[godelski]

What are we referring to as humanoids though? And what are we about as intelligent? Crows? Crows aren't going to build spaceships and don't really have the means to because a beak isn't a great manipulator, even though they use tools. I don't think the person above is saying that quadrupeds would be out of the realm of possibility (maybe they are. IDK I'm a computer scientist, not a biologist. I could totally see body size, caloric intake ratios, and brain mass being related in a way that would make these unlikely), but rather things like fractaling appendages would be expected because intelligent life would need to have fine motor control. (Is a centaur humanoid?) There are just more efficient ways to do things than other ways. Yeah, maybe alien life will have a beak. Maybe their pupils will look different but I'd still expect them to have eyes with squishy lenses because that's pretty much required to be able to focus and intelligent creatures need to be able to sense things both near and far (without technological enhancements). Light sensing isn't enough if you want to build things, you need depth perception. I think if you follow this line of reasoning you'll find that a lot of attributes humans have would be pretty likely for intelligent alien life as well.

[imbnwa]

Can echo location be used for depth perception?

[godelski]

Yes but it is very expensive. Here's some more on bats[0] (mentions expensive echolocation around 5:45 and moving from sonic location to echolocation evolution). Eyes do also convey more information. You can get colors in addition to depth and shape and that's a good reason and easy path for eyes to develop since light sensing is a pretty easy thing to develop. Also, bats aren't blind, despite common belief.

[0] https://www.youtube.com/watch?v=zWeYCULC0UQ

[ncmncm]

It can. One eye and echolocation gives you everything you get with two eyes except redundancy.

Cyclops got by with one eye and throwing rocks.