7. The Evolution of Hominids

7.0 Introduction

The geneticist Theodosius Dobzhansky published in 19371 his concept about the origin of Species. The views of the ornithologist Ernst Mayr followed in 19422. The paleontologist George Sympson contributed his own ideas3. These three views were synthesized into the concept of “Neodarwinism”, which Dobzhansky and Mayr proposed to the paleoanthropologists. The concept that hominid evolution processed simply by the gradual change of genes under the guiding hand of natural selection swept away vast panoply of mythology. Dobzhanski certified that only one kind of hominid could have existed at any time and Mayr asserted that only three successive species could be discerned within the genus Homo. These two assertions tremendously simplified the understanding of the human evolutive process, which became at once a long single-minded struggle from primitiveness to human perfection4. The incompleteness of the fossil record observed by researchers in the field was traced to “missing links” and these were consequently zealously searched. Each new find was touted as the missing link (e.g. Lucy).

Otto Schindewolf, a paleontologist expert not in anthropology but in ammonite mollusks, was of the opinion that all was not that simple. He suspected that the missing links were not found because they did not exist. He suggested that gaps in the record were not species boundaries but represented a saltation5. Paleoanthropologists, obsessed with tracing the history of the single species Homo back into the past, entranced by the notion of gradual change, unwilling to face and tackle complexity, spent much energy to reduce Schindewolf to silence4. Nils Eldredge and Stephen Jay Gould, who had studied the evolution of arthropods (trilobites) and snails, eventually vindicated Schindewolf6: far from being a single-minded linear struggle by a temporal succession of species, new hominid species spawned, competed and became extinct. Human evolution proceeded along lines similar to other species. Like the genus horse (see fig. 6.4), it was marked by numerous speciations and extinctions: modern humans are one twig on a great bush of experimental species.

Homo is one of the six genera that compose the tribe Hominini. Of these six genera, five are extinct. Ardipithecus, Australopithecus, Kenyanthropus, Paranthropus and Preanthropus7prospered essentially in Africa during the Pliocene, i.e. between 5.5 and 2.5 millions of years ago. The oldest known hominid, Sahel-anthropus tchadensis, has been unearthed in AD 2001 in Chad’s Djurab Desert and is dated to 6-7 million years ago. One may add to him Orrorin and a nameless Chad skull, both dating 6 million years ago. Australopithecus was fairly successful, the others not. All disappeared, despite their superior intelligence.

The sixth genus, Homo, starting with the Pithecanthropus and the Sinanthropus, is composed of at least 14 species of which all disappeared except one, Homo sapiens sapiens, who emerged during the Pleistocene and managed to survive to the present. The convergent line of the hominids (according to the theory developed by Kuhn, summarized in chapter 3.5) is characterized by several achievements among which the most significant are the ability to make tools, the ability to make fire and the ability to transfer information through an articulated language. These achievements were by no means realized all at once.

Several issues are subject of hot ongoing debates. The first is the origin of H. sapiens sapiens. Does he naturally evolve from H. erectus or is he the product of a convergent line? The second debate turns about the relation of brain size to migration out of Africa. Was the migration possible only after a large brain was acquired or was the migration staged earlier in the evolution of the hominids? The third issue is the level of hominisation reached by Neanderthal. Is his level of hominisation the same as the one reached by H. sapiens sapiens or was he inferior? Has he been physically wiped out by Sapiens according to the concept of “the struggle for life” or has he disappeared by interbreeding with Sapiens according to the concept “make love, not war”? The fourth issue is the ranking of various human cultures.

Political, moral and scientific correctness makes it hazardous to advance that some cultures are more evolved than others. The present confusion of values holds it as ethically incorrect to classify and rank Humans and human activities. To deem Neanderthal inferior to sapiens sapiens, belonging to another species than sapiens, brings the risk to be accused of ethnocentrism. It is very serious: the pressure for consensus and the intolerance for dissent have grown to monstrous proportions during the 1990′s and many scholars who have dared hold views that diverge from the mainstream (not only on the issues raised here but on the many issues I mention throughout this essay) have jeopardized thereby their careers and even lost their employment, even if the heterodox views they defended proved eventually to be correct. Modern States, and the scientific, economic and military assessors of these States, demand consensus, find dissent intolerable and practice censorship with the greatest of ease. Even the contention that mass extinctions are not due to meteoritic hits but rather to volcanic activity is a view that has been censored, as exposed by R. Zimmerman8 (This is the way the world ended. The Sciences, 39, 1999, 39-44).

A final problem, not commonly discussed, is the biochemical machinery that allowed the evolution of hominids towards higher levels of consciousness.

References

1. Genetics and the Origin of Species, New York, Columbia University Press, 1937

2. Systematics and the Origin of Species, New York, Columbia University Press, 1942

3. Tempo and Mode of Evolution, New York, Columbia University Press, 1944.

4. I. Tattersall: Paleoanthropology and evolutionary theory. In “Research Frontiers in Anthropology”, vol. 3, C. Ember, M. Ember and P. Peregrine (eds), Prentice Hall, 1997, 325-342

5. Grundfragen der Paleontologie, Stuttgart, Schweizerbart, 1950. He probably knew about the observation made by H. de Vries in primroses, that large-scale change could occur at once, suggesting that new species could arise by sudden major disruptions of the hereditary material in a single individual.

6. “Punctuated Equilibria: an alternative to phyletic Gradualism”, in T.Schopf (eds) Models in Paleobiology, San Francisco: Freeman, Cooper &Co, 1972,. 82-115

7. B. Wood and M. Collard : the human genus, Science 284, 1999, 65-71

8. I expose this contemporary problem of intolerance in the publication: R. Maes : Tuberculosis II. The failure of the BCG vaccine. Medical Hypotheses, 1999, 53: 32-39.and in the book : La France malade de sa médecine. Ed. de Paris, 2005

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