The Act of Life [antikvár]

Introduction: Dying for SurvivalImagine 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 the 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 environmentnever 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 agesgrowing 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 plantsfor 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 al' 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. For earth is constantly changing, and animals must be ready to adapt to earth's changes. As we saw in the first volume of this series, Oasis in Space, at least four times in the past 600 million years the reef communities around the world have 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 his "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 a perfect animal, much less an 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 acuter 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 the species, the species has a chance to come up with the answer. If the weather grows colder, for example, the thick-skinned individuals will tend to make it, the8