In the absence of brain tissues preserved in the fossil record, endocasts provide the only direct evidence of brain evolution. erectus followed an ontogenetic shape trajectory that was more similar to chimpanzees than humans.Įndocasts (i.e., replicas of the inner surface of the bony braincase) constitute a critical proxy for qualifying and quantifying variations in brain shape and organization in extinct taxa. Based on this new knowledge, neurocranial shape supports the assessment that KNM-ER 42700 is a young juvenile H. erectus that combines elements of both extant species. sapiens and chimpanzees, implying a unique trajectory for H. The data are also compatible with an ontogenetic shape trajectory that is in some regards intermediate between that of recent H. erectus despite their more distant phylogenetic relatedness. Instead, the chimpanzee pattern might be a better ‘fit’ for H. erectus individuals cannot be accommodated within the pattern of the postnatal neurocranial trajectory for humans. erectus juvenile from Mojokerto together with subadult and adult H. ![]() However, our study also reveals differences in the magnitudes and, to a lesser extent, directions of the species-specific trajectories that add to the overall shared pattern of neurocranial shape changes. erectus, for which only one well-preserved very young individual is known. This finding suggests that ectoneurocranial data from extant hominids can be used to model the ontogenetic trajectory for H. We show that all four species share common patterns of developmental shape change resulting in a relatively lower cranial vault and expanded supraorbital torus at later developmental stages. erectus and assess the proposed juvenile status of this fossil using recent Homo sapiens, chimpanzees (Pan troglodytes), and Neanderthals (Homo neanderthalensis) to model and discuss changes in neurocranial shape from the juvenile to adult stages. Here, we investigate (ecto)neurocranial ontogeny in H. Documenting the anatomy among other human species and including the variation over time within our own species are approaches that offer us a new perspective through which to appreciate what really characterizes the brain of humanity today.īased on ontogenetic data of endocranial shape, it has been proposed that a younger than previously assumed developmental status of the 1.5-Myr-old KNM-ER 42700 calvaria could explain why the calvaria of this fossil does not conform to the shape of other Homo erectus individuals. We also conclude that exchanges between these two disciplines will also be beneficial to our knowledge of the Homo sapiens brain. Models of intra- and inter-species variability in brain morphology inferred from large neuroimaging databases will help make the most of the rare endocasts of extinct species. The contribution of neuroimaging will allow us to better define the relationship between brain and endocast. ![]() ![]() Improving our understanding of the morphology of the endocast necessarily involves studying the external surface of the brain and the link it maintains with the internal surface of the skull. It undeniably emerges from the perspective we propose here that paleoanthropology has much to gain from interacting more with the field of neuroimaging. At the same time, paleoanthropology has to deal with partial reflections on the shape of the brain, on fragmentary specimens and small samples in an attempt to approach the morphology of the brain of past human species. Advances in neuroscience have made it possible to obtain increasing information on the anatomy of this organ, at ever-higher resolutions, with different imaging techniques, on ever-larger samples. We are interested here in the central organ of our thoughts: the brain.
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