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  • Writer's picturePete Salmansohn


To make sense of the world, one generally needs guideposts, perspectives and teachings

--- typically designed by brilliant and wise individuals, usually from the past. For many, that

might come from religion or the Bible. For others, it might be existentialism, Freud, paganism,

or various interpretations of spirituality. But for those of us seeking to understand how the

natural world works, a very useful and elegantly simple outline comes from the late Dr. Barry Commoner, one of the greatest ecologists of the last 100 years. His “Four Laws of Ecology,” first postulated in the early 1970s in his book

The Closing Circle, is something I have used for decades in my teaching and is, I believe, very much worth sharing with colleagues looking for a useful overview of a complicated world. Each “law” can be interpreted in dozens of tangible ways and it’s up to us educators, I believe, to find ways to share this wisdom with our audiences and to use in our daily lives as we seek to interpret current and global events.

Commoner’s First Law of Ecology: Everything is Connected to Everything Else.

Thus, all healthy ecosystems are interconnected and self-stabilizing; if any part of a natural ecosystem is damaged or overstressed it can trigger far wider problems. For example, the burning of fossil fuels is overloading the global carbon cycle, which in turn is triggering dramatic changes to climate, global ice cover weather patterns, ocean acidification, farming yields, sea levels, government budgets and worldwide refugee figures.

Any society that ignores Commoner’s first law – that everything is connected to everything else – invites “ecological and social turmoil.” An example of this here in the Hudson Valley is the drastic over-browsing of vegetation by an out-of-control deer herd.

Forests have become park-like landscapes, largely devoid of healthy groundcovers, native shrubs, and seedling trees. The unfortunate cascading effects include the loss of ground-nesting and lower-canopy birds like ovenbirds, wood thrush, rufous-sided towhees, song sparrows, and more. Vegetatively, we see the disappearance of spring ephemeral wildflowers and other plants. Overall, the local ecosystem is experiencing a sharp loss of biodiversity.

What are some of the historic events and patterns that led to this? 1) The extirpation by humans of deer’s natural predators such as grey wolves and mountain lions; 2) the suburbanization of wide areas of New York state which now provide deer with readily accessible plants; 3) the decline in hunting as our population ages and as towns

limit the ability to hunt; 4) deer’s adaptability to different foods and conditions. Unfortunately, deer do not eat Japanese barberry and it has rapidly spread into areas where native vegetation has been decimated. The deer tick population thrives; barberry has been shown to provide moist and protected mini-habitats for them (Cary Institute of Ecosystem Studies).

Since many elementary and middle school students study food chains and food webs, Commoner’s first law of ecology can easily be taught to this audience by asking them to imagine what would happen to a healthy web of life if a change occurred. For example, if we are considering a meadow habitat where cottontail rabbits and mice eat tasty grasses, herbs, and seeds, and where sly foxes prey on those critters, what happens if there is a prolonged drought and plants dry up? Even a change in weather patterns affects local or regional animal populations. We’re all connected…...

Commoner’s Second Law of Ecology: Everything Must Go Somewhere.

As many science writers have said, this is simply re-stating basic laws of physics: matter

is indestructible. In the natural world, there is no such thing as “waste,” materials are cycled and recycled untold times. I believe that this is a perspective in which to view the astounding beauty of planet earth. Think of the amazing water cycle, or how animals give off carbon dioxide which is then used by plants who give off oxygen that benefits animals -- self-regulating natural systems. But modern civilization produces gigantic

amounts of waste, much of it toxic or even deadly and it has to go somewhere. In stark and simple terms, “there is no such place as away.”

Our oceans, atmosphere and soils are presently and consciously being used as ad-hoc garbage dumps: a painful example of the old adage, “out of sight, out of mind.” However hard we wish, It still does not go away.

Educators, however, can teach so many stunning examples of cycles and transformations of matter that we can avoid the bad news when appropriate,

and focus on mind-boggling insights such as the rain that comes down today, which we can catch and taste on our tongues, might be water vapor exhaled millions of years ago by a Tyrannosaurus Rex.

Commoner’s Third Law of Ecology: Nature Knows Best.

As Dr. Commoner writes, “The third law of ecology holds that any major man-made change in a natural system is likely to be detrimental to that system.” A few examples of this are:

• Foresters preventing or suppressing naturally occurring wildfires instead of letting age-old patterns continue, especially in habitats which depend on such regular inputs, such as prairies, Ponderosa and Jack pine forests.

• The use of pesticides to control insects instead of using natural enemies or other organic means, thus bringing forth unforeseen and negative effects on ecosystems.

• The destruction of wetlands for channelization and development, leading to increased flooding. As educators, we can ask students what they have seen around them that shows nature knows best. What example of changes humans have made have been detrimental to natural systems? Are those changes reversible? (Examples might

include roads, dams, wind farms…)

Commoner’s Fourth Law of Ecology: There is No Such Thing as a Free Lunch.

“In a way,” writes Dr. Commoner, “this ecological law embodies the three previous laws. Because the global ecosystem is a connected whole, in which nothing can be lost or gained and which is not subject to overall improvement, anything extracted from it by human effort must be replaced. Payment of this price cannot be avoided; it can only be delayed. The present environmental crisis is a warning that we have delayed nearly too long.”

One striking example of this happened several decades ago when the USA, Russia, and other countries were intent on growing their arsenals by testing nuclear weapons on distant atolls in the Pacific:

* The atmospheric testing of nuclear weapons in the 1940s, ‘50s and ‘60s led to the spread of Strontium 90, a radioactive isotype which eventually made its way to cow’s milk and then to human baby teeth. Research found that levels of this chemical in children born from 1945 to 1965 had risen 100-fold and that the level of strontium-90 rose and fell in correlation with atomic bomb tests. Early results from the Baby

Tooth Survey, and a U.S. Public Health Service study that showed an alarming rise in the

percentage of underweight live births and of childhood cancer, helped persuade President John F. Kennedy to negotiate a treaty with the Soviet Union to end above-ground testing of atomic bombs in 1963.

*In a much more simplistic but evident way, every act we take here on earth has a cost whether we see it or want to see it. Example: a quick trip to the store in our car means we burn fossil fuel whose end products go up into the atmosphere. There is no such thing as a free lunch; everything we do and have done has an effect.


Interview with Barry Commoner in 2007:


Overview of Barry Commoner’s work and life:

Obituary in Washington Post:



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