Extinction

“ It would seem, however, as if each successive economy of organic life had contained within itself the seeds of extinction. It was, indeed, mainly a change of climate which first caused some species to disappear. But their destruction so disturbed the balance of creation that others followed, until total extinction was the result, which, however, was often hastened by catastrophes. ”

“ Doomed to premature extinction by privation of a mate— To extinction or reversion, for Unexpurgated Man Still awaits me in the backward if I sicken of the van. O the horrible dilemma!—to be odiously linked With an Undeveloped Species, or become a Type Extinct! ”

“ Had there been no wise ruling of the blind forces of nature, no subjection of the rough, unbridled powers of the air, and sea, and earth, the human race would have become extinct, as so many races of beasts have done. But there are no traces of the extinction of a human race in our Paleontology. The constitution of the globe is incontestably coincident with a plan to preserve and perfect Man. ”

“ Every rival, parasite or foe, every stress of climate, was studied in its influence on food or frame, while the ever-threatened doom for irresponsiveness was the extinction which befell countless forms once masters of the earth. ”

“ The natural tendency of species and genera, like that of individuals, has been towards extinction. Why it should be so we know not, further than that they are for the most part influenced by every change in physical geography. But they probably obey a still higher law which governs their duration, as the laws of vitality govern the life of an individual If we are but slightly acquainted with the agency by which the degradation of land is counter-balanced, we are still more ignorant of the laws that preserve the balance of life. Creation is a mystery, and such it must for ever remain. ”

“ It is now desirable that we should pause in our career of destruction long enough to look back upon what we have recently accomplished in the total extinction of species, and also note what we have blocked out for the immediate future. Here let us erect a monument to the dead species of our own times. ”

“ It rarely accounts for qualities associated with geographical distribution.
Extinction of Species.—The extinction of species may be noted here in connection with their extension of range. Prof. Herbert Osborn has recognized five different types of elimination.
[Pg 240]
1. That extinction which comes from modification or progressive evolution, a relegation to the past as the result of a transmutation into more advanced forms. 2. Extinction from changes of physical environment which outrun the powers of adaptation. 3. The extinction which results from competition. ”

“ I do not mean to say that when it takes a turn towards ultimate extinction it will be in a day, nor in a year, nor in two years. I do not suppose that in the most peaceful way ultimate extinction would occur in less than a hundred years at least ”

“ Extinction has been a fact of life since life first emerged. The present few million species are the modern-day survivors of the estimated half-billion species that have ever existed. Almost all past extinctions have occurred by natural processes, but today human activities are overwhelmingly the main cause of extinctions. ”

“ On Extinction.—We have as yet spoken only incidentally of the disappearance of species and of groups of species. On the theory of natural selection the extinction of old forms and the production of new and improved forms are intimately connected together. The old notion of all the inhabitants of the earth having been swept away at successive periods by catastrophes, is very generally given up, even by those geologists, as Elie de Beaumont, Murchison, Barrande, &c., whose general views would naturally lead them to this conclusion. ”

“ Within the range of history no well-marked instance of such development has been witnessed, and we speak with hesitation of doubtful instances of extinction. Yet in geological times myriads of evolutions and extinctions have occurred. ”

“ We may conclude therefore, from a survey of the tertiary and modern strata, which constitute a more complete and unbroken series than rocks of older date, that the extinction and creation of species have been, and are, the result of a slow and gradual change in the organic world. ”

“ But the extinction of a species will certainly affect other species which it either preyed upon, or competed with, or served for food; while the increase of any one animal may soon lead to the extinction of some other to which it was inimical. ”

“ And he feels this abrupt extinction of the Earth and its inhabitants to be tragic, notwithstanding that extinction is, by his doctrine, only the condition of creation, and that at the very moment of her ruin, some other earth will be celebrating its glorious birth. ”

“ Fluctuation in a downward direction, or temporary extinction, is brought about by changes in the physical world, by changes in the available supply of food, by the increase of enemies, or by adverse climatic conditions; whilst fluctuation in an upward direction, though due indirectly to a combination of circumstances in the external world favourable to the survival of large numbers of individuals, is directly determined by the impulse to seek isolation. ”

“ Where the road narrows and the animal in traversing it is obliged to sacrifice some portion of its structure and to adopt some restriction of habit the result is a limitation which must ultimately mean a bar to all progressive evolution in the acceptance of a particular limited sphere within which it may survive, but to leave which means extinction. Adaptation to sedentary life, parasitism, desert, cave, deep sea, polar frigidity or extreme heat is to shut the door of progress and give over to mere survival. ”

“ But whether the extinction of such vast groups of species as the ancient strata present to our notice, can be accounted for in this way, at least without assuming the occurrence of great catastrophes, which must for a time, have destroyed all forms of life in the district in which they occurred, appears to be more doubtful. The decision of these questions, however, is not essential to our purpose. What is important is, that immense numbers of tribes of animals have tenanted the earth for countless ages, before the present state of things began to be. ”

“ But as from the high geometrical ratio of increase of all organic beings, each area is already fully stocked with inhabitants, it follows that as each selected and favoured form increases in number, so will the less favoured forms decrease and become rare. Rarity, as geology tells us, is the precursor to extinction. We can, also, see that any form represented by few individuals will, during fluctuations in the seasons or in the number of its enemies, run a good chance of utter extinction. ”

“ But when we are following the light, even its extinction is a guide. ”

“ Extinction, likewise, seldom occurs simultaneously over the range of a group, but now here and now there in a way that to our ignorance appears to be arbitrary and capricious. The process may go on until extinction is total, or may merely result in a great restriction of the range of a given group, or may break up that range into two or more distinct areas. ”

“ Nevertheless, so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life! ”

“ There are always some peculiar and characteristic features in the physical geography of each large division of the globe; and on these peculiarities the state of animal and vegetable life is dependent. If, therefore, we admit incessant fluctuations in the physical geography, we must, at the same time, concede the successive extinction of terrestrial and aquatic species to be part of the economy of our system. ”

“ We are here concerned only with races that continue to exist; and may therefore leave out of consideration those in which the destructive forces, remaining permanently in excess of the preservative forces, cause extinction. ”

“ Whether natural selection has really thus acted in nature, in modifying and adapting the various forms of life to their several conditions and stations, must be judged of by the general tenour and balance of evidence given in the following chapters. But we already see how it entails extinction; and how largely extinction has acted in the world's history, geology plainly declares. ”

“ If we then turn to the present state of the animate creation, and inquire whether it has now become fixed and stationary, we discover that, on the contrary, it is in a state of continual flux—that there are many causes in action which tend to the extinction of species, and which are conclusive against the doctrine of their unlimited durability. ”

“ In order that the American people may correctly understand and judge the question of the extinction or preservation of our wild life, it is necessary to recall the near past. It is not necessary, however, to go far into the details of history ”

“ The difficulty attending the early extension of the human race is at once obviated by the geological doctrine of the extinction of species. We know that in past geological periods large and important groups of species have become extinct, and have been replaced by new groups extending from new centres ”

“ Geological changes, however gradual, must occasionally have modified external conditions to such an extent as to have rendered the existence of certain species impossible. The extinction would in most cases be effected by a gradual dying-out, but in some instances there might have been a sudden destruction of a species of limited range. ”

“ Changes in physical geography which must occasion extinction of species.—It will almost seem superfluous, after I have thus traced the important modifications in the condition of living beings which flow from changes of trifling extent, to argue that entire revolutions might be brought about, if the climate and physical geography of the whole globe were greatly altered. ”

“ To admit that species generally become rare before they become extinct—to feel no surprise at the comparative rarity of one species with another, and yet to call in some extraordinary agent and to marvel greatly [Pg 94] when a species ceases to exist, appears to me much the same as to admit that sickness in the individual is the prelude of death—to feel no surprise at sickness—but when the sick man dies to wonder, and to believe that he died through violence." [69]
Geographical distribution is an important element in this question of extinction. ”

“ And whoever reflects on this subject, must be convinced that the present order of things, and the comparatively recent existence of man as the master of the globe, are as certain as the destruction of a different order, and the extinction of numerous animal forms, of which no living types now remain on the surface of our planet. ”

“ Usually, some disturbing elements, such as a sudden change of physical conditions, or the immigration of new sets of forms from other areas and the consequent retreat or partial extinction of the older fauna, interferes with the continuity of organic development, and produces those puzzling discordances so generally met with in geological formations of marine origin. ”

“ And, when one comes to think of it, death and birth are so closely correlated that one could not destroy either without destroying the other at the same time. It is extinction that makes creation possible. ”

“ On a continent, the process of extinction will generally take effect on the circumference of the area of distribution, because it is there that the species comes into contact with such adverse conditions or competing forms as prevent it from advancing further. A very slight change will evidently turn the scale and cause the species to contract its range, and this usually goes on till it is reduced to a very restricted area, and finally becomes extinct. ”

“ We must accordingly be on the alert for all possible theories of extinction; and these theories themselves will fall under the universal principle of the survival of the fittest until we approximate or actually hit upon the truth. ”

“ The principle upon which I must here insist is that the mere fact of certain species being extinct, and others being now alive, gives no clue whatever to the relative age of these remains, until we first ascertain why, how and when this extinction was brought about. ”

“ We have seen, in Chapter X., how important an agent in producing extinction and modification of species must have been the repeated changes from cold to warm, and from warm to cold conditions, with the migrations and crowding together that must have been their necessary consequence. ”

“ Then follows a comparison between rarity (In the second edition, page 146, the destruction of Niata cattle by droughts is given as a good example of our ignorance of the causes of rarity or extinction. The passage does not occur in the first edition.) and extinction, which introduces the idea that the preservation and dominance of existing species depend on the degree in which they are adapted to surrounding conditions. ”

“ No satisfactory proof has yet been discovered of the gradual passage of the earth from a chaotic to a more habitable state, nor of any law of progressive development governing the extinction and renovation of species, and causing the fauna and flora to pass from an embryonic to a more perfect condition, from a simple to a more complex organization. ”