Posts Tagged 'Jebel Irhoud 1'

Modern human brain shape

In a very comprehensive (and elegant!) article Simon Neubauer and colleagues have now analyzed brain shape variation along the modern human lineage. Since the description of the skull and endocast of Jebel Irhoud, it was clear that modern human brain form could have evolved after modern human origin. So, at that time (150,000-300,000 years ago) we had modern humans without modern brains. If Jebel Irhoud was Homo sapiens, then “early modern humans” lacked our characteristic globular brain shape, which is due to parietal lobe bulging and cerebellar form. Then, some later “archaic modern humans” seem to display a sort of intermediate morphology. Only recently (30,000-100,000 years ago) modern humans have evolved modern brains, at least in terms of general proportions and gross appearance. Of course, it’s difficult to say whether this transition was gradual or more abrupt. This article of the Max Planck team follows a previous one on the same specimens, and provides a very detailed analysis of many fossils that describe the evolution of our own species. Although the fossil record is not continuous because of the many chronological gaps, results suggest that a gradual change was likely. They also emphasize that a full-globularity can be found at the same time in which we find the archaeological evidence of behavioural modernity (arts, symbols, complex tools …). I remarked this same point many years ago, but the statement was not much appreciated because of the many uncertainties on the cultural “modern revolution” (more or less gradual, more or less discontinuous). Whatever the process behind, the appearance of a modern brain form (largely influenced by parietal districts associated with visuospatial functions, body cognition and visual imagery) matches the appearance of a modern behaviour (largely based on visual cognition and visuospatial managements, ranging from simulation and imaging to body-tool integration). Maybe it is but a coincidence, but nonetheless … they match.

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The case of Jebel Irhoud 1

Bruner and Pearson 2013The cranial morphology of  Jebel Irhoud 1 still lacks a robust phylogenetic interpretation. Together with Osbjorn Pearson, we have just published on Anthropological Science a general synthesis on its neurocranial features. If we assume that this fossil is somehow related to the modern human lineage, the derived facial anatomy and plesiomorph neurocranial form lead to two main points. First, this braincase evolved by parallelism in both modern humans and Neandertal lineage, or else there is a unknown common ancestor with the same neurocranial organization. Second, the origin of the modern human brain is not strictly associated with the origin of the modern human lineage.


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    A recent work, analyzing the development and evolution of the primate cortical folding, evidences two separate folding processes of the neocortex. Namba and colleagues examine two subtypes of neocortex, the dorsal isocortex, defined as the portion of neocortex limited laterally by the lateral fissure (LF) and medially by the cingulate sulcus (CiS), and the p […]

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  • Seven Million Years of Human Evolution
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  • Researchers develop non-invasive deep brain stimulation method
    Researchers at MIT have developed a new method of electrically stimulating deep brain tissues without opening the skullSince 1997, more than 100,000 Parkinson’s Disease patients have been treated with deep brain stimulation (DBS), a surgical technique that involves the implantation of ultra-thin wire electrodes. The implanted device, sometimes referred to as […]

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