Science writer Ed Yong’s book revealing, at least to us civilians, the millions of microbes that dwell within each of us caused quite a stir and became a New York Times bestseller. Next week, I Contain Multitudes: The Microbes Within Us and a Grander View of Life comes out in paperback, from Ecco (an imprint of HarperCollins), which published the hardcover edition as well. Yong will be at Kramerbooks in DC this Tuesday, January 16, 2018, at 6:30pm to talk about his work. You can also connect with him here. This excerpt is from the book’s prologue.
WHEN ORSON WELLES said “We’re born alone, we live alone, we die alone”, he was mistaken. Even when we are alone, we are never alone. We exist in symbiosis—a wonderful term that refers to different organisms living together. Some animals are colonised by microbes while they are still unfertilised eggs; others pick up their ﬁrst partners at the moment of birth. We then proceed through our lives in their presence. When we eat, so do they. When we travel, they come along. When we die, they consume us. Every one of us is a zoo in our own right—a colony enclosed within a single body. A multi-species collective. An entire world.
These concepts can be hard to grasp, not least because we humans are a global species. Our reach is boundless. We have expanded into every corner of our blue marble, and some of us have even left it. It can be weird to consider existences that play out in an intestine or in a single cell, or to think about our body parts as rolling landscapes. And yet, they assuredly are. The Earth contains a variety of different ecosystems: rainforests, grasslands, coral reefs, deserts, salt marshes, each with its own particular community of species. But a single animal is full of ecosystems too. Skin, mouth, guts, genitals, any organ that connects with the outside world: each has its own characteristic community of microbes. All of the concepts that ecologists use to describe the continental-scale ecosystems that we see through satellites also apply to ecosystems in our bodies that we peer at with microscopes. We can talk about the diversity of microbial species. We can draw food webs, where different organisms eat and feed each other. We can single out keystone microbes that exert a disproportionate inﬂuence on their environment—the equivalents of sea
otters or wolves. We can treat disease-causing microbes—pathogens—as invasive creatures, like cane toads or ﬁre ants. We can compare the gut of a person with inﬂammatory bowel disease to a dying coral reef or a fallow ﬁeld: a battered ecosystem where the balance of organisms has gone awry.
These similarities mean that when we look at a termite or a sponge or a mouse, we are also looking at ourselves. Their microbes might be different to ours, but the same principles govern our alliances. A squid with luminous bacteria that glow only at night can tell us about the daily ebbs and ﬂows of bacteria in our guts. A coral reef whose microbes are running amok because of pollution or overﬁshing hints at the turmoil that occurs in our guts when we swallow unhealthy food or antibiotics. A mouse whose behaviour changes under the sway of its gut microbes can show us something about the tendrils of inﬂuence that our own companions insinuate into our minds. Through microbes, we ﬁnd unity with our fellow creatures, despite our incredibly different lives. None of those lives is lived in isolation; they always exist in a microbial context, and involve constant negotiations between species big and small. Microbes move between animals, too, and between our bodies and the soils, water, air, buildings, and other environments around us. They connect us to each other, and to the world.
All zoology is really ecology. We cannot fully understand the lives of animals without understanding our microbes and our symbioses with them. And we cannot fully appreciate our own microbiome without appreciating how those of our fellow species enrich and inﬂuence their lives. We need to zoom out to the entire animal kingdom, while zooming in to see the hidden ecosystems that exist in every creature. When we look at beetles and elephants, sea urchins and earthworms, parents and friends, we see individuals, working their way through life as a bunch of cells in a single body, driven by a single brain, and operating with a single genome. This is a pleasant ﬁction. In fact, we are legion, each and every one of us. Always a “we” and never a “me”. Forget Orson Welles, and heed Walt Whitman: “I am large, I contain multitudes.”
From I Contain Multitudes by Ed Yong. Copyright Ed Yong 2016. Excerpted with permission of Ecco/HarperCollins.