Читать книгу The Fate of Man - H.G. Wells - Страница 6

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WHAT in general terms are the relations of a species to the world about it?

A species may be living in practical harmony with its environment or it may be more or less out of balance with its surroundings.

In the former case it may continue recognizably the same species, living the same life, age after age. Any tendency to excessive numbers may be corrected by a correlated increase in the types that prey upon it, and there will be no definite biological encouragement for such variations and mutations as occur. Harmless mutations may indeed produce varieties and sub-species, and, as Henry Fairfield Osborn long ago pointed out, there may be purely mutational. efflorescences; the correlation of a species to its environment is never hard and exact; but only a minority of mutations seem to be without some quality of advantage or disadvantage. Abnormal individuals in a species in practical equilibrium will generally be eliminated, and the species as a whole will pursue the even tenor of its way indefinitely.

There are species that have been under no necessity to adjust themselves to circumstances over vast periods of geological time. But they are exceptions to the general ecological spectacle of species balancing themselves in a changing world. Most existing species, when their affairs are scrutinized as a whole, are discovered to be in a state of imperfect adjustment to their circumstances, and to be either undergoing adaptation to meet new requirements or to be losing ground in the struggle—if one may call anything so essentially passive a struggle-to survive. Over a large part of the animal and vegetable kingdoms, adaptation, the working adjustment of the species under stress, is made, if it is made at all, by the selective frustration and killing off of less well-adjusted individuals. Variations and mutations—it is not necessary to enter here into the controversial question of their causes; suffice it that they occur—variations and mutations, indifferent, favorable and unfavorable, play a considerable part in this selective adjustment. The adjustment is either sufficient or insufficient. In the latter case, the species dwindles and disappears. In the former, the species undergoes modification; it survives, changed, as a new species or as several new species according to the imperatives of its altered conditions.

All this again is practically common knowledge today. Most educated people know about it even if they do not think very much about it, or link it up with other systems of ideas in their minds. It needs to be repeated plainly here in view of that possibility of disregard.

The general history of life in the past is, as everybody knows, one of failure and defeat rather than adaptation. Great groups of living things have arisen, had their heyday, and then passed altogether from the scene, giving place to more plastic and adaptable forms of life. Comparatively insignificant forms with novel accommodations arise to take their place.

When we contemplate that greater past that science has unfolded for us, we see great groups and orders of mighty creatures dominating the earth, enormous reptiles, huge mammals flourishing and then waning and passing away. They have not kept pace with change; their exuberance has been almost a defiance of change; and change has overcome and obliterated them. The geological record can be presented, certain assumptions being granted, as on the whole a great progression, but that does not alter the fact that it is also a history of the ruthless extinction of whole species, genera and orders of living things. There are tremendous massacres in the geological record.

One of the greatest of these occurred at the close of the Mesozoic period, when in the course of perhaps only a few hundred thousand years, a vast reptilian fauna, ichthyosaurus, plesiosaurus, tyrannosaurus and so forth, an equally wonderful flora, scores of genera of ammonites and so on and so forth, were thrust out of existence. We know little or nothing of the changes that made so many hitherto successful forms of life impossible. We know surely only that they occurred. A change from conditions of all-the-year-round equable temperature to wide seasonal alternations of heat and cold may have resulted from some planetary disturbance. More recently there have been parallel massacres of groups of the early mammals, and there can be no question that today we are, from the geological point of view, living in a phase of exceptional climatic instability,-in a series of glacial and interglacial ages, and witnessing another destruction of animal and plant species on an almost unparalleled scale. The list of species extinguished in the past hundred years is a long one; the list of species threatened with extinction today is still longer. No new species arise to replace those exterminated. It is a swift, distressful impoverishment of life that is now going on. And this time the biologist notes a swifter and stranger agent of change than any phase of the fossil past can show—man, who will leave nothing undisturbed from the ocean bottom to the stratosphere, and who bids f air to extinguish himself in the process.

This species man is, as we all know, one of a great series of species which we can speak of roughly as cerebral animals. These are the mammals who have dominated the earth since the beginning of the Tertiary period and which display throughout a rapid development of the cerebral cortex. This cerebral cortex was a novelty in the history of life, and it brought with it a fresh, distinctive method of individual adaptation to special circumstances. It quickened the response of a species to changing conditions very greatly. Learning from experience appears indeed but very rudimentarily in cold-blooded vertebrata; it is only in the birds and mammals, and particularly in the latter, that it becomes of real importance in adaptation. Essentially the cerebrum is an organ for the storage and application of memories. It enables individuals to learn by experience. The history of the mammals in particular is a history of memory development. All through the Tertiary period, it is to be noted, brains in every group of mammals increase in relative size and complexity. With every increase, the power of learning from experience and of supplementing direct impulse by conditioned reflexes increases. A young fish or reptile comes into the world with a practically complete, almost unalterable set of instinctive responses. It survives or fails by its inherited outfit. Apparently it can learn to a certain extent, but it learns very little. A young mammal comes into life far less conclusively equipped, a tabula rasa, prepared to learn. It learns. And the ampler its cerebral equipment, the more it learns to take care of itself. To begin with, it is sillier and less certain than the cold-blooded type; it stands in need of protection; in the end it is far better adapted to meet the special conditions it faces.

Moreover, the young mammal and, to a rather different extent and in a rather different fashion, the young bird do not simply learn from individual experience. Generally speaking there is also a protective relationship between the parent and the new individual. By example and often by direct intervention the young individual is taught. It heeds and imitates.

As we ascend the scale of cerebral development the possibility of teaching increases. It becomes possible to domesticate and train these higher-brain animals in just the measure that their brains are developed. You can teach very little to a fish or a reptile, but directly you come to the higher cerebral mammals you are confronted by the new possibility of establishing an artificial, taught, motive system to control, supplement or altogether replace natural instinct. You must catch them young. Then you can socialize them and get to quite remarkable working understandings with them. The shepherd's dog, the blind man's dog, the polo pony, the polite, house-trained cat, are examples of the immense individual adaptability which is achieved through the establishment of a taught, secondary self in the cerebral cortex. None of these creatures are behaving in accordance with the primary tendencies they have inherited. They are behaving in accordance with an adaptive mental superstructure imposed upon their natural dispositions. It enables them to survive not simply as tolerated but as contributing individuals in a complex social organization which otherwise would have had no alternative but their extermination. They would have suffered the fate that is overtaking the unteachable Tasmanian Devil or the unteachable Tasmanian Wolf.