I had always heard of building a stack of cards but never seen it done.
I had always heard of building a stack of cards but never seen it done. So the other night I got out a deck of cards and decided to give it a try. I placed some of the cards on edge and laid others across them. The overlapping cards tied the structure together. As the stack grew it lost stability, but the more I worked at it, the better I got. Finally, I ended up with a construction that, when viewed from the side, resembled a triangle. I was sitting there basking in my success when my wife's cat jumped on the table and down came my stack of cards.
After chasing the damn cat all over the house until it climbed up into the rafters and sat there grooming itself with an air of disinterested arrogance, I gathered up the cards and began again. This time I was determined to build a stack that could resist a major disturbance. I found that the card pile was stronger if I made several horizontal layers, like floors in a building. I soon used up the entire deck, and had to dig around in seldom used drawers and boxes to find more playing cards. The search produced five decks of cards. I went back to work, bent on building something that would resist an earthquake. My efforts produced a structure that looked a lot like a pyramid. It was quite stable and could endure minor nudges and flicks of my finger. Now I was ready for that smart-alec cat, which of course, didn't come. My architectural marvel was still standing the next morning.
I decided to see just how strong my creation was and how much meddling it could stand. Bumping the table would make it tremble a little, but the pyramid remained standing. Slamming my fist down on the table caused one of the cards in the pinnacle to fall, but three remained holding up the top card. I returned the fallen card to its position, but now I had another idea. I studied the structure for a moment. Then I carefully removed a card from the middle of the stack. Nothing happened. The section immediately above the missing card sagged slightly, but nothing fell. I removed another card, and then another. When I slipped out the fifth card, which was near the first, the floor immediately above it drooped a couple of centimeters and the next level abruptly leaned over, toppling the pinnacle in the process, but the rest of the pile held firm. After removing another eight cards the pyramid collapsed and had to be rebuilt.
After a couple more experiments some basic principles began to emerge. It soon became apparent that the lower levels are more stable than those above them. Each individual card is more secure if it depends on several other cards for support. Cards are not all equally important, and there are always a few key pieces in the entire structure. The removal of the key cards will cause extensive damage, however, it isn't always easy to determine which ones they are.
My new diversion was turning into a learning experience. I couldn't help but think of how closely the stack of cards resembles the structure of life on earth. In the pyramid of life there are far more life forms in the lower layers than the upper ones. The simplest organisms have been around for more than three billion years and have developed a very high degree of stability and permanency. As life evolved, more layers were added. Less than one billion years ago the first simple animal forms evolved and life moved out of the oceans onto the land. More complicated organisms such as land plants and simple animals jockeyed for their positions in the structure. Later came the arthropods such as spiders and insects, and later still the vertebrates, including reptiles, birds and mammals. Each layer in the pyramid has less species than the layers beneath it.
The pyramid of life has grown stronger over time. Weaker and less adaptable species and families have perished and have been replaced by others that are fitter and better able to fill their niche in the system. Each time a damaged portion is rebuilt it is stronger than previously. The disappearance of one species may not cause a major collapse but could cause changes in the structure, more damage will be done to the whole system if many other species depended on the one that disappears. The elimination of a species will tend to affect the higher levels of the pyramid more than the lower ones.
With my card experiments, I found that when just the right key card was removed most of the structure collapsed. This event was always sudden, nevertheless there was previous minor damage that warned of the future catastrophe. Only a really major disturbance like tipping the table at a steep angle, dropping a basketball on the pile or setting the cards on fire would destroy the lowest layers.
Since our planet is home to so many species, that have been around for a long time, the pyramid of life is very strong and resistant to disturbance. Nevertheless, it has from time to time experienced some catastrophic events that severely damaged it. Scientists have determined that there have been five mass extinctions since the beginning of life on earth. The first happened over 400 million years ago, the last a mere 65 million years ago. The causes of these collapses are not clear, but evidence seems to indicate drastic changes in the planet to which many life forms couldn't adapt. The most recent was possibly due to the impact of a huge asteroid. This would be comparable to throwing a ping-pong ball at my stack of cards. Most of the upper layers would topple and most of the lower layers would hold steady. Each extinction can be compared to a partial collapse of the pyramid of cards.
And then, along came Homo sapiens. In the mere speck of geological time since our first ancestors appeared on earth, humans have learned to dominate the biosphere and its millions of species. According to noted biologist Edward O. Wilson, in his landmark work, The Diversity of Life, "Our species appropriates between 20 and 40 percent of the solar energy captured in organic material by land plants." Our superior intellect has given us such an ecological edge over other life forms, that we are able to subvert them, convert the environment to our own use, and, even eliminate entire species. Our dominion over nature is usurping a high percentage of the natural resources on the planet, and thereby destroying other living things that depend on those same resources.
In the past humans and their activities have eliminated many large animals from the face of the earth including mammoths, mastodons, giant deer, giant bison, giant sloths, the dodo and hundreds of other species. Soon the rhinos, tigers, pandas, Harpy's eagles, red-backed squirrel monkeys and many others may also disappear. These life forms are high up on the pyramid, and their disappearance hasn't caused a major impact on lower levels in the past and isn't likely to in the future. But now our activities are having a more profound effect. Habitat destruction, contamination with chemicals and waste, depletion of the protective covering in the stratosphere, and global warming are damaging and destroying entire ecosystems. The tall grass prairies, tropical dry forests, tropical rainforest and coral reefs are all either gone or diminishing at an alarming rate. Species are becoming extinct even before we discover and name them. The pyramid of life is beginning to sag.
Our present situation reminds me of the delicate relationship between a parasite and its host. If the parasite kills the host, both will perish. With humans the host is the entire biosphere with all the life forms it contains. In The Sixth Extinction, author Richard Leakey estimates that during the periods between the five mass extinctions, normal background extinction occurred at the rate of one species every four years. He figures that by the mid 1990s about 30,000 extinctions were occurring on the Earth annually.
Extinction at the rate of thirty-thousand a year, therefore, is elevated 120,000 times above background. This is easily comparable with the Big Five biological crises of geological history, except that this one is not being caused by global temperature change, regression of sea level or asteroid impact. It is being caused by one of Earth's inhabitants. Homo sapiens is poised to become the greatest catastrophic agent since a giant asteroid collided with the Earth sixty-five million years ago, wiping out half the world's species in a geological instant.
Can we continue to destroy our environment to the point that the upper layers of the pyramid of life drop abruptly and topple like the stack of cards? Although the analogy between the pile of cards and the pyramid of life may not be perfect, I believe there is one rule that always holds true for both. Whether eliminating cards or species, it takes a while for the pyramid to experience a collapse. With the cards the first to fall were the pinnacle, the ones at the very top. Who do you think occupies the pinnacle in the pyramid of life?
So we have a choice. To continue living as we are and risk suffering the same fate as the parasite that kills its host, or to go to work to restore the damage caused by past mistakes and learn to live in harmony with nature.
What can you do as an individual? There are lots of people working to restore the planet and teach others to value natural systems. There are many environmental organizations each of which works in its own particular way. Some are interested in wildlife and others in entire ecosystems. Almost all of them are doing good work. It doesn't make any difference which one, pick the organization that most appeals to you and go to work.
Additionally, you can inform yourself and then inform others. There are many periodicals and books available to those interested in learning more about their environment. You could start with the two books mentioned in this article. World Watch Magazine is an excellent bimonthly with a wealth of information. Also from World Watch is the annual report entitles State of the World 2003. This is available from the web site www.worldwatch.org.
I want to leave you with a final thought from Paul Hawkin, author of The Ecology of Commerce:
Underlying all ecological science is the inevitable fact that, given a chance, the earth will eventually restore itself. The salient question we need to discuss in our communities and businesses is whether humankind will participate in that restoration or be condemned by our ignorance to vanish from the planet.
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