Saturday, June 11, 2011

The Gravity of Life

Whose well-being is threatened by our changing relationship with the myriad organisms that shaped the evolution of our species?

By Rob Dunn

HarperCollins Publishers,

My body is crawling with life. Fungi live on my feet. Trillions of bacteria cling to my legs and up among my bits. In this mix live Staphylococcus hominis and aureus, which are found on my skin, and Enterococcus mundtii, the most common denizen of my belly button. But they are just the tip of the “life berg.”

Nearly two hundred species of bacteria have been found residing on human forearms alone. Some are probably bad; some, good; and some, essential. Others may simply be sojourners, pausing en route to some more distant shore. Inside my gut, there might be worms of several different species. There are certainly hundreds of species of microbes in my digestive tract upon which I rely to fully digest my food. There are fungi inhabiting my lungs. There are, I suspect, mites living in the pores of my forehead and yet more fungi in my hair.

All humans on Earth share their bodies with multiple biomes of many other species from which our existence is inextricable. Cataloging and understanding these organisms and how they are evolving as our lifestyles change—as we give up old, dirty ways for new, clean (and in some ways less healthy) ones—is part of what I write about in my new book, The Wild Life of Our Bodies.

Of course, these microscopic creatures are not the only partners in our dance. I also have a tiger in my body, snakes slithering among my neurons, honeybees and thousands of other species ingrained in my being. These ancestral predators and collaborators have all left deep signatures in my genome.

My relationship to the deadly and damaging organisms that influenced the fate of my ancestors, be they bacteria, or bears, is similar to that which exists between land plants and gravity. Plants that grow on land have evolved hormones that help them sense which way is up so they can grow against gravity. They require special structures in and around their cells to keep their flowers, leaves, and stems from surrendering to the planet’s mass. Evolutionarily, gravity killed, or at least disfavored, ancestral or proto-plants that did not adapt to its inescapable presence.

Yet, when NASA scientists grow plants in the microgravity of space, they become crooked and sick. Without gravity, up and down are rendered meaningless, and the plants suffer.

Something similar has happened with my body, and yours, as modern humans have altered our relationships with our evolutionary dance partners. Parasites and predators were the gravity that attended the evolution of our species. They were the forces which directed our history. The fight-or-flight response, for example, which prompts my body to make snap decisions in times of danger, anxiety, or stress, was honed and shaped by the dependable threat of snakes and other predators. My immune system evolved, in part, to cope with the constant presence of worms. Nor is it simply our ancient nemeses that shaped who we are. My taste buds evolved to lead me toward foods that were once rare but extremely valuable (salts, sweets) and away from those that were deadly.

But through technology and “civilization” we have changed the fate of the species that were such an intimate part of our development. We kill off the predators from around our villages. We eradicate the worms from our guts. We scrub some of the bacteria from our hands and faces.

The Wild Life of Our Bodies recounts the stories of the species whose influence persists in and on our bodies and explores the consequences of the evolutionary and ecological changes we have forced them to make. We may be able to grow a plant on the Moon (or near the Moon, at least), but we cannot escape the gravity of life, the forces that shaped us. As high as we jump, we always fall back down into the rest of life—that web of interactions and wild species from which we are made.

Rob Dunn is a writer and biogeographer at North Carolina State University (www.robrdunn.com). His writing explores the stories of the scientists who seek to understand our lives and the lives of the species with which we interact. His first book, Every Living Thing: Man’s Obsessive Quest to Catalog Life, from Nanobacteria to New Monkeys, won the National Outdoor Book Award for Natural History writing. His own science probes the geography of life—most recently of ants, belly-button microbes, and human diseases. Read an excerpt from The Wild Life of Our Bodies, Chapter 9–”We Were Hunted, Which is Why All of Us are Afraid Some of the Time and Some of Us are Afraid All of the Time.“

Source: The Scientist
http://the-scientist.com/2011/05/30/the-gravity-of-life/

The Wild Life of Our Bodies: Predators, Parasites, and Partners That Shape Who We Are Today [Hardcover]

Rob Dunn (Author)

Editorial Reviews

Review

“Adding touches of humor along the way, Dunn deftly explains complex biological systems for the general reader. […] Highly recommended for nature aficionados, this book should inspire many lively discussions.” (Library Journal )

The Wild Life of Our Bodies is an extraordinary book about a previously little explored subject. With clarity and charm the author takes the reader into the overlap of medicine, ecology, and evolutionary biology to reveal an important domain of the human condition. (Edward O. Wilson, University Research Professor Emeritus, Harvard University )

Product Description

A biologist shows the influence of wild species on our well-being and the world and how nature still clings to us—and always will.

We evolved in a wilderness of parasites, mutualists, and pathogens, but we no longer see ourselves as being part of nature and the broader community of life. In the name of progress and clean living, we scrub much of nature off our bodies and try to remove whole kinds of life—parasites, bacteria, mutualists, and predators—to allow ourselves to live free of wild danger. Nature, in this new world, is the landscape outside, a kind of living painting that is pleasant to contemplate but nice to have escaped.

The truth, though, according to biologist Rob Dunn, is that while "clean living" has benefited us in some ways, it has also made us sicker in others. We are trapped in bodies that evolved to deal with the dependable presence of hundreds of other species. As Dunn reveals, our modern disconnect from the web of life has resulted in unprecedented effects that immunologists, evolutionary biologists, psychologists, and other scientists are only beginning to understand. Diabetes, autism, allergies, many anxiety disorders, autoimmune diseases, and even tooth, jaw, and vision problems are increasingly plaguing bodies that have been removed from the ecological context in which they existed for millennia.

In this eye-opening, thoroughly researched, and well-reasoned book, Dunn considers the crossroads at which we find ourselves. Through the stories of visionaries, Dunn argues that we can create a richer nature, one in which we choose to surround ourselves with species that benefit us, not just those that, despite us, survive.