Most of our traits only exist for our survival. Limbs, eyes, ears…etc and intelligence was part of that so if an alien’s survival has other requirements due to a difference in environment and predators, then they may not have a need for hearing or eyesight for example but yet could still be just as intelligent or more so but likely in a different way. They could exchange information via chemicals rather than voice for example.
We owe most of our technology to wars with each other. The first device used to aid in throwing spears was believed to be invented due to a necessity to be very accurate and efficient during a war between 2 tribes or groups. If we weren’t so territorial and belligerent with each other, we may have turned out to be very different.
Nonsense! The spear-thrower was probably first used to aid in hunting, adding velocity, and therefore range and penetrating power, to a projectile. Hunting is a far more common activity than warfare, but a tool that can kill a deer or a seal can also kill a human. That’s just not its primary use.
Probability is just as much a measure based on how much information we have about an event in question. You’ve all seen that puzzle “So-and-so has two children, and one of them is a girl. What is the probability that the other is a girl?” If you specify which one is a girl (like, you say the oldest is a girl) then the probability is 1/2 that the other is a girl. If you don’t specify that, then the probability is 2/3 that the other is a girl. The biological facts haven’t changed, but the information you have available to you has. Same with estimating the probability of “humanoid intelligent ETs”.
They exist, or they don’t, but the probability is based on the available information we have about it.
Absurd (emphasis added). We would have no way of knowing that even if it were true. Even if you saw cave paintings of the atlatl used that way, we still couldn’t know that it was invented for that purpose.
Well, if God created Man in His own image, in His own image created He him, male and female created He them, and if furthermore God created equally intelligent creatures on other planets, would He not have surely created them in His own image too? Therefore, intelligent creatures on other planets are equally as humanoid as humans on this planet are, because we’re all actually, in fact, Godoid.
Did I say that, or did I say that it is a fairly parsimonious layout, in the sense of fewer moving parts and reduced energy use, so we should not be surprised if we were to meet an alien biped. Note that I am not saying we will meet ET or Spock, just something with a shape reminiscent of our own, if you squint. But here we run into varying definitions of “humanoid.” I use one less specific than yours.
Using birth difficulties in humans as an argument against the basic design is a ridiculous anthropomorphizing of the entire discussion. As for the improbability of a head containing the bulk of sensory and processing organs, look at how it developed on Earth. The first organisms moving on their own accord were doing it for a very simple reason, most likely to find food. Logic dictates that the most efficient place to place sensors to find the food (touch, smell, taste, and sight) is in the end going in the same direction as the body, and that the place to put the few cells that direct the body is near the inputs. There, you have a planarian. The rest is commentary.
I believe this was a quip in someone’s science fiction novel, where the aliens were recognizably mammalian…but were marsupials. One of them was arguing that placental mammals were impossible, because the developed brain would be too large to pass through the birth-canal.
I was hoping for that kind of whoosh, but his other objections suggest that he is looking for something just like us, a preposterous degree of parallel evolution, like on TV.
Not directly bearing on the possible form of ETs, but just on their probability, one might note that there is an estimated minimum of at least 100 billion planets in this galaxy alone, and probably several times that number. It’s not a figure we can conceptually understand, nor what it says about the probability of extraterrestrial life being essentially a certainty, barring the literally astronomical improbability of the prerequisites for life having occurred only on earth and nowhere else. The more interesting question is how improbable is it that similar evolutionary paths occurred elsewhere in similar environments. Another one is how long sufficiently intelligent biological organisms would remain purely biological, merely passive agents of evolution, as opposed to self-determining. So that if and when we encounter ETs, we might be dealing with something that isn’t naturally evolved at all, at least not in Darwinian terms.
Here’s an interesting diagram comparing our solar system (the little tiny rectangle) with only the several hundred known planets discovered so far. Imagine that diagram extended to all planets actually in existence in our galaxy. Printed on paper at the same scale, a rough calculation is that the paper would have to be at least five square miles in size, maybe ten or fifteen square miles or more. Even at the lowest estimate, you’d need about 420,000 500-sheet packs of typewriter paper to print the diagram, and the assembled sheet would weigh about 2.1 million pounds, not counting the Scotch tape.
I don’t think that’s exactly what his objection is. But I do agree far more with you, that the overall pattern – bipedal, sensory knob at the top, manipulating arms, tail optional – is a good one, than I do with his suggestion that this pattern is strictly limited to “… an intelligent creature evolved from brachiating apes to inhabit the grassy savannas of the Serengeti plains to use stone tools to gather plant seeds and fruits…” I think he’s limiting the case far too strictly, while you left plenty of room for generalization.
Some years ago, a computing group ran an evolutionary sim, trying to use evolutionary algorithms to produce a form that engaged in locomotion. The result was a weird thing that used a piston to shove a base-plate backwards and forwards, to “scoot” forward over the land.
I’d like to see this kind of sim done again, with more computing power and thus more simulated parameters. If we can execute a run that produces quadrupeds among other varieties of locomotion, I’d be mighty impressed. It would allow me to take those other varieties more seriously.
True, but HeXen is asserting the opposite claim, which on the face of it seems rather implausible.
Humans are omnivores, and evolved from omnivore ancestors.
Even if we were so aggressive that murder was something every human engaged in, it would still be something necessarily rare relative to the number of times we’d kill animals. Furthermore, it would be significantly more difficult than killing most or all species of animal.
I disagree. One of the main reasons humans are so bad at giving birth is that there’s something of a compromise between women being able to walk and able to birth (big-headed) babies. To try to make that compromise work, babies are also born with an un-fused skull, which illustrates that we’re probably at the extreme limit of how big a brain can get with this body shape.
Now, we could say on another world they might evolve a humanoid shape along a different evolutionary path and not encounter this problem. Or they find a compromise like we did. Fine.
But then why are we just dismissing other body shapes as sub-optimal, and not making similar assertions about them?
No one actually did that. dropzone said, “All told, the humanoid pattern is a pretty good layout, with a bias towards cheapness.” Not that it is an “optimal” pattern, and not that any other shape is “sub-optimal.”
He said, “. . . it is a fairly parsimonious layout, in the sense of fewer moving parts and reduced energy use, so we should not be surprised if we were to meet an alien biped.”
I think this is entirely valid. He didn’t say it’s the most parsimonious layout, or that it has the fewest moving parts, nor that it has the least energy use. All of those claims would be extremely hard to defend, and I would strongly disagree with them.
Seriously, what he’s saying is so completely moderate, the only way anyone seems to be disagreeing with it is by changing it so that it no longer reflects what he actually said.
Ok, I may have inferred a little bit, but that’s because it’s a thread about the likelihood of humanoid aliens vs other forms, and if we’re just going to say the humanoid shape is good in some ways…well, sure of course. It’s a product of evolution. It seems an empty statement to me. It’s also sub-optimal in some ways for the same reason.
OTOH, to try to make a point out of saying it’s low-energy use, we might say it’s a low-energy use shape relative to having more limbs (e.g. a centaur shape). I would agree with that.
Though there’s no reason to stop there in our analysis, and conclude that such a body shape is likely, and therfore we shouldn’t be surprised to encounter another humanoid alien.
One of the problems here is that pretty much all we can say are bland generalities. Our body layout is one workable model, but we really don’t know how many others there might be.
Larry Niven’s “Puppeteers” are a fascinating speculation: tripedal beings with manipulatory mouths, in two heads, each with one eye – and the brain stored away safely in the body. Cute as anything, and completely believable.
I’d like to see biologists (and engineers!) take on this puzzle as a challenge for arrant speculation. What kinds of body plans can we imagine that have that level of plausibility?
Can we rule anything out? For instance, I don’t believe in gaseous alien life-forms, and liquid ones only if contained in a membrane or surface-skin of some sort. I don’t believe in “energy beings.”
On the other hand, I have no problems with “hive minds.” (Vernor Vinge’s “Tines” – caninoid aliens who function in group or pack minds of about five physical individuals – are a lovely example of this.)
Science Fiction is a valid form of “thought experimentation.”
So, you’re arguing that an alien form would likely be “humanoid” in some sense that is “efficient”, but not human-like in ways that are not “efficient”, reasoning from general requirements to a very specific layout and basing those notions of efficacy upon the characteristics that are evolved that are particular to human evolution and the supposed logic which “dictates” said efficiency, which is the very epitome of anthropomorphizing. The claims of “fewer moving parts” and “reduced energy use” (with reference to what?) are in no way validated, and even a cursory examination of the human body form shows no special parsimony and that any efficiencies exist only in terms of its peculiar evolutionary development and environment. Why have five fingers–two, nearly useless for most tasks–and a delicate compound joint at the elbow than, say, three opposed thumbs and an inheretly stronger ball and socket or saddle joint? Why plantigrade mobility rather than the more energy efficient digitigrade motion which would require a far less complex foot and ankle structure? Why is the respiratory inlet the same route as that for the digestive system with frequently lethal consequences when food or liquid goes down the trachea? The answers to these questions can only be answered in the specific context of human evolution.
You can posit a definition of “humanoid” that differs substantially from these features–say, breathing out its arse, birthing through its chest vagina, or stacking its three eyes in a vertical line between its aural sensors–but the potential variation in form deviates further and further from anything recognizable as “humanoid” even if it is an upright biped with “a head containing the bulk of sensory and processing organs”. The possible variation in practical forms for an intelligent tool-using organism are so vast that happening to evolve something that we would agree as humanoid-like is improbably to say the least, even given the potentially vast number of planets that could support terrestrial-like life.
Here’s what we can say about possible intelligent, corporeal alien life: they’re likely but not assured to
[ul]
[li]be homothermic, and capable of adapting to a variety of environments,[/li][li]be tool users with some kind of gripping appendages, or some other means of physically manipulating their environment[/li][li]have some combination of senses of vision, touch, and taste/smell,[/li][li]use something akin to respiration (rather than fermentation) to process energy,[/li][li]have a cellular physiological structure, organized into discrete organs for various bodily functions,[/li][li]and have a complex central nervous system with a substantial portion dedicated to signals processing, communication, and conceptual thought.[/li][/ul]
About the anatomical arrangement we can say almost nothing definitive, other than the most obvious negatives (they probably don’t breathe through the bottom of their feet or communicate by projectile vomiting) and that both their metabolism and thought processes are likely to be entirely incompatible with ours.
Here’s what we can say about possible intelligent, corporeal alien life: they’re likely but not assured to
[LIST]
[li]be homothermic, and capable of adapting to a variety of environments[/li][/QUOTE]
I think already this is making some assumptions.
What if their environment is much hotter than ours and more stable (at least within the habitable area)? There would be little benefit to evolving the features you mention.
When we look for candidate planets for life, we look for planets within similar temperatures as earth, far enough away to not be tidally locked etc, only because we know a world like this gave rise to life.
Not because we know worlds unlike this cannot.
I find the idea of a gaseous being about as plausible as biological quantum spooky action at a distance, which is what you’d have to get to get a telepathic hive mind (I hate that term, BTW - eusocial insects don’t have a “hive mind” at all, or there’d be no need for bees dances or queens fighting).
Telepathy of the group-mind sort would require both a radically-different theory of Mind from our current one, as well as naturally-evolved radios or some other communication system.
Telepathy is the one SF trope that doesn’t seem to get as much hard-SF hate as, say, FTL, even though it’s just as impossible by our current models of physics.
This is a disgustingly old argument in science fiction. It’s always been spurious.
There are whole epochs of our own planet’s geologic history that lack much evidence of a major sapient humanoid species. There are intelligent creatures on this planet that are not hominids, and two groups known for their animal intelligence, the elephants and the cephalopods, even have alternative manipulative organs.
The four limbs of the Tetrapoda are a fluke. Outside the Chordata, many many animals have six or more limbs. And their mouth parts are wildly different. And some of them have wildly different respiratory systems. And by definition, their skeletons are different.
Very roughly anthropomorphic? Sure. Some kind of hands? Could happen.
But an actual looks-human face shape? Very unlikely, because there’s no good reason for it. Human-like plantigrade feet? Meh.
Take Rocket Raccoon (or a real raccoon). Give him a third pair of limbs, like a centaur. Scale him up to the size of a double-decker London bus. Replace his eyes with a “crown” of several conical antennae that respond to a section of the microwave range (as the lifeforms in that Bilenkin story). And that might be the ***most *humanlike extraterrestrial intelligent species we meet in our arm of the galaxy. (I’m cheating and handwaving you a physically impossible warp drive for the sake of argument.)
You are well justified to be skeptical, hence my qualification that this list of conditions is “likely but not assured”. However, it should be noted that the function of the human (and generally mammalian) nervous system as an electrochemical potential generating and releasing system is highly dependent on temperature to function, and variation in temperature, and especially temperatures exceeding mean body temperature (37 °C for humans) by even a few degrees result in substantially degraded cognitive performance. Although we often think of thermoregulation as generating the internal heat to keep the body temperature elevated above the ambient, the more elaborate and critical functions are rejecting excess heat and keeping the temperature below a the threshold upon which the brain starts randomly shooting off neurons in a positive feedback condition. The same is true for aves (albeit with significantly different thermoregulatory mechanisms). Of other macrofauna, the only other class to demonstrate high conceptual intelligence are certain members of Cephalopoda which are ectotherms (conform to external temperature). In this case, they have a number of respiration features to regulate neural activity and action potentials within the nervous system despite environmental changes. However, this depends on being submerged in water which is used as a coolant, which may partially explain why cephalopods have not adapted to terrestrial environments despite their wide array of adaptation in the marine environment.
Can we generalize from our singular cohort of data to how life in general may evolve? Well, some means of thermoregulation, whether innate or external, is probably necessary for a species to evolve to the point of being able to expand across its available habitat and industrialize the way humans have, and it is highly likely that any terrestrial environment will have a wide variability of temperature. As humans, we cope with this partially through our innate thermoregulatory ability and partially by tool use. An alien life form may depend more or even exclusively on the latter, and so we should not dismiss the possibly that an intelligent form could also be an ectotherm but thermoregulation was certainly obligatory and critical in our own evolution and indeed, the general rise of aves and mammals, so it isn’t a feature particular to just the human form. Hence, why would anticipate this development in an alien intelligent form of life, albeit not to exclusion.
