October 22, 2013
Dental Analyses Find No Common Ancestor Of Humans, Neanderthals
redOrbit Staff & Wire Reports - Your Universe Online
The search for a common ancestor that links modern humans to the ancient Neanderthals that roamed Europe thousands of years ago is far from over, according to a new study published online this week in the journal Proceedings of the National Academy of Sciences (PNAS).An international team of experts, including scholars from George Washington University, the Konrad Lorenz Institute for Evolution and Cognition Research in Austria, Indiana University and the Atapuerca Research Team in Spain, analyzed the shape and structure of dental fossils and found that none of the hominid species believed to be the so-called “missing link” fits the expected profile of an ancestor of both Neanderthals and modern humans.
As part of their work, the team used quantitative methods to study fossils of approximately 1,200 molars and premolars from 13 species or types of hominins -- both humans and human relatives/ancestors. Their research also uncovered evidence suggesting that the lines leading to Neanderthals and modern humans actually diverged approximately one million years ago – far earlier than studies centered on molecular evidence claim.
The results “call attention to the strong discrepancies between molecular and paleontological estimates of the divergence time between Neanderthals and modern humans,” according to lead author Aida Gómez-Robles, a postdoctoral scientist at the Center for the Advanced Study of Hominid Paleobiology at George Washington University.
Gómez-Robles and her colleagues used both morphometric analysis and phylogenetic statistics in an attempt to reconstruct the dental morphology of the last common ancestor linked both to modern humans and to Neanderthals. Following their research, they report “with high statistical confidence” that none of the hominins usually put forth as a common ancestor (including Homo heidelbergensis, H. erectus and H. antecessor) are “a satisfactory match.”
Furthermore, their research finds that possible human ancestors discovered in Europe are morphologically closer to Neanderthals than they are to modern men and women. This discovery suggests that the evolutionary line that led to Neanderthals occurred approximately one million years ago, and that the divergence of humans occurred far earlier than 350,000 years ago, as has been suggested by previous research.
“None of the species that have been previously suggested as the last common ancestor of Neanderthals and modern humans has a dental morphology that is fully compatible with the expected morphology of this ancestor," Gómez-Robles said. She and her colleagues suggest using their methodology to study other body parts represented in the fossil records of hominids, and that studying hominin remains from Africa could help find that common ancestor.