[mytailorisrich]

> the product of parallel evolution.

Famously, their eyes are almost identical to ours, and are purely the product of parallel evolution.

One difference, though is that at some point during our evolution there was a glitch, or at least it took a less-than-optimal turn, that resulted in our retina being 'inverted', i.e. light must traverse the nerves and some tissue before reaching the light receptors, while theirs is as one would expect, i.e. with the light receptors at the front. [1] This also means that our retina has a blind spot, while theirs does not.

[1] https://thehumanevolutionblog.com/2015/01/12/the-poor-design...

[ncmncm]

The last common ancestor had eyes. The same genes control development and placement of eyes. I.e., you can stick a human put-an-eye-here gene into a fruit fly, and an eye grows there.

Fun fact: death after mating is controlled by a single gene. If there were any net benefit to not dying after, one or other species would have it turned off.

[mytailorisrich]

I'm not sure it's clear how 'advanced' the last common ancestor was. From the hypothesised date, if it had 'eyes' they probably were simple light sensors:

" But our last common ancestor with the octopus was probably some kind of wormlike creature with eye spots that lived as many as 750 million years ago; " [1]

[1] https://www.wired.com/2013/10/how-the-freaky-octopus-can-hel...

[Aeronwen]

It's because your whole body develops "inverted" compared to theirs. Evolution got your eyes to point the right way and do something useful even though there's a blind spot, instead of growing optimally but facing inward and being useless.