Study explores Gavin de Beer's enduring concepts in vertebrate skull development

An article published in the Philosophical Transactions B journal examines the enduring ideas of Gavin de Beer about modularity, homology, and heterochrony in vertebrate skull development. The authors, Dr. James Hanken and Dr. Brian K. Hall, analyse de Beer's shift from embryology to comparative skull studies, highlighting current perspectives on these concepts and emphasizing cellular roles and evidence for the evolution of middle ear ossicles.

De Beer's foundational concepts have withstood the test of time as our understanding of the underlying biological processes has evolved. The study scrutinizes de Beer's transition from experimental embryology to comparative and descriptive studies of skulls, jaws, and middle ear ossicles. It includes his later research on mammalian skull and head segmentation. Contemporary insights into the role of neural crest and mesodermal cells in skull development are incorporated, using developmental, paleontological, and molecular evidence to illustrate the current understanding of modularity, homology, and heterochrony.

The article begins by reflecting on the phrase 'the mammalian skull' and the implicit assumption that a conserved structural pattern exists among all mammals that is distinct from other vertebrates. It underscores the challenge of identifying a skull as mammalian due to diverse variations in morphology, proportions, and adaptations observed within and among living vertebrates. To appreciate nuances in skull morphology—known as 'morphospace'—the authors suggest exploring natural history museums or comprehensive online collections.

The article highlights de Beer's exploration of skull development and evolution with particular attention paid to his recognition of variation and dedication to unraveling intricacies. De Beer's work expanded the scope of 'skulls' beyond craniums to include mandibular and hyoid arch skeletons, upper and lower jaws, as well as middle ear ossicles. The authors underscore de Beer's contributions to understanding modularity, homology, and heterochrony, exploring how these concepts have evolved in light of contemporary research and emphasizing the ongoing relevance of his work.

The article was published by Royal Society Publishing: Brian K. Hall and James Hanken, "Modularity, homology, heterochrony: Gavin de Beer’s legacy to the mammalian skull," Phil. Trans. R. Soc. B (May 2023). DOI: doi.org/10.1098/rstb.2022.0078