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You’re Surrounded by Bacteria That Are Waiting for You to Die

Antibiotic-resistant Staphylococcus aureus bacteria (yellow) killing and escaping from a human white blood cell.
Antibiotic-resistant Staphylococcus aureus bacteria (yellow) killing and escaping from a human white blood cell.
Photograph by NIAID

You are filled with bacteria, and you are covered in them. And a whole lot of them are just waiting for you to drop dead.

As soon as you die, they’ll swoop in. This week, we learned exactly how microbes chow down on us. A brave and strong-stomached team of scientists spent months watching dead bodies decompose, tracking all the bacteria, fungi, and worms, day by day. Forensic scientists can use this timeline, published in Science, to help determine time—and even place—of death. (More on that in a previous Gory Details.)

The microbes in your intestines get first dibs, the scientists found. As soon as you die, they’ll start decomposing you from the inside out. Meanwhile, other bacteria on your skin or in the soil beneath you start mounting an attack from the outside in. As Michael Byrne at Motherboard so nicely summed it up, “Earth is just waiting for you to drop dead.”

That’s a little unsettling, if you think about it. And it begs the question: What keeps all those bacteria from decomposing you alive?

That’s silly, you say. I’m alive. Only dead things decompose.

Yes, but why?

What keeps all those bacteria from decomposing you alive?

As the new study points out, two of our most crucial defenses against being decomposed are toppled as soon as we die. Our immune system shuts down, and our bodies cool off. Bacteria like this; they don’t have an easy time growing in a hot body. (Think about it: When we have an infection our bodies develop a fever to ward it off.)

Basically, a big part of life involves your cells waging a battle to the death with bacterial cells. As long as you’re alive and healthy, your cells are winning. Decomposition is when your cells lose. 

One of the clearest descriptions I’ve read comes from Moheb Costandi’s “This is what happens after you die“:

Most internal organs are devoid of microbes when we are alive. Soon after death, however, the immune system stops working, leaving them to spread throughout the body freely. This usually begins in the gut, at the junction between the small and large intestines. Left unchecked, our gut bacteria begin to digest the intestines—and then the surrounding tissues—from the inside out, using the chemical cocktail that leaks out of damaged cells as a food source. Then they invade the capillaries of the digestive system and lymph nodes, spreading first to the liver and spleen, then into the heart and brain.

As soon as you die, your body essentially gets its first break from a war that it has been fighting every moment of your life.

When the bacteria start to win that war in a living person, we call it an infection, and we try to flush the invaders out of a wound. Or we go in with antibiotics to poison them.

Let’s pause for just a moment to appreciate those antibiotics. We thought we had outwitted bacteria. But now we’ve overused and misused antibiotics, giving the bacteria a chance to figure out our defenses. They’re adapting, becoming resistant to our weapons, and we’re already seeing the failure of some of our last lines of defense, leading to more infections, illness, and death.

Ultimately, we lose our battle with bacteria when we die. But until then, it’s pretty amazing to think of the fine line between life and becoming bacteria food. Imagine the evolutionary arms race that has led to an immune system so vigilant that it can fend off constant attack for decades. 

I’m just grateful not to be decomposing right now.

48 thoughts on “You’re Surrounded by Bacteria That Are Waiting for You to Die

  1. I’m also grateful not to be decomposing! It would be great to see whcih bacterial species disappear first when they run out of ‘resources’.

  2. Never really considered bacteria as predators, though that is obvious, until I read how they first go to the liver after they eat their way out of the intestines. Just like the larger predators, they know where to get the most nutrition. Whenever I read of bacteria behavior, I am always amazed how we don’t consider them to be intelligent beings. They communicate nearly instantly across species, they will sacrifice their lives in order for their children to be born, and so on. Apparently, they don’t possess the required nervous systems we insist is an indicator of intelligence. And yet, we deny them this. Of course, I am not a bacteriologist, but a layman who majored in history.

    1. Well, bacterial “children” are clones produced asexually. In this regard there’s not really a sacrifice.

      Think about it in terms of your own cells which die on command for the greater good of your being. In the time it takes to read my reply something like 50 million of your cells will have died. But the cells that they produced before dying will live on, each containing more or less identical DNA to their progenitor.

      You might like Blood Music by Greg Bear which deals with the theme of microbial intelligence. Even his are still collectives. One bacterial cell by itself seems about as capable of intelligence as one of my brain cells by itself.

      1. I should have put in the hive mind thought, but it skipped my mind then. Ants are so fascinating in that regard. Watching them build a bridge out of themselves is an amazing sight! Thanks, Jim

    2. “Social IQ score of bacteria is a recently proposed quantitative score[1] devised as a comparative genomic tool to assess the genome potential of bacteria to conduct successful cooperative and adaptable behaviors (or social behaviors) in complex adverse environments.

      The need of the new measure follows the current realization that bacteria are smart creatures that can conduct intricate social life in large and complex colonies using sophisticated chemical communication.[2][3] We have only recently begun to decode how they can rapidly adapt to changes in the environment, distribute tasks, “learn from experience”, prepare for the future and make decisions.[4][5][6] While the number of bacteria in a colony (Figure 1) can be more than 100 times the number of people on Earth, bacteria are able to make sure they are all synchronized by sharing simple chemical messages.” https://en.wikipedia.org/wiki/Social_IQ_score_of_bacteria#Harnessing_bacterial_intelligence

      1. Oh great! So now I’m not even as smart as bacteria. It’s almost as if my inferiority complex is really me being wildly over-optimistic! 🙂

    1. There are zombies! I’ve been waiting for that apocalypse to end for decades. Proof? Look at the faces of your coworkers. Especially if you live in cubicle world. They are the living dead. 🙂

      1. +1

        Zombies could actually be defined as “beings that are driven by other forces than Life”.
        Then we could begin to see them in parliaments, senates, and other elitist places, moving about and obviously propelled, animated and motivated by, say, greed, political affiliations, free-ranging intelligence vacuum, or specific arrays of complexes. 🙂

  3. Good article; I enjoyed reading it simply because it was a concise description of what actually happens.

    Many people never think about this type of thing, can’t comprehend it, or would be “grossed out” if discussed because we’re not dealing with a polite after dinner topic here, but it will eventually happen to every living body, and unless a person is in a profession that deals with it, seldom is a thought given to what happens “when.” But continual war is exactly what life is on the cellular front.

    I really enjoy these articles daily; this is a great service.


  4. Bacteria ain’t the only ones waiting in or out there… there’s the social security, maybe some relatives, hehe, and also those which earn their daily bread by doing away with the remains.
    As far as I’m concerned, once I’m gone they can have it all.
    I won’t be needing anything of what they’re after. 😉

  5. As soon as we pop into this world we are immediately under attack and risk from bacteria, viruses and fungi. It’s a ruthless battle of the microbial world. It’s also a battle in which humanity withstands the assaults from the Machine that runs this world. It throws many obstacles in our path. The good news is that it’s just a scary ride and when it’s over we go on to a better reality where these experiences make us stronger of spirit since we are eternal beings.

  6. What are you crazy?

    You just found out?

    This has ALWAYS been the case. WIth EVERY living thing.
    Since the beginning of time.

    The bacteria breaks own the molecules of the body to be absorbed back into the earthand recycled.

  7. They came – invaders in my walls,
    Picking their spots from which to fight.
    My forces were on constant calls
    To minimize their awesome might.
    Uneasy peace – many a year,
    They would attack just now and then.
    My mercenaries would appear,
    And send them back to wait again.
    But they were patient ever so.
    I weakened as the time went by.
    Slowly my defenses did go.
    ‘Twas just the way, no matter why.

    Bacteria throughout me spread.
    They won, I lost – cuz I am dead.

  8. I wonder how the Egyptians were so successful in the preservation of their bodies so long ago.
    They,unlike us today, were ahead of their times.

  9. All this info and comments are right, we can’t escape this, it’s life and short, let’s think about been great full and happy. And one thing about being sick when we are sick our temperature rises yes it’s because the body is fitting and doctors give you tempra to lower it, how right are they? Most of the time they don’t know what bug is making you sick.

  10. “Dust to Dust”.
    Now which is better ….burial or cremation ??
    In the former, the bones survive for a few decades or longer, in the latter the body is dust or ash at the pyre.

    Would like some responses

    1. Cremation helps to spread deforestation. Burial (as long as you aren’t embalmed with pointless chemicals to keep your corpse all beautiful) feeds the worms which enrich the soil. I plan on being buried in a cardboard box coffin (yes, they are out there) without being embalmed and having a garden growing over my grave rather than a cement slab. Hope that helps.

  11. Interestingly- when all the “clues” are in, and the perpetrators have been identified, the authorities may go after them and in the circus of life, sentence them to death… and then, they too will be eaten from within. Weird.

  12. The Point of Fever is perfectly explained, If we all understand that our body has a basic temperature. This temperature is set in such a way that this bacteria are bumped off everytime. Also the immune system is only that helps in every place and every time. If we boost our immune system by good habits, ( exercise and yoga), the microbes are put in check.

  13. It’s an interesting twist to put this process in terms of a war within the body when it’s actually a natural efficient process of the body breaking itself down into its elemental forms of nature, that is, recycling itself back into nature from where it came. Our bodies are of nature after all.

  14. I am no scientist, but am fascinated by these sorts of things. One question, though, once the body has been eaten up (decomposed) by the microbes, where do they go? What happens to them?

    1. That brings up another simple question, if you get buried and the bacteria eat most of your body up, and then they have to die when they finished, then where does the material go?
      If you are cremated, the material goes into the air and what remains is ash which is a good fertilizer.
      But what happens when you rot in a crypt?..
      Oh, wait.. the bacteria can give out gas!.. so you will be like going up the chimney too!
      Only the bones may stay for a long time.
      I think dying must be not “ecological” because it must participate in “CO2” gas emissions, so try not to do that.

      On a second thought, if death releases gases into the Atmosphere, why not come up with a real “Ecological” way of disposing of the bodies, which traps the CO2?
      You could start a viral successful business on that, if you can find a way to dispose of bodies without releasing harmful gases! You could even get subsidies for that!
      You could make lots of money, on account that both burying and cremating, release gases into the Atmosphere, producing more Global Heating!
      You know we should not throw electronics into the garbage, because they will poison the fish.
      But how about a true “Ecological” disposal of our own bodies?
      What do you think?

      What if.. a body would be boiled to destroy all bacteria, wrapped up in a Polyethylene foil, or canned in an inoxidable steel casket, and then stacked in a collective burial place?
      It would be Eco-friendly!
      Or irradiate it with harsh Gamma rays.
      Or bake it to kill the bacteria. We don’t want bacteria, they will release gases right?
      Trouble is.. producing the inoxidable steel caskets will probably produce more CO2 than the bodies themselves..
      But there might be a solution for that too.
      Bury the bodies in mass graves, along with radioactive waste from the nuclear power plants, so they kill the bacteria.

      No-no-no there is a better solution! And truly “Ecological”!
      Some ancient tribes apply it!
      It’s drying the bodies on scaffolds!
      The water returns to the Atmosphere, the bacteria are dead in the dried-up body, and the CO2 stays there and is not released!

      Now we do have an Ecological procedure, and a base to establish a world-wide business!

    2. I’m getting buried in one of those decomposable cardboard caskets without being embalmed. Then just start a flower garden over where I was put down. Figure that would be pretty cool.

  15. If ever there was a thought to make me feel tiny and insignificant in facing the universe, this is it. I will never look at yogurt the same way again.

    1. Dear, it is said we have about 1lb. of bacteria inside and outside our bodies, and we are in serious trouble without them, because they are “friendly” bacteria.

      “Aggressive” bacteria, kill their host, and that causes them to die too. Along the time, bacteria are forced to modify, and to not only let their host live, but even help it. The relation develops, in such a way, that some bacteria thrive by actually helping the host to live.

      Take the ruminants.. they don’t actually eat hay. They prepare the hay by chewing it and mixing it with enzimes, and they feed the paste to bacteria in their stomach. It’s a complex process, but I understand in fact they eat bacteria as well as some protozoa, fungi and yeast and their by-products.

      So these micro-organisms can be deadly, but they can also adapt and become a real life-line!

      So don’t worry about eating yoghurt or soured milk 🙂

  16. The ultimate in recycling!

    “A long time ago in a galaxy far, far away….” are the opening words to the first Star Wars epic series of films. Many stars in many galaxies through nuclear processes brought into existence the lightest through to the heaviest elements in existence. That includes every atom in our bodies, every living thing and every inanimate object in the universe. We are the results of the remnants of nuclear reactions (ie. ashes or nuclear debris) within stellar processes. We and all living organisms are made from molecules consisting of these atoms.

    It is interesting to note a continuous is war is being waged within our bodies, between ‘good’ bacteria (who are aiding our very existence) versus the ‘bad’ bacteria (attacking and destroying our body cells). Unfortunately, the ‘bad’ guys eventually win when we pass into eternity. Then comes the decomposition processes when we get recycled into the basic elements once again to ‘feed’ the earth that we once trod on. From ashes whence we came to ashes we return.

    Millions of years hence, the sun will become a red giant star and engulfs the earth its outer layers, the earth gets burnt to a crisp. Millions of years will go by when the Andromeda galaxy collides with our galaxy resulting in an enormous fireworks display. Our atoms will be dispersed throughout the resulting maelstrom. Nobody can ever guess where the atoms that formed our bodies will end up. Could be in a rock, a tree, some alien being, etc. Every atom on this earth will be recycled into something anew in the many millions or billions of years to come.

    You are not totally dispensable but totally recyclable!

  17. It is an interesting article, factual and clear. From a scientific point of view, it matters because they discovered why dead bodies decompose and that help explain time and even place of death. This is important especially in cases of unnatural death were crimes are involved.

    Thanks to the scientific community members who tirelessly engage in lengthy and complex studies to find answers to societal complex problems.

    However, for us human beings who are temporary visiting Mother Earth, that is a natural process the body must undergoes once the immune system went to sleep.

  18. I have to say that this is a little overly dramatic and the fact that our microbiome, i.e. bacteria co-existing within us, actually helps our immune system fight against microbes that are trying to infect us. You praise antibiotics but not the bacteria that are possibly required for our existence; without bacteria in our gut we would have a weakened immune system and inefficient vitamin metabolism. I appreciate the article and its discussion on what happens to the body after we die but if you want to bring the discussion to how bacteria interact with us while we live don’t just vilify but instead look into the current research on our microbiome and the mutualism that goes with it.

    Thank you for your time.

  19. We knew that all along.
    However, I object to the stance.
    The bacteria, are more successful when their carrier is alive.
    If they kill their carrier, they die too. They don’t hop around, the carrier has to take them from here to there, so if the carrier is dead, the whole colony of bacteria will die too.
    So I take a different look at this thing. I look at it as when one animal dies, there is a severe unbalance showing up, and the bacteria break loose, but only to their own deaths.
    Because there is nobody to carry them around anymore, and soon, nothing to feed on.
    So don’t envy the bacteria too much.

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