Are endocasts reliable proxies for brains? A 3D quantitative comparison of the extant human brain and endocast

Dumoncel, Jean; Subsol, Gérard; Durrleman, Stanley; Bertrand, Anne; Jager, Edwin de; Oettlé, Anna Catherina; Lockhat, Zarina I.; Suleman, Farhana Ebrahim; Beaudet, Amélie

doi:10.1111/joa.13318

Cited by 26 publications

(33 citation statements)

References 31 publications

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“…The endocranium is a reliable proxy for the brain in a range of craniates, including mammals (e.g. Dumoncel et al, 2020; Early et al, 2020). Relative masseter size was calculated as masseter volume divided by endocranial volume.…”

Section: Methodsmentioning

confidence: 99%

Ontogenetic and in silico models of spatial‐packing in the hypermuscular mouse skull

2021

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Anatomical structures physically interact to varying degrees throughout ontogeny, adulthood, and evolution. During ontogeny, genetically mediated changes in one structure can simultaneously affect important epigenetic changes in several surrounding structures. Moreover, interactions that reliably generate the same or similar phenotypes over successive ontogenies can shield from selection mutations in genes that would have otherwise defined those traits (see Green et al., 2017;Lahti et al., 2009;Zheng et al., 2019). These mutations can then accumulate, leading to punctuated phenotypic diversification as conditions prevail that destabilise the protective network of interactions and expose the gene variants to selection (Gould, 2002;Laland et al., 2015). Interactions also allow for phenotypic adjustments during life, which can accommodate behavioural changes of, for example, dietary niche or physical activity (e.g. Anderson et al., 2014). This capability extends into adulthood and can help genetically similar individuals and populations to tolerate and thrive under different environmental conditions (see Murren et al, 2015). The premise that structural interactions help define and maintain morphological outcomes has a long history and has taken many forms

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Section: Methodsmentioning

confidence: 99%

Ontogenetic and in silico models of spatial‐packing in the hypermuscular mouse skull

2021

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“…For instance, it was shown recently that scalp curvature is not related to brain gyrification [3]. However, very few such studies have been carried out on the links between cortical morphology and the internal interface of the skull, which gives rise to the endocasts of paleoanthropology [4]. This is an important topic addressed in this study.…”

Section: Introductionmentioning

confidence: 90%

“…However, the correspondence between these limited records of convolutional patterns and details of the surface of the brain remains to be demonstrated in modern humans. A few pioneer studies have considered this problem [4,44]. Moreover, it is necessary to develop new tools for the automatic and reliable determination of the endocranial sulci [45].…”

Section: Does the Endocast Reflects The Brain?mentioning

confidence: 99%

What Are the Synergies between Paleoanthropology and Brain Imaging?

Balzeau

Mangin

2021

Symmetry

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We are interested here in the central organ of our thoughts: the brain. 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. 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. It undeniably emerges from the perspective we propose here that paleoanthropology has much to gain from interacting more with the field of neuroimaging. 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. The contribution of neuroimaging will allow us to better define the relationship between brain and endocast. 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. We also conclude that exchanges between these two disciplines will also be beneficial to our knowledge of the Homo sapiens brain. 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.

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“…The analysis of endocranial morphology using 3D digital models generated from computer tomography (i.e., endocasts) allows us to include a larger number of species in the comparative analysis. Even though the endocasts do not provide detailed information about all gyri and sulci or subcortical regions, the inner surface of the skull is a good proxy for global asymmetry of the brain (Fournier et al 2011;Dumoncel et al 2021). Previous studies have shown that the analysis of endocast shape allows the quantification of external brain morphology because it represents a good proxy for describing correlated changes in relative size and position of brain lobes (Aristide et al 2016;Neubauer et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have shown that the analysis of endocast shape allows the quantification of external brain morphology because it represents a good proxy for describing correlated changes in relative size and position of brain lobes (Aristide et al 2016;Neubauer et al 2020). In this way, endocasts are a valuable source of information being increasingly used for studying the evolution of the brain in extinct and extant species (Neubauer et al 2010;Watanabe et al 2019;Dumoncel et al 2021;Early et al 2020). Particularly for the latter, endocasts are used because it is not always possible to collect specimens under the conditions required to preserve the soft tissues, and in some cases the capture of wild specimens and endangered species is not allowed.…”

Section: Introductionmentioning

confidence: 99%

Endocranial asymmetry in New World monkeys: a comparative phylogenetic analysis of morphometric data

et al. 2021

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Brain lateralization is a widespread phenomenon although its expression across primates is still controversial due to the reduced number of species analyzed and the disparity of methods used. To gain insight into the diversification of neuroanatomical asymmetries in non-human primates we analyze the endocasts, as a proxy of external brain morphology, of a large sample of New World monkeys and test the effect of brain size, home range and group sizes in the pattern and magnitude of shape asymmetry. Digital endocasts from 26 species were obtained from MicroCT scans and a set of 3D coordinates was digitized on endocast surfaces. Results indicate that Ateles, Brachyteles, Callicebus and Cacajao tend to have a rightward frontal and a leftward occipital lobe asymmetry, whereas Aotus, Callitrichinae and Cebinae have either the opposite pattern or no directional asymmetry. Such differences in the pattern of asymmetry were associated with group and home range sizes. Conversely, its magnitude was significantly associated with brain size, with larger-brained species showing higher interhemispheric differences. These findings support the hypothesis that reduction in inter-hemispheric connectivity in larger brains favors the lateralization and increases the structural asymmetries, whereas the patterns of shape asymmetry might be driven by socio-ecological differences among species.

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Are endocasts reliable proxies for brains? A 3D quantitative comparison of the extant human brain and endocast

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 26 publications

References 31 publications

Ontogenetic and in silico models of spatial‐packing in the hypermuscular mouse skull

Ontogenetic and in silico models of spatial‐packing in the hypermuscular mouse skull

What Are the Synergies between Paleoanthropology and Brain Imaging?

Endocranial asymmetry in New World monkeys: a comparative phylogenetic analysis of morphometric data

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