I'm trying to build a designer organism that would prove a threat to all life on Earth. Sort of a semi-organic von Neumann ecology of microscopic nitrogen-eaters that rapidly consume nitrogen to fuel their own growth, which not only threatens to drastically accelerate the depletion of Titan's nitrogen atmosphere (which millions of off-world human colonies need to grow food) but also disrupt the nitrogen cycle that's vital to all life on Earth, killing all Earth-born life wherever it goes.

To this end, if I want my organism to have the kind of properties I've just described, then I need to know what happens if it enters a human body and starts living in there by cannibalizing its nitrogen content. What might happen to a person who rapidly loses their normal bodily concentration of nitrogen, dropping from say 3% to 1% or lower?

  • $\begingroup$ This sounds very similar to the Blight of interstellar... $\endgroup$
    – AngelPray
    Feb 13, 2017 at 21:21
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    $\begingroup$ Are your organisms able to eat nitrogen directly from human bodies? If not, then your question is "how would people deal with malnutrition?". There are hundreds of books and papers on that, so it might be too broad. $\endgroup$
    – Mołot
    Feb 13, 2017 at 22:57
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    $\begingroup$ It depends on what they do with the nitrogen! Surely if the creatures eat so much they will produce waste - which will complicate the scenario, for better or for worse, greatly $\endgroup$
    – Zxyrra
    Feb 14, 2017 at 0:48
  • $\begingroup$ "I'm trying to build a designer organism that would prove a threat to all life on Earth". Hopefully only in a story! $\endgroup$ Feb 14, 2017 at 2:42

3 Answers 3


They would die. Nitrogen is an essential component of protein, and if you lose 2/3 of the protein in your body, you are dead.

  • $\begingroup$ Well, yes, I figured that much. But what happens before that? What symptoms would they experience before their body fails? $\endgroup$ Feb 13, 2017 at 21:26
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    $\begingroup$ Symptoms would depend very greatly on the specifics of how your organism operates. You'll see very different effects if it works its way from the skin inwards than if it gets all through the body and starts robbing it of nitrogen equally. You'll also get a different effect if it canabalizes the easy to acquire nitrogen first (like the free nitrogen in the blood stream) before digging into the difficult to get nitrogen in our protiens. $\endgroup$
    – Cort Ammon
    Feb 13, 2017 at 21:54

It depends.

If it can attack any nitrogen compound, it would essentially "disintegrate" the body. While the body is mostly not nitrogen by weight, structural components - skin, bones, tendons, ligaments, etc. - are rich in collagen (a structural protein). This is probably really hard to do, though, since microbes evolve really fast and we don't see any evidence of "everything with bones or cartilage suddenly dissolves"-type mass extinctions in the fossil record.

If it lives in the digestive system and co-opts nitrogen compounds (e.g. amino acids) before they're incorporated into the body, but doesn't actually tear the body apart, the result would be death by malnutrition, similar to lack of the "essential amino acids" in the diet (except worse, because the person also wouldn't be getting the nitrogen needed to make the amino acids the human body can synthesize).

On the other hand, the nitrogen in Earth and Titan's atmosphere is strongly bonded nitrogen gas, N2. Using this is very chemically different from using nitrogen in organic compounds. In Earth's nitrogen cycle, some microbes fix nitrogen using enzymes called nitrogenases. If the organisms you're describing are meant to be a super-quick-acting version of nitrogen-fixing microbes (maybe an agricultural tool gone wrong), they're unlikely to be able to infect the human body successfully, since they wouldn't be adapted to survive the human immune system and might not be designed to use the organic forms of nitrogen available.


It really depends how rapidly. If you mean within a few days then the first symptoms would be general fatigue, weakness, lightheadedness (caused by the heart not being able to pump sufficient blood to the brain).

After a day or so their body would start to necrotise causing extreme pain and physical dysfunction until their nerves fail at which point they'd become completely paralysed (even though they would have already been pretty much incapable of movement due to the pain and their exceedingly weak muscles) and then finally they'd die of total organ failure.

  • $\begingroup$ Where did you get your data from? $\endgroup$
    – Mołot
    Feb 13, 2017 at 22:55
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    $\begingroup$ @Mołot Data? Death by lack of nitrogen isn't something we have data about. However these conditions are all characteristic of not being able to produce/maintain amino acids (of all of which nitrogen is an essential component) within the organism. As the body's protein breaks down so do the its muscles (including the heart). In addition since amino acids are a vital part of the functioning of living cells, the cells start die without reproducing (leading to necrosis). Total organ failure is simply a consequence of the latter. $\endgroup$
    – AngelPray
    Feb 14, 2017 at 0:08
  • $\begingroup$ We have a lot of data about death from lack of protein, and protein is where most of nitrogen is. $\endgroup$
    – Mołot
    Feb 14, 2017 at 8:03

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