Last week, I rediscovered WIRED magazine while listening to a discussion on NPR about the microbiome. One of the guests was the author of a recent WIRED article, ”Your Body Is Surrounded By Clouds Of Skin And Fart Bacteria.” You might have heard it, too. Someone on the program drew a comparison between the nebula of dirt associated with Charles Shulz’s character Pigpen and the “aura of microbes” surrounding each of us, all the time.
That cloud of bacteria emanates from our hair, skin, and anal gas (farticles) and floats across our lives whenever we say, clap, spit an imperative, run our hands through our hair, or touch someone. The WIRED article talked about this microbial bubble as being composed of myriad lighter-than-air bacteria, yeast cells, and cell parts that we’re constantly shedding. It also introduced the possibilities of tracking down criminals by tracing their personal microbial cloud or studying these clouds to discover the origins of diseases. Pretty neat.
I’d recently learned that the cells of our personal microbiome, inner and outer, make up about 98 percent of the cells in and on our bodies, so this inquiring mind wanted to know more. The WIRED journalist, Nick Stockton, also wrote about the microbes of African hunter-gathers. He reported that the women of the Hadza tribe of Western Tanzania who spend their time growing and preparing tubers and the men who spend theirs out hunting game from dawn to dusk have different gut bacteria. Microbes tend to be sex-biased. Researchers have found that male and female mice have different microbiomes. Most autoimmune diseases are sex-biased, and all autoimmune diseases have a relationship to microbiomes.
A study at Duke University confirmed that the microbiome of pre-industrial humans is very different from those of modern humans. The big idea: the gut microbiome adapts not only to our diets but also to our environments.
Another WIRED writer studied the bacteria in his small New York City apartment, swabbing the place from top to bottom. And googling beyond WIRED, I learned more about the world that van Leeuwenhoek, the father of microbiology, opened up to us three-plus centuries ago when he magnified plaque he scraped from his own teeth.
Here are a few more recent discoveries about our microbiota:
- The microbiome in a woman’s uterus changes right before she gives birth.
- In general, the more diverse our microbiome the better.
- Infants with less gut microbiome diversity tend to have more allergies.
- Microbial diversity improves with exercise.
- Gut flora may influence a person’s tendency to easily gain or not gain weight.
- The bacteria, christensenella minuta, which also appears to be the most heritable gut bacteria, is far more common in lean people and can reduce weight gain in mice.
- Research around christensenella minuta seems to indicate that our genomes may control the makeup of our microbiome.
- Fecal microbiota transplantation, FMT, from an obese donor may well cause obesity in the recipient.
- Certain gut bacteria seem likely to play a role in lymphoma, ulcers, stomach, and colorectal cancer.
- Mice with healthy microbiomes respond better to cancer treatments.
I shared what I’d learned about the microbiome with a friend from high school, now a doctor in Buffalo. It turns out she’s also fascinated by the subject, especially in relation to disease, since that’s the focus of a number of her colleagues. Here are some of the connections they’re investigating: one between our microbiome and our metabolism, another between plaque and breast cancer, and another between the brain and the mircrobiome. “We know that the microbiome in your gut can affect your brain: more and more data have recently shown that. But can it go the other way? Can brain changes,” asks the UB researcher, “affect your gut microbiome?”
My friend and I agreed that our favorite new study around microbiota concerned athletes: apparently roller derby girls, whose sport has a lot of skin contact, have a signature team bacteria, which, it seems, they generously, though inadvertently, share with their opponents.
“It is by invisible forces that we are most shaped,” wrote Nietzsche. The German philosopher was talking about Nature, in a 19th-century way, but the statement, which has stuck with me since college, could be used to describe the microbiome in a 21st-century way.