I know evolution is governed by chance and it is random but does it make sense to “ruin” sleep if there’s light? I mean normally, outside, you never have pure darkness, there are the moon and stars even at night. In certain zones of the Earth we also have long periods of no sunshine and long periods of only sunshine.
I don’t know if my question is clear enough but I hope so.
Bonus question: are animals subject to the same contribution of light or lack of it to the quality of sleep?
Sometimes…
Depending on if you’re talking about motion, color, or lowlight.
But since when is “optimized” just “better than a goat”?
Like, cats easily blow everything else out of the water.
Optimised just means designed for something at the expense of other parameters. We lost our tepetum lucidum at some point in evolution, probably for the 3x-ish resolution gain, while becoming much more shit in lowlight in the process. That’s a tradeoff, but a good one for a tree-based diurnal frugivore.
Cats (for example) still have theirs, which means light as two chances to hit their retina, but means there’s an upper limit on how clear an image can be, exactly because there’s light bouncing around. It sounds like 20/100 is typical for them, from a quick search. Cats are traditionally thought to be dichromats, as well.
And humans usually have three, but sometimes it’s two, and even rarely 4…
With that much variations (including other ways) it’s hard to say human eyes are optimized for any condition.
There are very few examples of things in nature that are truly optimized for all of its environment.
Humans are just too widespread with too much variation to say we’re optimized for anything.
We just have too much in species variation.
We actually have less genetic variation than most animals. There was a lot of bottlenecking in the paleolithic. And what little we do have is still mostly confined to Africa, because the rest or the world shared common ancestry as we left our original continent.
Like, 1 in 200 people is colourblind, or something? I don’t think that’s a reasonable argument that we’re not trichromats.
You’re talking genetic variation, I’m talking phenotype variation…
…
Again, you’re talking genetics, where it is clearly broken down in 2,3,4.
However like pretty much everything else, it’s not that clear cut just because the plans were.
Two people with the same amount of different types of cones are not guaranteed to have the same rod/cone ratio. Even when they have similar genetics for the ratio, things rarely go according to plan as a human develops.
Like, you know that’s why facial symmetry is attractive right? It shows that things on both halves went according to plan. Which especially for women is a huge bonus for reproductive health.
Especially for something made up of a whole bunch of small things like rods/cones, it’s not even perfect for identical twins.