Dying for Survival
Imagine an immortal animal. Evolution so fashioned his glands and organs that his parts replace themselves as soon as they cease to function. His teeth may wear down or be knocked out, but he always has another set handy. His joints never suffer from arthritis; his legs remain forever as springy as an adolescent's. His bones do not grow brittle or his skin flabby. Cataract is unknown to him. No plaques of cholesterol deposit on his arterial walls. His heart muscle and alveoli of his lungs renew themselves. He is invulnerable to cancer and all forms of viral, microbial, bacterial infection. He exists in total harmony with his environment--never too cold or hot, never hungry or thirsty, never wanting for oxygen. As he has no reason to die he doesn't, but lives on and on through the ages--growing a bit bored, perhaps, but animals seem to agree that life is better than death on almost any terms.
Has evolution ever produced such a prepossessing creature? Theoretically it should be possible for the various components of the endocrine system of an animal so efficiently to collaborate that physical obsolescence is simply banished from its life program. We know of certain plants--for example, lichens and the bristlecone pines of California's Inyo Forest--that live many thousands of years, near enough to immortality so far as animal lifespans are concerned. But the oldest animal of which there is a record seems to be a tortoise that managed to struggle through 150 years (plus, perhaps, another 25 years or so)--not all that much older than many old men.
Paradoxically, if immortality has ever been attained, it has quickly been eliminated, simply because immortality cannot survive. An immortal animal would be a dead animal--the representative of a vanished species. As we saw in the first volume of this series, Oasis in Space, as least four times in the past 600 million years the reef communities around the world have all been all but obliterated by upheavals in the environment still not completely understood. Skeletons of palm trees have been discovered in Antarctica. At one time there were meadowlands on that continent, now under hundreds of feet of ice, not unlike the plains of the American West. Faced with this dimension of drastic environmental transformation any immortal animal would be helpless. His ideal adjustment to the old environment spells certain extinction in the new. Locked into this "perfection," he cannot adjust. Immortal or not, he must die.
The mechanism by means of which the animal world responds to the challenges of a changing environment, and by means of which species establish themselves and adapt and survive, is the births and deaths of individual animals. There is no such thing as the perfect animal, much less the immortal one. But in any large population there is one individual with a thicker hide, another with a more flexible snout, another with a bigger cerebrum, another with the tendency to bear twins, another with sharper hearing. And so on. In other words, any successful species presents the environment not with an army of perfect individuals but with a smorgasbord of different characteristics dispersed through its membership. Then, when the environment challenges its species, the species has a chance to come up with an answer. If the weather grows cold, for example, the thick-skinned individuals will tend to make it, the thin-skinned ones to die out. As the cycles of sex, birth, and death follow one another down the generations eventually all members of the species carry the thicker skin and there is an adjusted balance between the demands of the environment and the capacities of the animal. The species has adapted and survived.
The process does not always work so simply. Immense as the dinosaur population was at the end of the Cretaceous Period, some 65 million years ago, the smorgasbord of natural variations within the species was too limited for the challenges the environment posed it. The dinosaurs had gone too far down one particular evolutionary road; unable as individuals and species to find a solution to the radically altered climate, they died out. And there are other factors which compromise or exaggerate the "normal" operations of natural selection. These belong to the story of evolution. But man is the great zoological eccentric who should command our attention here. For man's brain gives him tools with which to participate directly, consciously, in his own evolution. To start with, he has grown as interested, or almost interested, in individual survival as in species survival. Egged on by this concern for individual survival he has learned to screen himself from many of the "natural" agents of the selection process. Puerperal fever, tuberculosis, pneumonia, smallpox, diphtheria, plague--all these grim reapers which for thousands of years winnowed out the human species are mostly fears of the past. A boy who 150 years ago might have died f whooping cough can now live to maturity--perhaps to become a great physician who discovers the cure for yet another mankilling disease.
If man is a unique exception as an animal it is a recent phenomenon. He is what he is because of the loves and deaths and births of uncountable legions of animals who have lived and perished since the first tiny cells stirred in the ancient oceans 3 billion or so years ago. From these lowly entities the natural-selection process has moved man steadily forward: past the jellyfish and the mollusk, past the turnoffs to equally successful evolutionary strategies like the insects', into the early experimental chordates, the mammals with their invaluable specialty of caring for their young, to the primates--to himself! Trillions of generations, trillions of deaths--each on a small link in the chain of evolution, each one a survival-ticket for man. Biological sciences are only a few generations short of being able to interfere consciously with genetics and to produce eternal youth. If we are reasonable enough to avoid a nuclear holocaust and to control population, immortality will no more be a Utopian dream.
Introduction by Jacques Cousteau from the 1972 book series, "The Ocean World of Jacques Cousteau" Volume 2.
Edited by dukenukem, 15 March 2006 - 08:06 PM.
