develops large muscles to do the lifting part. It doesn’t need a skeleton either, it might only lift something by holding on to a tree branch with some tentacles, and holding an object in the other.
YES I’m quite aware. And I’m also quite aware that an elephant could never do the fine manipulation required for developing a civilization. It was tentacles I referred to as weak. Elephants are incapable of developing real technology for other, rather obvious, reasons.
YES I’m quite aware. And I’m also quite aware that an elephant could never do the fine manipulation required for developing a civilization. It was tentacles I referred to as weak. Elephants are incapable of developing real technology for other, rather obvious, reasons.
Adequate for SURVIVAL. Not adequate for technology which that species would use ages after it physically developed. An elephant can pull something free and put something in its mouth, it’s not going to solder electronics with that trunk. Our ancestors and apes alike (not the same thing) evolved hands for a lot more dexterous work and can still apply some force, anything other than hands won’t do. I could almost imagine a poor hand alternative by combining both fine tentacles for precision work and a crude claw for lifting, but that seems inefficient. Certainly not as likely as a 1-fits-all solution which is energetically cheaper to develop.
And we are talking about likelihoods, not certainties.
The only animals on Earth without (or mostly without) a skeleton are aquatic. As said, bones give leverage to movement. And movement is a lot harder on land…
An octopus for instance is pretty intelligent, but those octopi which can crawl out of the water can still barely move on land due to their boneless shape. I don’t think it’s going to discover fire underwater either, or steam engines or laptops. In fact I don’t think it even is going to develop paper to write on. Technology, real technology, is the prerogative of land animals.
Perhaps an animal could use some sort of hydrostatic skeleton, like, well, like the swelling bodies of male genitalia. A skeleton that you could turn on or off for your tentacles when required. It would be considerably less leverage than a bony hand and less dexterous than a real tentacle even in off mode, but perhaps that would suffice for at least some degree of technological development. But it would still be a poor man’s hand.
Elephants are intelligent and they have a “limb” that can manipulate objects. What else is needed?
The average primate hand isn’t going to be soldering electronics, either. Their “precision grip” isn’t very precise.
Actually, no - nothing evolves “for” anything. Animals are full of jury-rigged work-arounds. That’s why we wind up with problems like carpal tunnel syndrome.
So? It doesn’t matter if there is some inefficiency as long as it works good enough most of the time.
Hands aren’t perfect. For example, we lost the heavy claws a lot of animals use for defense/offense/digging/other purposes. We can’t regenerate lost digits. They aren’t strong enough to support our bodyweight as long our primate cousins can. That whole “handedness” thing - would there be an advantage to symmetrical hands that don’t come in left and right varieties? Or would it be better to have one very, large, strong hand for power applications and one small, very dexterous hand for fine manipulation?
Since we have only the example of our own planet we really don’t know what is likely or not in the wider universe.
Octopi are descended from a lineage that has members with hard parts that could be used as leverage. Their “cousins” the cuttlefish still has a “bone”. Such structures could potentially serve as anchor points or for leverage.
It doesn’t matter if it’s a “poor man’s hand” as long as it’s good enough to get the job done, said job being crafting tools of some sort. We have a lot of tools that apply more force than our hands, or more precision than our hands (micro surgery tools for one of the more advanced examples), thus “improving” our hands.
There are actually many examples of small animals that do just fine. Slugs and earthworms to start with.
Human technology, at least, started with stone tools. There’s nothing except brainpower preventing an octopus from doing that right now.
You’re being unfair by jumping to steam trains next. Look a little further back. What did we do before steam trains? Draft animals. Nothing stopping a smart octopus from training whales or dolphins to carry things around. Also, before steam trains we had wind and water mills for tasks like grinding flour. This technology is also open for use by an octopus under water.
Once they’ve mastered spears, weaving, and domesticating animals, I suspect they’ll be in a good position to start experimenting in that air-world above them. Transportation in the air can be solved to some extent - they can build crutches for themselves. Maybe they can even find and domesticate horses or cows to carry them around.
Then they need to figure out the whole breathing thing…
Anyway, the point is that I wouldn’t rule out an aquatic intelligence eventually developing all of the technology we have. It will be a different route, surely, and it will have some unique hurdles, but you’re too eager to call it impossible.
