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We are in a far future setting where humans (or transhumans I should say) achieved two things:

  1. be able to modify themselves genetically to the point where they can have completely different organs to what we have now
  2. be able to customize the earths atmosphere to their needs without causing unwanted side effects (like global warming)

The goal is now that nobody has to eat anymore in the way we do now and the plan is to get the necessary nutrients from breathing the customized atmosphere. This can either work by having nutrients directly in the air or the components are in the air so when the transhumans breathe, their new and specialized organs can produce any necessary nutrient. Removing the necessity to drink is not a priority. If they can get their water supply from their atmosphere it is a nice bonus but if they drink it like we do now it is also okay.

My question is: Can this be possible given the two assumptions above?


There are a few potential problems I can think of with this method of nutrient supply:

  • breathing may not be efficient enough
  • the constant access to food may be a problem
  • the needs for nutrients vary too much to have one atmosphere composition that works for anyone anywhere anytime
  • the air would be so heavy that it would get too dense in low altitudes or that only people living in low altitudes would have access to food
  • other organsims may reproduce incredibly fast in this nutrient rich atmosphere
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  • $\begingroup$ Breath vaporized food through a nebulizer can be acceptable? $\endgroup$ – Stefano Balzarotti Feb 21 at 11:03
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    $\begingroup$ If they still drink, why not just have liquid food? This is totally achievable today. $\endgroup$ – Matthew Feb 21 at 17:14
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    $\begingroup$ There are people who claim to be able to live without food or drink already. Don't try this at home... $\endgroup$ – Darrel Hoffman Feb 21 at 18:14
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    $\begingroup$ From a storytelling perspective, you'd have a better time justifying the existence of a naturally-occurring planet with a nutrient-rich atmosphere, than justifying the artificial creation of such an atmosphere. $\endgroup$ – cowlinator Feb 21 at 18:34
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    $\begingroup$ @cowlinator It'd be easy to justify in a space station, because you're having to maintain the atmosphere anyway. $\endgroup$ – nick012000 Feb 23 at 10:27
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The current atmosphere is just fine

As you're aware, plants are mostly carbon, and they get it entirely from carbon dioxide in the atmosphere. They get extra nutrients from the soil, but in much lower quantity. Since you allow drinking, you should be able to enrich the water with all the minerals needed. Clearly trees exist, so the mechanism for converting carbon dioxide and minerals to organic matter is out there. The only problem is it requires huge amounts of energy, so trees need a huge surface area for photosynthesis.

If you can replace photosynthesis with wireless power, you're all good.

You'd need a huge network of power plants, which we already have. Additionally you want power transmitting antennas all around the world. We sort-of have this capability with mobile networks, but it's incomplete and they don't send enough power. But this should be a doable engineering feat if we chose to do it. Finally you need a custom organ that includes a giant coil to efficiently capture power. Once you have the energy you need an equivalent to photosynthesis to go from electric energy to organic compounds. And that's about it.

Final note is that our current breathing rate should also be sufficient. When you lose weight you are literally burning fat, with the exhaust CO2 going through your blood and out of your lungs. All the weight you lose goes through your lungs or the water you pee. Thus the throughput of CO2 going through your blood and out the lungs should also work in reverse and let you grow at about the same rate as losing weight.

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    $\begingroup$ "Since you allow drinking, you should be able to enrich the water with all the minerals needed." That's basically what I said. And we can do that now, without needing to alter humans. (The resulting "enriched water" won't look a lot like water, however.) Incidentally, there is also a naturally occurring enriched water that some animals already survive on, albeit not for their whole lives. We call it "milk". $\endgroup$ – Matthew Feb 21 at 18:59
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    $\begingroup$ Marv wants a world where "no one has to actively eat food". I think milk or soylent still requires an active process of drinking it, it's a decent effort to drink enough soylent so you feel full. Besides with plenty of power you should have another organ that extracts enough water from the air for day to day functioning. You'd only need extra when exercising or once a month to replenish minerals. $\endgroup$ – csiz Feb 21 at 19:05
  • $\begingroup$ Electric Smoothies! $\endgroup$ – Joe Bloggs Feb 21 at 20:01
  • $\begingroup$ You wouldn't need to drink something like milk, which contains macronutrients (sugars, fats, proteins). In principle, we could genetically engineer people to reduce carbon from CO2 and fix nitrogen from N2 using enzymes known from other organisms. In practice, this would be really hard, of course, but then people would need no macronutrients at all and could survive with just minerals. I think sodium, potassium, and chloride would run out the fastest, followed by sulfur, phosphorus, calcium, and magnesium. Everything else is needed only in very small amounts. $\endgroup$ – WaterMolecule Feb 21 at 22:17
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While possible, I don't think that a society of transhumanists would do what you're proposing as it would be a massive waste of resources. Saturating the entire atmosphere with enough "nutrients" to make it practical for transhumans to use would be a colossal effort and probably completely destroy all native ecosystems. Most air never gets inhaled by humans anyways since the vast majority of "air cycling" on Earth is done by plants.

If you want to eliminate the need for transhumans to eat regularly, then maybe only make them take supplements while they're growing of if they need to repair themselves. For energy needs, batteries along with wireless charging could be the solution or people could grow nuclear reactors inside themselves and swallow a vial of tritium every couple decades or so.

Additionally, I think that any society of transhumanists would be rather diverse with different people choosing different upgrades or enhancements. It's possible that people would need highly customized or specialized diets for their specific body parts and adapting a one-size-fits-all solution might not be the right call.

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    $\begingroup$ As it would take a long time to refactor the earths atmosphere there may be enough time for ecosystems to adapt to that, maybe they would even benefit from nutrients in the air. Or maybe the transhumans use plants and animals to do the atmosphere customization. The specialization of transhuman individuals is a good point which might be a problem here. Or maybe they would then have organs/lungs that filter out the nutrients they need? Or the air just contains the components of nutrients and each individual has the organs to build their own nutrients. $\endgroup$ – Marv Feb 21 at 9:57
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This will be a massive undertaking, and is probably not economically viable enough. As other answers pointed out, saturation the entire atmosphere with nutrients is near impossible, and a gigantic inefficient waste. But even if it can be done, this will not negate the need for food production, as the nutrients will still need to come from somewhere.

This will also need to be taken over by a sitting government entirely, the production as well as the distribution, as this is not really an opt-in kind of situation. Either everyone will need to do it, or nobody can. So not only will you need a gargantuan amount of resources, you will also need to unify the earth under a communist regime. As plenty of examples have shown us, communism doesn't always work the best, because of human nature. If you genetically modify humans, their mentality is where you would need to start.

On top of all this, there is the cost of genetically modifying humans. This can't be done to just a few humans, as they will need to effectively repopulate the earth. That is if their gene modding doesn't have any averse effect on human physique to begin with, especially their reproductive ability. And if the modified gene is carried on through reproduction to begin with. Forced evolution like that will not be easy.

You could offset it by only allowing this in enclosed spaces, perhaps as large as (domed) cities. But this will still be a huge undertaking nonetheless. And anyone not living in the city (or travelling) will not have access to food, as all of it is used to supply the cities. All in all the convenience of food consumption is unlikely to ever be so big an issue that it will need a solution like this.

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    $\begingroup$ I like that you point out the economical and political problems with my idea. Maybe the problems can be softened by making a slow transition. Modify ecosystems and humans slowly so they can adapt to the new atmosphere (maybe a bit faster by genetic modifications). But you are right with the fundamental problem: all humans (at least all authorities) would have to consent to do this. Doing this in a space station or some kind of colony ship seems more realistic. $\endgroup$ – Marv Feb 21 at 13:00
  • $\begingroup$ @Plutian you might have the wrong idea about what communism is $\endgroup$ – Blueriver Feb 21 at 17:38
  • $\begingroup$ @Blueriver I don't think I do. The core concept is all resources are owned by the community and everyone contributes to it. This is exactly what I mean. $\endgroup$ – Plutian Feb 21 at 17:44
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    $\begingroup$ @Plutian but why are you suggesting that ALL resources need to be owned by the community? Pumping food to the atmosphere would most likely only work if it's done by the government, but why does the government need to also own all the means to produce said food? Or the stores where people buy clothing? Or the keyboard that I'm using to type this comment? $\endgroup$ – Blueriver Feb 21 at 17:49
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https://en.wikipedia.org/wiki/Radiosynthesis_(metabolism) - "eat" PU238 once every 20 years or so, the stomach equivalent produces melanin which, in its activated metastable form, is circulated by the blood stream to carry the necessary energy into the cells. Biochemistry is no longer needed as a source of energy, all the other supporting processes are tuned to maintain the brain and reproductive organs. Like photosynthesis, except at higher energy levels and not limited by the surface of skin that can see the sunlight.

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They’d be filter feeders that eat highly dense pollen.

The transhumans you describe sound very much like the Astomi from Orion’s Arm.

They’re filter feeders who live in specialised space habitats that include plants that produce large amounts of pollen that they feed upon. They do this by using a layer of fine hairs that cover their bodies that collect an amount of pollen before retracting under the skin so that the pollen can be digested before extruding again. Since the human body doesn’t have enough surface area to make this a viable feeding strategy on its own, they supplement this with a symbiotic “flower” implant on their backs that greatly increases the surface area available for them to feed with.

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Have you thought about making these humanoids undergo photosynthesis? That way, they can get many of their nutrients without even the need for air, just sunlight. I'm no biologist, but it seems like your people would then only require water and the air we know.

Furthermore, it seems like your second point counters any issues that might arise.

EDIT: As you pointed out to me, photosynthesis does not provide enough energy to sustain a human, so that possibility flies out the window.

To answer your question, though: It seems like your two stated facts, that these transhumans can pretty much adapt themselves to any environment and that you handwave the risks of pumping the air full of nutrients, this idea should work. This constant access to food might be unhealthy to individuals who require less energy, like children, so keep that in mind.

So: It works, you just gotta make it believable.

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    $\begingroup$ In this question: worldbuilding.stackexchange.com/questions/107159/… the answerer says that photosynthesis is too weak to provide humans with enough energy. Maybe some of the new organs would need less power but I think that would not be enough. Anyway if the transhumans came to the conclusion that photosynthesis would help they can use it. $\endgroup$ – Marv Feb 21 at 7:40
  • $\begingroup$ Also not a biologist but photosynthesis is not powerful enough to generate enough energy for a human (at least with only the surface area of a regular human). $\endgroup$ – Stefan Feb 21 at 7:41
  • $\begingroup$ With enough handwaving anything is possible but I want to know if this is realistically possible. Maybe breathing is not efficient enough or maybe the constant access to food you pointed out might be a problem or the needs for nutrients vary too much to have one atmosphere composition that works for anyone anywhere anytime. Or maybe the nutrients would just be too heavy and only people living in low altitudes would get them. Or maybe there are problems I don't even see ... this is what I want to know :) $\endgroup$ – Marv Feb 21 at 9:09
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This is not realistically possible, unless your transhumanism includes serious cybernetics, in which case "breathing" would stop being a thing anyway. The vast majority of the food you digest serves as fuel. Your body reacts this fuel with an oxidizer taken from the air to provide the energy you need to survive and maintain the high activity of an animal.

If your "solution" is to mix this fuel into the air at densities sufficient to support human activity, then you have a reactive fuel-air mix that would ignite and potentially kill everything in the world at the first lightning-strike, or if someone lit a match in the open.

If your "solution" is to remove the oxidizer from the air, then you've simply switched from eating fuel to eating oxidizer, which requires even more biological changes, as our carbon-based systems are not designed to chow down on solid / liquid oxidizers.

If your solution is to forgo the fuel entirely and switch to photosynthesis, you don't get enough energy. There's a reason plants are virtually inactive. You need roughly 8MJ (2000 food Calories, which is actually 2,000,000 calories) per 24-hour period to survive. Sunlight averages roughly 160 Watts per square meter over the course of a day, which translates to 14MJ per square meter per 24-hour period. If you can capture sunlight with 100% efficiency, you need to have a cross-section of 0.6 square meters exposed to the sun throughout the day. Photosynthesis only captures 6% of the sun's energy (it's 60% efficient within the wavelengths it absorbs.) so you would need 10 square meters exposed to the sun throughout the daytime to capture enough to survive on chlorophyll. Photoelectric panels are 20% efficient, and have a theortic maximum of 33% efficiency. If you powered your transhumans with maximum efficiency solar panels, they'd need to average 1.6 square meters of skin facing the sun throughout the day. The entire body of a healthy adult has approximately 2 square meters of skin, which translates to less than 1 square meter that can be faced in any one direction.
To make this work your transhumans would need large bat wings made out of photoelectric materials (and some efficient way of converting electrical energy into biological energy), and would have to lie with them spread out toward the sun throughout the day time. (So, it might be possible, but everyone would have to ask whether it was realistically worthwhile.)

If your solution its to replace all the messy bits with metal and power yourself with electricity, then there's not much point in breathing (other than using air for cooling).

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