Paleoanthropology

Skulls of Homo sapiens , a chimpanzee (Pan troglodytes), an orangutan (Pongo pygmaeus) and a macaque (Macaca).

Paleoanthropology is the branch of physical anthropology that studies the human evolution. Human evolution refers to the various steps that have resulted in modern humans, Homo sapiens from its ancestral primates. It does not limit itself to consideration of gender Homo but more generally includes all members of the subtribe of hominins thus including taxa that are not, strictly speaking, our ancestors. The hominins ^History

Man knows that for a century and a half he has a history, which at the very scale of this story represents a very brief period. Toumai ( Sahelanthropus tchadensis ), discovered in 2001 in Central Africa is currently the more distant ancestors known and has 7 million years .

First period of discoveries

In the early ^nineteenth century , the Old Testament is the reference book describing the history of man on Earth. It was read literally, and for a vast majority of human adventure is primarily heavenly in its origin as in its evolution. Within half a century, the combination of the evolutionary theory of Charles Darwin and discoveries from his senses will gradually change this view that man has of him, leading him to consider biblical writings as more allegorical, and especially pushing to develop the fact that he was indeed a past Earth, which is perhaps much more extended in time than what could have been imagined.

In 1829, Philippe-Charles Schmerling , Belgian doctor, discovered in caves Engis several fossil bones, including a human skull that will be much later identified as that of a Neanderthal child. The association, in the same stratigraphic context, remnants of extinct animals, human remains and tools cut, leads him to say that there existed a fossil man . But it is then still too early to admit the former existence of another human species. In 1848 a skull of an adult, much more characteristic, is found in Gibraltar, it will suffer the same fate as his Belgian friend.

In 1856, a career in the German Valley Neander , workers uncover bones and a skull fragment they give to Johann Carl Fuhlrott , passionate about natural history. One immediately notices the peculiarity of these bones which, although clearly different from those of modern man, still possess certain characteristics. But again, we will not immediately recognize the kinship of the hominid skull that belonged to which our species. The name of the place of discovery is yet to become famous after that in the years following the discovery of bones of this kind have multiplied. The species Homo neanderthalensis was described in 1864 and it is the first hominid fossil found. Other discoveries include both old fossils of Homo sapiens ( Cro-Magnon in 1868) and Neanderthal Man, whose skeletons of the Grotto of Spy in 1886 and La Chapelle-aux-Saints in 1908.

In 1859, the first crucial date for the theory of evolution, Charles Darwin publishes The Origin of Species. Following the theories outlined in this book, the German biologist and philosopher Ernst Haeckel proposed a theoretical pedigree of man in which he reveals a " missing link ", a being intermediate between ape and man. In his book The natural history of creation published in 1868, he named this hypothetical creature Pithecanthropus alalus . The genus name is formed from the root Greek , pthkos " monkey "and , anthropos," man. " The species name is formed on the privative prefix "a-" and / laleo, "talk": the absence of articulate speech was indeed regarded as one of the necessary characteristics of Pithecanthropus.

This theory in turn will cause the Dutch anatomist Eugene Dubois in expeditions to Malaysia and Indonesia. Starting in 1891, he discovered on the island of Java fossil bones belonging to the famous Pithecanthropus. He then defines the species Pithecanthropus erectus unfmur unearthed belonging undoubtedly be a biped.

In 1921 the Swedish geologist Johan Gunnar Andersson (in) discovers at Zhoukoudian in China, near Beijing, fossils that Canadian Professor Davidson Black in 1927 described as belonging to a new kind of contemporary Pithecanthropus erectus, the Peking man. Pierre Teilhard de Chardin discovered later in the same location, an impressive number of remains of hominins of the same type, but they will be lost during the Second World War , while they are en route for America.

Today, the Peking man and Pithecanthropus are grouped within the species Homo erectus , confined to Asia by some paleoanthropologists.

In 1871 Darwin published The Descent of Man and Selection in Relation to Sex , a book in which he argues that in the current nature, chimpanzees and gorillas are the closest to humans and that one day we find common ancestors and that the two will be African. paleoanthropology.

In 1912, we announced the breakthrough discovery in England at Piltdown , a human skull that has all the characteristics of modern man, except a primitive jaw. It can be seen in the fossil "missing link" as desired between ape and man. It has about 600 000 years and is then described as the true ancestor of modern humans, to the detriment of the Neanderthal. It was not until 1953 for a showing that Piltdown Man was a hoax.

Second period of discoveries

In 1924 Raymond Dart discovered the fossil of the Taung Child in South Africa and is the first australopithecine known. But at this point, the Piltdown Man is considered the ancestor of man and gain acceptance in the community that the Taung child, aged more than 2 million years, African moreover, is the true ancestor is not easy. Dart is going to fight until 1953, when the remains of Piltdown were further analyzed, and where the fraud is revealed. We discover in the following years other australopithecines in South Africa.

In 1959, Louis and Mary Leakey found the first robust australopithecine in Central Africa . They create the species Australopithecus boisei , dating from 1, 75 million years.

In 1967, Wilson and Sykes, molecular biologists, say that between the bonobos , a species of chimpanzee and human, there is no more than 2% difference at the genetic level. Darwin's prediction of 1871 is then partially verified. They estimate the date of the dichotomy between chimpanzees and humans around 3 million years ago 3 million years would have lived a common ancestor to monkeys and humans, who have given birth to two branches.

In 1974, Lucy ( Australopithecus afarensis ) is discovered, still in East Africa has 3.2 million years and challenges the predictions. Yves Coppens popularized the East Side Story a few years later, a theory which locates the cradle humanity in eastern Great African Rift. Since these discoveries, biologists have reassessed the time of dichotomy and think it may have occurred 6.3 Ma ago According Michel Brunet , whose team unearthed Toumai , the separation between man and monkeys from the common ancestor would have occurred around 8 Ma, which is still a hypothesis to be tested.

In 1982, David Pilbeam discovers a hominoid face in Pakistan dating from about 10 Ma and is attributed to a new species of primates, the Ramapithecus , this fossil is now considered the female of a species already known, the Sivapithecus , a species related to the orangutan today.

In 1995, a fragment of mandible of an individual nicknamed Abel ( Australopithecus bahrelghazali ) was found in Chad, the fossil dates from 3.5 to 3 Ma and is more or less contemporary with Lucy. The sensationalism of this discovery lies in the fact that Abel is located 2,500 km west of the Great Rift in Central Africa, which calls into question the theory of 'East Side Story.

In 2000, Orrorin tugenensis is found in Kenya, he has 6 Ma

In 2001, Ardipithecus kadabba (5.8 to 5.2 Ma) and Toumai ( Sahelanthropus tchadensis , 7 Ma) are found, respectively in Ethiopia and Chad.

These last three Miocene hominid discovered recently still arouse much debate, especially regarding their possible membership in the subtribe hominins.

Reactions to the theory of evolution

The theory of evolution based human paleontology and is not immune-specific responses to any major breakthrough on the one hand an extreme reaction to rejection, and also an extreme reaction of acceptance ^{Scientific Framework}

Paleoanthropology is based on the theory of evolution and use knowledge from multiple disciplines to offset the difficulties caused by the low number ^{Tools used}

Collecting fossils

Studies of dental development

Paleomagnetism

Discoveries

Since the 1980s , discoveries of fossil beds have increased, and with them, the number of species or subspecies of the genus Homo.
At the same time, the evolutionary history of man has fallen from a tree line to a tree with many branches, and species that we thought our ancestors until recently have suddenly become our deceased relatives.
This article proposes to present the state of currently accepted theories, as well as some alternative theories.

Evolution of hominids

Until the early 1980s, the state of research allowed to represent the evolution of men in Pliocene and Pleistocene as follows:

The discoveries of the time suggesting that the evolutionary tree of the genera Australopithecus and Homo was linear and that the species followed one another in an ongoing and regular, each species is the ancestor of the other. This hypothesis had its heyday in the years 1960-1970, a period of strong influence of the Synthetic Theory of Evolution ( TSE ) in the different disciplines of paleoanthropology. Some researchers even forcefully defended the theory of species unique to a given time could be only one species of hominid. The evolutionary tree of man was then seen as "a big trunk with few branches."
This simplistic theory is sometimes still taught today, although it does not incorporate the discoveries of recent years. We know for example that there are about 2 million years ago lived in the same regions of East Africa and Paranthropus , and Homo rudolfensis and Homo habilis.

Nowadays, many fossils on all continents have completely transformed our evolutionary tree into a "bush" furry. Several models have been proposed and one of the most complex is the following:

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