Ancient skull raises questions about human evolution
The earliest modern humans migrated into northern Africa and Eurasia sometime after 50 thousand years ago. But Eurasia was already populated by a different early human form, the Neanderthal, beginning about 130 million years ago. Exactly when Neanderthals disappeared is a topic of debate, and it is unknown whether they interacted with modern humans when the latter migrated to Europe. A recently discovered 40 thousand year old skull from a Romanian cave suggests that they did.
Based upon its proportions, the skull is clearly that of a modern human, making it and other bones from the same cave the oldest known modern human remains in Europe. Yet the skull also includes several Neanderthal-like characteristics including its receding forehead and large molars. The anthropologists who discovered and described the skull say this mosaic of traits suggests that humans and Neanderthals did meet, interact, and interbreed. If so, elements of the Neanderthal gene pool may have been preserved in modern humans even as Neanderthals themselves went extinct. Other scientists remain skeptical, claiming that the two species never actually met one another. Only the discovery of additional remains can resolve the still-raging debate and support or reject hypotheses about how these two branches of the human family tree influenced one another's evolution.
Another interpretation of the newly described skull includes "evolutionary reversal," that is, the appearance of archaic traits in a lineage of modern humans even without hybridization. Alternatively, the scarcity of ancient human remains may simply have left us with an incomplete catalog of diversity of early modern humans, and this find could be one step toward a more complete picture.
The skull is described in the January 23, 2007, issue of the Proceedings of the National Academy of Sciences.
University of Bristol news release
CNN news story
livescience.com story, containing additional links to human evolution resources
Video clips and more human/ Neanderthal information from Washington University
Homepage of author Erik Trinkaus
PNAS
Questions for Review and Discussion
1. Examine a timeline of human evolution based on the evidence to date. When did Neanderthals arise and disappear? According to the new study, how does the timing of Neanderthal disappearance relate to the migration of modern humans into Eurasia?
2. What characteristics of the newly discovered skull are human-like? Neanderthal-like?
3. How do anthropologists interpret the combination of traits in this skull? What additional evidence would be needed to support or reject each possible interpretation?
