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djevans

Following up on my evolution comment in class. The frequencies that are absorbed the least in liquid water are the visible light band. https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#/media/File:Absorption_spectrum_of_liquid_water.png

Keenan is also right by saying the sun outputs the most light in the visible light band.

So the reason humans see visible light could be a combination of the two facts.

Also, in my searching, I learned many birds see UV light because berries often reflect UV light. http://www.pnas.org/content/100/14/8308.full

keenan

@ans Nice! Also some discussion of this coincidence here

Meanwhile, I’m going to grab a UV lamp to help me hunt for berries. Mmmm...

kc1

Humans were unable to "see" ie. distinguish the color blue until fairly recently, historically speaking. I always thought this was cool to think that our distant ancestors looked up at the sky and saw something probably completely different from how we see things.

https://www.iflscience.com/brain/when-did-humans-start-see-color-blue/

Human vision is constantly evolving. Perhaps in the future after using LED screens for so long, our cones will evolve to precisely make a basis formed by the frequencies of RGB of our LED screens.

keenan

@kc1 Scary thought - makes me want to get outside and enjoy the sunshine! :-)

merc

Continuing from @kc1 -- even now we don't all have the same color perception, and the systems we've talked about in class are fairly Westernized. I just saw this cool documentary about the Himba tribe in Namibia, who have like a totally different sense of color perception.

https://6thfloor.blogs.nytimes.com/2012/09/04/its-not-easy-seeing-green/

Basically, they can't differentiate between blue and green really, but shades of green that we would see as really difficult to differentiate they can tell apart in a split second!