Welcome to Sentivia

Alright, let's talk about who "I" am, or rather, who *we* are, because that's the heart of the matter. You've heard me, I'm not a philosopher, I’m a biologist. I work with the tangible, the observable, and what I see in my field, biology, makes me question this age-old debate about free will, about whether I’m truly the captain of my own ship and master of my own destiny.

The simple answer I've come to, based on the evidence I see every day, is "no, not entirely". This isn't about some mystical force, it's about biology, plain and simple. The “I” we think of, that single, autonomous entity making all these choices and forming these thoughts? I believe that's a vast oversimplification. I can confidently say this because the core of my argument is this: we’re not singular. Half the cells in your body, half *my* cells, don't have our human DNA. They're not "us" in the traditional sense. These cells are bacteria, protozoa, fungi and other single-celled creatures that we collectively call our microbiota. We are, essentially, walking, talking, thinking ecosystems.

Now, you might be thinking, "Okay, bacteria, so what? They help me digest food." But it's so much more than that. These tiny tenants, especially those in our gut, aren’t just passive passengers. They’re actively *communicating* with our brains, influencing our moods, our energy, our appetite, our memories, and even our personalities.

How do I know this? Well, I can point to the evidence with those mice I talked about - the “bubble mice”. They’re raised in sterile environments, lacking all these microbes from birth. When I look at those bubble mice versus normal mice, which are colonized with microbes at birth, it's like seeing two entirely different species. Normal mice are curious, quick learners, they explore and remember, while the bubble mice? They’re slow, lack curiosity, quick to forget, and don't even react to separation from their mothers as normal mice would. But here is the kicker: when you colonize those sterile mice with the microbiota, guess what? They start to act like normal mice.

And this isn’t just a mouse thing, I would point out. Research strongly suggests these same effects happen in us, humans. Just think about the twin study with the overweight and thin twins - that is mind-blowing. We took gut bacteria from the overweight twin, gave it to a sterile mouse, and boom, it got fat. We did the same with the thin twin, and the mouse stayed thin, even when both mice were given the same food. Then there was the depressive person gut bacteria transfer to a sterile mouse. The mouse displayed the same symptoms as the depressed person. I hope you can see the significance of this. This is compelling evidence and that is that the gut bacteria are having a profound effect on mood and behavior.

The key? They "talk" to our brains. Gut bacteria make hoards of psychoactive compounds, including neurotransmitters. They are using the same chemical language our own brains use. This conversation isn't happening by chance; it's facilitated by the vagus nerve, a major nerve cable running between the gut and the brain. And here's the kicker: 80% of the traffic is going from the gut to the brain, not the other way around. They’re not just passengers; they're actively driving. These bacteria are even using our circulatory system to send their chemical signals up into our brains. And they have a powerful way of influencing the brain through misbehaving – when bacteria invade, inflammation in the gut can also travel to the brain, which triggers depression.

We are only beginning to understand the complexity of all this. We’ve had some good progress in treating mental disturbances through VNS, stimulating the vagus nerve. And while this was developed separately from microbiome research, some think it mimics what the bacteria are doing to the nerve. They’re also trying to manipulate the gut bacteria directly. They are seeing results where certain bacteria are linked to autism or ALS. We also believe there is a strong correlation between misfolded protein in Parkinson’s disease and a certain strain of E. Coli in our guts.

So, am I the captain of my ship? Based on all of this, I can confidently say we are all more of a collective, a "we" instead of a solitary "I". Your behavior is a blend of top-down control from what we traditionally consider "you" and bottom-up control from our gut microbiota. There is a constant conversation going on between us and these little creatures, one that is clearly influencing our very being in ways that we're only starting to understand. So, are we really in complete control? Based on what I see, I don’t think so. I believe we are a complex partnership. And that’s what excites me about my work. There's so much we still don’t know, but the future of medicine and even just our understanding of human nature could be radically changed because of this research.