[ExI] Infrared vision via vitamins (well, not really)

[Bryan Bishop]

Infrared vision with vitamins
http://www.edkeyes.org/blog/050825.html

"""
Although I've mostly been interested in sensory augmentation by means
of technology, there was an interesting third-hand report of
augmentation through diet and biochemistry. The military during WWII
(there are mentions of both US and British forces) evidently
experimented with putting people on diets that replaced the normal
form of vitamin A with a slightly different chemical, in the hopes
that the red-sensitive photopigment in the retina constructed from it
would be changed to a chemically similar form, present in other
animals, with spectral sensitivity extending into the near infrared.
The idea, of course, was to be able to see signal lights and so forth
that were invisible to enemy soldiers.

I did some quick checking on this, and though I couldn't find any
references to military research, there were some examples in the
regular civilian literature. Yoshikami, Pearlman, and Crescitelli
(Vision Research 9:633-646 1969) did a similar experiment on rats,
putting them on a diet which was deficient in vitamin A and
supplementing it with additions of either vitamin A1 (the normal form)
or A2 (the altered one). No behavioral studies were done, but they did
extract the retinas and perform some spectral analysis, with the
result that there was indeed some alteration of the photopigments,
specifically the addition of a second form with sensitivity shifted
redward by about 20nm.

That study cited Millard and McCann (Journal of Applied Physiology
1:807-810 1949) which was an experiment on humans, albeit with fairly
loose controls on diet. They found that behaviorally the group taking
A2 supplements had slightly improved red sensitivity, but didn't
provide any detailed spectral response curves.

So it seems to be the case that this effect is real, but small: the
best you can hope for is a shift of about 20nm, which is not really
enough to be of military significance or even detectable without
careful testing. Still, it's an interesting "hack" on human
biochemistry.
"""

What wavelength spectrum would you want to get up to- near infrared?
far? There was an article recently about cryptochrome, a protein in
avian retina for sensing magnetic fields. I can think of a few designs
for experiments for improving infrared vision, maybe through directed
evolution of (tethered?) photopigments.

- Bryan
http://heybryan.org/
1 512 203 0507