Are Microbes Good or Bad for Humans?


Magnifying lenses like the ones in today’s
microscopes gave us, of course, our first glimpses into the world of the microcosmos. But it was not the first time people had guessed
that there might be more to the world than met our eyes, particularly regarding illness. Marcus Terentius Varro, a Roman scholar in
30 BC, wrote about the need to be cautious around swamps “because there bred certain
animalculae which cannot be seen by the eyes, which float in the air and enter the body
through the mouth and nose and there cause serious diseases.” Marcus, thus, managed to guess at a reality
that it would take thousands more years, and a great deal of debate to confirm. Even now, when it comes to human understanding
of our unseen neighbors, our focus is almost always driven by negative interactions. Our most vivid, collective encounters are
also some of the most unpleasant: the sneezing, the coughing, the upset stomachs, the death evidence of an apparent tension between our bodies and the microbial world. This strange little guy is a parasitic flatworm,
but for now, it’s in its cercarial form, a larva in search of a host—preferably animals
like duck, geese, and raccoons—where it can feed on their blood and then mature into
adulthood and release eggs through the infected animal’s waste. From the eggs will emerge a ciliated larva
that will seek out particular species of aquatic snails to serve as an intermediate host as
they develop into their cercarial stage and complete the cycle. For all the hosts this parasite will go through,
it turns out that we humans are not a particularly great one.They can infect us, and when they
do, they will burrow into the skin and create little bumps, inciting an allergic reaction
that produces a rash formally known as cercarial dermatitis, but it’s more frequently known
as “swimmer’s itch” thanks to its aquatic origin. But for the cercaria, the real challenge is
that we just aren’t the right bodies to house its development into adulthood, and
instead, it will die. The word “germs” might be the very first term
many of us learn to describe microbes, an easy word that warns us from an early age
that there are things we cannot see that nonetheless we must watch out for. And with medical necessity often shaping the
direction of scientific research, their potential danger is further emphasized because it has
inspired and shaped so much of our understanding of microorganisms. And so we know a great deal about the microbes
that can hurt us and next to nothing about the ones that can’t. But necessity is now driving us to better
grasp the complexity of microbes in relation to us, the idea that they are only ever enemies
is contradicted by our developing understanding of the organisms that live in and on us, not
just as freeloaders, but potentially as part of our body’s mechanics. Words like “microbiome” and “probiotic”
are now part of our understanding of the world, and also part of active research, though a
far smaller part than research focused on pathogens. But, and stop me if you’ve heard this before,
it turns out, the world is bigger than humans, and beyond our own perimeters, there’s the
importance of microbes to the world around us. What is known about that world is a tiny percentage
of what there is to know. Now as we delve more into the balance between
microbes that both help and harm, we do want to remind you that however harmless or beautiful
or fascinating the microbes we show you here are, you should still wash your hands and
get your shots, and having done away with that though, let’s remind you, most microbes
cannot hurt you. While it would be challenging to calculate
the exact percentage of microbial species out there that are pathogenic and could potentially
make us sick, estimates put it somewhere less than 1%. Figuring out whether the bacteria in our samples
lie in that slim percentage would require isolating and growing them up in cultures
so that we can sequence and properly identify them. But we just take the safe route and you know,
we don’t drink the pond water. Bacterial species do run a range as well,
giving us everything from cheese to tetanus. For us though, their presence helps sustain
the many bacteria-eaters we feature, and we keep them fed on droplets of milk, water from
boiled hay, cooked rice, or even liquid plant fertilizer. Now Nematodes, on the other hand, might seem
like a more clear cut danger. More commonly known as roundworms, they are
plentiful, with estimates counting them at around 60 billion nematodes for every person
on Earth, and around 40,000 species in total. But it’s a select few of those species that
are particularly notorious for humans, able to enter humans as eggs in contaminated food
or as larva that can penetrate the skin depending on the species. So it’s understandable if you respond to
the image of a nematode with some revulsion. But the vastness of them means that their
impact is so much more complex when you examine them across their different intersections
with life, from ecosystems where they can move other microbes around the soil and cycle
nutrients like nitrogen, to agriculture, where some nematode species may be pests while others
are helpful controls of insect populations. But these complications aren’t always strictly
about pathogens. We’ve featured Euglena here before, their twisty
bodies both fascinating and seemingly harmless. But in 2002, 21,000 striped bass died in a
facility in North Carolina. The culprit? A bloom of Euglena sanguinea, which released
a toxin called euglenophycin that is similar in structure to fire ant venom. And yet this danger poses a potential
as well, as scientists study the use of euglenophycin to fight cancer. And unlike nematodes, which we decidedly do
not want to ingest, there is some culinary promise for Euglena. Like Euglena gracilis, which for all of its
small size, manages to pack in large amounts of proteins and vitamins. There’s an underlying question in this video
about all these microbes we’ve seen: are they good? Or bad? Or neither? The answer, of course, varies. We’re still grasping the extent of what
it means to share a world with organisms that we weren’t able to even see until a few
centuries ago, dealing not only with the consequences of their existence but also of our own response
to what we’ve learned. Understanding bacteria and other microbes,
for example, that helped us usher in the modern era of antibiotics, which has saved so many
lives. But antibiotic overuse has also led to the
growing threat of antibiotic-resistant bacteria. We can’t not try to fight disease or find
uses for microbes, just as we can’t not interact with the world around us. The challenge then of making use of our knowledge
responsibly, of categorizing good and bad—whether at the scale of a microbe or much, much larger—hinges
on our ability to identify our place among all of this, to better understand the complexities
of the good and the bad of our own actions. Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you of course to all of the people who support this channel at patreon.com/journeytomicro. If you want to see more from our Master of Microscopes, James check our Jam and Germs on Instagram. And if you want to subscribe to this channel. You should. Do that.

100 Comments

  1. Daniel Foland said:

    1:54 Using gastropods as an intermediary? There is truly something diabolical afoot!
    A, um, stomach-foot I guess

    November 12, 2019
    Reply
  2. Daniel Foland said:

    7:48 "Who else here feels like dancing?
    I feel like dancing!
    ** booogie boogie boogie boogie **
    Just me? Okay!"

    November 12, 2019
    Reply
  3. lnopia said:

    This channel is such an amazing lens to peer into the micro cosmos

    November 12, 2019
    Reply
  4. Melon Lord said:

    Something good? Something bad? A little bit of both?

    November 12, 2019
    Reply
  5. Kid Mohair said:

    a wise person once said,
    "…you and I, and most of the life that we look on as advanced, are nothing more than coherent slime mold…"

    November 12, 2019
    Reply
  6. Kid Mohair said:

    so the answer to the question,
    in my mind, is
    they are us

    November 12, 2019
    Reply
  7. samiamrg7 said:

    So, Marcus was a time traveler, right?

    November 12, 2019
    Reply
  8. Gupie Dziecko said:

    2:00 ti looks like one slice of hydra

    November 12, 2019
    Reply
  9. First Name Last Name said:

    Asmr anyone?

    November 12, 2019
    Reply
  10. Mauro Molinero said:

    you can test whats bad for a human for yourself.
    try swallowing 1 kilograms of microbes vs 1kg of antimicrobial soap and see what makes you feel worse.

    November 12, 2019
    Reply
  11. Marmalade said:

    Cercaria looks like an IUD im js

    November 12, 2019
    Reply
  12. Broken Games said:

    microbes are eating you alive.

    November 12, 2019
    Reply
  13. judy churley said:

    A nit-pick: 30BC + 2000 is 1970, so' thousands of years' cannot be correct since microbe theory of disease being confirmed is less then 2 thousand years old. Ok.

    November 12, 2019
    Reply
  14. Lynette Hannan said:

    I do so wish all teachers spoke like the narrator here. Your voice is very calming and your attitude is very much a conversationally one-on-one mentoring; rather than speed-yelling the info at you (like you're in amongst a noisy classroom) like an advertisement interrupting a movie – you are the movie! I do sit up and take notice, I hang on your words and I understand, I want to keep learning more!

    November 12, 2019
    Reply
  15. Louis Gedo said:

    Another marvelous episode!

    November 12, 2019
    Reply
  16. CaramelLeek said:

    Are microbes good or bad for humans?
    It's complicated.
    Yes and no.
    Both.
    Depends.

    November 12, 2019
    Reply
  17. Rayhan S said:

    Microbs are like your companions. Some of them are good for you and some of them are bad.

    November 12, 2019
    Reply
  18. Fairy GoodMüller said:

    these videos are great

    November 12, 2019
    Reply
  19. Jason said:

    Years ago I got swimmer's itch when I was 14 after swimming in a lake my family visited every spring. I later went to a summer camp with itchy spots all over my stomach, chest, and thighs. It was absolutely horrible. Not only was I incredibly itchy all the time, but I also had flu-like symptoms such as fever, nausea (with vomiting), diarrhea, and stuffy nose. Thankfully most of these symptoms went away within a week, but I had to get taken home before the camp week was up. I learned to ALWAYS shower thoroughly after swimming in any fresh water lake.

    November 12, 2019
    Reply
  20. Metal Venom said:

    1:43 into the vid… Calming Wisdom Innocence. Hank rules the mosh pit

    November 12, 2019
    Reply
  21. myhumbleascension said:

    This channel is getting better and better with every next video.

    November 12, 2019
    Reply
  22. Ugly Cactus said:

    9 nematodes did not liked this video

    November 12, 2019
    Reply
  23. Metal Venom said:

    9:07 into vid…. Hank for President Hank for Messiah Hank for President Hank for Emporer Hank for President Hank for Sainthood

    November 12, 2019
    Reply
  24. Orka DRLJAČA said:

    for freak sake why is your every video pure fcking perfection?!?!?!!??!?

    November 12, 2019
    Reply
  25. Lord Slapaman said:

    I like to imagine the fact that these little guys don't know we exist. They don't know that humans are living being like them, or anything thats around them is alive. They don't even know the concept of "life" or others. They only know that they exist, never knowing of the ancestors that came before them, that evolved into them or even how they function. They only exist

    November 12, 2019
    Reply
  26. Cam RSR said:

    Really!! wash your hands and get your shots!!
    mind your biz!
    or just say nothing.
    I know you meant well but dont treat us like like mindless shit throwers! lol

    November 12, 2019
    Reply
  27. Mina Ichihara said:

    'most microbes cannot hurt you' was this aimed directly at John? XD

    November 12, 2019
    Reply
  28. Genil Júnior said:

    Some trematodes (flatworms, the ones that have a cercaria stage) can in fact infect humans, eg some from the Schistosoma genus.
    Most trematodes are hermaphrodites and live in the intestines, but Schistosoma are dioecious (having both Male and female adult worms) and live inside blood vessels. Their eggs can get trapped inside the host's body and cause a strong immune reaction, which leads to what we call schistosomiasis or bilharzia. The symptoms vary depending on the Schistosoma species as they can live either in blood vessels near the liver and intestines, or near the bladder.

    November 12, 2019
    Reply
  29. Napo G59 said:

    Jesus. Christ. look at all those patrons.

    November 12, 2019
    Reply
  30. simon sivil said:

    You just said antibiotic overuse ect.
    They announced earlier this year that they suspect actually, the main culprit for this problem isn't our overuse, but in fact its where we flush antibiotic poop out to sea!. where its then consumed by the food chain then reconsumed by us.

    November 12, 2019
    Reply
  31. Xirpzy said:

    Are there microorganisms outside our visible lightspectrum?

    November 12, 2019
    Reply
  32. Rotifer said:

    What are you doing in my microbial swamp!

    November 12, 2019
    Reply
  33. Rotifer said:

    I'm good for humans.

    November 12, 2019
    Reply
  34. Gothead420 said:

    Answer:
    It depends on many different factors…

    November 12, 2019
    Reply
  35. Starfals said:

    This video was really scary for me, even though I've heard about those kinds of things before.. it's just like watching scenes from the THING.

    Then again.. I'm scared from Octopuses too lol.

    November 12, 2019
    Reply
  36. pariodeusex said:

    fantastic video as always! For a future video you could explore the relationship between plant roots and microbiology eg, bacteria converting inorganic minerals to organic minerals then being eaten by predators and their poop being the food for the roots and the plants role in cultivating bacteria by giving out exudates (sugar) to farm them. Plant roots are teaming with bacteria for this very purpose, i'm sure you could get some great shots!, keep up the good work!

    November 12, 2019
    Reply
  37. Nelson Cabrera said:

    6:30 When Madonna's "Vogue" starts to play.

    November 12, 2019
    Reply
  38. Brodie Bennett said:

    So…
    What will UV light do to these little buggers?

    November 12, 2019
    Reply
  39. Pyro1456 said:

    Some doctors are actually recommending you get parasitic worms, as it helps suppress allergies

    November 12, 2019
    Reply
  40. vitas75 said:

    Question: how fast do their apendiges move? In mm/s.

    November 12, 2019
    Reply
  41. rpbajb said:

    The microphotography is excellent, but I really enjoy your little forays into philosophy.

    November 12, 2019
    Reply
  42. Steph P. said:

    I’m noticing a lot of microorganisms running into other microorganisms.. neither of them seem to care. Is a crash/avoidance not that big of a deal because they’re all so flexible or something…?

    Thank you for the new, informative video!

    November 12, 2019
    Reply
  43. Darkasthenight06 said:

    As someone who researches the microbiome and its positive impact on health and nutrition, I am so glad that this channel exists. Microbes can be intensely beautiful as well as being highly useful for us as a species. It's a shame people often just see them as "germs". Keep up the good work!

    November 12, 2019
    Reply
  44. WireMosasaur said:

    This episode had some strong Mushishi vibes- can highly recommend that anime if you're into the whole "strange neutral microbial philosophy and chill music" thing

    November 12, 2019
    Reply
  45. Lívia Tupinambá said:

    2:00 lil guy looks like he's struggling to do the splits

    November 12, 2019
    Reply
  46. Anilite said:

    The twitch of a cercaria makes it so much more creepy tbh, really adds to its parasitic vibe.

    November 12, 2019
    Reply
  47. Freeride Serbia said:

    Ima li Srba kojima je mikroskopiranje hobi?

    November 12, 2019
    Reply
  48. Russ Forgus said:

    Everything is generally bad for humans.

    November 12, 2019
    Reply
  49. Gupie Dziecko said:

    maybe i am a little bit noutorius with this but can you make video about senescence/ageing in MiCo?

    November 12, 2019
    Reply
  50. dolandlydia said:

    I hope they take over the world. HAHAHAHAHA I saw one that looked like my beagle.

    November 12, 2019
    Reply
  51. Albert Martí said:

    Are you going to feature some obscure stuff?? I understand you want to appeal to a large public, but I think they would like small examples as well.

    November 12, 2019
    Reply
  52. kiraPh1234k said:

    Next: Is water really good for you?

    November 12, 2019
    Reply
  53. JR Rodriguez said:

    As a physician, good plumbing has done more to improve and save human life than all physicians and scientists combined.

    November 12, 2019
    Reply
  54. John Opalko said:

    Nicely done, but I have a minor objection to your title. The phrase "good or bad" sets up a false dichotomy. However, I understand why you did this. It's unfortunate, but that's the way most people think.
    So, are microbes good or bad for humans? The only answer, to this and to most of life's other questions, is, "It depends."

    November 12, 2019
    Reply
  55. kiraPh1234k said:

    6:45 also nematoads are important food sources. In oyster mushroom fungi for example, they are a critical nitrogen source.

    November 12, 2019
    Reply
  56. mattsgrungy said:

    Hank: "Nematodes are plentiful. Around 60 Billion…"
    Me: "That is plentiful…"
    Hank: "…for every human on the planet"
    Me: "FFFFFFFFFUUUUUUUUUUUUUUUUUUUUUUUU……"

    November 12, 2019
    Reply
  57. Naomi Williams said:

    1:33 I'm just gonna say it. That looks like an IUD 😂

    November 12, 2019
    Reply
  58. Delgen1951 said:

    yes!

    November 12, 2019
    Reply
  59. mavrick45 said:

    anyone think of Doug Funny anytime nematode is mentioned?

    November 12, 2019
    Reply
  60. parkertin said:

    I just got a higher resolution monitor, and I wonder, could we get (later?) videos in higher resolution? 🙂 I.e. over FullHD 1080p, e.g. 1440p or 2160p (4K)?

    November 12, 2019
    Reply
  61. Big Lumpy Beetle said:

    Yes

    November 12, 2019
    Reply
  62. emmanuel muleshe said:

    Please do coccidia

    November 12, 2019
    Reply
  63. SnoopyDoo said:

    8:08 I'm sure it's taking a piss.

    November 12, 2019
    Reply
  64. Freeda Peeple said:

    I would love to know the logic or thought pattern that led to Marcus figuring out that microscopic critters existed.

    November 12, 2019
    Reply
  65. Bill Malcolm said:

    Yo Hank! Can you guys do an episode on things that cause allergic reactions? Them floating balls and that little Cercaria causing dermatitis got me wondering about the little bastards that make me sneeze uncontrollably for 5-10 minutes at a time.

    November 12, 2019
    Reply
  66. TacticalMelonFarmer said:

    I know it's difficult, but an episode on plant cells would be amazing.

    November 12, 2019
    Reply
  67. steve1978ger said:

    Both, it depends

    November 12, 2019
    Reply
  68. Dan Giles said:

    The opening shot looks like the CMB!

    November 12, 2019
    Reply
  69. Sun Wukong said:

    These videos make me want to dig out electroplankton on the DS.

    November 12, 2019
    Reply
  70. popindosin228 said:

    This micro cosmos videos are perfect to watch before sleep

    November 12, 2019
    Reply
  71. CheshireTomcat68 said:

    Cercaria – damn those Aquachiggers!

    November 12, 2019
    Reply
  72. Joey Cook said:

    I wonder how many of the things in the microcosmos can hear… I’m guessing none? It’d be pretty hard to carry on like we don’t exist to anything that has ears, and we’d be extremely annoying.

    November 12, 2019
    Reply
  73. Andrew Piltenko said:

    It's sad seeing you have fewer and fewer views :c

    November 12, 2019
    Reply
  74. Will S said:

    I prefer to believe that Marcus guy was an alien making the best of things after crash-landing on Earth. Much more interesting and also difficult to disprove.

    November 12, 2019
    Reply
  75. OtakuMage said:

    Short answer: Yes
    Long answer: It depends

    November 12, 2019
    Reply
  76. Eric Taylor said:

    2:40 Also, humans make terrible hosts because we have the ability to attack them deliberately. If you are alive and not a human, humans must just seem like a bad idea.

    November 13, 2019
    Reply
  77. notsosxechris said:

    Wait… if there's approximately 60 billion nematodes for every 1 human and there's approximately 7 billion humans on the planet… does that mean nematodes are the dankest species?

    (Sorry, I couldn't resist.)

    November 13, 2019
    Reply
  78. Scott Farley said:

    We're just meat bags colonized by bacteria. All hail our bacterial overlords!

    November 13, 2019
    Reply
  79. madcat789 said:

    Maybe this winter I'll catch something that'll get me quick. I don't care how painful, just quick.

    November 13, 2019
    Reply
  80. PrivateCheeselaw said:

    #RotiferLivesMatter

    November 13, 2019
    Reply
  81. Eduardo R. said:

    4:27 boing boing

    November 13, 2019
    Reply
  82. Paul Gardner said:

    Any High School student should be able to answer this or is our education system this terrible?

    November 13, 2019
    Reply
  83. Brant Wedel said:

    It's strange that Hank wanted us to pause the video for a moment halfway through 🤔

    November 13, 2019
    Reply
  84. Ronan Linnett said:

    the answer is yes

    November 13, 2019
    Reply
  85. uriel garciagbj said:

    I see Dynobrion, I like.
    Also with Dinoflagellates, Synura, Phacus, Closterium, Rotifers, Stentor.
    I basically like every video of yours.

    November 13, 2019
    Reply
  86. The Pencil Cunts said:

    7:31
    ( ͡° ʖ ͡°)

    November 13, 2019
    Reply
  87. shella bella said:

    As much as I love the content of these videos alone, they really are the best asmr on youtube also

    November 13, 2019
    Reply
  88. Camilla Whatcott said:

    Something about that ending music awoke all my Cyriak memories and I half expected to see a nightmarish kaleidoscope of shifting morphing germs

    November 13, 2019
    Reply
  89. El Comodo said:

    microbiomes sculpt environments

    November 13, 2019
    Reply
  90. NOSRN AMARA said:

    What are the bumpy yellow guys floating around the flat worm and swimmer’s itch guy? They’re really pretty!

    November 13, 2019
    Reply
  91. MseeBMe said:

    This has to be one of the best channels on YouTube.
    Thank you for providing it.

    November 13, 2019
    Reply
  92. pauljs75 said:

    Sure the Roman guy was guessing? There are some odd artifacts here and there that suggest what is effectively a water-drop microscope predates the glass-lensed invention (which made the instrument official) by a significant period of time. Documentation seems limited, but there's not much else that would suggest another use for those objects.

    November 13, 2019
    Reply
  93. Anotherordinaryguy 499 said:

    Depends on the context

    Diseases? No

    Amount of cheese being produced? Yes

    November 13, 2019
    Reply
  94. zerendipity said:

    Ur voice for microcosmos is like David Attenborough for "bigger" nature xD

    November 13, 2019
    Reply
  95. Moses Jonson said:

    I thought you'd never talk about the human microbiome

    November 13, 2019
    Reply
  96. Vaishali Rani said:

    Love that channel seriously. Crazy for bio

    November 13, 2019
    Reply
  97. Marcos Pereira said:

    This channel must be the Kryptonite of John Green

    November 13, 2019
    Reply
  98. Vee Dragon said:

    Dont drink the pond water is good advise lol

    November 13, 2019
    Reply
  99. Andrew Jimenez said:

    This channel is just plain ol' quality. I could watch this for hours.

    November 13, 2019
    Reply
  100. J F said:

    thank you for one of the most wonderful presentations on you tube.

    November 13, 2019
    Reply

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