Wednesday, April 10, 2013

Letting Biodiversity get Under Our Skin: Why Cleanliness Might be Making Us Sick

This is a very interesting article, perhaps a revolutionary idea. And, it may have important lessons for complex human systems.

Rob Dunn[1] writes in the recent edition of Utne Reader, “We live at the crossroads of three global megatrends, three barreling and intertwined juggernauts of modernity. The first is the massive migration of humanity to the world’s cities. By 2050, two-thirds of all humans on Earth will live in urban areas.

The second is the loss of biodiversity. Species are disappearing, both from the places where we live and from the earth as a whole. If our hairy ancestors were to visit our cities and suburbs, they would wonder how the escalators work, but they would also question where the plants and animals have gone. What have we done with all the birds? Some, like the Carolina parakeet, are just gone. Others live on, but at a distance—geographically removed from our daily lives, far away from the majority of people.

And then there’s the third trend—the one that, at first glance, seems not to belong with the others. The prevalence of allergies and chronic inflammatory diseases among urban populations in developed countries has skyrocketed in recent years. Incidences of asthma, Crohn’s disease, multiple sclerosis, and even depression (which can have an immune component) are on the rise
The parallels in geography and timing between urbanization, the loss of biodiversity, and the rise in immune-system problems raise an intriguing—and troubling—question. Could our distance from nature and our chronic immunological discontent be related? Some now say … yes.”

The author summarizes the work of Ilkka Hanski, a Finnish scientist working in the field of ecology at the University of Helsinki, Finland, “comparing the allergies of adolescents living in houses surrounded by biodiversity to those of adolescents surrounded by simplicity—the modern landscape of cement and grass. They found that those individuals who lived in houses surrounded by a greater diversity of life were themselves covered with different kinds of microbes. They were also less likely to show the telltale immunological signs of allergies.”

This is a potentially revolutionary finding. But, as Dunn points out, “No one has offered a very compelling explanation of how the diversity of plants or life in general in backyards alters the composition of bacteria on human skin. But the bigger question is how the composition of bacteria on our skin (perhaps in concert with the diversity of plants and other organisms outside) influences our potential to develop allergies. Several options have emerged.”

·         “…the immune system is our sixth sense. It is our inner taxonomist. And this inner taxonomist needs to see a lot of species to learn to distinguish good from bad from innocuous. If it does not, it makes mistakes. It sees our body’s own cells or pollen grains and judges them to be dangerous. In this model, the world around us needs to be diverse enough for our immune system to gain perspective.”

·         “…the odds of having some beneficial bacteria species in a house increase with certain kinds of microbial diversity.” This results in a kind of “insurance policy.”

·         “Finally, a third possibility harks back to ancient wars. Bacteria and fungi compete. Fungi are everywhere in households and, in contrast to bacteria, seem more likely to cause allergies than to prevent them. Fungal diversity appears to be lower in houses where bacterial diversity is higher. Maybe more diverse household bacteria can fight off fungi, winning an invisible war on our behalf.”

I would speculate that there may be another reason. Maybe it takes a naturally occurring complex system of bacteria to produce a health immune system.

In 1999, maybe George Carlin was right in his rant about germs and our immune system. He said[2], “When I was a little boy in New York City in the 1940s, we swam in the Hudson River and it was filled with raw sewage okay? We swam in raw sewage! You know… to cool off! And at that time, the big fear was polio; thousands of kids died from polio every year but you know something? In my neighborhood, no one ever got polio! No one! Ever! You know why? Cause we swam in raw sewage! It strengthened our immune systems! The polio never had a prayer; we were tempered in raw shit! - I never get infections, I don’t get them, I don’t get colds, I don’t get flu, I don’t get headaches, I don’t get upset stomach, you know why? Cause I got a good strong immune system and it gets a lot of practice.”

Dunn concludes with, “As we wait for more understanding, we continue to simplify the world. We will become more urban and thus more likely to suffer from allergies and autoimmune diseases, at least if Hanski is right. And if he is right, there may also be a way forward, a way out of our sick and simple morass. Could we rewild the places around us, plant a richness of species in our backyards and so raise healthier children covered in more kinds of bacteria? Whatever we do, we will be measured by our immune systems and our microbes, which in their function or dysfunction seem to record the richness of our lives.”

Perhaps the lesson we could learn for this is that attempts to simplify complex systems that have to operate in complex environments will only harm the system in the long run. We could learn this from the failures of regimented, hierarchal political systems, or corporate systems. Yet we continue to attempt simplification of, for example, education by trying to reduce it to a standardized test. Or, racial, ethnic, religious or thought purity.

“Letting Biodiversity get Under Our Skin: Why Cleanliness Might be Making Us Sick”, Rob Dunn, Utne Reader, March – April 2013 from Conservation,

[1] Rob Dunn is a science writer and biologist in the Department of Biology at North Carolina State University. His new book is The Wild Life of Our Bodies. Excerpted from Conservation (Fall 2012), an independent science magazine published by the University of Washington.

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