Imagine New York City with the lights all on, but nobody home — indeed, nobody anywhere. A city fully intact and yet uninhabited. Would it still be a city, or would we refer to it as the place formerly known as New York City?

The image I’m conjuring up is not meant to represent the aftermath of some catastrophe, but rather, if we were to think of NYC as representing a human body, what that body would be like if it was stripped of its microbial life.

When the human body is described as being a host to a multitude of microbial organisms, by implication those organisms are viewed as guests. We might have some sense that we need these guests — even that we cannot survive without them — but they belong to us rather than us to them.

Why?

The “I” that stands at the center, possessed — or so it imagines — with some kind of regal authority over this domain called a person, is really a fiction.

Life in the city which is the body, continues just the same whether the monarch is awake or unconscious.

Jane Brody writes: We may think of ourselves as just human, but we’re really a mass of microorganisms housed in a human shell. Every person alive is host to about 100 trillion bacterial cells. They outnumber human cells 10 to one and account for 99.9 percent of the unique genes in the body.

Katrina Ray, a senior editor of Nature Reviews, recently suggested that the vast number of microbes in the gut could be considered a “human microbial ‘organ’” and asked, “Are we more microbe than man?”

Our collection of microbiota, known as the microbiome, is the human equivalent of an environmental ecosystem. Although the bacteria together weigh a mere three pounds, their composition determines much about how the body functions and, alas, sometimes malfunctions.

Like ecosystems the world over, the human microbiome is losing its diversity, to the potential detriment of the health of those it inhabits.

Dr. Martin J. Blaser, a specialist in infectious diseases at the New York University School of Medicine and the director of the Human Microbiome Program, has studied the role of bacteria in disease for more than three decades. His research extends well beyond infectious diseases to autoimmune conditions and other ailments that have been increasing sharply worldwide.

In his new book, “Missing Microbes,” Dr. Blaser links the declining variety within the microbiome to our increased susceptibility to serious, often chronic conditions, from allergies and celiac disease to Type 1 diabetes and obesity. He and others primarily blame antibiotics for the connection. [Continue reading…]

Want to diversify your own ecosystem?

It’s easier than you might imagine. Just start making your own kefir — a fermented milk drink. There’s very little skill required.