Remarkable Fossil Discovery in Africa

An international archeological research team has discovered the fossilized remains of a six- to seven-million-year-old skull in the Sahel desert in the central African country of Chad. The significance of the Sahel skull rivals that of Australopithecus, discovered in the 1920's, and is described as the paramount archeological find of our time.

The fossil represents a new genus and species of hominid (organisms that appear to be more closely related to present-day humans than to present-day chimpanzees). Previous hominid fossils have been found eastern and southern Africa. That this new fossil was found in central Africa, suggests our human ancestors were more widely-distributed than scientists had suspected. The new fossil has been assigned the taxonomic name Sahelanthropus tchadensis.

Scientists look to hominid fossils for clues about human evolution. When compared with the other known hominid groups—Homo, Paranthropus, Australopithecus, Kenyanthropus, Ardipthecus, Orrorin—the newly discovered Sahelanthropus is the eldest, dating back to a time when modern humans had recently diverged from chimpanzees.

After more than twenty-five years of searching, archeologist Michel Brunet and his colleagues uncovered the near-complete cranium, fragments of a jaw bone, and several teeth from the sands of the Sahel desert. Their meticulous analysis of the skull reveals a hominid with a surprising mixture of both primitive and more advanced characteristics. The size of the skull's interior indicates a small brain, while the facial structure and teeth are human-like. The fossil has a pronounced ridge that runs along the brow, a characteristic not exhibited in humans.

Many scientists believe that humans and chimpanzees share a common ancestor. Until now, scientists believed the human and chimpanzee lineages to have diverged sometime between five and seven million years ago. These estimates are based on comparisons between human and chimpanzee DNA. But Sahelanthropus sheds new light on the past, indicating that our common ancestor existed further back in history than previously estimated.

Notes

1. Michel Brunet of the University of Poitiers, France was the leader of the team that made the discovery of the Sahelanthropus skull.
2. The Sahelanthropus skull is nicknamed 'Toumai' which means 'hope of life' in the African Goran language.
3. The discovery of the Toumai skull was published in July 2002 in the journal Nature. The specimens described in that paper were collected between July 2001 and February 2002. Please refer to Table 1. Specimens of Sahelanthropus tchadensis for additional details.

Sources

• Brunet, M. et al. 'A new hominid from the Upper Miocene of Chad, Central Africa'. Nature 418:145. July 2002.
• Scientists Delight in Ancient Skull Find (BBC News)
• Q&A: Chad Fossil Discovery (BBC News)
• It's a Wonderful Thing (BBC News)
• Reaction From 'Lucy's' Discoverer (NPR)
• Ancient Skull Challenges Human Origins (CNN)

Graphite Drawing © Laura Klappenbach.