The word “biodiversity” means the number and variety of living things existing in a specific area. The more biodiverse an ecosystem, the more resilient it is to perturbation or upset. We normally think of biodiversity in terms of the animals and plants we can see. But biodiversity may be even more important in the world we can’t see.
Starting in the 1950s, U.S. doctors and scientists noticed an increase in the kinds of diseases that couldn’t be related to a specific “bad” germ…things like asthma, allergies, Crohn’s disease and ulcerative colitis. In fact, these diseases seemed to be caused by inflammation within the body itself. Is it simply that we now live long enough to develop other diseases? Scientists don’t think so.
According to the Microbiome (or Hygiene) Hypothesis, as westernized life disconnected from the earth that nourishes us and moved indoors, we weakened our immune health. Michael Pollen, the author of Omnivore’s Dilemma, is quoted as saying, “Some researchers believe that the alarming increase in autoimmune diseases in the West may owe to a disruption in the ancient relationship between our bodies and their 'old friends'—the microbial symbionts with whom we coevolved.”
Each of us is home to 100 TRILLION BENEFICIAL organisms living in and on us, in complex communities that are essential to our health and survival. They protect our skin from invasion, synthesize and transfer amino acids, ferment and digest fiber, signal cells to wage war against harmful viruses, on and on.
In 2007, the National Institutes of Health launched the Human Microbiome Project (HMP) to genetically sequence the microbial biodiversity of healthy humans. By 2013, several studies were pointing out that loss of microbial diversity and changes in the “community architecture” play a role in Crohn’s and inflammatory bowel diseases. (https://commonfund.nih.gov/hmp)
A 2012 Finnish study reported in the journal Pediatrics that babies raised with dogs had fewer colds and ear infections than those raised in a pet-free household, especially if the dog spent time OUTSIDE.
In a 2012 study of Amish and Hutterite children reported in the New England Journal of Medicine in 2016*, Amish kids were much less allergic than Hutterite children even though the house dust from Amish homes had seven times more bacterial remnants than that of Hutterite homes. Amish and Hutterites are genetically very similar. However, Amish live on single-family farms and use animals for farming. Hutterites practice large-scale modern agriculture, using tractors, fertilizers and pesticides, with their homes located farther from their fields. Amish kids have daily contact with work animals and the earth. When an extract of Amish house dust was introduced into the nasal passages of germ-free mice that had induced asthma symptoms, the mice exhibited reduced airway excitability and inflammation.
But, before you start creeping around in Amish houses to collect dust to enhance your immune system, consider stepping out into your own backyard. Healthy soil rich in organic matter can contain up to one BILLION bacteria per teaspoonful. Allow your hands to come in contact with the soil. Go barefoot for a minute. Plant something in the dirt. Grow some of your own fruits and vegetables. It will increase your own biodiversity.
We all live very close to our national forests. Go there! A square meter of forest floor may contain hundreds of thousands of microarthropods representing thousands of species (Ecology Center). Touch a tree; make contact with the soil. The Japanese practice of being quiet in the forest (“forest bathing”) provides not only psychological and spiritual benefits, but real physical benefits as well.
For the sake of all our immune systems, let’s get our hands dirty!
* https://www.nejm.org/doi/full/10.1056/NEJMoa1508749
Source: Never Home Alone by Rob Dunn; “Absence as a Disease” Hachette Book Group, New York, 2018.
Rebecca Miller-Cripps is a University of California Cooperative Extension Master Gardener of Tuolumne County.
UCCE Master Gardeners of Tuolumne and Calaveras Counties can answer home gardening questions. Call 209-533-5912 or go to: Ask a Master Gardener to fill out our easy-to-use problem questionnaire. Check out our website at: https://ucanr.edu/site/uc-master-gardeners-central-sierra. You can also find us on Facebook and on the radio at kaad-lp.org or 103.5 FM on Motherlode Community Radio.