Inasmuch as bones and tusks of the mammoth are dug up in enormous quantities over tracts now almost bare of trees, and scanty as to other vegetation, certain naturalists have assumed that in times coeval with mammoth or mastodonic life the vegetation of these regions must have been richer than now, otherwise how could such troops of enormous beasts have gained their sustenance?
On this point Sir Charles Lyell bids us not to be too confident affirmatively. He remarks that luxuriance of vegetable growth is not seen at the time being to correspond with the prevalence of the associated fauna. The northern island of the New Zealand group, at the period when Europeans first set foot there, was mostly covered by a luxuriant growth of forest trees, of shrubs and grasses. Admirably adapted to the being of herbivorous animals, the land was wholly devoid of the same. Brazilian forests offer another case in illustration; a stronger case than the wilds of New Zealand, inasmuch as the climate may be assumed as more congenial to the development of animal life. Nowhere on earth does nature teem with an equal amount of vegetable luxuriance; yet Brazilian forests are remarkable for almost the total absence of large animals. Perhaps no present tract is so densely endowed with animal life as that of South Africa, a region where sterility is the prevailing characteristic; where forest trees are rare and other vegetation scant; where water, too, is infrequent.
Present examples, such as these, should make a naturalist hesitate before coming to the conclusion that Siberian wilds, even as now, were wholly incompatible with the existence and support of troops of mammoths or mastodons. Speculating now as to the latest time of the existence of mastodons in Siberia, a circumstance has to be noted that would seem to countenance the belief in the existence of it up to a not very remote period of historic times. In the year 1843, the season being warmer than usual, a mass of Siberian ice thawed, and, in thawing, untombed one of these animals, perfect in all respects, even to the skin and hair. The flesh of this creature furnished repast to wolves and bears, so little alteration had it undergone. Another mastodon was disentombed on the Tas, between the Obi and Yenesei, near the arctic circle, about lat. 66° 30' N., with some parts of its flesh in so perfect a state that the bulb of the eye now exists preserved in the Moscow museum. Another adult carcass, accompanied by an individual of the same species, was found in 1843, in lat. 75° 15' N., near the river Taimyr, the flesh being decayed. Associated with it, Middendorf observed the trunk of a larch tree (Pinus larix), the same wood that now grows in the same neighborhood abundantly.
It is no part of our intention to discuss the causes of mammoth extinction. This result has assuredly not been caused by any onslaught of the destroyer man. The Siberian wilds are scantily populated now, and it has never been suggested that at any anterior period their human denizens were more plentiful. Nature often establishes the balance of her organic life through a series of agencies so abstrusely refined, and acting, beside, over so long a period, that they altogether escape man's cognizance. The believer in the God of nature's adaptation of means to ends will see no reason to make an exception in animal species to what is demonstrated by examples in so many other cases to be a general law. The dogma, that no general law is without exceptions, though one to which implicit credence has been given, may nevertheless be devoid of the universality commonly imputed. On the contrary, the application of this dogma may extend over a very narrow field; may be only referable to the codifications, artificial and wholly [{528}] conventional, which mankind for their convenience establish, and under a false impression elevate to the position of laws. If logical proof in syllogistic form be demanded as to the proposition that laws established by nature have no exceptions, the fulfilment of demand would not be possible; inasmuch as human reason is too impotent for grasping, and too restricted in its energies for investigating, the multifarious issues which the discussion of such a thesis would involve. As coming events, however, are said by the poet to cast their shadows in advance, so, as heralds and harbingers of truths beyond logical proof, come beliefs, faiths, even moral convictions. Of this sort is the assurance of the balance established by nature at each passing epoch of being in the world.
The naturalist is impressed with the firm belief that the number of animal species existing on the earth, and the number of individuals in each species, are balanced and apportioned in some way and by some mysterious co-relation to the needs of the universe.
Some presumptive testimony in favor of this belief is afforded by the discussion, barely yet concluded, relative to the effect of small bird destruction. Without any more elaborate reasoning on this topic than follows necessarily as the result of newspaper reading, the general concession will be made by any one of unbiased mind, that if small bird destruction could be enacted to its exhaustive limits—if every small bird could be destroyed—the aggregate of vitality thus disposed of would be balanced through the increase of other organisms. Insect life would teem and multiply to an extent proportionate with the removal of an anterior restraining cause.
The nature of the topic on which we are engaged does not force upon us the question whether such proportionate increase of insect life be advantageous or disadvantageous. What we are wholly concerned in placing in evidence is the balance kept up between vital organisms of different species by nature. Nor is the balance of vitality established between different animal species. It also may be traced, and even more distinctly, between the vegetable and animal kingdoms; each regarded in its entirety. Vegetables can only grow by the assimilation of an element (carbon) which animals evolve by respiration, as being a poison. Consideration of this fact well-nigh forces the conclusion upon the mind—if, indeed, the conclusion be not inevitable—that if through any vast cataclysm animated life were to become suddenly extinct throughout the world, vegetable life would languish until the last traces of atmospheric carbon had become exhausted, and then perish.
In maintenance of her vital balance through the operation of some occult law, it often happens that animals that have ceased to be "obviously useful," as taking part in a general economy around them, are seen to die out. Whilst wolves and elks roamed over Ireland the magnificent Irish wolf-dog was common. With the disappearance of wolves the breed of wolf-dogs languished, and has ultimately become extinct. As a matter of zoological curiosity many an Irish gentleman would have desired to perpetuate this gigantic and interesting race of dogs; but the operation, the tendency to vital equilibrium has been over-strong to be contravened—the race of Irish wolf-dogs has fleeted away. Speaking now of the huge Siberian mammoths, from which we diverged, of these faith in nature's balanced adaptation assures us that they died out so soon as they ceased to be necessary as a compensation to some unknown force in the vital economy.
Spans and periods of time, such as those comprehended by the human mind, and compared with the normal period of individual human existence, dwindle to nothingness when attempted to be made the units of measurement in calculations involving the duration of species. Perhaps the data are not available for enabling the most careful investigator to come to an approximate [{529}] conclusion as to the number of years that must elapse before the race of existing elephants, African and Indian, will become extinct, departing from the earth as mammoths have departed. The time, however, must inevitably arrive for that consummation under the rule of the present course of things.
Without forest for shade and sustenance the race of wild elephants cannot exist; and, inasmuch as elephants never breed in captivity, each tame elephant having been once reclaimed from the forests, it follows, from the consideration of inevitable results, that sooner or later, but some day, nevertheless, one of two possible issues must be consummated—either that man shall cease to go on subduing the earth, cutting down forests and bringing the land into cultivation, or else elephants must become extinct. Who can entertain a doubt as to the alternative issue? Man has gone on conquering and to conquer from the time he came upon the scene. Animals, save those he can domesticate, have gone on fleeting and fleeting away. It is most probable, nevertheless, that one proportionate aggregate of vitality has at every period been maintained.