DAVID SUZUKI: Getting dirty may be good for you

Early indications are that introducing some germs to one's environment may help boos immunities

For much of human history we lived close to the natural world. As civilization evolved we became increasingly urbanized, and most of us now live in cities. As we’ve moved away from nature, we’ve seen a decline in other forms of life.

Biodiversity is disappearing. The current rate of loss is perhaps as high as 10,000 times the natural rate. The International Union for Conservation of Nature’s 2008 Red List of Threatened Species shows 16,928 plant and animal species are threatened with extinction.

According to an article in Conservation magazine, there is a link between biodiversity and human health. Ilkka Hanski and his colleagues at the University of Helsinki compared allergies of adolescents living in houses surrounded by biodiverse natural areas to those living in landscapes of lawns and concrete. They found people surrounded by a greater diversity of life were themselves covered with a wider range of different kinds of microbes than those in less diverse surroundings. They were also less likely to exhibit allergies.

What’s going on? Discussion of the relationship between biodiversity and human health is not new.  Richard Louv, author of Last Child in the Woods, says people who spend too little time outdoors experience a range of behavioural problems, which he calls “nature deficit disorder.” It fits with theories of modern ecology, which show systems lacking in biodiversity are less resilient, whether they’re forests or microbial communities in our stomachs or on our skin.

Less resilient systems are more subject to invasion by pathogens or invasive species.

Hanski studied a region in Finland where few people move far. He randomly selected 118 adolescents in an equal number of homes, some in the city, others in the woods or on farms. The team collected skin swabs from subjects and measured the biodiversity of plants around each house. Their data revealed a clear pattern: higher native-plant diversity appeared to be associated with altered microbial composition on the participants’ skin, which led in turn to lower risk of allergies.

The immune system’s primary role is to distinguish deadly species from beneficial and beneficial from simply innocent. To work effectively, our immune system needs to be “primed” by exposure to a diverse range of organisms at an early age. In this way it learns to distinguish between good, bad and harmless.

If not exposed to a wide array of species, it may mistakenly see a harmless pollen grain as something dangerous and trigger an allergic reaction. We also know that bacteria and fungi compete. Fungi are often associated with allergies, and it could be that high diversity of bacteria keeps the fungi in check.

A conclusive explanation for Hanski’s observations is not yet available. But we know we evolved in a world full of diverse species and now inhabit one where human activity is altering and destroying an increasing number of plants, animals and habitats.

We need to support conservation of natural areas and the diverse forms of life they contain, plant a variety of species in our yards, avoid antibacterial cleaning products and go outside in nature and get dirty – especially kids.

Our lives and immune systems will be richer for it.

Just Posted

Vancouver measles outbreak prompts vaccine vigilance on Island

Island health authorities push measles vaccinations - and not just for kids

Watershed concerns prompt opposition to alternate Malahat routes

Motion submitted to Regional Water Supply Commission opposing highway in watershed

Crews are on scene after a water main break on Goldstream and Strathmore in Langford

Some residences have been evacuated and traffic is being diverted

Remembering Nirvana in Victoria on Cobain’s 52 birthday

Nirvana played one show in Victoria on March 8, 1991 at the Forge

Head-on collision in Saanich draws attention to rural road safety

Saanich says additional road safety measures are already planned or underway

‘Riya was a dreamer’: Mother of slain 11-year-old Ontario girl heartbroken

Her father, Roopesh Rajkumar, 41, was arrested some 130 kilometres away

Greater Victoria Wanted List for the week of Feb. 19

Greater Victoria Crime Stoppers is seeking the public’s help in locating the… Continue reading

Market volatility, mortgages loom over upcoming earnings of Canada’s big banks

Central bank interest hikes have padded the banks’ net interest margins

Hearings into SNC-Lavalin affair start today, but not with Wilson-Raybould

She has repeatedly cited solicitor-client privilege to refuse all comment

VIDEO: 8 things you need to know about the 2019 B.C. budget

Surplus of $247 million with spending on children, affordability and infrastructure

Tilray to acquire hemp food company Manitoba Harvest for up to $419 million

Tilray will pay $150 million in cash and $127.5 million in stock.

Tears, flowers at impromptu memorial for Syrian children killed in Halifax fire

The family had only lived in the Quartz Drive home for a few months

NDP candidates push for stronger climate action as Singh supports LNG Canada

Singh has tried to project unity in the party while facing internal criticism for poor fundraising and low support in the polls

‘Bullet missed me by an inch’: Man recounts friend’s killing at Kamloops hotel

Penticton man witnessed Summerland resident Rex Gill’s murder in Kamloops

Most Read