The plurality of the human race

by G. Pouchet

Étienne Geoffroy had been the worthy successor of Lamarck, with a larger and more philosophical mind. He never fell into his exaggerations, nor into the restrictive applications of the system, like Darwin. Let us see how Isidore Geoffroy[307] continues his father’s theory: “Species is variable under the influence of the ambient medium; differences, more or less considerable according to the power of the modifying causes, may in time be produced, and the present beings may be the descendants of the former being.” This doctrine is our own also.

As to the idea of limited variety, propounded by Isidore Geoffroy, we can only see in it an unfortunate restriction of his father’s theory,—one of those errors into which even the most judicious minds are liable to fall. Limited! Does he mean that there is a point where these variations stop, and consequently a point where they have commenced? Does he mean that some neighbouring animal species are derived from a given prototype, similar to themselves, and without any antecedents in the organic world? This is to return to Cuvier! Limited! Does he mean that the modifications will not be considerable in the present state of things, on account of this present state being more or less modified? It comes to nothing directly we admit variety as a consequence of the medium. Étienne Geoffroy was led by this kind of idea, when, limiting his view to the short period of historical time, and thinking he had discovered that our present climates do not sensibly alter existing species,[308] he asked, “if there had not been on the earth revolutions and disturbances of so vast a character that their influence may not have been enormous; whilst in our days, changes may have been according to the power of their effects, that is to say, almost nothing.” And he explained everything by this convenient theory of geological floods.

Before going farther, let us consider what we ought to think about the disturbances of the terrestrial globe thus invoked by Étienne Geoffroy. Now, to our mind, we have no authentic proof that the past of our planet has really been marked by such frightful revolutions, and geology does not make the tradition as clear as some have desired. We think, although this is not the place to prove it, that if the changes which have happened to the surface of the globe have been considerable, they ought to be proportionally weak, resulting less from sudden and powerful efforts than from those small and continuous actions[309] in which nature puts forth its most formidable energies, but the progress of which is not to be measured by the memory of man. In general, our mind seizes but badly the notion of duration beyond certain limits. It is not the same with the notion of force. Hence, the belief in floods. In the presence of gigantic effects, the mind, in the appreciation of the movers of this effect, has done what we have done every day in mechanics. “It has changed mind into force.” It is certain that weak but continuous forces (everywhere, however, the most powerful) have been able to play a grander part in the history of our globe, than these disturbances which we are in the habit of seeing everywhere.

We consider that there ought to be an entire revolution in the system of geological research; it ought to commence at ancient times, and come down to the present day, not vice versâ; we ought, in fact, to substitute synthetic for analytical geology. After having carefully noticed contemporaneous phenomena, we should doubtless be in time able to read simply the trace of a feeble revolution in the geological past, accomplished under the government of the same forces which are daily preparing new lands, new elevations, new depressions, and a new organic world on the surface of the globe, for the future. If it is probable that the atmosphere has changed within certain limits, if the nature of the waters has also been altered,—at least all these geological phenomena, these abysses, chains of mountains, and submerged continents, can only be the result of the forces now at work under our own eyes,—the comparison of animals which formerly existed with those which exist at the present day, shows, as we shall see farther on, that the conditions of life have not sensibly changed on the surface of the globe since the formation of the rocks subjacent to the metamorphous rocks.

We deny that the earth is actually passing through a period of repose, and we do not believe that it has ever formerly been more disturbed. Since the age of the first vestiges of the organic life, which we find in the most ancient rocks, we think that our planet has not ceased to move in a calm and continuous march of existence; we think, in fact, that geological phenomena of all sorts, which we hear of now-a-days, are the exact history of the past, during which some volcanic phenomena have also taken place, but in an entirely sporadic manner. “The day is, perhaps, not very distant,” said M. Lartet, at the Institute,[310] in 1858, “when it will be proposed to strike out the word ‘flood’ from the vocabulary of positive geology.” This day approaches still nearer.[311]

Before mooting, in our turn, a theory about the vertebrate animal kingdom (the only one which ought to occupy our attention) on the surface of the globe, we simply ask, what is meant by Étienne Geoffroy by the words some considerable time? This is a difficulty, we own, and we have just said so. We wish that the thirty thousand years,[312] the maximum time which we give to the farthest origin of man, should be considered as being the age which separates us from the first organic matter cast into the bosom of the waters, in the same proportion as the radius of the earth is to the distance which separates our sun from the most distant star of the most distant nebulous system which the best telescope can observe. The extent alone of the heavens can give us an idea of the extent of the past.

This being granted, let us see how we can represent the history of organic development upon the earth in a few words, without hiding from ourselves the immense obscurity which covers all origins. We are here expressing merely a hypothesis. It will suffice us to see if this hypothesis will agree in a satisfactory manner with the facts noticed at the present day, on the surface and in the interior of the globe.

At the origin of the vertebrate world, since we are only examining this, it seems rational to admit a primordial commencement, which nothing prevents us from considering as a new and special combination of organic matter, derived from the invertebrate world, which we may believe to have formerly existed. In the heart of this embryo will have appeared, by spontaneous generation, the first organism connected with the vertebrate type. This was, doubtless, a simple anatomical element, like that which histologists see every day formed in certain granular liquids.

We do not imagine that the origin of life can be otherwise represented; for to admit, as Isidore Geoffroy has done in certain passages of his works, that the will of a God peopled the earth suddenly with perfect beings, fit for producing other beings like themselves, would be to admit a miracle, and science teaches us at the present day what to think of all divine interventions, either past or present.[313]

We defy anyone to get out of this alternative,—either that there was an instantaneous and miraculous creation of a certain number of perfect animals;[314] or that there was a successive evolution, which is Lamarck’s idea, modified by the sense of the new knowledge which we have at the present day, arising, on the one hand, from geology, and on the other, from philosophical anatomy.