The human microbiome is one of the most important discoveries in modern biology — not because these organisms are new, but because we have only recently developed the tools to see them and begin to understand what they are doing. And what they are doing turns out to be far more consequential than anyone suspected.
Meeting the Microbiome
The real numbers, the myth of the "10:1 ratio," and why you are roughly half-microbe by cell count.
Built Together
How viruses gave us the placenta, how a transposon built the immune system, and why 8% of your DNA is viral.
Your First Inheritance
The birth canal, breastmilk, the first thousand days — how your microbiome is assembled and what happens when that process goes wrong.
The Body's Ecosystems
The gut, the skin, the mouth, the lungs, the urogenital tract — each site harbours a distinct microbial community with its own ecology.
The Gut–Brain Axis
How gut microbes communicate with the brain through the vagus nerve, neurotransmitters, and immune signalling — and what this means for anxiety, depression, and neurodegenerative disease.
What We're Doing to It
Antibiotics, ultra-processed food, environmental chemicals, caesarean sections — the modern assault on the microbiome and the disappearing microbiota hypothesis.
The Probiotic Paradox
Why the most popular remedy for gut health may sometimes do more harm than good — and what the science actually supports.
What's Next
Faecal transplants, phage therapy, precision prebiotics, and the frontier of microbiome-based medicine.
Written for a general readership with no specialist background required, the book follows the science wherever it leads — including the places where we are getting it wrong.
