|28 June 2010
Common ancestor not yet found
A doctoral study performed at the Centro Nacional de Investigacion sobre la Evolucion Humana, University of Granada (Spain) attempted to reconstruct the history of human evolution by performing analyses on teeth from almost all species of hominids that have lived. Going back over 4 million years, the morphology of dental fossils from Asia, Africa and Europe was compared.
A statistical analysis was done to determine the probabilty of correctly assigning each tooth to the species from which it was taken. The results revealed Neanderthal features in ancient European populations. But, according to Aida Gomez Robles, the author of the study, "None of (the samples) has a probability higher than 5% to be the common ancestor of Neanderthals and Homo sapiens. Therefore, the common ancestor of this lineage is likely to have not been discovered yet." This could put the divergence of the two species 500,000 years earlier than previously believed based upon genetic studies.
The analysis techniques used in the study allowed researchers to correctly assign a species to the tooth sample 60 to 80 percent of the time. If multiple teeth were analysed from the same individual, the success rate rose up to 100 percent in some cases.
This project employed cutting edge computer simulations to mathematically model the effect of environmental changes on tooth shape. The technique has been used in the past to study other mammals, but never in human evolution.
Robles used fossils from sites as diverse as Burgos (Spain), and Dmanisi (Republic of Georgia), as well as collections in Paris, Frankfurt, Berlin, Beijing, New York and Cleveland. The research was published in The Journal of Human Evolution, 2007 and 2008.
Sources: EurekAlert!, ScienceDaily, Machines Like Us (June 23, 2010)
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