Embryogeny and Phylogeny of the Human Posture 2. Anne Dambricourt Malasse

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      If, even before the Oligocene, the group of Tarsiers, which seems to be interposed between the Lemurs and the Simians, was approaching maturity, it must be assumed that, from that time on, the group of the superior primates¹ was in full growth. This gives depth to our views on the group to which we belong: a Tarsier found, almost entirely formed, in the Phosphorites may mean that, somewhere on Earth, at that same time, Anthropoids were already sketched out [...]. They come, independently of each other, from a still unknown group of very small animals with a large brain which must have lived in the Paleocene, or even an earlier epoch. (Teilhard de Chardin, Sur l’origine tarsienne de l’Homme, 1921, author’s translation)

This theory of a third phylum of large-brained Simiiformes, already differentiated at the end of the Secondary era, was the reasoning of Teilhard with two evolutionary levels, that of the trunk or the succesion of morphotypes illustrated by generalized (not specialized) species, and that of the branches, or the specialization of species which have diverged from the trunk. The trunk was the dynamic of encephalization, while the divergences were the specializations that stabilized the organism and slowed down the complexification dynamics of the central nervous system. The trunk concerned the generalized species which would transmit this process of complexification of neurogenesis and followed an acceleration from the final Paleocene. And this trunk was the ancestral lineage of Man which became its apex and the current process of neural complexification.

      The theory of a Paleocene simiiforme phylum has never been corroborated.

      Teilhard’s paleontological study nevertheless marked a major milestone in paleoprimatology, and the American George Gaylord Simpson (1902–1984), one of the great figures of 20th century in paleontology, paid tribute to him by giving his name, Teilhardina, to the oldest fossils of primates that lived in Asia, Europe and North America, from the Upper Paleocene to the Lower Eocene (between 56 and 47 million years ago). Today, the oldest primates are dated to 55 million years and were discovered in central China in 2003 in Hubei and in 2004 in Hunan. The fossils are kept at the Institute of Vertebrate Paleontology and Paleoanthropology of China, in Beijing. The first fossil from Hubei is an almost complete skeleton of very small size (7 cm and 20 cm with the tail) named Archicebus achilles (Ni et al. 2004). The orbits are small and the appendicular skeleton is that of an arboreal primate. The second fossil Teilhardina asiatica from Hunan has preserved only fragments of the skull and mandible.

      As long as the chordal skeleton is not straightened and since locomotion is not the mechanical cause of straightening, these locomotor adaptations do not allow us to speak of simiiforme features. It is the simians, characterized by the straightened embryonic cord, that have inherited these arboreal characters. It would be interesting to compare the axial endoskeleton of Archicebus with the current species of Loris in Southeast Asia. The last study in 2019 confirms, using dental characteristics, the distinction between these two Chinese fossils (Morse et al. 2019).

      Pierre Teilhard de Chardin defended his thesis entitled “Les mammifères éocènes inférieurs français et leurs gisements” (“French Lower Eocene mammals and their deposits”), which earned him international renown, at the Sorbonne University in April 1922. He was 41 years old and received the prize of the Société géologique de France (Geological Society of France) and the Roux prize of the Académie des sciences. He was elected President of the Société Géologique de France in 1926.

2.4. Human paleontology is a branch of planetology

Teilhard was in regular contact with Henri Breuil, himself trained by Albert Gaudry, and thus steeped in Lamarckian doctrine. Teilhard understood that the cosmos, which he contemplated from the volcanoes of Auvergne, was in reality the state of a disappeared cosmogenesis, just like the history of the Earth and the complexification of the life at the origin of the biosphere. The fruitful union between environment and organism did not shock him. On the contrary, for a mind that felt consubstantial with nature, like Leibniz and Goethe, it was conceivable to believe in a kind of cosmic super-organism. But the universe was no longer a being as in Haeckel’s monism, and at the present moment, the universe is the stage for multiform growth. Terrestrial organisms are thus compositions built by the physico-chemical laws of their environment, and the essence of consciousness relates to these specific laws which allow the organization of complex autonomous systems. The human being, as a collective reflexive consciousness, was seen as a reflection of this growing being on the Earth, potentially able to become conscious of themselves. But the stage of growth of this cosmic consciousness reached a critical state, as the “planetarization” of conflicts testified. Theological heresy was thus consumed, the truth was no longer in the old texts written by human hands for more than 2,000 years. The authenticity of a cosmic purpose remained the only question which justified, in his eyes, all the sacrifices at the planetary scale; Teilhard set out to discover it, for the first time since the philosophers of the Antiquity, who had not conceived of the necessity to prove it.

      Marcellin Boule wanted Teilhard to meet the holder of the chair of Mineralogy at the Catholic Institute of Paris, where higher education in the sciences was still poorly developed. It was important that natural sciences and evolution be taught in private establishments run by the clergy. Father Gaudefroy offered him the chair of Geology, pending the nomination of a professor; Teilhard accepted and became a lecturer. He taught geology there from 1920, defended his thesis at the Sorbonne in 1922, and was finally appointed Assistant Professor of Geology and Paleontology at the Institut Catholique de Paris. Teilhard de Chardin was therefore a professor and continued his teaching during the 1922/1923 academic year, while in agreement with the Society of Jesus, he devoted himself to paleontology in the basement of the Muséum’s gallery and participated in international conferences.

His teaching was innovative, he was not content to simply teach what he had just learned at the Sorbonne. He thought about the mechanisms of evolution on the large scales of space and time, the “continentalization”, or “granitization” (silicification) of the Earth’s crust, and the complexification of organisms which form the biosphere, as far as Man, who discovers himself a generic link with the physico-chemical transformations of the planetary surface. Here, we find Buffon again, but with the search for a physico-chemical, even telluric link (electric and magnetic fields) between the dynamic organization of molecules to form monocellular and then pluricellular autonomous units. The Earth’s crust moves thanks to tectonics (only vertical, for the geologists at this time) and was dragged into the irreversible “drift” of its cooling toward a state of equilibrium, while climates changed and fauna migrated, but with an additional constraint: the surface of the Earth is finite, closed in on itself and the shape of the continents is, in itself, a factor of selective pressure on populations. Peninsulas are dead-ends, isolation routes, while intercontinental bridges are routes of diversity. Teilhard’s evolutionary school of thought was being built: according to him, there is a planetary engine with which the increasing complexity of organisms was associated, from the tectonics of the continents and seabed to the dispersion of the oceans.

      This intelligibility of an earthly planetology approached as a growing living organism is already perceptible from the earliest years of his teaching. In 1921, Teilhard published the beginnings of his evolutionary thought in an article for the Études², “How is the question of Transformism posed today?”:

Not only the fact, but the very mechanism of evolution seemed clear: to explain the metamorphoses of life, it was enough to have recourse to adaptation or natural selection, and to heredity, already a little schematized, the figure of Transformism from Lamarck to Haeckel [...]. The lines formerly drawn disintegrated, so that new explorations brought to light a plethora, in the geological layers, the remains of absolutely new animals, which forced the multiplication of families and zoological orders. Leaves began to hide the twigs, and the twigs, which were too numerous, increasingly hid the branches. For that reason, life became more and more overwhelming for the classifiers, by the richness of its СКАЧАТЬ