What is the likelihood of actual rubber forehead aliens?

[clearspira]

I thought this would be an interesting thread (hopefully) as it is one that appeals to people like us both as sci-fi fans and as fans of actual astronomy: what is the likelihood in real life of rubber forehead aliens? That is, aliens who basically look like us but with some small differences - which of course are the mainstay of pretty much every science fiction show that we enjoy.

Some things to consider: Life can indeed take any form, however, I would argue that INTELLIGENT life capable of matching our own must have certain similarities to us.

1) A large brain. This is the obvious one. A being with a brain the size of a walnut isn't matching us.
2) Opposable hands for tool use. A creature with paws, hooves, tentacles, trotters or anything similar is not building anything.
3) The ability for advanced speech, meaning a mouth. No language, no advanced transmission of ideas.
4) It must be able to access the land. A sea creature cannot harness fire which means no advanced metals.
5) Water/food/oxygen. The essentials for life as we know it and would require organs similar to ours.
6) Legs. A species that cannot move cannot do much at all.
7) Eyes. You cannot build if you cannot see.
8) Reproduction. It needs to be simple. And our system of reproduction is about as simple as it gets.
9) Omnivorous and adaptable. The ability to adapt to any environment is precisely the reason we managed to spread out across the Earth. Being limited to one ecosystem is potentially disastrous.

IMO, the human form is the most likely form to create a creature that can match us and thus will be repeated elsewhere. What do you guys think?

[Robovski]

Let us say hypothetically we are the result of alien contamination of the Earth before life truly got started, or perhaps the contamination is the multi-celled life that pushed aside the single-celled life then dominant. In that case I can have a reasonable expectation of some similarity to life as we know it. That said, the Cambrian explosion shows how crazy life can be for just carbon-based multi-cellular life.

The Great Filters should mean that there will be aspects of intelligent life that we expect regardless of how intelligent life arises, like tool use, some means of sensing the world around us, some means of movement... But is bipedal bilateral symmetry the only expected answer? I don't think so.

[King Green]

Your talking about trying to find sugar in a cocaine pile, the probability is only possible if Roddenbury became a god and transferred all of us who watched the series into that universe. While there is an alternate world like that it would be more chaotic and disturbing that what chuck would parody it. Goddamit, I probably created Janeway into physical Satan!

[Darth Wedgius]

Humans are pretty basic for the above requirements, which might make us more likely than more complicated arrangements. I think we aren't the only form by any means.

Look at Larry Niven's Pierson's Puppeteers. No hands like we have, but they have two heads on long, flexible necks, and their lips have flexible, finger-like projections. Their brain is in a hump between the necks. They have two forelegs and one hind leg.

They kind of have hands in that their mouths work as hands (they work as mouths, too), but nobody would confuse them with a human with a rubber forehead.

There are disadvantages with their arrangement, but there are problems with ours, too.

[BridgeConsoleMasher]

Also gaseous gastrointestinal byproduct. Pretty much every animal on the planet farts, I doubt aliens would be able to get away without it.

[TGLS]

1) A large brain. This is the obvious one. A being with a brain the size of a walnut isn't matching us.
2) Opposable hands for tool use. A creature with paws, hooves, tentacles, trotters or anything similar is not building anything.
3) The ability for advanced speech, meaning a mouth. No language, no advanced transmission of ideas.
4) It must be able to access the land. A sea creature cannot harness fire which means no advanced metals.
5) Water/food/oxygen. The essentials for life as we know it and would require organs similar to ours.
6) Legs. A species that cannot move cannot do much at all.
7) Eyes. You cannot build if you cannot see.
8) Reproduction. It needs to be simple. And our system of reproduction is about as simple as it gets.
9) Omnivorous and adaptable. The ability to adapt to any environment is precisely the reason we managed to spread out across the Earth. Being limited to one ecosystem is potentially disastrous.

Well, 1's non negotiable, but the rest?

2) Tentacles could plausibly be precise enough, especially if they developed finger like implements.
6) As before, doable. Think snails or snakes (something about sn-).
3&7) Really divergent senses could resolve this (vibration sense maybe? Or cuddlefish style color changing?)
9) This is two stuck together. Adaptivity is a must. Obligate carnivores would be at a disadvantage (meat is very costly), and herbivores might have some trouble gathering energy to power the brains, but there's nothing ruling the other out.
5) Non-carbon life could be possible if I recall.
8) I could imagine complex reproductive systems that could support intelligence just as well (i.e. ant style), but pretty much everything is a two sex system, apart from Earthworms or something.
4) Apart from really divergent technology schemes, probably. On the other hand intelligence without metal is entirely doable.

In all honesty, missing a few could be plausible, but missing all? Probably not. Though finding complex alien life (or even simple, in the case of 5) would probably make some of these questions more answerable.

[Nealithi]

I wanted to talk on this or at least see if others would go over some points rattling around in my head.
So while I don't have New ideas, I have heard a few different inputs. So here are some thoughts.
First is the evolutionary needs section. And a section of Grrl Power covered some of that in a way I thought made some sense. https://grrlpowercomic.com/archives/comic/grrl-power-759-its-evolutionary-my-dear-washington-post/
Meaning the basic form is efficient. I also think being omnivores is a help toward intelligence. Because how much intelligence do you need to sneak up on a clump of grass? Carnivores are pretty good at their job of taking down their prey. Hunt to much they don't learn farming, they starve. Evolution is kind of unforgiving.
Then the discussion turns to tool use. Now here is where the idea of a humanoid might breakdown. See everyone including Chuck mentions manipulators. Going back to that basic tool, the stick/club. But it occurs to me that there is a similarly old tool we still have today. The dog. We domesticated an animal to aid us and help us do work. From pulling the plow and hunting beside us. We have continued to work this animal for combat, alarms, to slipping into vermin burrows to remove said animals that damaged crops and stores. Then we domesticated other animals like cows, sheep, and horses for our needs. But the dog has been around a long time. So why mention him? Reverse the roles. Dogs domesticated a primate, and got it to do the tool use for them. They have the large cranium and the primate the manipulators. This is one of those areas I can see the humanoid intelligence not being the case.

[Darth Wedgius]

I also think being omnivores is a help toward intelligence. Because how much intelligence do you need to sneak up on a clump of grass? Carnivores are pretty good at their job of taking down their prey. Hunt to much they don't learn farming, they starve. Evolution is kind of unforgiving.

I've wondered about that. An herbivore doesn't have to be smart to sneak up on a plant (ignoring that alien "plants" might be able to run away, defend themselves, etc.) but does need to be able to outsmart predators, so I think there still would be some pressure towards smarts. But if you're a predator then you have to be able to sneak up on prey and stronger predators both, which might be more of a push.

Carnivores could raise crops for their livestock, though.

[McAvoy]

Assuming the alien species evolves in a similar way humans did then sure. Probably more like the Xindi Primates.

My running theory is that you could easily have crab people. Four legs with a hard shell with a complicated set of claws/hands with a head that swivels either in front or on top. Possibly can be on land or on sea. If on sea, they could be large and able to take down their own versions of carnivore animals in the sea. While at the same time eating sea plants on the bottom.

[Riedquat]

Some birds have the ability to make and use simple tools using their beaks to manipulate them. It's a rather bigger barrier to getting a technological species than hands but perhaps not an insurmountable one.

The great difficulty in thinking of alternatives is that we've only got life on Earth to compare with, so it's very hard indeed to have much of a clue just what other solutions might arise. Central brain or distribution throughout the body for example? Some ability to manipulate the world is a given, there's possibly quite a variation in shape and form possible.

I very much doubt there'll be anything that looks all that similar to us. You've got a better chance of similarity to birds and perhaps fish, where the environmental constraints are more rigid, at least with an approximately Earth-like planet.