[ExI] Benchmarking the Singularity
avant at sollegro.com
Sun Jul 21 20:51:02 UTC 2019
Quoting John Clark:
> <johnkclark at gmail.com>To: ExI chat list
> <extropy-chat at lists.extropy.org>Sent: Sunday, July 21, 2019,
> 12:35:31 PM PDTSubject: Re: [ExI] Benchmarking the Singularity
> On Sun, Jul 21, 2019 at 12:56 PM William Flynn Wallace
> <foozler83 at gmail.com> wrote:
>> Well, John, that's a lot of interesting information and no joke.The
>> eye - is it possible that if strong sunlight were to aim directly
>> at retinal cells it would be too strong? If so, then it's not
>> backwards. It's a necessary filter.
> We have an iris for that, if the light gets too bright the iris gets
> smaller so its safe and as a bonus the image gets sharper. Having
> nerves and blood vessels on the wrong side doesn't decrease light
> sensitivity significantly but it does reduce sharpness due to
> diffraction. And that blind spot is just nuts. I think the first eye
> probably couldn't do much more than tell the difference between
> night and day and so it didn't matter which side of the film, aka
> retina, the nerves and blood vessels were on, but when the eye
> started to improve it did make a difference but by then it was too
> late to backtrack. I think it was a coin toss and could have gone
> either way, the ansestors of squids were just lucky while the
> ansestors of the vertebrates were not.
Actually only primates got the short end of the stick out of the deal.
The other vertebrate eyes are not kludges because, they have backward
facing retinas as a trade-off for night-vision. It allows their
tapetum lucidum to reflect photons that don't get absorbed the first
time through the rod cell back through through the retina for second
chance. The the backwards facing retina together with the tapetum
allows most vertebrates to make the most out of very low light levels.
But you are right in that primates would be better off with cephalopod
eyes. We lost the tapetum as a trade off for color vision (I think),
but squid and octopi have better color vision than we do.
But the trade off here is that both squid and primates have crappy
night vision. For example, the nocturnal tarsier needs gigantic eyes
to see its prey and the deep-sea dwelling colossal squid needs both
gigantic eyes AND the bioluminescent equivalent of headlights inside
their eyeball. Their eyes literally glow in the dark like flashlights.
So I don't think vertebrate eyes are kludgy at all. Unless you're a monkey.
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