A Bioinformatics Analysis of RUNX2 (A Transcription Factor Essential for Osseous Morphogenesis and Metopic Suture Closure Regulation) with Possible Implications for Hominin Brain Evolution

DOI: 10.14673/HE2015121005
Published in:
 Human Evolution – Vol.30 – N.1-2 – 2015

Abstract

Recent sequencing of the Neanderthal genome reveals signs of positive selection in the modern human variant of the RUNX2 (CBFA1) gene, which is known to affect metopic suture fusion, as well as being essential for osteoblast development and proper bone formation. It is possible that evolutionary changes in RUNX2, affecting aspects of the morphology of the upper body and cranium, were of importance in the origins of modern humans.

To contribute to a better understanding of the molecular evolution of this gene, probably implicated in human evolution, we performed a comparative bioinformatic analysis of the coding and coded sequences of RUNX2 in Homo sapiens, Pan troglodytes, Gorilla gorilla, Pongo abelii, and Macaca mulatta. We found differences between Homo sapiens and the other Primates examined in amino-acid sequences of certain RUNX2 protein isoforms, which may have important implications for the timing of metopic suture closure. However, further studies are required to clarify the potentially distinct developmental roles of different species-specific N-terminal isoforms. Future studies may be particularly important for gaining a better understanding of possible evolutionary changes in the molecular mechanisms underlying the likely modification of frontal neurocranial ossification patterns that occurred during hominin brain evolution.

Magherini, S.
Morucci, G.
Branca, J.J.V.
Pacini, S.

Department of Experimental and Clinical Medicine,
University of Firenze, Viale Morgagni 85, 50134, Firenze, Italy.
E-mail: stemaghe@libero.it

Fiore, M.G.

Serrao, A.
Ruggiero, M. 

Department of Experimental and Clinical Biomedical Sciences,
University of Firenze, Viale Morgagni 50, 50134 Firenze, Italy.

Chiarelli, B.
Laboratory of Anthropology and Ethnology, Department of Evolutionary Biology,
University of Florence, Via del Proconsolo 12, 50122, Florence, Italy.

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Pages: 17
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Evolution of the Hominin Brain: A Review of Variations in Size and Shape

DOI: 10.14673/HE2015121001  
Published in Human Evolution – Vol.30 – 1-2-2015

Keywords: endocranial casts, hominin brain evolution, primate comparative neuroanatomy

Abstract
If we aim to understand the acquisition of human cognitive organization during hominin evolution, two fundamental and complementary lines of evidence must be taken into account: the first is paleoneurological, based on the analyses of brain “endocasts” (endocranial casts) of our evolutionary ancestors’ fossils, namely casts made of the neurocranium interior of hominin skulls; the second is neurological, based on comparative neurological data on living primates, assuming that changes occurred from an ape-like forerunner, whose neuroanatomical relationships were somewhat similar to those of extant chimpanzees and gorillas, the closest living evolutionary relatives of present-day humans.
In this article, we summarize how advances in the study of hominin endocasts, together with comparative neurological data presently available on the cerebral neocortex and cerebellum of modern humans and extant apes, impact on our understanding of the nature and timing of hominin brain evolution.
The major external phenotypic effect that can be observed from the hominin fossil record is an increase in brain size, but the evolutionary development of the hominin brain must have actually been much more complex. The paleoneurological and comparative neuroanatomical evidence suggests that brain size and neurological reorganization were both important variables in the course of hominin brain evolution. During the last three million years, there have occurred allometric and non-allometric brain size increases, interspersed (or interdigitated) with critical reorganizational changes.

Magherini, S.
Morucci, G.
Branca, J.J.V.
Pacini, S.

Department of Experimental and Clinical Medicine,
University of Firenze, Viale Morgagni 85, 50134, Firenze, Italy.
E-mail: stemaghe@libero.it

Fiore, M.G.
Ruggiero, M. 

Department of Experimental and Clinical Biomedical Sciences,
University of Firenze, Viale Morgagni 50, 50134 Firenze, Italy.

Chiarelli, B.
Laboratory of Anthropology and Ethnology, Department of Evolutionary Biology,
University of Florence, Via del Proconsolo 12, 50122, Florence, Italy.

File format: PDF
Pages: 47
Price Euro: 12,00

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