Microbes, Biodiversity and the Benefits of Getting Dirty

By David Suzuki with con­tri­bu­tions from David Suzuki Foundation’s Senior Edi­tor Ian Hanington

We’re sur­rounded by life, but Earth’s most plen­ti­ful liv­ing things are invis­i­ble to the naked eye. Microbes are not only around us, they live on and in us. Although some cause mal­adies rang­ing from food poi­son­ing to small­pox, there are many we couldn’t live without.

Ben­e­fi­cial microbes break down food and pro­duce vit­a­mins in our guts. They coat our skin, pro­tect­ing us from attacks by harm­ful microbes. Out­side our bod­ies, they decom­pose organic waste, fix nitro­gen and pro­duce half the world’s oxygen.

Sci­en­tists refer to the micro­bial com­mu­ni­ties on and in our bod­ies as “micro­bio­mes”. Every one of us hosts as many as 100 tril­lion microbes — our guts alone are home to 500 to 1,000 dif­fer­ent bac­te­ria species!

Just as human activ­ity is harm­ing the diver­sity of vis­i­ble life, it’s also dimin­ish­ing micro­bial diver­sity. As researchers learn more about the pro­found ways good microbes keep peo­ple healthy, they’re also see­ing how our urban­ized, indoor lifestyles have trans­formed our micro­bio­mes, increas­ing the risk of disease.

Just as we pol­lute the envi­ron­ment out­side us, we can also pol­lute and upset the “nor­mal flora” of our bod­ies by what we eat and do. Effects range from indi­ges­tion to deadly dis­ease. One mod­ern con­se­quence of our lack of under­stand­ing about the neces­sity of healthy micro­bio­mes is seen in our use of antibi­otics. Despite their ben­e­fits, decades of overuse for per­sonal san­i­ta­tion, minor mal­adies and to pro­mote growth in live­stock has led to new ill­nesses and infec­tions as sometimes-harmful bac­te­ria evolve to resist antibi­otics and our own micro­bial defences.

Accord­ing to Alan Logan, author of Your Brain on Nature, diet and where we live and play have a tremen­dous influ­ence on the micro­bial ecosys­tems on our skin and in our noses, mouths and intestines. Logan and experts from a range of dis­ci­plines at the Nat­ural Envi­ron­ments Ini­tia­tive work­shop at Har­vard School of Pub­lic Health found peo­ple who live in areas with rich plant diver­sity have more diverse micro­bio­mes. The air we breathe, the soil we dig and the out­door plants we come into con­tact with include a vari­ety of microbes that may be absent in indoor and built environments.

Researchers have even found dig­ging in dirt, whether gar­den­ing or play­ing, can ben­e­fit our phys­i­cal and men­tal health. A microbe com­mon to mud and wet soils, Mycobac­terium vac­cae, has been shown to influ­ence brain neu­ro­trans­mit­ters to reduce anx­i­ety and improve cog­ni­tive func­tion­ing. Another microbe encoun­tered in nat­ural envi­ron­ments, Acine­to­bac­ter lwof­fii, has been shown to ben­e­fit the human immune sys­tem, pre­vent­ing asthma, hay fever and other ail­ments in chil­dren who have been exposed to it — although it can also cause infec­tions and gas­tric prob­lems for peo­ple with com­pro­mised immune systems.

Research by Ilkka Han­ski and col­leagues at the Uni­ver­sity of Helsinki found microbe diver­sity reduced the inci­dence of aller­gies. They com­pared ado­les­cents liv­ing in houses sur­rounded by bio­di­verse nat­ural areas to those liv­ing in land­scapes of lawns and con­crete. From skin swabs, they learned that higher native-plant diver­sity appears to be asso­ci­ated with greater and more diverse micro­bial com­po­si­tion on the par­tic­i­pants’ skin, which led to lower risk of a range of allergies.

It’s likely that, as we learn more about the micro­bial world, we’ll find other ben­e­fi­cial microbes in nature. The research also high­lights the impor­tance of over­all bio­di­ver­sity to human health. A good solu­tion to pro­tect­ing bio­di­ver­sity, from the small­est microbe to the largest ani­mal, and to keep­ing our­selves healthy, is for all of us to spend more time outside.

Accord­ing to the Amer­i­can Pub­lic Health Asso­ci­a­tion, “Peo­ple of all ages and abil­i­ties enjoy higher lev­els of health and well-being when they have nature nearby in parks, gar­dens, green­ways, nat­u­ral­ized school­yards and play­grounds, and nat­ural land­scap­ing around homes and workplaces.”

Peo­ple respond­ing to David Suzuki Foun­da­tion sur­veys after our annual 30X30 Nature Chal­lenge report sig­nif­i­cant mood improve­ments, more vital­ity and energy, and increases in nature-specific emo­tions like awe, curios­ity and fas­ci­na­tion. Research has also shown peo­ple who develop deeper con­nec­tions with nature are more likely to care for and pro­tect it, a phe­nom­e­non renowned biol­o­gist E.O. Wil­son called “biophilia.”

Con­sider it an inspi­ra­tion to get out­side every day of the year. It’s good for your health, mood and micro­biome — and nature!