Small or Simple: generality and causality of brain size reduction and simplification of cortical folding in insular large mammals

• Applicant: Roberto Rozzi, Ph.D.
• Subject Area: Palaeontology ; Evolution, Anthropology ; Systematics and Morphology (Zoology)
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 435314312

The evolutionary anomalies of island life are among the most spectacular phenomena in nature. Insular mammals often exhibit remarkable adaptations, such as dwarfism and gigantism, increased molar crown height, transition towards a low-gear locomotion, and changes in brain size and morphology. A reduction of relative brain size has been recorded in a few extinct insular large mammals, such as the diminutive Hobbit man Homo floresiensis, and it has been hypothesised that a simplification of cortical folding would characterise the brain of phyletic dwarfs. Yet, relatively little is currently known, in any detailed systematic way, about the selective forces influencing brain evolution in these biotas. In this project, I propose to integrate data on fossil and living species to investigate the generality and causality of ecogeographic patterns of brain size variation and changes in the degree of cortical folding in insular large mammals. To achieve this end, the project will concentrate on Artiodactyla, one of the most diversified and widespread clades of mammals, which include a large number of insular species that inhabited or are still living on islands located in different regions and characterised by different environmental features and palaeogeographic histories. I will combine advanced methodologies in palaeoneurology, such as high-resolution computed tomography (μCT) and 3D segmentation and modelling, to obtain and describe digital neurocranial endocasts of the focal species. Moreover, an extensive dataset of ecological and geographical variables will be assembled and machine learning methods will be implemented to investigate the causal mechanisms driving brain evolution in insular large mammals. The proposed project will enable development of an evolutionary conceptual model that will have the potential to inform broader comparative questions about mammalian brain evolution.

• DFG Programme: Research Grants
• Co-Investigators: Faysal Bibi, Ph.D.; Professor Dr. Johannes Müller