Effects of brain and facial size on basicranial form in human and primate evolution

Bastir, Markus; Rosas, Antonio; Stringer, Chris; Cuétara, José Manuel de la; Kruszynski, Robert; Weber, Gerhard; Ross, Callum F.; Ravosa, Matthew J.

doi:10.1016/j.jhevol.2010.03.001

Cited by 191 publications

(169 citation statements)

References 38 publications

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“…For example, the midline basicranium attains adult morphology around 6 years of age in modern humans 32 -33 . Th e primate midline cranial base is not only determined by the morphology of the brain 34 but also by intrinsic factors of its endocranial precursors 9 and by facial size 35 . Although in primates large brains are associated with more fl exed cranial bases, larger faces are associated with less basicranial fl exion 35 , which explains why large-brained and large-faced Neanderthals have less fl exed cranial bases than equally large-brained, but small-faced modern humans 35 .…”

Section: Discussionmentioning

confidence: 99%

Evolution of the base of the brain in highly encephalized human species

et al. 2011

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The increase of brain size relative to body size -encephalization -is intimately linked with human evolution. However, two genetically different evolutionary lineages, Neanderthals and modern humans, have produced similarly large-brained human species. Thus, understanding human brain evolution should include research into specifi c cerebral reorganization, possibly refl ected by brain shape changes. Here we exploit developmental integration between the brain and its underlying skeletal base to test hypotheses about brain evolution in Homo. Three-dimensional geometric morphometric analyses of endobasicranial shape reveal previously undocumented details of evolutionary changes in Homo sapiens . Larger olfactory bulbs, relatively wider orbitofrontal cortex, relatively increased and forward projecting temporal lobe poles appear unique to modern humans . Such brain reorganization, beside physical consequences for overall skull shape, might have contributed to the evolution of H. sapiens ' learning and social capacities, in which higher olfactory functions and its cognitive, neurological behavioral implications could have been hitherto underestimated factors.

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Section: Discussionmentioning

confidence: 99%

Evolution of the base of the brain in highly encephalized human species

et al. 2011

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“…the chondrocranium plays a key integrative role in craniofacial development and evolution in genus Homo (Moss and Young, 1960;Enlow, 1990;Ross and Ravosa, 1993;Lieberman et al, 2000;McCarthy and Lieberman, 2001;Spoor, 2002, 2004;Bastir et al, , 2010Lieberman et al, 2008), the influence of the nasal septum, as one component of the chondrocranium, has not been as widely considered. There is, nevertheless, fossil evidence to suggest that an integrated nasal septal/premaxillary complex may account for variation in facial size between archaic and recent modern humans as Neandertal and recent human subadults exhibit taxonomic variation in the timing of premaxillary suture fusion.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, although nasal septal growth may be influenced by larger cranial base dynamics, it is potentially more highly integrated with the facial skeleton. Given the recent emphasis placed on elucidating developmental factors that affect the intrinsic growth of the facial skeleton Holton et al, 2010;Bastir et al, 2010), including during prenatal development Spoor, 2002, 2004), determining how the nasal septum may influence facial form is important to provide a more thorough understanding of the complex ontogenetic processes that were presumably altered during genus Homo evolution.…”

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confidence: 99%

Nasal Septal and Premaxillary Developmental Integration: Implications for Facial Reduction in Homo

Holton

Franciscus

Marshall

et al. 2010

The Anatomical Record

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The influence of the chondrocranium in craniofacial development and its role in the reduction of facial size and projection in the genus Homo is incompletely understood. As one component of the chondrocranium, the nasal septum has been argued to play a significant role in human midfacial growth, particularly with respect to its interaction with the premaxilla during prenatal and early postnatal development. Thus, understanding the precise role of nasal septal growth on the facial skeleton is potentially informative with respect to the evolutionary change in craniofacial form. In this study, we assessed the integrative effects of the nasal septum and premaxilla by experimentally reducing facial length in Sus scrofa via circummaxillary suture fixation. Following from the nasal septal-traction model, we tested the following hypotheses: (1) facial growth restriction produces no change in nasal septum length; and (2) restriction of facial length produces compensatory premaxillary growth due to continued nasal septal growth. With respect to hypothesis 1, we found no significant differences in septum length (using the vomer as a proxy) in our experimental (n ¼ 10), control (n ¼ 9) and surgical sham (n ¼ 9) trial groups. With respect to hypothesis 2, the experimental group exhibited a significant increase in premaxilla length. Our hypotheses were further supported by multivariate geometric morphometric analysis and support an integrative relationship between the nasal septum and premaxilla. Thus, continued assessment of the growth and integration of the nasal septum and premaxilla is potentially informative regarding the complex developmental mechanisms that underlie facial reduction in genus Homo evolution. Anat Rec, 294:68-78, 2011. V V C 2010 Wiley-Liss, Inc.

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“…Most empirical studies have focused on integration within populations, investigating how the variation among individuals is structured. This is only one aspect of the problem, however, because the concept of integration also applies at different levels [4], including genetic and environmental integration [8,9], integration of fluctuating asymmetry within individuals [9][10][11][12][13][14][15] and evolutionary integration across taxa in a clade [16][17][18][19][20][21]. Most plants, because of their modular body plans, offer additional opportunities to study integration among structures such as leaves or flowers within and among individuals in a population [22,23].…”

Section: Introductionmentioning

confidence: 99%

Studying morphological integration and modularity at multiple levels: concepts and analysis

Klingenberg

2014

Phil. Trans. R. Soc. B

283

301

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Although most studies on integration and modularity have focused on variation among individuals within populations or species, this is not the only level of variation for which integration and modularity exist. Multiple levels of biological variation originate from distinct sources: genetic variation, phenotypic plasticity resulting from environmental heterogeneity, fluctuating asymmetry from random developmental variation and, at the interpopulation or interspecific levels, evolutionary change. The processes that produce variation at all these levels can impart integration or modularity on the covariance structure among morphological traits. In turn, studies of the patterns of integration and modularity can inform about the underlying processes. In particular, the methods of geometric morphometrics offer many advantages for such studies because they can characterize the patterns of morphological variation in great detail and maintain the anatomical context of the structures under study. This paper reviews biological concepts and analytical methods for characterizing patterns of variation and for comparing across levels. Because research comparing patterns across level has only just begun, there are relatively few results, generalizations are difficult and many biological and statistical questions remain unanswered. Nevertheless, it is clear that research using this approach can take advantage of an abundance of new possibilities that are so far largely unexplored.

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Effects of brain and facial size on basicranial form in human and primate evolution

Cited by 191 publications

References 38 publications

Evolution of the base of the brain in highly encephalized human species

Evolution of the base of the brain in highly encephalized human species

Nasal Septal and Premaxillary Developmental Integration: Implications for Facial Reduction in Homo

Studying morphological integration and modularity at multiple levels: concepts and analysis

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