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Published online by Cambridge University Press: 02 April 2024
The first principle of evolution is immutability; the primary objective of a species is to perpetuate itself. A transition from one species to another has never been observed and never will be; even in paleontology the study of fossils will never bring to light a continuity in the history of life: the passage from one form to another is always abrupt, and the “missing links” are only a creation of our imagination, an answer to satisfy our expectation.
1 N. Eldredge and S. T. Gould, “Punctuated Equilibria: An Alternative to Phyletic Gradualism,” in Schopf, ed., Models in Paleobiology, San Francisco, Freeman, Cooper & Co., 1972, pp. 82-115.
2 Darwin is considered as the father of modern evolutionism, and “natural selection” or the “struggle for life” are never brought up without his name being mentioned. Much less often do we find the name of the other “father” of evolutionism, Alfred Russel Wallace, who, independently of Darwin and at the same time, came to conclusions that were identical to his. At the insistence of his friends, he renounced the publication of his master work, which would have appeared in the same year as the Origin of Species. His doctrine differed from that of Darwin on only one point: the question of the origin of man. Wallace, who was closely involved with the spiritualist current, did not admit that selection alone could explain the human phenomenon. This stand, that was associated with idealism and that Darwin feared because he had no solid arguments to oppose to it, has caused the discretion that up until today has surrounded the contribution of this great scholar.
3 The other great extinction, that of the cretacious superior, 65 million years ago brought about a global catastrophe on the continents, on the seas and in the air. The disappearance of the dinosaurs is only the best-known episode of this immense drama. As in the case of the Permian extinction, we know practically nothing about the cause of this event.
4 Since the appearance of the first article by Gould and Eldredge (and in some cases, before its publication) a number of researchers have come to conclusions that are analogous to theirs, either in support of the “punctuated equilibria” or in expanding and modifying the theory. Thus we have seen the birth, or rather rebirth, of the notion of megaevolution. We think today that megaevolution is alone responsible for the creation of new species and we oppose it to microevolution, limited to slight modifications in existing forms. The elaboration of this new theory is especially due to the geneticists, who see the regulatory genes as the principal agent of evolutive changes belonging to megaevolution. According to them, on the other hand, mutations of the structural genes would bring about only unimportant modifications, ascribable to microevolution. Whatever the case may be, the theory of Gould and Eldredge is helped by it.
5 Let us remember, for example, that the first fish to leave their acquatic milieu 350 million years ago, whose descendants became amphibians, left in order to look for other sources of water in regions that had become desert. In one sense, if the fish became amphibian it was because of his determination to remain a fish at whateyer cost. Here, as in other cases, the creative force of evolution was the “desire” not to change.
* The model of determination of species is called “allopatric” when geographic isolation exists, and “sympatric” when the opposite is the case. The allopatric notion is primary in evolutionism and constitutes the key word to the present study.
6 This consideration has no effect whatever on the fact that this is one of the richest and most refined cultures in the world. However, it is evident that its evolution has been slow, and even null. This can be seen in Chinese art, rigorously conservative. Let us also remember the Chinese cult for old age and the aged, in contrast with the absence of any role played by youth in public life and artistic creation.
7 R. G. Wesson, “Wrong Numbers,” Natural History, Vol. 88, No. 3, 1979.
8 It goes without saying that this figure of 12 civilizations has no absolute value and that it is subject to variations according to the theory of history we adopt. We may, with Toynbee, advance the figure of 25 civilizations or, with Spengler, count 7 or 8. However, the examination of this question would take us away from our subject without changing the tenor of our conclusions.
9 The brain of dolphins, a species whose intelligence is by now widely recognized, has not changed in 20 million years. Did the intelligence of dolphins arise all at once, with the appearance of the species, or was it perfected by means of a certain “cultural” evolution? It is a difficult question to answer. In any case, if there was evolution it was not rapid, and dolphins may be given as an example of an unfinished evolutive chance.
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