Brains of Neanderthals and Modern Humans Developed Differently
ScienceDaily (Nov. 9, 2010) — Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany have documented species differences in the pattern of brain development after birth that are likely to contribute to cognitive differences between modern humans and Neanderthals.
The brains of Neanderthals and modern humans are very similar at the time of birth. A reconstruction of a Neanderthal baby is compared to a modern human newborn. While the face of the Neanderthal is already larger than in a modern human at the time of birth, their brain shapes and volumes are very similar. Internal casts of brain cavities of skulls (Neanderthal: red; modern humans: blue) provide information about the relative size and form of the brain. (Credit: Max Planck Institute for Evolutionary Anthropology)
Whether cognitive differences exist between modern humans and Neanderthals is the subject of contentious disputes in anthropology and archaeology. Because the brain size range of modern humans and Neanderthals overlap, many researchers previously assumed that the cognitive capabilities of these two species were similar. Among humans, however, the internal organization of the brain is more important for cognitive abilities than its absolute size is. The brain's internal organization depends on the tempo and mode of brain development.
Based on detailed measurements of internal shape changes of the braincase during individual growth, a team of scientists from the MPI has shown that these are differences in the patterns of brain development between humans and Neanderthals during a critical phase for cognitive development.
Discussions about the cognitive abilities of fossil humans usually focus on material culture (e.g. the complexity of the stone tool production process) and endocranial volumes. "The interpretation of the archaeological evidence remains controversial, and the brain-size ranges of Neanderthals and modern humans overlap," says Jean-Jacques Hublin, director of the Department of Human Evolution at the MPI-EVA in Leipzig where the research was conducted. Hublin adds, "our findings show how biological differences between modern humans and Neanderthals may be linked to behavioural differences inferred from the archaeological record."
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Current Biology, Volume 20, Issue 21, R921-R922, 9 November 2010
doi:10.1016/j.cub.2010.10.018
Brain development after birth differs between Neanderthals and modern humans
Philipp Gunz1, §, , , Simon Neubauer1, §, Bruno Maureille2 and Jean-Jacques Hublin1
1 Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Deutscher Platz 6, D-04103 Leipzig, Germany
2 Université de Bordeaux, UMR5199 PACEA – Laboratoire d'Anthropologie des Populations du Passé, CNRS Université Bordeaux 1, MCC F-33405 Talence cedex, France
Corresponding author
§ These authors contributed equally to this work
Summary
Neanderthals had brain sizes comparable to modern humans, but their brain cases were elongated and not globular as in Homo sapiens[1,2]. It has, therefore, been suggested that modern humans and Neanderthals reached large brain sizes along different evolutionary pathways [2]. Here, we assess when during development these adult differences emerge. This is critical for understanding whether differences in the pattern of brain development might underlie potential cognitive differences between these two closely related groups. Previous comparisons of Neanderthal and modern human cranial development have shown that many morphological characteristics separating these two groups are already established at the time of birth [3,4,5], and that the subsequent developmental patterns of the face are similar, though not identical [6]. Here, we show that a globularization phase seen in the neurocranial development of modern humans after birth is absent from Neanderthals.
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