The Human That Isn’t Human: Inside Your Stranger Self

 

A Question That Will Change Everything

“I think, therefore I am,” is the foundational statement of Descartes’ philosophy. The act of doubting proves the existence of the doubter. To think, I must exist first. But I am here to look at the “I” from a biological perspective. What exactly do we refer to when we say “I” or “me”? Are you a single entity?

Let me explain. Your body contains approximately 37 trillion human cells. Impressive number, isn't it? But here's where it gets interesting: you're also hosting roughly 38 trillion bacterial cells. That's right—you are outnumbered in your own body!

When you say "I" or "myself," who exactly are you talking about? Are you referring only to human cells? Or must you include trillions of bacteria living in your gut, on your skin, in your mouth?

This isn't just wordplay. This question strikes at the very heart of who we think we are. And by the end of this article, I promise you'll never think about yourself the same way again.

 

The Numbers That Shook Philosophy

Let me share some numbers that should make every philosopher in history deeply uncomfortable.

Your genetic reality: You have about 20,000 human genes in your DNA. That's it. But your microbiome—this community of bacteria, fungi, and viruses living in and on you—contributes more than 20 million genes (estimates vary). Do the math! You are genetically 99.9% microbial and only 0.1% human. From a genomic perspective, you're not a human being with some bacteria. You're a bacterial ecosystem that happens to have a human component!

Your weight reality: An average adult carries about 1.5 to 2 kilograms of microbes. That's the weight of a human brain! So you're literally carrying around a brain's worth of bacteria. And unlike your actual brain, which just sits there thinking, these microbes are working 24/7—digesting your food, fighting your infections, even influencing your moods.

Now, let me connect this to something closer to home. How many of you have heard your parents or grandparents say, "Beta, your gut feeling is telling you something—listen to it"? We've been saying this in our cultures for centuries, haven't we? Turns out, they were, to some extent, correct! Your gut is literally talking to your brain. And it's not even entirely your gut doing the talking—it's those trillions of bacteria!

 

A Tale of Two Patients: The Transplant Mystery

Let me tell you a true story that happened in an American hospital, but it could have implications for every single one of you here.

A woman—let's call her Javeria—was suffering from a dangerous infection called Clostridium difficile. This infection was destroying her gut, causing severe diarrhea, pain, and weight loss. Antibiotics weren't working. She was desperate.

Her doctors suggested something called Fecal Microbiota Transplantation—FMT for short. Now, I know what you're thinking. Yes, it involves exactly what it sounds like. They would take stool from a healthy donor and transplant the bacteria into Javeria's gut. Not the most pleasant dinner conversation, but stay with me!

Javeria agreed. Her teenage daughter volunteered as the donor. The procedure worked brilliantly—the infection cleared up within days. Success! But then something unexpected happened.

Over the next 16 months, Javeria gained more than 15 kilograms.

She hadn't changed her diet. She hadn't stopped exercising. But she kept gaining weight. Her doctors were puzzled until they looked at the donor—her daughter. The daughter was overweight. And somehow, that trait had transferred along with the bacteria.

Now here's my question to you: After this transplant, who is Javeria?

She has all her original memories. Her human DNA hasn't changed one bit. Her face in the mirror is the same. But trillions of organisms that came from another person are now living in her body—organisms that are influencing her weight, her metabolism, maybe even her cravings. Has she, in some real sense, become her daughter partially? Or does this reveal that she was never just "herself" to begin with?

Let's take a moment with this. Is Javeria still 100% herself? Or has she somehow become a mixture of herself and her daughter? Difficult questions. Keep thinking.

 

The Four Paths: How Should We Think About This?

Let me walk you through four different ways philosophers and scientists have tried to answer this question. Think of these as four different paths up the same mountain—the K2 of self-understanding.

 

Path 1: "I Am Only My Human Cells" (The Exclusive Self)

This is the conservative path. It says: Look, bacteria are useful, even essential, but they're tools. When a farmer uses a plough, he doesn't become the plough. When you use bacteria to digest food, you don't become the bacteria. You remain fully yourself—a human being who happens to have helpful microbial servants.

Is this view fine? It matches how we feel! Right now, you feel like one person, not a committee of trillions. When you decide to eat biryani instead of daal chawal, you experience that as your choice, not a bacterial democracy vote.

But here's the problem: Can you really call something a "tool" when removing it would kill you? You can put down a plough and walk away. But remove your microbiome, and you'd be dead within weeks. Your immune system would fail. You couldn't digest food. Your intestinal lining would deteriorate. This isn't a tool—this is part of your life-support system!

 

Path 2: "I Am an Ecosystem" (The Holobiont Self)

This is the ecological path. Scientists who study coral reefs and forests noticed something: you can't understand a coral without understanding the algae living inside it, providing it with food. You can't understand a tree without understanding the fungi connected to its roots, sharing nutrients.

They created a term: holobiont—meaning "whole living unit." It's the idea that the proper unit of life isn't an individual organism but an entire community.

Applied to you, this means: You are not a human with bacteria. You are a human-bacterial superorganism. An ecosystem. A walking, talking forest!

Let me give you a powerful example. How many of you can digest milk as adults? Quite a few. Now, most adult humans globally cannot digest milk—they're lactose intolerant. But in populations with a long history of dairy farming—parts of Europe, parts of India, and Pakistan—many adults retained the ability to digest lactose.

But here's what's fascinating: your ability to digest milk depends not just on your human genes but also on which bacteria you host! Some people can digest milk because they have Bifidobacterium species that help break down lactose. So the question "Can you digest milk?" isn't really about you alone—it's about the holobiont. It's about the team!

The problem with this view? If bacteria count as part of me, what about the mites living in my eyelash follicles? What about viruses? Where do I stop and the environment begin? Do I have moral obligations to my gut bacteria as I do to my own liver?

 

Path 3: "My Mind Extends Into My Microbes" (The Extended Mind)

Here's a more philosophical path. Some contemporary philosophers—like Andy Clark and David Chalmers—argue that your mind doesn't stop at your skull. When you use your smartphone to remember phone numbers, that smartphone has become part of your cognitive system. When a blind person uses a cane, over time, the cane becomes an extension of their sense of touch.

What if your microbiome is like that? An extended part of your emotional and cognitive systems?

Consider this: Your gut bacteria produce neurotransmitters—the same chemicals your brain uses to think and feel. They produce serotonin (which regulates mood), dopamine (which affects motivation and pleasure), and Gamma-aminobutyric acid (which calms anxiety). About 90% of your body's serotonin is actually produced in your gut!

There's a nerve called the vagus nerve that runs from your gut to your brain like a telephone cable. Your gut bacteria send signals up this nerve, influencing your emotions and decisions. In a very real sense, your bacteria are part of your nervous system—an outsourced emotional processing unit!

Here is a stunning experiment: Scientists took mice with anxiety-like behaviors and mice that were calm and bold. They swapped their gut microbiomes. And guess what? The anxious mice became bold. The bold mice became anxious. Their personalities transferred with their bacteria!

But here is a question: If you suffer from depression or anxiety, is it just "you" who's struggling? Or is it your holobiont—your human-microbial system—that needs healing?

 

Path 4: "I Am the Story I Tell" (The Narrative Self)

Now here's the most culturally resonant path for many of us. In our South Asian traditions, there's a long recognition that the self is not a fixed thing but a flowing process. The Buddha taught anatta—no permanent self. Rumi wrote about the self as a guest house, with different visitors constantly coming and going.

Modern philosophers like Daniel Dennett echo this: your self is not a thing but a story. It's a narrative you construct through memory, anticipation, and the stories you tell about your life.

From this perspective, are bacteria part of "you"? Well, do you include them in your life story? When you tell someone about yourself, do you say, "I'm a teacher, I have two children, and I have Bacteroides in my colon"? No! You don't think about your bacteria, so they're not part of your felt identity.

This explains why Javeria, our FMT patient, didn't have an identity crisis. Even though trillions of her bacteria came from her daughter, her memories remained intact. Her life story continued. She was still Javeria.

But here's the catch: Just because you don't think about something doesn't mean it's not important! You don't think about your liver either, but it's certainly part of you. So this narrative approach might be too subjective, too dependent on what we happen to notice or care about.

 

The Science: Just How Deep Does This Go?

Now let me share some research that will make all of this feel less abstract and more urgent.

Your Mood is Not Just Yours

Let me describe an experiment that sounds like science fiction but is absolutely real.

Scientists identified humans suffering from depression. They took samples of their gut bacteria. Then they transplanted these bacteria into mice that had been raised completely germ-free—mice with no microbiomes at all. And those mice started showing depression-like behaviors! They gave up more quickly when faced with challenges. They showed less interest in pleasurable activities. They behaved depressed.

Then the scientists did the reverse. They took bacteria from healthy, happy humans and transplanted them into germ-free mice. Those mice behaved normally—curious, resilient, engaged.

Let that sink in for a moment. A mental state—depression—can be transferred through bacteria. Your sadness, your anxiety, might not be entirely "yours." It might be, at least partially, a property of your ecosystem.

This has practical implications. In fact, some promising studies are showing that certain probiotic strains—they're calling them "psychobiotics"—can reduce anxiety and improve mood. We're not talking about miracle cures, but we're talking about real, measurable effects.

Question for you: If a probiotic can help lift depression, does that make the depression less "real"? Less worthy of compassion? I'd argue exactly the opposite! It shows how deeply biological, how systemic, mental suffering truly is. It's not "all in your head"—it's in your gut too!

 

Your Cravings Might Be Bacterial Demands

How many of you have experienced this? You're sitting at home, minding your own business, and suddenly—powerfully—you crave something sweet. Maybe jalebi, maybe gulab jamun. You need sugar. Is that your craving? Or is it your bacteria's?

Here's what we know: Different bacterial species thrive on different nutrients. Some love sugar. Some love fiber. Some love fat. And there's growing evidence that they can influence your brain to crave what they need!

Let’s talk about an experiment with mice. Scientists altered their gut bacteria. Mice that had been eating normally suddenly changed their food preferences. Some started craving more fats. Others wanted more carbohydrates. The cravings followed the bacterial composition.

Now, I'm not saying every time you want biryani, it's a bacterial conspiracy! But I am saying the picture is more complicated than "I chose to eat this." Your choices emerge from a conversation between your conscious mind, your human body, and your microbial partners.

Think about Ramadan. During fasting, your microbiome composition changes significantly. By the end of Ramadan, many people report that their cravings have shifted—they desire simpler foods, less sugar. Is that spiritual growth? Physical adaptation? Or bacterial evolution? Maybe it's all three! Maybe these categories aren't as separate as we thought.

 

The Obesity Mystery

Let me tell you about another shocking experiment. Scientists took two groups of mice. One group was obese, and the other was lean. Both groups ate exactly the same food and exercised the same amount. The only difference was their genes—some genetic strains of mice tend toward obesity.

Then researchers did something clever. They took the gut bacteria from the obese mice and put them into germ-free lean mice. What happened? The lean mice became obese! Without any change in diet or exercise, just by changing their bacteria, they gained significant weight.

They did the reverse too—took bacteria from lean mice, transplanted them into germ-free obese mice. And those mice lost weight!

What this means for humans: Yes, genetics matter. Yes, diet and exercise matter. But your microbiome also matters—a lot. It affects how many calories you extract from food, how you store fat, and how your metabolism functions.

This should change how we think about body weight. If someone struggles with obesity, telling them "just eat less, exercise more" ignores a crucial part of the equation: their bacterial ecosystem. We need to think about metabolic health as a property of the holobiont, not just the human.

 

Your Immune System Went to Microbial School

Here's something that should make every parent pay attention.

When a baby is born—especially through vaginal delivery—they're immediately colonized by bacteria from the mother. This is not accidental. This is nature's plan! Within hours, trillions of bacteria take up residence in the baby's gut, on their skin, everywhere.

And here's the critical part: these bacteria train the baby's immune system. They teach it the difference between dangerous invaders and harmless substances. They're like the baby's first teachers, running an intensive boot camp for immune cells.

What happens when this doesn't occur properly? When babies are born by C-section (which is sometimes medically necessary, of course), or when children grow up in overly sterile environments, or when they're given too many antibiotics too early?

Their immune systems don't receive proper education. And the result? Higher rates of allergies, asthma, eczema, and autoimmune diseases. The immune system, never properly trained, starts attacking harmless things—pollen, peanuts, even the body's own tissues!

This is called the "hygiene hypothesis," and it's been confirmed by studies across different countries. Children who grow up on farms—exposed to dirt, animals, diverse bacteria—have significantly lower rates of allergies than children in cities. Their immune systems received a better education!

The wisdom of our grandmothers: How many of you were told, "Don't be afraid of a little dirt!" or "Beta, you need to build your immunity!"? They were onto something profound. Our traditional acceptance of children playing in soil, eating with hands, living closely with extended families—all of this provided microbial diversity. Sterility, it turns out, has costs.

 

The Big Questions: What Does This Mean for How We Live?

Now that we understand the science, let's grapple with the implications. Because this isn't just abstract philosophy—this changes how we should think about medicine, ethics, and life itself.

 

Question 1: Are You Really Responsible for Your Actions?

If bacteria influence your mood, your cravings, your decisions—are you still fully responsible for your choices?

Let me be clear: Yes, you are. But let me explain why this doesn't contradict what we've learned.

You're also influenced by your genes, your upbringing, your culture, your education, the books you've read, and the friends you keep. None of us makes choices in a vacuum. We're all products of countless influences. But we still hold people accountable because they have the capacity to reflect, to resist impulses, to change.

Your microbiome is just one more factor in this complex equation. It doesn't eliminate free will—it contextualizes it. It shows us that will is never entirely "free" in the sense of being uncaused, but it's still meaningfully yours in the sense that you experience it, you can reflect on it, and you can work to change it.

Practical wisdom: This should make us more compassionate—toward ourselves and others. When someone struggles with depression, with obesity, with addiction, we should recognize the biological complexity involved. This doesn't excuse harmful behavior, but it should soften judgment and increase support.

 

Question 2: What Does This Mean for Medicine?

If you're a holobiont—an ecosystem—then medicine must become ecological.

The problem with antibiotics: When you take broad-spectrum antibiotics, you're essentially napalming your gut. You kill the bad bacteria causing your infection, but you also massacre beneficial species. You destroy ecosystems that took years to establish.

This is sometimes necessary! If you have a serious bacterial infection, antibiotics can be life-saving. But we're using them far too casually—for every minor cold, every viral infection (where they don't even work!), every slight discomfort.

Better approach: Precision. We need antibiotics that target specific pathogens without destroying beneficial bacteria. We need probiotics and prebiotics to rebuild damaged ecosystems. We need to recognize that treating the human body requires treating the entire holobiont.

For you personally: Ask your doctor if antibiotics are truly necessary. If you must take them, ask about probiotics to help rebuild your microbiome. Eat fermented foods—yogurt, lassi, achaar (pickle), kefir—which introduce beneficial bacteria. Eat fiber—the food your bacteria need to thrive.

 

Question 3: Does This Change Who Gets Moral Consideration?

Here's an uncomfortable question: If bacteria are part of you, do they have moral status? Should we feel guilty about killing them?

Most ethical frameworks say no—bacteria lack consciousness, subjective experience, the capacity to suffer. They're more like cells in your liver than like pets or people. Killing bacteria isn't murder.

But—and this is important—we should recognize bacteria's value. Not moral value in the sense of deserving rights, but instrumental value in maintaining the ecosystem we call "you." Destroying your microbiome unnecessarily harms you, so we should avoid it.

Environmental connection: Once you see yourself as an ecosystem, you realize you're continuous with larger ecosystems—your family, your community, your environment. The chemicals we dump in rivers harm bacteria there and in our guts. The antibiotics we give to livestock enter the food chain and affect human microbiomes. The pollution in our cities disrupts microbial communities everywhere.

Protecting the environment isn't just about saving polar bears or rainforests (though that's important too!). It's about protecting the microbial diversity that all life—including human life—depends on.

 

So... Who Are You?

We've come full circle. Let me answer the question I started with: When you say "I," who are you talking about?

Here's my answer, and I think it's the only honest one: You are all of it.

You are the 37 trillion human cells carrying your unique DNA.

You are the 38 trillion bacterial cells that co-evolved with you, that digest your food, train your immune system, and influence your moods.

You are the conscious experience—that felt sense of being someone, of seeing through these eyes, of thinking these thoughts.

You are the story—the memories linking your past selves to your present self, the anticipation linking you to future selves.

You are the relationships—son or daughter, brother or sister, friend, colleague—existing in a web of connections.

You are the ecosystem—the holobiont—a walking universe of interdependent life.

These are not contradictory. They're different levels of description, all simultaneously true. Like how water can be described as H₂O molecules, or as a flowing liquid, or as the ocean's majesty—each description captures something real.

The mistake is thinking identity must be simple, singular, and bounded. The truth revealed by biology is that identity is complex, plural, and porous. And that's not a problem to solve—it's a wonder to embrace!

 

“I” is We

You started reading this article thinking you were one person. Now you know you're trillions. You thought you ended at your skin. Now you know you're continuous with all life. You thought identity was simple. Now you know it's marvelously complex.

And that's not a loss of self—it's an expansion of self beyond anything you imagined.

You are not a drop in the ocean. You are the entire ocean in a drop - Rumi

I am because we are – African proverb

 

Thank you—thank you to all the trillions of bacteria that made it possible for each of us to write and read this article!