So we humans get big into genetic modification and figure out how to make ourselves photosynthesize through our skin, and somehow it generates enough energy to be worth our while. Obviously we'd still need to eat, but adding sunlight to our diet is pretty cool. Let's assume we all get this modification.

Now... What would our clothing look like after this change has occurred, what type of materials (real or fiction) would they be made of? Would be just be nekkid when we could?

I'd like the focus to be on clothing design and materials, but societal concerns about decency should be considered.

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    $\begingroup$ We'd probably evolve away from doing it because it would provide so little energy that it won't be worth it. $\endgroup$ – A. C. A. C. Aug 3 '17 at 19:30
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    $\begingroup$ Given that people already sunbathe, why would this change ? $\endgroup$ – StephenG Aug 3 '17 at 19:38
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    $\begingroup$ To be honest, we would probably be naked all the time, to allow max sunlight hit our skin. $\endgroup$ – The Mattbat999 Aug 3 '17 at 19:41
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    $\begingroup$ Are you asking about the technical aspect of designing clothes to allow a maximum of sun-exposure while still preventing any damage from radiation? Or are you asking about the social ramifications that lead to / prevent from going about naked? $\endgroup$ – dot_Sp0T Aug 3 '17 at 19:42
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    $\begingroup$ If they could photosynthesize, I'd assume they don't tan (the result of skin damage via the sun). Thus, they'd wear as little covering as is modest in their society, so long as the climate was tolerable. If it was colder, they may wear clear clothing made to trap heat while allowing sunlight to get through. They may also have lighting indoors designed to feed the photosynthesis as well. So in terms of clothing, first decide what's modest and immodest, then have people's clothing range from covering appropriately to on the edge of modesty, the general rule aiming for less clothing, I'd think. $\endgroup$ – Iter Aug 5 '17 at 23:22

If genetic modification gets going as radical as adding photosynthesis decency is long gone. You could add fur, or make everything interesting retractable, or have enough diversity that traditionally interesting stuff is the least interesting stuff around.

To make photosynthesis work you need area. It is suggested that at least 100 square meters of crops are needed to feed a person. It is suggested that ten times as much energy is required to make a food source than the eater receives, so let's guess you need at least 10 square meters of photosynthesis to power a human directly. A human typically has less than 2 square meters of skin.

So if all our skin (even the soles of our feet) was used in direct sunlight for making energy it would not work out all the way. So we need leaves to increase our surface area without adding a lot of mass we have to feed, or we need to keep eating, or we need to become a lot more efficient.

If you add leaves, you need clothing that doesn't interfere with them, and probably the leaves need to be retractable (10sqm is a parking space). Possibly clothing helping support the leaves in the extended or retracted position would be nice, or you could hang interesting things off them. The leaves might also cover any parts you don't want to display reducing modesty clothing without giving up modesty.

If we eat we can just eat more when we wear clothing over some fraction of our skin. We can wear whatever we want if we have enough to eat. Leading to normal clothing, just getting skimpier the less you want to eat.

If we are more efficient we probably end up cold blooded, so don't need clothing, but we have to avoid places that are too cold. (They probably don't have good sun anyway) Or we slow down. Either way a similar trade off as eating, the less clothes you wear the less you have to use the other strategy.

If you change photosynthesis to use a non-visible part of sunlight (IR or UV) you could have normal looking clothes made of materials transparent to those frequencies.

And real humans are able to do largely without clothes even in cold places.

  • $\begingroup$ I kinda got off on a couple tangents, but I did sneak a line in attempting to answer the question directly. $\endgroup$ – user25818 Aug 3 '17 at 20:41

Define "decency". I've lived through 2 fashion periods where women's nipples were visible thru their blouses or dresses and even today many women choose tops so that their nipples protrude. Same thing for guys and tight pants, some men chose them so that the outline of their penis is readily visible.

Either you are very young, extremely oblivious, or both as far as current events go. Women not wearing a burqa have been arrested and even stoned top death. Similarly in New York City, the laws covering nudity (last I heard) make no distinction between men and women. Anywhere where it is legal for men to be shirtless, it is legal for women as well.

And anyone with even a poor education knows that some hunter/gather cultures tolerate complete nudity (especially in children). So, it is ridiculous to ask about cultural absolutes as far as nudity.

My guess is that a culture should tolerate only exposure of skin which is sanitary - that is doesn't significantly spread "germs". Both sweat and waste from the anus, urethra, and vagina (as well as (lactating) breast leakage) would be expected from nearly all healthy individuals. Fluids from unhealthy or injured individuals also needs to be considered. Given our (current) anatomy, it seems to me that in an environment where temperatures (winds, humidity, sand, pollution, UV,...) don't require protection, then a loincloth would be a minimum.

However it seems to me that there's almost no advantage to having photosynthetic skin in the groin, armpits, inner thighs or soles. To be effective, the photosynthetic skin will be more vulnerable than skin might be without it. Although I can think of several tropical plants with very tough leaves, in general the surfaces of leaves are not very robust. So, like everything else, any redesign of human skin and metabolism will have both advantages and disadvantages.

One (obvious) function of modern clothing is moisture control. Seems to me that we might be able to have moisture permeable, colored clothing which only slightly filters light in the blue to orange part of the spectrum (violet and red colors would take out the least energy). Thickness would matter: thicker, greener clothing would be a status symbol, as would multiple layers.

Hair would be counterproductive, but sunglasses (or modified eyes) would be useful. I should mention that obviously someone living at the North Pole would have different optimal trade-offs than someone living at the Equator, similarly someone living in a city or rainforest compare to living in the desert.

  • $\begingroup$ "2 fashion periods where women's nipples were visible" - when was this, where was I??? Or where was this going on? $\endgroup$ – Xen2050 Aug 4 '17 at 3:32
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    $\begingroup$ Also, decency came later. Clothing most likely started in order to protect the soft squishy bits from tall, sharp, savanna grasses. $\endgroup$ – Draco18s Aug 4 '17 at 5:35

I'm going to look at this a bit differently. Since a human being or even a large animal like a cow does not have the surface area to effectively photosynthesize, the genetic modifications would essentially increase the surface area by at least an order of magnitude (while even this might not be enough, since traditional agriculture often requires at least 1/4 acre of land area to feed one person, we can always handwave that additional genetic tweaking has increased the efficiency of photosynthesis from its current 1% to between 5-10% of the catered energy).

In order to have enough surface area, the "photoanimal" might be covered in leaves resembling pine needles.

enter image description here

The new you

This covering would be similar to a coating of long, coarse fur, which would effectively cover the various openings and sensitive areas of the body.

Going further. a "photoanimal" would be somewhat symbiotic. The "waste products" of the plant part could be directly absorbed into the bloodstream of the animal part, and the waste of the animal part would be absorbed by the "roots" of the plant part. A photoanimal would have radically different designs for things like guts, lungs, kidneys and so on. This means that you might not even find an analogue for an anus or a mouth on a photoanimal, or it would be in a very different place and serve a different function (scooping up dirt to add micronutrients for the plant, for example).

The most radical design might be making a human symbiotic to a "hyperplant" with large leaves as a means of existing in free space. The hyperplant could not only gather sunlight and convert human wastes back into oxygen and carbohydrates, but even act as a solar sail for propulsion. The human part of the hyperplant would steer between NEO's to gather water and micronutrients which have leaked out of the closed loop ecosystem established by the human/hyperplant symbiont.

enter image description here

Human/hyperplant in orbit

In either case, the amount of light gathering surface (the leaves) of the photoanimal or human plant symbiont would effectively be the clothing, or at least covering, of the creature.


I do not believe we would see any substantial change in clothing due to this.

Most clothing is worn for warmth and photosynthesis will not yield nearly the energy that would be needed to compensate for the lack of insulation. Even when it's not needed for warmth it's often needed for other protective purposes. The amount of time someone actually could dispense with the clothing is low.

As for the other part of the question--"decency", there is no absolute standard of decency. Most societies say that the reproductive and eliminatory organs and the female nipple be covered. Some go far beyond this, some grant exemptions for nursing mothers, some western societies have decreed that requiring the female nipple to be covered is sexist and that the same standard must apply to men and women. Some tropical societies also do not require the covering of the female breast. One society has no problem with the penis so long as it is tied up with a string, but a loose penis is indecent.

I have traveled in many third world locations, I have seen plenty of bare breasts that were obviously socially acceptable, I have seen plenty of naked preschoolers, I have seen full adult female nudity whose acceptability was uncertain. (There were nearby guards {soldiers, not rent-a-cops} that would in all probability have at least thrown her out had they known of her presence, thus it was impossible to know what her apparent fear was of. Our best guess was that she had nothing and had slipped in to get some warmth from our fire--she did not strike us as a crazy and that level of poverty wouldn't be out of the question given the situation. She did not respond to any language our group could muster so we don't know the details.)

Thus what is "decent"?? Expect most societies to adapt to what is practical.

If somehow the photosynthesis created enough energy to matter I would expect that the law would change to basically reflect nudist standards--your genital/eliminatory organs are not to touch common surfaces. This very well might be implemented as requiring a garment equivalent to underwear, although I could also see the nudist towel standard being adopted.


If we could engineer photosynthesis capable skin and still want to preserve decency and yet need to live lives not entirely spent sunbathing, then we'd need batteries. Maybe convert under garments and clothes into rechargeable batteries which when worn negate the need to sun bathe all day.

Alternatively if we must photosynthesise as we go about our day then clothes would have to be a combination of tiny mirrors and anti glare screen attachments which reduce the viewing angle of a pc (anti eavesdropping) fashion then becomes not a way to attract attention but rather a means to facilitate life.

This wouldn't fly for too long as the more artistic among us would need to self express and we'd crave a way to differentiate ourselves to potential mates. Entire masses would thus try the 'beggar my neighbour' policy but on an individual level.


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