Free-for-all Friday: The human microbiome and behavior

Oh my gosh! Time flies. It’s been more than a minute since I wrote anything about the human microbiome. My first post was in 2015. Yips! Since then, the NIH funding for human microbiome study has increased 40-fold. It’s branched out into nearly every area that the NIH studies. The original site is for archive purposes only.

And to think, that when I first started talking about it, people looked at me like I had a screw loose, or that I went down a conspiracy rabbit hole. Wowza.

When I published my first post of the human microbiome, I reported that our bodies consisted of more microbial cells than human cells. By a margin of ten to one. And they were everywhere. Scientists had isolated microorganisms everywhere except the brain. That, they thought was just a matter of time.

Babies show different behavior patterns linked to their microbiome as early as six months.

No, scientists have not yet found microorganisms in the brain.

What do we know about microorganisms and human behavior? It’s the gut microflora that tells the story. Mothers ranked their babies on positive behaviors, such as approachability and negative behaviors, such as fear and reactivity.

…infants whose feces (and hence, gut microbiota) consisted of the bacteria Bifidobacterium and Enterobacteriaceae were found to exhibit better emotional regulation at 6 months of age. Furthermore, infants whose gut microbiota was composed of higher levels of the bacteria Bifidobacterium and Streptococcus wound up exhibiting more positive emotionality. Just as importantly, infants whose microbiota was less diverse, or consisted of fewer bacterial species, exhibited greater reactivity and expression of fear and negative emotions.

Psychology Today
close up photo of crying baby
Photo by Pixabay on

Diets high in yogurt, kefir, and sauerkraut, promote the microflora that we want for positive personality traits. “The growing notion of gut bacteria being a key correlate to good neurological and psychological function is an exciting one. The notion of intervention for gut microbiota modification opens up a whole new avenue that is worth pursuing further.” (Psychology Today.) Some of the extreme intervention is gut transplants. I’ll let you use your imagination with that one.

Your cat’s microflora just might cause you to start your own business

Say what? I know that’s an eye catcher, but here we go. Remember the Toxoplasmosis that we all dreaded when we were pregnant or knew someone who was pregnant? We kept away from cat litter and sometimes even cats. Well, it turns out that about 11% of us are infected with the organismToxoplasma gondii (T. gondii) that causes Toxoplasmosis.

According to studies, T. gondii causes mice to be less afraid of cats, resulting in them being eaten by cats, thus allowing T. gondii to complete it’s life cycle. Now, I’ve read a couple of different things about this.

assorted color kittens
Photo by Pixabay on

Theory 1: the mice actually become attracted to the odor of cat urine and seek it out. That risky behavior results in death. One group of scientists believe that this may cause infected individuals to exhibit “cat lady” behavior. You know, that person with many cats that just doesn’t seem to want to leave the house and doesn’t realize how bad it smells.

Theory 2: T. gondii changes the mouse’s behavior leading him to take more risks, leave the edge of the wall he generally scurries along and come out where he can be snagged by a hungry cat. That’s the theory purposed by Medical News Today. According to the article I read, people infected with T. gondii are more likely to get in car accidents. And they are more likely to take risks.

Now, a new study suggests that infection with the cat-borne parasite Toxoplasma gondii could make people change their behavior so that they become more prone to business and entrepreneurial ventures.

Medical News Today

Stephanie K. Johnson conducted a study on the saliva of over 200 students. She found that people with T. gondii were almost twice as likely to start their own businesses than students without T. gondii.

Infectious diseases have strongly shaped human history and culture over millions of years. Today, we like to believe our decisions and destiny are ours alone, but the contributing roles of our microscopic companions are increasingly apparent.

Medical News Today

That’s just two of the ways, according to scientists, that the human microbiome effects our behavior.

I’m really glad that the Human Microbiome Project had the foresight to set up an ethics component. Geesh! This is like science fiction, but without the fiction.

It’s no wonder the funding for research increased 40-fold

These journal articles got my scientific juices revved up. There’s a difference between causation and correlation. The mothers are reporting on their babies’ behavior. Could the data say as much about them as they do about the babies? Can a microorganism evolve to both attract a predator and to cause the predator to become less risk averse.

What do you think? Does the human microbiome freak you out? Get you excited? Or does it just bore you half to death? Well, you know what it does to me. Please tell me what you think.