SAHELANTHROPUS TCHADENSIS: CHARACTERISTICS, TOOLS, CULTURE - BIOLOGY - 2024

Sahelanthropus tchadensis is the scientific name for the oldest hominin species known to date. It represents the basal lineage of the evolutionary tree of Homo sapiens. This species was defined from a collection of skulls and other bones found at a paleontological site in the Republic of Chad.

The fossil bones were located between 2001 and 2002 in three locations close to each other in the Djurab desert area (Toros-Menalla sector, Chad) in the Sahel of Chad. The collection available so far consists of a nearly complete skull, various jaw parts, loose teeth, and a fractured femur.

Reconstruction of Sahelanthropus tchadensis, one of the first primates. Author: TheCarlagas, from Wikimedia Commons

The name of this fossil genus, for now monospecific (made up of this single species), means "Man from the Sahel." And the specific epithet (tchadensis) refers to the current place of origin of the collected samples.

According to the dating made, Sahelanthropus tchadensis existed about 6 to 7 million years ago. It is thought to have been a small, erect hominin that lived in swampy areas.

The first individual found of this species (the skull) was baptized as Toumaï (French spelling) or Tumai, a word in Dazaga, a Nilo-Saharan language. Tumai means "hope to live."

characteristics

-Systematic

It does not have a pronounced cranial ridge at the top, although it is more towards the nape. It had a rather orthognathic face (face with a vertical plane tending straight), although somewhat prognathic (projected forward) in the jaw.

The mandibular apparatus is robust, although the dental arch is small and narrow, U-shaped.

-Habitat

Sahel

Sahelanthropus tchadensis fossils were located towards the northern part of the Sahel, more desert.

It is the ecoclimatic strip of transition between the Sahara desert that occupies a large part of North Africa. With the exception of the Maghreb (the fertile strip of the North African coast in the Mediterranean), and the South African savannas.

Currently it is made up of a combination of desert areas, dunes, sandy savannas with scattered stunted trees and thorny scrub. Its topography is mostly flat. It has a bi-seasonal climate, with a dry season from October to June, and a rainy season from July to September.

The temperature in the shade varies from a minimum of 23.5ºC to a maximum of 44.3ºC. In the soil the temperature can reach 50 ºC.

Possible Tumai habitat

It is considered that 6 or 7 million years ago (late Miocene) they were marshy areas. At this time Sahelanthropus tchadensis inhabited these lands. The evidence of the fossil fauna found associated with the remains of S. tchadensis supports this hypothesis.

Anthracotheriidae (intermediate animals between pigs and hippos, extinct about 5 million years ago) were found. There were also remains of Hippopotamidae (hippos), Proboscidia (ancient elephants) and a primitive wild pig (Nyanzachoerus syrticus).

On the other hand, the substrate where the samples were located was identified as perilacustrine sandy rocks. This would indicate that Tumai possibly lived on the shores of a lake. This would be the Paleo-Lake Mega Chad.

Controversial discovery

Bipedalism

Some anthropologists have questioned the possible bipedal condition of Sahelanthropus tchadensis. More detailed analysis of the found femur and skull appears to be required to reach a definitive conclusion. This is essential to locate Sahelanthropus tchadensis as part of the hominids.

An ape?

There are those who consider that Sahelanthropus tchadensis was an ape, closer to modern chimpanzees than to the direct evolutionary line of Homo sapiens. Furthermore, it is suggested that it was not an obligate but occasional biped, like chimpanzees.

The arguments that support this position are based on the position of the foramen magnum in the skull, in addition to some characteristics of the molars. On the other hand, there is still no complete analysis of the found femur.

However, considerable evidence has also been provided that continues to support the initial hypothesis of Sahelanthropus tchadensis as a hominin and not as a monkey.

Among these we have 3D reconstructions of the skull. Likewise, tomographic analyzes of the found teeth and jaws have been carried out.

Therefore, the controversy about the correct location of Sahelanthropus tchadensis within primates remains open.

Tools

In the fossil deposit where Sahelanthropus tchadensis was located, no type of elaborate tool was found.

Nor is there any direct evidence that this species, although it was probably bipedal, has used any type of object such as stones or sticks as possible rudimentary tools.

Therefore, at the level of paleontological inference, the reduction of the canines has allowed to speculate on the possible use of tools.

They could replace the diminished tear capacity of these diminished teeth. The hypothesis is also supported by the bipedal condition, which leaves the use of the hands free.

Brain capacity

According to estimates of the volume of the almost complete skull belonging to Tumai, Sahelanthropus tchadensis must have had a brain capacity of 320-380 cm³, closer to that of a modern chimpanzee (approximately 400-450 cm³), and far removed from 1,350-1500 cm³ of current Homo sapiens sapiens.

Diet

Due to the characteristics of the dentition, it must have been an omnivorous animal. Possibly their main diet would be composed of fruits, seeds and roots, supplemented with small animals.

Culture

Remains of around six individuals were found at the Toros-Menalla sites. This can lead to the conclusion that like all hominids and primates in general, it was a social, gregarious animal.

Beyond that, there is no evidence available to unravel whether he had developed any relevant cultural element.

References

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6. Wolpoff MH, B Senut, M Pickford and J Hawks. (2002). Sahelanthropus or 'Sahelpithecus' ?. Nature 419: 581-582.
7. Zollikofer CPE, MS Ponce de León, DE Lieberman, F Guy, D Pilbeam, A Likius, HT Mackaye, P Vignaud and M Brunet. (2005). Virtual cranial reconstruction of Sahelanthropus tchadensis. Nature, 434 (7034): 755-.