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Comment by yourenotsmart | Hacker News Reader

DNA is extremely flexible, there's no macroscopic form or shape it can't take, as various insects camouflaging themselves as sticks and leaves and what not shows.

So the idea we'll see some vastly different concepts with different starting blocks is possibly unfounded.

Alien life might be very different at low level depending on their environment, but in terms of macroshapes, things like the formation of a head with eyes and mouth, upper and lower limbs, bilateral symmetry and so on will repeat over and over.

We'll see (in another life probably).

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Yeah, but so what? The geometric shape isn't very interesting. The insect camouflaging itself as a leaf still functions as an insect. It doesn't perform photosynthesis.

Considering that we have a whole class of lifeforms that have nothing like a head with eyes and mouth or limbs, the idea that this would evolve independently more likely than something completely different, is also possibly unfounded.

Having two eyes, as a simple example, is arguably the cheapest way to perceive 3d at things-may-want-to-eat-me distance: just two points that enable triangulation. Similar constraints reduce the configuration space a lot. It still remains huge, but I don’t think someone that believes about certain convergence to be necessarily naive.

Having three eyes, as a simple example, is arguably the cheapest way to percieve 360-degree view of things-may-want-to-eat-me.

Plenty of animals that have 2 eyes and no 3d vision, they try to get as close to 360 coverage as possible.

> DNA is extremely flexible, there's no macroscopic form or shape it can't take, as various insects camouflaging themselves as sticks and leaves and what not shows.

That feels like a really bold claim given the evidence.

Let me know when you spot an animal that drives around on wheels.

Physically you could have wheeled animals, but wheels just won't evolve. They are perfect for somewhat smooth surfaces where you want to travel in a somewhat straight line. Organisms just cannot confine themselves to that and survive.

Unless we find a planet composed entirely of solid smooth rock we won't find wheeled animals.

How would wheels get fed with nutrition? Would they have tiny mouths?

Gears have evolved, though, which is equally cool IMO.

Half-gears.

rotifers

Rotifers do not, in fact, have wheels.

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