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Nathalie Lacaux - 26/01/2011

The brain of Cro-Magnon versus Modern Man: a matter of size

A multidisciplined team comprised of researchers from Inria, the French National Centre for Scientific Research (CNRS) and the French National Museum of Natural History has unveiled for the first time a study on changes in the brain during the evolution of our species, Homo sapiens, over the last 30,000 years.

The starting point: Cro-Magnon, an emblematic "ancestor"

A few months ago, Antoine Balzeau, a palaeoanthropologist and research scientist at the CNRS , and Dominique Grimaud-Hervé , a palaeontologist at the French National Museum of Natural History , reconstructed the endocranium of the "Cro-Magnon 1" specimen in 3D using imaging and prototyping methods. The endocranium is the inside surface of the cranial cavity and contains imprints left by the different regions of the brain, the veins and the meningeal network - a veritable goldmine of information in itself!

Antoine Balzeau  then compared the endocranium of the Cro-Magnon specimen with those of well-preserved fossilised Homo sapiens  discovered in modern times and dating from around 30,000 years ago. The analysis of these fossilised humans was then compared with a sample of 102 endocraniums from today's humans.

Benoît Combès  and Sylvain Prima, respectively PhD student and research scientist in the Inria project-team VisAGeS , also carried out an analysis of this reconstructed endocranium, automatically quantifying and mapping its asymmetries (anatomical differences between the two hemispheres). It is essential to study these, as they are often considered to be the biological substratum of the very high-level cognitive faculties that differentiate humans from other animal species, particularly other hominids.

Smaller and reorganised, our brain has evolved over 30,000 years.

The results obtained show that the main specific characteristics of the brain of Homo sapiens are found in the fossilised specimens. However, they also show that the brain has decreased in size and has been reorganised in our species over the last 30,000 years. Today, our brain is smaller, lower and compressed at the level of the frontal and occipital lobes, while the temporal lobes and the cerebellum have become enlarged compared with our predecessors. This demonstrates the anatomical plasticity of the brain of Homo sapiens , as well as the complexity of the relationships between its size and shape and its cognitive capacities.

What is "Cro-Magnon 1"?

Discovered in 1868 in the famous rock shelter of Cro-Magnon in Dordogne, this first skeletal specimen dubbed "1" is the most famous. It comes from an elderly male and consists of a near-complete skull. This was the first time that fossilised Homo sapiens  had been observed, which also closely resembled humans at the time. The finding of these fossils was such a major event that the term "Cro-Magnon" is still widely used to refer to prehistoric humans.

Keywords: Endocranium Visages Cro-Magnon Homo sapiens Inria Rennes - Bretagne Atlantique Modelling Images