Regarding the matter in this way, there is legitimate scope for science in tracing the long lines of the different types of ancient animals to the modern period, and endeavouring to discover which of our so-called species are original types and which are mere derivative varieties or races.
It is evident that nothing is gained here by assuming that the whole geological record is but one of innumerable vast æons of æons, which have gone on in endless succession. If the world is made to stand on an elephant, and this on a tortoise, and this on lower forms, it helps us not at all if the last supporter must stand on nothing. The difficulty thus postponed only becomes greater; and at the end we have to imagine, not only life and organization, but even matter and energy as fortuitously originating or creating themselves, unless produced by an Almighty Eternal Will.
In pursuing studies of this kind, it is best for the present to content ourselves with tracing the continuous chains of similar creatures throughout their extension in geological time, rather than to seek for connecting links between different lines of being. I endeavoured some years ago to give a popular outline of this method in a little work entitled "The Chain of Life in Geological Time."[49]
[49] Religious Tract Society, London; Revell Publishing Co., New York, Chicago, and Toronto.
Taking, for example, the earliest Protozoa—the Foraminifera and Radiolaria—we find two lines of being that in endless varieties, but with little material change, extend from the earliest periods to the present time. In successive ages they are represented by families, genera, and species, which are regarded as distinct, and known by different names. But these humble animals are very variable, and what seem to us to be new types may be merely varieties of ancestral forms. We might even affirm that, for all we know, these two great groups, as they exist in the present ocean, are lineal descendants of those that flourished in the Eozoic. We could not prove this, unless we were to find somewhere a continuous succession of deep-sea deposits that would show the gradual changes that had occurred. On the other hand, it is hard to believe that one individual life, so to speak, could have continued unimpaired to animate successive and increasing masses of matter in all the vast time extending from the Eozoic to the modern. It is also at least equally possible that the causes and conditions, whatever they were, that produced the earliest Protozoa may have acted again and again in later times, originating new lines of descent with renewed vitality.
Still, the tracing of these almost incredibly long lines of descent, if they are such, is a proper, though difficult, subject of scientific research, whatever may be the result. Something has been attempted in this direction over limited portions of time; but a vast amount of patient labour is required before certainty can be attained even in this department of investigation.
When, on the other hand, we turn to the question whether such lines of creation or descent have given off branches leading to new types, as, for instance, from Protozoa to various Crustaceans or Mollusks, we are entirely destitute of facts, and the statement lately made by a leading agnostic evolutionist, that "if there is any truth in the doctrine of evolution, every class of the animal kingdom must be vastly older than the past records of its appearance on the surface of the globe," shows us that all the attempts to construct genealogical trees of the descent of animals are, so far as at present known, quite visionary. It seems, indeed, that each leading line, as we trace it back, ends in a blind alley, just where we might suppose that it was about to pass into another path. This is one reason of the frequent complaints as to the imperfection of the geological record, and of the occurrence of "missing links" between different types of being. The only feasible explanations of this are as yet the suppositions that the times of introduction of new types may have been unfavourable to the preservation of their remains, or that the first representatives of each new group were soft-bodied animals incapable of preservation, or that they happened to be introduced in regions yet unexplored. But such accidents could scarcely have been the rule in every case. Even in relation to man himself, he is still man in all the deposits in which we can find his remains, and as remote from the apes of his time, in so far as we know, as he is from those now his contemporaries. It would seem, in short, as if, ashamed of his humble origin, he had carefully obliterated his tracks in ascending from his lowly parentage to the dignity of humanity. But in this he is only following the example of other animals, his predecessors. We may, as is now constantly done by evolutionists, fill up these gaps by plausible conjectures; but this is not a scientific mode of procedure, unless we are content to regard these conjectures as working hypotheses in aid of researches yet without result.
It is important that general truths of this kind, impressed upon us by our descent to the ascertained beginnings of life, should be generally known, as counteractive to the confident statements so frequently put forth by enthusiastic speculators and caterers of sensational popular science. In point of fact, we still occupy the position so long ago defined by the Apostle Paul, that "God's invisible things from the creation of the world are clearly seen, being understood by the things that are made, even His eternal power and divinity"; and the rational student of nature must still be a pupil in the school of the Almighty Maker of all things.
Realizing this, we can learn something both as to the dignity and the humility of our own position. On the one hand we perceive that, in the whole chain of life, man is the only being in the likeness of the Maker, fitted to be His deputy in the world, to understand His great work, and to be the heir of the whole. To man alone He has proclaimed, "I have said ye are gods, and all of you children of the Most High." To man alone has He given that "inspiration of the Almighty" which makes Him the interpreter of nature. On the other hand, when we consider the long extent in time of the great chain of life before man, and along with this the vast oceanic area inaccessible to us, yet ever since the dawn of life teeming with living things innumerable, we find that man is not even in this little world the only object of Divine care, and we learn a lesson of humility and of the obligations which rest on us not only in relation to our fellow-men, but toward our humbler companions who share with us the care of their Father and ours.
Finally, it is plain that scientific investigation can never bring us within reach of the absolute origin of life, otherwise than by the action of a creative Will. Had we stood on the earliest shore, and had we seen living things appear in the waters where before had been merely inorganic sand or rock, we should have known as little as we know to-day of even the proximate causes of this new departure in nature. If agnostics, we might have said, "this is spontaneous generation"; but such an expression would convey no distinct idea of the nature of the change which had occurred. It would be merely a cloak for our ignorance. If theists, we might say, "this is creation"; but we would have heard no audible fiat, nor seen any process or manipulation, nor known by what subordinate agency, if any, the result was produced. We could have given no further explanation than that of the ancient writer who tells us that God said, "Let the waters swarm with swarmers." We are told that when these great creative changes occurred, they were witnessed by higher intelligences than man. "Then the morning stars sang together, and all the sons of God shouted for joy"[50]; but even they could perhaps know little more than we, though they might be better able to trace the future development of the wonderful plan commenced in the humble Protozoa and culminating in man and immortality.