[extropy-chat] FWD [Skeptic] Re: Looking for examples of naturally evolved X-ray vision?

BillK pharos at gmail.com
Fri Jan 20 20:43:43 UTC 2006

On 1/20/06, kevinfreels.com wrote:
> This is all true. What I found particularly interesting and what you are
> leaving out is that the human eye IS capable of detecting X-rays. That was
> my initial point. Evolution has been generous enough to give us all sorts of
> improbable things. Natural selection and random chance make their
> contributions. It's hard to believe that at some point some animal hasn;t
> come around that is more capable than us at seeing X-rays. I grant that
> there isn't much to build on there. And I am not arguing the point. But it
> is these kinds of assumptions that have left scientists baffled time and
> again with each new discovery.

I think your phrase 'the human eye IS capable of detecting X-rays' is
misleading. The rods and cones in the human eye have evolved to
respond to a very narrow band of the radiation spectrum that we call
visible light.

That does not mean that all radiation outside that narrow band has no
effect on the human eye.

The eye contains physical mechanisms that can be affected or damaged
by extreme radiation. Astronauts have reported seeing flashes or
streaks that were put down to cosmic ray nuclei passing through their
eyes. But nobody claims that they were 'seeing' cosmic rays. Similarly
x-rays probably cause induction of phosphorescence in the eyeball,
which the brain interprets as a 'glow'. If you shut your eyes tightly
you induce flashes of light and colors.  Light sensations have also
been reported from cancer patients receiving eye irradiations.

'phosphenes' is the technical term for these eye side-effects. Try
googling on that term plus a few others like radiation,
phosphorescence, etc.
I found
Particle Induced Visual Sensations in Heavy-Ion Tumor Therapy


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