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We all know the usual staples of genetically-engineered super-soldiers. Rattlesnake DNA to see in the dark etc etc. But what about a modification that's a little more exotic, and far more advantageous than night vision or increased stamina? What about optical camouflage?

Everybody knows the chameleon and to a lesser extent the cuttlefish. Could you splice genes from species with these color-changing traits using CRISPR and give humans the same ability to alter the pigmentation of their skin through conscious effort?

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    $\begingroup$ "far more advantageous than night vision"? Why? Humans fight clothed, with little, if any, skin exposed. $\endgroup$ – Mołot Nov 2 '16 at 12:30
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    $\begingroup$ There are night vision goggles and camouflage clothing. But soldiers still need to rest and sleep. Increased stamina is the 'far more advantageous' of the things you listed. $\endgroup$ – kingledion Nov 2 '16 at 12:54
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    $\begingroup$ Humans are squishy, forcing your super soldiers to fight naked to make use of the camouflage sounds like a step in the wrong direction... $\endgroup$ – Helmar Nov 2 '16 at 13:24
  • $\begingroup$ When you say "we all know the usual staples of genetically-engineered super-soldiers," are we talking reality or science fiction. This doesn't look like a reality question, but if it's a science fiction question where you're already assuming genetic engineering works like that, is there a reason you need to even ask if human cromoatophores are possible? $\endgroup$ – Cort Ammon Nov 2 '16 at 21:25
  • $\begingroup$ Invisible naked people are attacking! Fire! Fire! $\endgroup$ – ShadoCat Feb 15 '18 at 22:59
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Unlikely. Gene splicing works best when replicating single proteins, not complex structures, and chromatophores are highly complex structures.

Chameleon chromatophores are melanin-filled cells that are spread out over other, colored cells. In response to nerve triggers, the melanin-filled cells can concentrate or disperse their internal melanin packets, covering or revealing the colored cells underneath.

Cuttlefish chromatophores are even more complex, consisting of pigment-filled sacs, each one of them surrounded by hundreds of tiny radial muscles that can expand, contract, and change the shape of the sac to change its color.

Giving a human chromatophores is kind of like giving them wings: you're adding a whole new type of organ. You can't do that by simply sticking the right piece of cuttlefish DNA into them.

If you want color-changing soldiers, go with nanotech instead. Scientists are already working on "invisibility cloaks" that use the same principles. If your story is set in the near-future, you can probably make color-changing nanomachine tattoos that work the same way.

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    $\begingroup$ This has the advantage of allowing for armor, or at least not fighting naked. It could still operate with a mind/machine interface to allow for fast on-the-fly changes. $\endgroup$ – AndyD273 Nov 2 '16 at 14:09
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Yes, you can splice in chromatophores

but how useful would that be? Humans haven't been naked for tens of thousands of years.

In the strictest interpretation of the question, yes, it would be possible with CRISPR-CAS9 to inject the genes for building chromatophores into human DNA. In addition to the coding for chromatophores, a genetisist will need to include all the required development genetic instructions (so the chromatophores form at the skin, not internally where they aren't useful) and any changes to human neurology to accomodate the information processing required to make chromatophores work as camouflage. Remember that cephalopods have huge brain-to-body ratios to handle the additional processing load of making their skin match their surroundings (in additional to the computational load of figuring out what to do with eight arms).

Brains! Brains! Brains!

If no changes to human brain structure are possible, then there will need to be a reduction in some other capability to make way for controlling the chromatophores. Should this compromise be unacceptable, then changes to brain size/structure will be require which brings up questions about fetal cranium size and the corresponding size of the human birth canal (Women's hips are only so wide and can only pass fetal skulls below a certain girth).

[A more recent thought on brains] We see in octopii that much of their "brains" are in the limbs themselves. Even in humans, certain types of signals just go to the spinal cord then back to the limb. Given these examples, we may be able to keep the current brain architecture but distribute the processing required to make chromatophores work out to the skin.

There's a couple of interesting implications here. Because of the distance between the brain and the skin, the color of the skin may be part of the autonomic nervous systems which the conscious mind has little to no control over. My bet is that there's a ton of social signaling that can be derived from this kind of a system.

In short, adding the genes for chromatophores is a fairly straight forward task with CRISPR. Massaging the rest of human anatomy & physiology, infant development, and neurology into a viable life form is much more challenging.

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  • $\begingroup$ can only pass fetal skulls below a certain girth - Then simply increase the height, not the girth: static.tvtropes.org/pmwiki/pub/images/TheLeader_1498.jpg. Women's hips are only so wide Then genetically engineer humans so that women have larger hips - no image provided for that! $\endgroup$ – johannes Nov 2 '16 at 21:04
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This would be a monumental effort. Not only would you have to produce the chromatophores themselves, you'd need to to add a parallel nervous system to control them, plus a rewiring of the brain. This would involve wholesale modifications to the visual system to make the connection between what is seen as the environment and the control of the chromatophores. The added neural function would have to replace parts of the current brain architecture (unless you're willing to specify an increased brain size), so it's not clear that the resulting soldiers would remain psychologically human.

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What if instead of using a nerve signal you had them respond to certain hormones. Do you think they could act like easily changeable permanent tattoos?

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    $\begingroup$ Hi, welcome to Worldbuilding! Would you be able to expand more on this idea, explaining which hormones and how it would work? Thanks. If you have your own question, you're very welcome to ask your own, linking this one if it helps $\endgroup$ – Mithrandir24601 Aug 16 '17 at 21:55

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