Sahelanthropus Tchadensis and Early Human Bipedalism
Author: French National Centre for Scientific Research
Published: 24 Aug 2022 - Updated: 14 Jul 2026
Publication Details: Peer-Reviewed | Anthropology News
Table of Contents:
Synopsis - Definition - Introduction - Main - FAQ's - Insights, Updates - Related Content
Synopsis: This research presents a peer-reviewed analysis, published in Nature, of three limb bones - a femur and two ulnae - belonging to Sahelanthropus tchadensis, the oldest currently identified representative of humanity at roughly 7 million years old. Conducted by paleontologists from the CNRS, the University of Poitiers, and Chadian partners, the work is authoritative because its conclusions rest on measurements of more than twenty skeletal characteristics compared against a broad sample of living and fossil apes, using biometric, geometric morphometric, and microtomography imaging methods. The findings indicate that Sahelanthropus walked on two legs on the ground while still moving through trees using a distinctive arboreal clambering, which is useful for anyone interested in human origins because it pushes the emergence of upright walking far earlier than many earlier accounts assumed and shows that bipedalism coexisted with other forms of movement.*
At a Glance
- 1 - The fossil remains were discovered in 2001 at Toros-Menalla in the Djurab Desert of Chad.
- 2 - The well-preserved skull, nicknamed Toumai, first pointed to two-legged locomotion through the position of its occipital foramen.
- 3 - The ulnae reveal that its tree climbing relied on firm hand grips, clearly differing from gorillas and chimpanzees that lean on the backs of their finger bones.
- Topic Definition: Bipedalism
Bipedalism is a form of terrestrial locomotion where an organism moves utilizing its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped meaning two feet. There are several states of movement commonly associated with bipedalism:
- Jumping/hopping: Moving by a series of jumps with both feet moving together.
- Walking: One foot in front of another, with at least one foot on the ground at any time.
- Running: One foot in front of another, with periods where both feet are off the ground.
- Standing: Staying still on both legs. This is an active process in most bipeds, requiring constant balance adjustment.
Introduction
Sahelanthropus, the oldest representative of humanity, was indeed bipedal... but that's not all!
The acquisition of bipedalism is considered a decisive step in human evolution. Nevertheless, there is no consensus on its modalities and age, notably due to the lack of fossil remains. A research team involving researchers from the CNRS, the University of Poitiers(1), and their Chadian partners examined three limb bones from the oldest human representative currently identified, Sahelanthropus tchadensis. Published in Nature on August 24, 2022, this study reinforces the idea of bipedalism being acquired very early in our history, at a time still associated with the ability to move on four limbs in trees.
Main Content
At 7 million years old, Sahelanthropus tchadensis is considered the oldest representative species of humanity. Its description dates back to 2001 when the Franco-Chadian Paleoanthropological Mission (MPFT) discovered the remains of several individuals at Toros-Menalla in the Djurab Desert (Chad), including a very well-preserved skull. This skull, in particular the orientation and anterior position of the occipital foramen where the vertebral column is inserted, indicates a mode of locomotion on two legs, suggesting that it was capable of bipedalism(2).
In addition to the skull, nicknamed Toumaï, and fragments of jaws and teeth that have already been published, the locality of Toros-Menalla 266 (TM 266) yielded two ulnae (forearm bone) and a femur (thigh bone). These bones were also attributed to Sahelanthropus because no other large primate was found at the site; however, it is impossible to know if they belong to the same individual as the skull. Paleontologists from the University of Poitiers, the CNRS, the University of N'Djamena, and the National Centre of Research for Development (CNRD, Chad) published their complete analysis in Nature on August 24, 2022.
The femur and ulnae were subjected to a battery of measurements and analyses concerning their external morphology and internal structures using microtomography imaging: biometric measurements, geometric morphometrics, biomechanical indicators, etc. These data were compared to those of a relatively large sample of extant and fossil apes: chimpanzees, gorillas, orangutans, Miocene apes, and members of the human group (Orrorin, Ardipithecus, australopithecines, ancient Homo, Homo sapiens).
The structure of the femur indicates that Sahelanthropus was usually bipedal on the ground but probably also in trees. According to results from the ulnae, this bipedalism coexisted in arboreal environments with a form of quadrupedalism, that is arboreal clambering enabled by firm hand grips, clearly differing from that of gorillas and chimpanzees who lean on the back of their phalanges.
The conclusions of this study, including the identification of habitual bipedalism, are based on the observation and comparison of more than twenty characteristics of the femur and ulnae. They are, by far, the most parsimonious interpretation of the combination of these traits. All these data reinforce the concept of very early bipedal locomotion in human history, even if other modes of locomotion were also practiced at this stage.
This work was supported by the French Ministry for Europe and Foreign Affairs, the Chadian Government, the French National Research Agency (ANR), the Nouvelle-Aquitaine Region, the CNRS, the University of Poitiers, and the French representation in Chad. It is dedicated to the memory of the late Yves Coppens, precursor and inspirer of the MPFT's work in the Djourab Desert.
References:
(1) - At the PALEVOPRIM laboratory (CNRS / University of Poitiers).
(2) - See these two articles:
- A new hominid from the Upper Miocene of Chad, Central Africa, Michel Brunet, et al., Nature, 11 July 2002.
- Virtual cranial reconstruction of Sahelanthropus tchadensis, Christoph P.E. Zollikofer et al., Nature, 7 April 2005.
Frequently Asked Questions
NOTE: Researched FAQ's by Disabled World (DW)
Who was Yves Coppens and why is this study dedicated to him?
Yves Coppens was a French paleontologist who inspired and helped guide the Franco-Chadian research in the Djurab Desert, and the study is dedicated to his memory.
What does the name Sahelanthropus tchadensis mean?
The name references the Sahel region and Chad, where the fossils were found, combined with the Greek root for human, marking it as an early human relative from that area of Central Africa.
Why does the position of the occipital foramen indicate bipedalism?
The occipital foramen is the opening where the vertebral column meets the skull, and its forward, downward orientation suggests the head sat atop an upright spine, which is consistent with walking on two legs.
How do scientists estimate that Sahelanthropus is 7 million years old?
The age is based on the geological context of the Toros-Menalla site and dating of associated fossil fauna, placing the remains in the late Miocene epoch.
What is microtomography and why was it used on the bones?
Microtomography is a high-resolution scanning technique that images internal bone structure without damaging the fossil, allowing researchers to study cortical thickness and mechanical stress patterns tied to locomotion.
Does this study prove humans evolved directly from Sahelanthropus?
No, the study identifies Sahelanthropus as the oldest known representative of the human group rather than a confirmed direct ancestor, and its exact place on the family tree remains a subject of ongoing research.
Insights, Analysis, and Developments
Editorial Note: Because the femur and ulnae cannot be confirmed as belonging to the same individual as the Toumai skull, some caution is warranted, yet the convergence of more than twenty independent skeletal traits toward habitual bipedalism makes this one of the more carefully argued cases for upright walking at the very root of the human lineage, and a fitting tribute to the late Yves Coppens to whom the work is dedicated.*Attribution/Source(s): This peer reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by French National Centre for Scientific Research and published on 24 Aug 2022, this content may have been edited for style, clarity, or brevity.
* Editorial additions by Ian C. Langtree.