A herd of buffalo can only move as fast as the slowest buffalo.
A herd of buffalo can only move as fast as the slowest buffalo. And when the herd is hunted by wolves and mountain lions, it is the slowest and weakest ones at the back that are killed first. This natural selection is good for the herd as a whole, because the general speed and health of the whole group keeps improving by the regular killing of the weakest members.
This natural culling process affects all living things. Baby sloths sometimes tumble from the tops of tall trees. Sometimes they die, but often they suffer little or no damage from the fall. At Hacienda Barú National Wildlife Refuge, we occasionally find a young sloth on the ground and its mother high in the treetops. Even though unharmed from the fall these infants are doomed. If they don't fall prey to a predator or scavenger, starvation comes quickly. The interesting thing is that the mother sloth makes no attempt to rescue her baby, even when humans intervene and try to return it to her. The mothering instinct has its limits where species survival is at stake. What the female is really saying to her young is, "Sorry kid; you know the rules. If you can't hang on, get your butt out of our gene pool."
Another example is the great barrier reef of Australia, one of the great natural wonders of the world. The outside of the reef takes an incredible beating from great waves which come rolling unimpeded across the Pacific Ocean. On the inside of the great barrier reef the sea is calm and the coral has an easy life. Our first reflection may tell us that inside the reef the coral will be in excellent healthy condition and outside it will be tattered, broken and damaged from the constant battering. In reality, exactly the opposite is true. On the outside the weak and defective coral is eliminated, and that which survives to pass on its genes is the strongest and most vigorous. On the inside of the reef, without the intense natural selection, the coral tends to degenerate.
Think of an elite soldier who, under adverse conditions, pushes his body and mind to the limit every day. Now imagine an overweight office worker whose most strenuous physical exertion is clicking his mouse, lifting his coffee cup and dunking his donut. Which of the two is better equipped to survive hardship?
Humans are not exempt from natural selection. In primitive societies where hospital care is nonexistent, the weaker individuals who are unable to resist disease and the rigors of life, simply die. A woman whose pelvis is too narrow for her to give birth will die during labor and neither she nor her child will pass on the genes for a narrow pelvis. Those who bring no benefit to the population as a whole perish naturally or by cultural convention. When they become a burden to the rest of the tribe, the elderly in some primitive societies will submit themselves to mother nature who will mercifully end their life cycle. This is the case with Eskimos where older people who can no longer keep up with the migrating tribe, sit on the ice and wait for the polar bear to take them into the next world. In Australia the aborigines always put the oldest passenger in the last seat of the canoe, the position most vulnerable to crocodile attack. In Borneo, some tribes have improved on this theme by putting the mother-in-law in the tail end of the canoe, an excellent example of primitive people's true ingenuity.
As a student, more years ago than I care to remember, I was taught that civilized humans are pretty much apart from nature and are, in fact, far superior to it. With a really big brain and an opposing thumb, our destiny is to dominate nature, control it and bend it to serve our own needs. As proof of our superiority I was taught that, among other triumphs, we had already eradicated small pox, and were well on the way to doing the same with tuberculosis and malaria. The big news in science was that by the turn of the century, forty years in the future, we would live in a "disease free" world.
Those forty years have now passed and so has the turn of the century. According to the World Health Organization, well over two million people died of tuberculosis in 1998. AIDS, a disease that didn't even exist when I was in school, kills about a million people each year, and that isn't even enough to get it a place in the top ten fatal diseases. Mad cow disease is another new one. This infection is caused by something called a prion that can't even be destroyed by fire. Small pox which we "eradicated" many years ago is now showing signs of revival. Our medicines seem to be more expensive than ever before and less effective.
So what happened to our dominion over nature? What went wrong? A look at the battle between humans and malaria may yield a few clues. Malaria is a disease that can be eliminated by destroying or controlling either of the two lower life forms involved, the carrier, a mosquito, or the perpetrator, a blood parasite, neither of which has a big brain or an opposing thumb. That sounds like a piece of cake. Let's have a look at what happened in the war against malaria.
Prior to 1950 humans living in malaria infested regions developed a natural immunity. Everyone became infected with the disease at an early age; the weakest and least fit died as infants and the strongest survived. Those who survived were immune for about a year, and reinfection continually renewed their natural defenses against malaria, much like a booster vaccine. The process of natural selection had created an equilibrium or standoff between humans and malaria. The disease was a major cause of infant mortality, but people had learned to live with it.
Then civilized humans put those really big brains to work and invented a chemical called dichloro-diphenyl-trichloroethane, more commonly known as DDT. This was the big gun that was going to finish off malaria once and for all. It was just the weapon needed to eradicate Anopheline mosquitos, the principal carriers of the disease. War was declared against mosquitos. In the 1950s and 1960s, millions of tons of DDT were sprayed all over the world, on wetlands where mosquitos breed and in homes where they infect people. No place that might harbor malaria bearing mosquitos was spared. Uncounted billions of mosquitos died. The ultimate goal of the war was the total extinction of Anopheles mosquitos, and it soon became apparent that victory would likely be achieved.
But the war against mosquitos was only one battle front. Anopheles is merely the carrier or vector. We can also attack the cause of malaria, the Plasmodium blood parasite. The first effective treatment was quinine, a natural remedy derived from the bark of a tree. It was discovered by the indigenous peoples of the Amazon. They used it to alleviate the fevers caused by malaria and later gave quinine powder to Jesuit missionaries. From there it spread over the entire globe, and the demand for it nearly drove the cinchona tree, from which it is derived, to extinction. Later several artificial substitutes were discovered of which chloroquine was the most widely used. Mass application of chloroquine allowed some of the malaria warriors to rid human populations of the Plasmodium parasite while others were eliminating Anopheles mosquitos.
The results of the war against mosquitos are now history. Homo sapiens won almost every battle, but Anopheles won the war. Additionally massive application of DDT did grave damage to a number of bird species, killed off many beneficial insects, accumulated in the fatty tissues of humans and became concentrated in mother's milk. It also created super mosquitos. It killed off the weakest ones with the least resistance. If only one out of a million mosquitos survived; that one was the most resistant to DDT and lived to mate with other survivors. Each generation of Anopheles was genetically stronger than the previous. After about five years of spraying with DDT mosquitos achieved close to 100 percent immunity. Later they developed resistance to other pesticides as well.
On the other battle front, the war against Plasmodium, medical teams distributed large quantities of chloroquine, not only for treatment of malaria but also for prevention. It became the recommended malaria pill for travelers. Several other drugs were developed, but they were all quite similar to chloroquine in chemical structure and really offered nothing new. When the parasite built up resistance to chloroquine it also became partially resistant to the others. Every weapon modern medicine has been able to throw at Plasmodium, has soon lost its effectiveness. In much of the world the parasite is now totally resistant to treatment by any available drug or cocktail of drugs.
Meanwhile the temporary respite from malaria, due to early victories, had caused the inhabitants of formerly infested areas to lose their immunity. Once Anopheles became resistant and returned to those areas, carrying Plasmodium parasites, the results were devastating. Not only that, but widespread use of DDT had been very detrimental to the environment and the people. Some of those problems wouldn't be recognized until much later. In 1972 DDT was banned from use in the United States.
Fortunately, Costa Rica has been pretty much malaria free for the last 30 years. The war against malaria here has been successful up until now. But, all it would take is a few infected Anopheles mosquitos in the cargo hold of a ship from Africa. No place where mosquitos live is safe from an outbreak. Millions of Americans were thrown into panic in 1999 when a wave of West Nile Fever, another mosquito borne disease, struck New York City, causing a number of deaths in humans, birds and horses. New Yorkers were said to have developed mosquito phobia during the epidemic.
Let's have a look at the final score in the war against malaria. In the end we accomplished four things: 1.) We created super mosquitos and super malaria parasites. 2.) We weakened the natural defenses of humans in malaria infested regions. 3.) We contaminated our own environment with dangerous chemicals. 4.) We produced fortunes for the manufacturers and distributors of DDT and chloroquine. Andrew Spielman, Sc.D., one of the world's foremost authorities on the subject, in his recent book, Mosquito, sums up the current situation precisely. "Every year, 10 percent of the world's population suffers from malaria. Every twelve seconds a malaria-infected child dies." That adds up to 2,628,000 children per year.
So much for dreams of a disease free world. The dismal final outcome of the war against malaria illustrates that much of our modern approach to disease is completely out of touch with Mother Nature. Our attitude of superiority and lack of respect for her has only made us more vulnerable to her whims. More often than not, our meddling and attempts to alter our planet get us into trouble. If we believe the illusion that we can dominate every other species on earth and by-pass the natural selection process, we may end up getting ourselves selected right out of existence. Humans continue to combat diseases through the massive use of drugs. In so doing, we become weaker while, at the same time, the agents of disease become stronger and more difficult to combat or contain. We need to find ways to live in harmony with our environment not dominate or destroy it.
Remember how natural selection works in the herd of buffalo, making the herd stronger and faster by culling the slow and weak? The other day I heard a new twist to it. Here goes: Much the same as the herd of buffalo, the human brain can only operate as fast as the slowest brain cells. Excessive intake of alcohol, as we know, kills brain cells. But naturally, it attacks the slowest and weakest brain cells first. In this way, regular consumption of beer eliminates the weaker brain cells, making the brain a faster and more efficient organ. That's why you always feel smarter after a few beers.
So I guess each of us is going to have to think things over and make a decision. Either we get in touch with nature and go to work for a healthy environment, or have another beer and let George take care of it for us.
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