The origins of the human line
Present-day humans belong to the Hominina (or hominins) sub-tribe of hominids, which includes all species of the human lineage, separated from the chimpanzee lineage (Panina) at least 7 million years ago, and of which Toumaï is thought to be the oldest individual known to date. The most distinctive feature of Hominina is bipedalism, whereas chimpanzees and gorillas are quadrupedal, although they may occasionally use bipedalism.
Charles Darwin hypothesized that the human lineage (Hominina) originated in Africa as early as 1871, in his book The Sonship of Man and Sex Selection. He was among the first to suggest a common origin for all living organisms, putting forward the idea that Man, Chimpanzee and Gorilla shared a common African ancestor. Darwin proposed that this ancestor, despite having a small brain, walked upright, which would have freed his hands and favored the development of his intelligence.
A little paleoanthropology
This little-known science is a blend of paleontology and anthropology, studying the evolution of the human line exclusively, i.e., attempting to highlight the evolutionary stages between primates and modern man. This science is not limited to the genus Homo, but extends to all "hominins", the sub-tribe of hominids that includes all human species. Paleoanthropology's main approach is based on the study of fossils, but other approaches, such as the study of primates, help to validate or invalidate the initial hypotheses put forward with the discovery of each new important fossil. This discipline has to make do with fossil material that is often fragmentary and rare. What's more, scientists' research frequently leads to hypotheses that are not unanimously accepted by paleoanthropologists, and are often called into question by new discoveries. In exploring such a delicate subject as the origin of Homo sapiens, paleoanthropology has had a tumultuous history and is still in its infancy.
Until the middle of the 19th century, the reference work describing the history of man on earth was still the Old Testament, read at the time in a very literal way, and for a majority of thinkers of the time, the human adventure remained above all of divine origin. It wasn't until Charles Darwin's studies on the evolution of species that we began to see that the biblical writings should be considered as allegorical rather than literal, and that man's origins go back much further than most had previously imagined.
Paviland's red lady
Although not identified as such at the time, the Red Lady of Paviland is the oldest scientific discovery of prehistoric human remains. The bones were discovered in South Wales, UK, when the Paviland cave was explored in 1823. The remains were covered in ochre-coloured earth, and the skeleton was decorated with numerous ivory and shell jewels. A skull of what was thought to be an elephant was also discovered next to the skeleton. William Buckland, Professor of Geology at Oxford, was the first to study this discovery and concluded, on the strength of his Judeo-Christian upbringing, that it was the skeleton of a woman dating from around Roman times, and that the jewels were made of elephant ivory. In the course of the 20th century, however, advances in technology demonstrated that Paviland's lady was in fact a man in his twenties, that the jewelry was made from MaMMouth ivory and that the remains were from the Palaeolithic period. It has been known since 2009 that these human remains date back some 33,000 years to the present day. Since the middle of the 19th century, one hominin fossil after another has been discovered, constantly pushing back estimates of the time of humanity's origin, leading scientists to ask a crucial question: when did humanity begin and where did it take root?
Lucy
It was probably in 1974, when an international team of paleontologists including Yves Coppens unearthed 52 bones dating back more than 3 million years, that public interest focused on the question of dating the origin of mankind and its geographical location. Scientists had just made an essential discovery: although 52 bones represent barely a quarter of a complete skeleton, they were enough to reconstruct a faithful image of the 3-million-year-old woman now known the world over as Lucy. The name is taken from a well-known Beatles song, which the researchers listened to while sorting the fossils in their tents at night. Lucy's discovery in the Ethiopian desert strengthened Coppens' belief in the theory known as the "East side story". This theory, initially developed by ethologist A. Kortland and popularized by Coppens, explained the appearance of the human lineage by a major climatic change linked to the formation of the Great Rift in East Africa, which forced hominids to switch to bipedalism in order to adapt to their new environment.
Abel, one of the first australopithecines
Abel (his vernacular name) was discovered in 1995 in Koro Toro (Chad) by Michel Brunet and his MPFT (Mission Paléoanthropologique Franco-Tchadienne) team. The first hominid discovered 2,500 km west of the Great Rift, it was thanks to him that Yves Coppens' theory began to be challenged. Importantly, Brunet's team aimed to test the "East side story" hypothesis, but instead of discovering an ancestor of the great apes (such as chimpanzees or gorillas), they uncovered the first known australopithecine west of the Rift Valley. Abel is estimated to have lived around 3 million years ago, a little after Lucy, and his shorter face makes him look even more like modern man.
Toumaï
It wasn't until 2001, with the discovery of a new fossilized skull in the Chadian desert, that the search for the origin of mankind took another 3-million-year leap forward and completely challenged the East Side Story theory, the Toumaï skull having been discovered over 2,000 kilometers from the Great Rift Valley. Michel Brunet, the paleontologist whose team discovered the skull of the man later named Toumaï by Marshal Idriss Déby, in memory of a comrade-in-arms who died in battle, has demonstrated through his studies that Sahelanthropus Tchadensis was in fact the first hominin, differentiating itself from the ape (hominid), in particular from its closest cousin, the chimpanzee (Paniné), by standing upright.
Brunet's demonstration was initially widely disputed, as paleontologists had few bones (the skull and a few bones that were difficult to identify at the time) with which to draw reliable conclusions about Toumaï's supposed upright posture, today, however, the scientific community agrees that the Toumaï skull is the oldest hominid fossil, since the orientation and position of its occipital orifice (where the skull joins the rest of the skeleton) suggest that Toumaï moved mainly in an upright position.
A few figures to give you an idea of the dates involved
When it comes to prehistory, it's always difficult to appreciate the differences in the duration of the periods referred to. Here are a few key dates to help you realize that the human period represents only 1/2000th of the recognized duration of the universe's existence!
Origin of the universe: 14 billion years (first perception of light).
Sun: 4.6 billion years.
Life: 4 billion years (4,000 million).
Toumaï: 7 million years.
Lucy: 3.2 million years.
Homo sapiens (modern man): 300,000 years.
From Toumaï to modern man
The story of mankind after Toumaï is a fascinating evolutionary saga that unfolds over several million years, marked by key milestones in the evolution of hominids up to the appearance of modern man, Homo sapiens.
Here are a few key dates in this evolutionary saga:
1. Australopithecines (4 to 2 million years) After Toumaï, Australopithecines appeared in Africa. The most famous are Australopithecus afarensis, whose best-known specimen is Lucy
2. Homo habilis (2.4 to 1.4 million years) is often considered the first member of the Homo genus. This "skilled man" is associated with the use of primitive stone tools, marking a significant advance in cognitive capacity and dexterity.
3. Homo erectus (1.9 million to 110,000 years) is a key hominid in human evolution, being the first to leave Africa and spread to Asia and Europe.
4. Homo heidelbergensis (700,000 to 200,000 years) is considered the direct ancestor of Homo neanderthalensis in Europe and Homo sapiens in Africa.
5. Homo neanderthalensis (400,000 to 40,000 years). Neanderthals lived in Europe and western Asia. They had a complex culture, practicing art, advanced toolmaking and funerary rituals.
6. Homo sapiens (300,000 years to present day). The first Homo sapiens appeared in Africa around 300,000 years ago. Around 70,000 BC, Homo sapiens began to spread out of Africa, colonizing Asia, Europe, Australia and eventually the Americas.
7. Development of civilizations. With the end of the last Ice Age, around 12,000 years ago, agriculture developed, leading to sedentarization and the birth of the first civilizations.
Chad, one of the cradles of humanity
In short, Chad's paleontological and archaeological discoveries make it one of the cradles of humanity, if not the only one. But it's part of a much bigger picture. The whole of Africa can now be considered the cradle of humanity, with significant contributions from many regions, including East and Southern Africa. Future discoveries will continue to add to our understanding of this complex evolutionary history.
