Articles, Blog

You Are Mainly Microbe… Meet Your Microbiome!

August 20, 2019

We humans tend to obsess over cleanliness.
We wear masks in public when we feel a cold coming on, we cover ourselves daily in scented
soaps and antibacterial gel, and we’re crazy about our hand sanitizer. But no matter how
much we steam, sterilize or scrub ourselves, we’re still outnumbered by our inner ecosystem.
Meet your “microbiome.” The average adult human is made up of about
ten trillion cells, but each of us is carrying ten times that number of bacteria–a hundred
trillion microbes–on our skin, hair, mouths, and inside of our intestines. You and I and everyone on Earth is mostly
microbe. But we’re not born that way. We start out in a sterile womb, completely free
of bacteria, and we get our first dose of bacteria before we’re even done being born.
As we pass through the vaginal cavity, we ingest a tiny bit of this guy: It lives in
our intestines, where it’ll join about 600 other species that come along with our mother’s
breast milk. Their job? To break down sugars in that milk that we couldn’t digest on
our own. As we are cuddled and kissed and eat and play
in the dirt, eventually over a thousand species of bacteria will call our guts home. Early
on our little friends start fighting off bad bacteria and help teach our immune system
the difference between good and bad. Mice without a microbiome are much sicker as adults.
Children who take too many antibiotics, which kill our good bacteria along with bad, can
be more likely to get asthma and intestinal diseases later in life. These bacteria don’t
just protect us–they help feed us. Vitamins like B3, B6, B12, and K are all produced by
our microbial friends and taken up by our bodies. When babies switch from milk to mashed
carrots and pureed peas, plant-eating species take over their intestines. Our microbiome goes way beyond our guts. Antonie
van Leeuwenhoek became the first person to ever lay eyes on our little friends in 1683
when he scraped his teeth and placed them under a microscope. Even after we brush our
teeth, hundreds of species live in our mouths fighting disease and tooth decay. No two people
have exactly the same mouth bacteria, and you share your mix with everyone you kiss.
We used to think that sterile lungs were healthy. But there’s bacteria there, too, helping
prevent asthma and lung infections. We’ve even found them in ears and arteries, and
manufacturing antibiotics in our noses. And then! there’s our largest organ: the skin.
About a trillion bacteria live on our hair follicles and epidermis. Some are playing
defense, making our skin slightly acidic or producing chemicals to keep fungi from setting
up shop. Some skin bacteria prefer to live in warm, dark places on our bodies munching
on our skin oils and sweat and releasing chemicals that give us our particular . . . “aroma” There’s a lot of weird microbiome science
that we don’t understand: Regardless of your age, diet, gender, or where you’re
from, you probably have just one of three intestinal ecosystems. Like blood types, we
all share only a handful of gut microbiome types across all people. Have you heard of
bacterial mind control? The vagus nerve serves as a sort of direct phone line from your gut
to your brain and mice that have certain friendly bacteria in their intestines are calmer and
less anxious than those who don’t. Maybe you really ARE what you eat. Here’s another
weird microbe mystery: If you looked at all the species of bacteria on your right hand,
only about 1/5th of them would also live on your left hand. Even if you do this! [rubs
hands together vigorously] It’s like our bodies are a new planet that
we’ve just discovered. One team of scientists found 1,458 brand new species in just 60 belly
buttons. All in all, we carry about 20,000 or so human genes and three million or so
bacterial genes. In a sense, we’re 1% human and 99% bacterial. Sure, some bacteria are
bad, but most of them are just happy to call us home, and happy to help us stay healthy.
If we don’t start treating our microbiome like the friends they are, they might rise
up against us.


  • Reply jose carlos Munoz April 5, 2013 at 1:05 am

    so………um……..where can i get the shirt?

  • Reply It's Okay To Be Smart April 5, 2013 at 2:47 am

    There's a link in the description the the online store where I got mine. Everyone should join team microbiome!

  • Reply Hunter Gatherer April 5, 2013 at 2:52 am

    Hey! this is such a neat video! We (a group of Emory Undergrads) recently produced an educational video on the same topic. Check out our channel!

  • Reply Krista English April 6, 2013 at 6:13 pm

    Great until the end. Even though it's just a joke and meant to be cute/funny, it reminds me of political commentary guised as a joke. I like your videos though.

  • Reply The Whovian Hipster April 9, 2013 at 2:50 pm

    What about if babies that are fed formula? Do they still get the same benefit of the bacteria?

  • Reply It's Okay To Be Smart April 9, 2013 at 3:19 pm

    Researchers know there is a microbiome difference in babies who are breastfed vs those on formula, but honestly not enough research has been done to know if there's long-term health effects. I wouldn't be surprised if there was, but it will be several years before we know more.

  • Reply The Whovian Hipster April 9, 2013 at 6:46 pm

    Thank You 🙂

  • Reply MaxTperson April 11, 2013 at 12:33 am

    but the ambient body virii, in concentration, needed in mother critter's body for the fertilized egg to attach at all ? we are not born sterile at all then… we are not born at all without enough of them transient symbiant (semi)creatures present: viruses ?

  • Reply Dangles April 13, 2013 at 8:00 pm

    He mentioned that the first exposure babies get to a microbiome is through the vagina while being born, I wonder if there is any noticeable difference in babies that were delivered by c-section, and never passed through the birth canal.

  • Reply It's Okay To Be Smart April 14, 2013 at 2:59 am

    Yep! Babies delivered by c-section have different species in their microbiomes than those who are delivered vaginally. That doesn't mean one is better than the other, but people are actively researching that.

  • Reply Kristina Kyidyl April 16, 2013 at 1:23 am

    Hey Joe, if certain bacteria make for healthier people than others, do you know of any research being done on the viability of mixing bacteria from one person with another and seeing if it helps them?

  • Reply Reckless Roges April 17, 2013 at 2:45 pm

    There is some research in the area of diabetes and weight loss using, Faecal Transplantation.

  • Reply The Science Of Life April 22, 2013 at 3:36 am

    I wonder if that bit about more microbe species being found on the right hand than the left hand is seen in right-handed people, and is reversed for left handed people.

  • Reply It's Okay To Be Smart April 26, 2013 at 9:27 pm

    It's not necessarily more or less on either hand, it's just that they don't share the same species.

  • Reply It's Okay To Be Smart April 26, 2013 at 9:29 pm

    People with intestinal diseases or infections (like C. dificile) have been treated with fecal transplants from healthy people. If we can figure out which species are doing the good work, we could make a microbiome "injection" and skip that whole feces part.

  • Reply subliminalman May 8, 2013 at 11:50 pm

    Theres a great Freakonomics podcast episode called the power of poop about a poop transplant which treated multiple sclerosis.

  • Reply Ry P May 12, 2013 at 7:17 pm

    Every living organism is full of microbes…
    …execpt for, the microbes.

  • Reply Joe Gelman May 14, 2013 at 2:02 am

    If the micro-biome is first seeded (in a sense) when a child exits through the vaginal canal, are babies born via C-section at some sort of microbial disadvantage?

  • Reply It's Okay To Be Smart May 14, 2013 at 9:37 pm

    They are definitely born with a different set of microbes, but I think it's too early to say if it's a "disadvantage". Or as we like to say, "more research needed"

  • Reply Megan Davis May 16, 2013 at 9:16 am

    Thank you so much for your videos! As a high school student, I find your videos highly informative, yet simple to comprehend. It's truthfully amazing that you're making science accessible to a wide breadth of ages. This video is a favorite; I am captivated by the human relationship with our microbiome.

  • Reply Megan Davis May 16, 2013 at 9:21 am

    I have heard the transplants to be highly successful for intestinal disease. They are cheap in a hospital and very fast. Little research is currently being done for the reason that they bring in much less revenue over a shorter period of time. They are much less profitable to insurance companies and hospitals than the normal treatment of extended hospital stays with heavy dosages of antibiotics.The transplants work best when taken from a family member who will have a similar microbiome.

  • Reply Neueregel June 1, 2013 at 6:51 am

    Yes, gut flora is very important.

  • Reply zikSartin June 9, 2013 at 11:40 pm

    As our microbiomes only weigh a few pounds at most, we are not mainly microbe by the most intuitive measures, weight and volume. Some people, not understanding that microbes consist of far tinier cells than ours, will be confused by this video or think its central claim is stupid. You explained things properly when it came to genes, and you should have done the same with cell size and count.

    Otherwise, I liked the video.

  • Reply sydneyca July 16, 2013 at 10:50 pm

    So in a way, the kid from elementary school that ate dirt was actually enhancing his/her personal ecosystem…interesting.

  • Reply It's Okay To Be Smart July 16, 2013 at 11:04 pm

    There is genuine research suggesting that's true. Look up the "hygiene hypothesis"

  • Reply Rafael Cordeiro July 22, 2013 at 3:42 pm

    I was about to ask how much these 99% bacteria account for in weight, thanks for answering already! 🙂
    (And yes, a bit weird at first, but with time we get used to our "room mates"!)

  • Reply CreepyPastaSpiders July 27, 2013 at 10:10 pm

    love that little hip wiggle you're doing next to the chalk board

  • Reply JoeNietzsche August 3, 2013 at 12:11 am

    Are you the dude in the video?

  • Reply It's Okay To Be Smart August 3, 2013 at 4:43 pm

    I am!

  • Reply JoeNietzsche August 3, 2013 at 7:08 pm

    Well, then, as a fan of all things science, to yourself and the team involved involved in crafting these fine little productions, I say thanks and well done.

  • Reply Holden C August 5, 2013 at 5:52 am

    Could you explain "you are what you eat" more

  • Reply Willy August 6, 2013 at 7:59 am

    This channel is perfect for America now. Our education is crashing, and the majority know less even though the internet has given us the ability to be much smarter than the people in the last century. The reason is people are more and more distracted. TV, videogames, and sadly YouTube are contributing to people just not caring anymore.

  • Reply TehConqueror August 8, 2013 at 5:40 pm

    I don't trust the claim we're mainly microbe if the support is by number of cells and not by weight or volume

  • Reply rascouet August 16, 2013 at 6:03 pm

    Desperately looking for the average percentage of our bacteria that live in our gut. Any idea?

  • Reply It's Okay To Be Smart August 17, 2013 at 4:37 pm

    I'm not sure of the exact number, but certainly more than 90% of our microbiome lives in our gut

  • Reply Laura Merwin August 21, 2013 at 9:54 pm

    Can we ingest certain types of probiotics that inhabit a particular area of our body (like the small intestine, large intestine or even somewhere other than the gut) to promote the healthy growth and balance of beneficial microbes in that area?

  • Reply Smalde September 1, 2013 at 10:54 am

    How would be look like with no bacteria on and in us?

  • Reply It's Okay To Be Smart September 2, 2013 at 7:23 pm

    We would be dead. We're helpless without our tiny friends.

  • Reply David Shi September 3, 2013 at 7:18 pm

    How about in terms of weight?

  • Reply It's Okay To Be Smart September 4, 2013 at 8:10 pm

    Your microbiome = 2-5 pounds of bacteria according to most estimates.

  • Reply BariumCobaltNitrog3n September 11, 2013 at 8:29 am

    Occupy. different group.

  • Reply Erik G. September 17, 2013 at 5:34 am

    1% human

  • Reply Erik G. September 17, 2013 at 5:36 am

    99% bacterial

  • Reply Joanna Lum October 1, 2013 at 3:24 pm

    But hand sanitizers are fun…

  • Reply mikkel larsen October 14, 2013 at 8:49 pm

    Why are the bacteria keeping the fun guy away?

  • Reply It's Okay To Be Smart October 14, 2013 at 10:00 pm

    I see what you did there . . . and I like it.

  • Reply mikkel larsen October 14, 2013 at 11:24 pm

    Biology puns are the best.

  • Reply izthemovie October 27, 2013 at 7:54 pm

    I love my little microbe friends.

  • Reply nonchalantd October 29, 2013 at 7:01 pm

    I was expecting him to write something on the board.

  • Reply aditya menon November 6, 2013 at 7:32 am

    This almost makes one want society to go back to "home deliveries" completely. How do you balance that then, the need for exposure to important good bacteria, but also the need to minimize infant and maternal fatality, a reduction sterile hospital deliveries have brought us.

  • Reply epickipje March 15, 2014 at 7:54 pm

    my microbes go on strike, every time when I get lazy

  • Reply d4anc April 12, 2014 at 10:07 pm

    I got lyme disease after taking two years of antibiotics for my skin. I got infected before taking the antibiotics, but after that my immune system was destroyed.. 

  • Reply Jan Rijk June 13, 2014 at 2:18 pm

    NNNNNO ,, we are not mainly microbe ,, the numbers of microbes may be higher than our own cells but thats all ,, onkly their numbers are higher ,,  ,, compare the size of a virus with the size of a leucocyte and you can understand what i mean ,,,not very smart 🙁

  • Reply Austin Murre June 17, 2014 at 6:08 pm

    Must… stop… watching….

  • Reply 1234kalmar July 8, 2014 at 8:38 am

    100 tirllion passangers, in a huge legged carrier… I'M A HUMAN AT-AT!! 😀

  • Reply cardog kitchen July 10, 2014 at 3:35 am

    billions of years later, microbes outlive humans

  • Reply librarychannelify July 24, 2014 at 8:54 pm

    I am left handed is this the same?

  • Reply Optimus Prime August 25, 2014 at 7:02 pm

    I think you're confusing quantity with mass. Mass wise, your ratio is a bit skewed.

  • Reply Julian Kirby September 28, 2014 at 12:41 pm

    Hello my fellow collective organism!

  • Reply John Citizen September 29, 2014 at 12:09 am

    1:31 had way too much eye contact.. it kind of scared me

  • Reply Isabella Felipe de Oliveira Campos February 18, 2015 at 6:38 pm

    I, for one, welcome our microbe tenants. I'd like to remind them that as their home they could be helpful to me in rounding up others to toil in my underground sugar caves that I call my intestines!

  • Reply Max Hess June 9, 2015 at 2:03 pm


  • Reply Max Hess June 9, 2015 at 2:06 pm

    lol nice 2 no im part of da 1%

  • Reply Michael Block July 17, 2015 at 11:34 pm

    Lactobacillus Johnsonii ? that's funny.

  • Reply Ryan Gillen July 21, 2015 at 5:53 am

    I've always wondered, how much does all the microbes in our body weigh?

  • Reply Francisco Arandano August 5, 2015 at 4:29 pm

    By cell numbers, wouldn't we be 91% bacteria?

  • Reply Kha Doan October 2, 2015 at 8:41 pm

    If we're made up of 99% microbes, then shouldn't they be visible to the eyes? OMG bacterias has stealth technology.

  • Reply Neonwritingninja October 27, 2015 at 9:05 pm

    Nice shirt.

  • Reply Devine Ogidigben November 16, 2015 at 8:24 pm

    nice and a lil bit funny

  • Reply Equalibrium November 21, 2015 at 5:35 pm

    2:32 Seriously on the D

  • Reply MrBoh11 November 23, 2015 at 11:26 pm


  • Reply andres perez aguilar December 20, 2015 at 1:17 am

    A quick question. If the microbes took over our body and made us 100% microbe, would we be a walking bacteria???

  • Reply sarcastichearts January 5, 2016 at 11:12 am

    i really like jo; i love how he finds solace in science and uses it to explain simple questions. even if he doesn't give us the answers people might want to hear, he explains why they're not answers that we should fret about. you're a really great host, man, keep it up!!

  • Reply John Smith January 8, 2016 at 6:58 pm

    This may be a little nit-picky, but since first-born children are the ones parents tend to over-protect, and therefore likely to give too many antibiotics, has there been a study or survey regarding birth order and asthma that might support the idea of a correlation between antibiotic use and asthma? Just a thought. I know it wouldn't be conclusive proof, but it may at least add additional support (or it may even indicate a different direction for more research)

  • Reply Samuel Yang March 3, 2016 at 10:15 pm

    Wait so my body weight without bacteria is 10 lbs….

  • Reply MrBoh11 March 4, 2016 at 8:18 pm

    nice mustache

  • Reply Xbox360Player350 March 27, 2016 at 10:55 pm

    Why do we look human if we contain more bacteria than human cells?

  • Reply Rebecca Harwell May 9, 2016 at 10:39 pm

    I can agree we have become crazy about bacteria. But I didn't realize that we have such bacteria all over us and inside and they are necessary for us to live. And it makes you wonder how often you should take  an antibiotic. I wonder if they could give people good bacteria in their gut like the mice and make people more calm.

  • Reply にゃあエイリアンMeowAlien May 19, 2016 at 7:36 am

    very nice video yet not even 100k view? this make no sense

  • Reply T.F.B YouTube May 29, 2016 at 8:36 am

    What if c-section

  • Reply Lucifer Broke August 29, 2016 at 10:02 am

    Is your ass itchy? I can't help but notice your hips!

  • Reply Arun Prasath March 1, 2017 at 7:02 am

    How about inside our skull? The brain doesn't have ways to cope with mechanical strain, nor is there even a way to sense the strain(pain) either as far as I've heard of it. Is the brain practically 'zero-infected' by(or 'not living with' to be polite) our own microbiome?

  • Reply omar oyt March 7, 2017 at 1:15 pm

    eww kissing is disgusting I have never done it and I will never do FFS

  • Reply Kevin Trombly March 12, 2017 at 5:28 pm

    Asthma is a disease? Fascinating…

  • Reply Technical Difficulties May 3, 2017 at 12:47 am

    Frack. I'm an AT-ST.

  • Reply nick martinez May 7, 2017 at 1:26 pm

    Ok, this might make me out to be a guy you would want to hang out with, but I promise I'm not too overly indulgent if you will; just ideas, nothing more.

    I have two video suggestions:

    1) The science of why we forget everything after a certain level of drunk, (black out).

    2) The link between THC and cancer treatment.

    I'd just love to know the science behind these things! I've look up some scholarly articles on the second one and the only stuff I've found that says THC reduces cancer and tumor growth was seen in mice so I don't know on what level, if at all, it works on humans.

  • Reply Subhransu Mohapatra May 25, 2017 at 2:27 pm

    70%water , 99% bacteria .

  • Reply ChiefFrog August 29, 2017 at 6:57 pm

    he didn't say stay curious

  • Reply burnt penguin October 3, 2017 at 2:00 pm

    LOL 1:10

  • Reply Charles November 19, 2017 at 6:10 pm

    Oh no! It's the communist rise of the bacteria!…..MURICA DEMOCRACY TIME!

  • Reply Zulthyr November 28, 2017 at 1:31 pm

    Bernie Sanders

  • Reply IlluminatiBG January 23, 2018 at 3:42 am

    Actually, there is no "bad" bacteria. A lot of bacteria dies if we die, because they rely to us producing complex substances they need. However, not all bacteria is compatible with our body. In fact if several hundred generations pass "bad" bacteria, both bacteria and our body would change to reduce the mutual harm. So no bacteria is actually try to kill us, but it is an accident caused by mutual incompatibility.

  • Reply Pravin Tiwari February 19, 2018 at 2:30 pm

    Hello sir can you make video on what science actually is and why are people interested to know it ….Thanks for all your videos ☺☺👍👍👍

  • Reply James Deininger April 25, 2018 at 12:30 pm

    Can you do a video explaining how the gut microbiome creates serotonin and influences the foods we crave??

  • Reply Random Derpy Family May 21, 2018 at 11:18 am

    Lazy bugs.

  • Reply SportVideoPro July 4, 2018 at 4:57 pm


  • Reply Ethan McDonald July 31, 2018 at 8:07 am

    @Your Title. I beg to differ. I wouldn't say I'm mostly bacterial. The amount of sand on earth outweighs the stars in the galaxy nearly a billion to one. But nobody would say the galaxy is mostly sand. The amount of bacteria in or on me is about 2-5 pounds according to most estimates. I weigh well over 2-5 pounds. So I'm not mostly bacteria. Even if there are more bacteria cells in me than there are me cells. Because me cells are much bigger.

  • Reply Cedric Radloff August 29, 2018 at 3:54 am

    If that sweat smell is apart of this microbiome then why does it start during puberty? How do we all attract this micro thingy around the same time?

  • Reply Samuel Smith April 7, 2019 at 6:12 am

    You forgot to tell me to stay curious 🙁

  • Reply MisT Daily May 10, 2019 at 5:54 pm


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