According to genetic analyzes, the long road to modern humans began six to ten million years ago, when the branches of humans and chimpanzees separated in the family tree. There was a big change at the very beginning of this development.
Adept at climbing, if a little more sluggish than the chimpanzee ancestors, it probably still could, Guillaume Daver and Franck Guy of the University of Poitiers and their team conclude from the analysis of a femur and two forearm bones of this species. The fossils are was excavated in 2001 in the north of today’s Republic of Chad in the Sahara, the researchers report in the journal “Nature”.
“This analysis fits well with a skull of the same species that was found in the same place at the same time,” explains Friedemann Schrenk. The early and prehuman researcher from the Senckenberg Research Institute and Natural History Museum and from the Goethe University in Frankfurt am Main also works in Africa, mainly in Malawi and Tanzania, and was not involved in the study by the team from France and the Republic of Chad.
In addition, the group examined the right and left ulna, which are thought to have come from the same individual. These bones of the forearm are well suited to a creature carefully climbing through branches, but not to an ape walking across the ground on all fours.
According to this, the upright gait developed around seven million years ago, very early on on the way to humans and soon after the separation from the chimpanzee lineage.
“There is hardly any doubt about this age,” explains Friedemann Schrenk. It fits in with the major changes in the environment in Africa at the time. “During this time, the earth’s climate cooled down,” says the Senckenberg researcher. Tropical rainforests dwindled and at the same time the rift valley in East Africa opened up and changed rainfall enormously. “For the first time in Africa, savannahs emerged, which were initially more of bushland with grass on the ground,” Schrenk describes the change in ecosystems at that time.
