You’re not alone if you draw a big blank for the question “What are microbes?” Even though they make up 90 percent of the cells in the human body, genes and environmental factors usually get more focus in conversations about our wellbeing. Alanna Collen, a science writer who holds a Ph.D. in evolutionary biology, puts them in the spotlight in her new book, 10% Human: How Microbes Hold the Key to Health and Happiness. She argues that the 100 trillion microbes — microscopic organisms, including bacteria, fungi, archaea, and arguably, viruses — hitchhiking in and on our bodies act as an “unseen organ,” and that they play an enormous role in our overall health.
Which is exactly why you should stick around for this post and figure out what in the heck they are.
The idea of sharing our bodies with all kinds of bugs and germs isn't the most pleasant, but Collen’s evidence for how each person’s microbiota, or personal community of microbes, impacts his or her health is undeniably powerful. She creates compelling connections between microbes and the “twenty-first-century illnesses” that affect all of us in some way, shape, or form. With evidence suggesting that our microbiotas are involved in everything from autism to allergies and mental health to obesity, Collen demonstrates how they could be used to revolutionize medicine.
The potential seems fantastic and even a little frightening, but most of all, it’s fascinating.
I probably shouldn't admit this, but at points, I even found myself wondering if the idea of Peter Parker’s spider-bite turning him into Spider-Man wasn't so far-fetched. Microbes aren’t creating super-humans yet, but here are 6 surprising ways they have a huge impact on you and your body:
You Personality Isn't Set In Stone (Especially You, Cat Lady)
We often think of personality as a matter of nature vs. nurture — do your genes or the environment you grew up in play a bigger role? Yet there’s another factor: our microbiotas. Collen introduces the Toxoplasma parasite, a microbe that actually causes personality changes in infected humans. And it’s not rare.
If you’re already freaked out, I hate to break this to you, but any cat owner or person who spends time around cats can be affected. In women, it’s not so bad, as it makes them “more easygoing, warm-hearted, and trusting,” as well as “self-assured and decisive.” Men, on the other hand, “become less pleasant, disregarding societal rules and losing their sense of morality.” Collen also describes them as “more suspicious, jealous, and insecure.” From now on, owning a cat is going to be a strike against any guy I date, I guess?
What You Weigh Isn't Just Determined By Calories In And Out
You know your country has an obesity problem when your First Lady has to dance at schools to get kids moving. The idea is that encouraging our youth to exercise now will make them healthier in the long run. But what if losing weight isn’t just about burning more calories than you take in?
Collen shares a study where 12 sets of twins ate an extra 1,000 calories a day for a set period, which should have resulted in a 24-pound weight gain for each, based on the amount of excess calories they consumed. Strangely, none gained the expected weight, and the average gain was only 18 pounds. The “why” isn’t known for sure, but studies suggest that microbes may change the way our bodies convert energy and store fat.
In multiple experiments with animals, researchers have found that different bacteria and viruses are present in their obese subjects compared to their lean ones. By changing their microbiota, they can make them gain or lose weight. This may be good news for humans, Collen says. In Belgium, research is being done with a bacterium called Akkermansia muciniphilia, found in higher amounts lean people, to see if it can help battle weight gain.
Sexual Attraction Is About More Than Looks
There’s a famous study in which female college students rated how attractive they thought male students were simply by smelling shirts the guys slept in. Their rankings revealed that the ladies — completely unconsciously — were most attracted to men whose type of immune systems were most different from their own. Collen points out that the guys’ scents were produced by skin microbes, meaning that those pheromones we hear so much about are at the mercy of the microbiota. (Warning: Taking the pill messes with your ability to do this; but then again, not getting pregnant can be a useful skill, too.)
Smell isn’t the only way humans evaluate potential partners. It turns out that we don’t kiss just because it feels good; it serves yet another biological purpose. Collen describes kissing as a way to get “a sample of one another’s microbiotas.” How romantic.
What’s In Your Gut Can Change Your Mental State
Getting to someone’s heart through her stomach might not be such a bad plan after all. Collen details a French clinical trial where participants were split into two groups and each group ate a fruity-tasting bar daily for a month. The only difference between the two groups’ bars was that one group’s contained two strains of live bacteria. It may sound gross, but at the end of the month, the participants who had been eating the live bacteria scored happier than they had at the beginning. They were also less anxious and less angry. The control group didn't experience the same benefits, so that’s enough to overcome the “ick” factor if you ask me.
Good Health May Be Transferable
The real “ick” factor is actually still to come, but again, the benefits are there. When people become seriously ill, restoring their stomach’s microbiota can make a world of difference. The thing is, well, there’s no sugarcoating it, it involves a fecal transplant. (Yes, as in poop.) Collen cites many cases where such treatment helped patients with a range of medical conditions, including multiple sclerosis, horrible cases of diarrhea, rheumatoid arthritis, and Parkinson’s disease. She points out that because feces aren’t drugs, this can be a DIY treatment. Of course, you’d probably want to do your research first.
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