Dec 11, 2006
Scientists recently announced an important discovery in the study of human evolution. They found a fossil skeleton of an individual they believe lived 3.3 million years ago in the Dikika region of Ethiopia.
The fossil skeleton comes from the same species as the famous “Lucy” skeleton, Australopithecus afarensis, a species that may be on the line of descent between humans and their last common ancestor with apes. But it is of a very young individual, and its skeleton is more complete than any previously discovered.
The completeness of the skeleton is giving scientists a better understanding of how humans evolved. The Dikika fossil shows that this species had some similarities to humans and other features more like those of apes.
The species was a hominid, meaning it walked upright on two feet, like humans. The fossil’s shoulder blades, on the other hand, show that this species had powerful arms and shoulders that gave it the ability to swing from trees. The curved shape of the fossil child’s fingers was also better for grasping tree limbs and also indicate that it probably clung to its mother while she moved – more like chimp babies do than human babies, whose mothers set them down while they do other things.
Earlier fossils from this species show that it had a larger brain – proportionate to its size – than apes do. But the fossil child’s brain was smaller than that of a young chimpanzee at the same age. The fossil’s discoverers believe the skeleton shows that the child’s brain developed more slowly than those of apes – like human brains do.
It took scientists working on this fossil almost six years of diligent work to get to the point they could make this announcement. And new discoveries could change the significance of some of these details.
But the discovery of this extraordinary fossil adds to the picture of evolution as a process in which species arise having a mixture of features of earlier and later species.