Aside from humanoid, what other body builds would be viable for an (intelligence wise) human-like sentient species? [closed]

Question

Sentient alien species in fiction are almost always at least vaguely humanoid. Is being humanoid required to have human-like intelligence and sentience? If not, what other body builds would be viable for a (intelligence wise) human-like sentient species?

Assume earth-like conditions. For simplicity’s sake, this species should only need to be capable of doing what humans are capable of, such as tool building, construction, researching, social behaviors and utilizing or building vessels if needed. This species should also be placed similarly to humans in the food chain.

Answer 1

It can be assumed that two basic conditions must be fulfilled:

Manipulators

The being must be able to change its environment (for example, a whale could be more intelligent than a human being - it would still not be able to build a technological civilisation). For this it needs extremities with which it is possible to produce and use a tool. Here it is conceivable that this does not have to have any resemblance to human hands at all. Claws, trunks, tentacles, etc. are also plausible. Similarly, the number of these manipulators does not matter as long as they are applicable for the purpose of tool use. Anything from one to any number is possible. On earth, almost all living beings are symmetrically shaped. Whether this has to be the case universally is questionable, however.

Ratio energy intake/energy consumption

The effort to acquire energy (food) must be in a certain ratio to the consumption of this energy. A being that has to spend most of the day taking in food will find it difficult to find the time to invent the use of tools. Under Earth-like conditions, this would be difficult above a certain weight. At least in the case of mammals, a certain size should probably not be undercut, since a very fast metabolism also consumes too much energy. Apart from Earth-like conditions, almost any form is possible here - it depends on the ecological conditions and these in turn on the planetary conditions.

Apart from these two basic prerequisites, everything is actually somehow plausible.

For a technological civilisation, communication and information transfer over longer periods of time is necessary. Humans have developed language (acoustic signals) and later writing (optical signals) for this purpose. However, other forms are also conceivable for this. For example, optical signals instead of spoken language, manipulation of the magnetic environment, use of a tactile sense and much more.

Whether individual self-awareness is necessary to build a technological civilisation is an open question. It seems at least plausible that collectives of living beings (on Earth e.g. bees and ants) could be able to manipulate their environment to such an extent that a technical civilisation emerges in the end.

A good reading tip on this subject would be Adrian Tchaikovsky's Children of Time, where he describes in great detail and plausibly how spiders build a technical and eventually spacefaring civilisation.

Answer 2

Pretty much all of them

All that a technological species needs is some sort of manipulator, enough sociality to transmit knowledge, and the basic intellect needed to make tools

Every one of these traits can easily arise within almost any bodyplan at all. So long as the animal is macroscopic and not specialised to a low-energy mode of life, then there is absolutely no reason that prohibits it from having manipulators and sociality

Answer 3

The octopus building plan might be fun.

The cognitive capacities and behavioural repertoire of octopuses have led to speculation that these animals may possess consciousness. However, the nervous system of octopuses is radically different from those typically associated with conscious experience: rather than being centralised and profoundly integrated, the octopus nervous system is distributed into components with considerable functional autonomy from each other. Of particular note is the arm nervous system: when severed, octopus arms still exhibit behaviours that are nearly identical to those exhibited when the animal is intact. Given these factors, there is reason to speculate that if octopuses do possess consciousness, it may be of a form highly dissimilar to familiar models. In particular, it may be that the octopus arm is capable of supporting an idiosyncratic field of consciousness. As such, in addition to the likelihood that there is something it is like to be an octopus, there may also be something it is like to be an octopus arm. This manuscript explores this possibility.

Answer 4

All you need is a closed circulatory system(better for transporting oxygen or similar element), a big cranium(big brain means better thinking), manipulatory appendages, and the ability to walk and eat.

A radial body plan isn't the greatest because it may be more energy intensive. There may be a reason why the dominant creatures are bilateral. On a radial creature they would have far better vision because they would have eyes looking in every direction.

The reason humans walk on two legs is because it is less energy intensive. You can absolutely have a four legged creature as long as it has two arms with manipulating hands.

Icthys King and EdvinW both questioned why a large cranium is needed. Unless you are going for a slug or sea star shape, a big noggin is needed. This is because of the massive size a brain would have to be to promote human-like intelligence. In a slug creature the brain would be at the top of the body, alongside the ears, eyes, mouth, and nose. For a sea star creature the brain would be in the center, like that of a sea star.

Icthys King questioned why I originally said opposable thumbs were needed. I said this because the only creature that has ever taken over a planet has them. But other forms of manipulators aren't out of the question. EdvinW asks about tentacles, which would work fine. Octupi use them all the time. An assortment of arms wouldn't be the best idea. This is because many appendages are energy intensive and most creatures evolve to use all the energy they have to the best of its potential.

Answer 5

Slug/Worm

If you're specifically looking at a sapient alien species, then the only realistic choice would be a slug-like or worm-like form, perhaps with leg-tentacles or even some sort of shell

This isn't just for sapients, but all alien animals: All of the special traits like bones and veins and ears are relatively rare among the different phyla of life on Earth, which seems to imply that they'd also be rare amongst the phyla of distant worlds. If we also consider the possibility of more complex phyla being extincted, most worlds would be limited only to simple worm-like forms for all life, including its sophonts