3D modelling to analyze heat dissipation on fossil endocasts

Abstract

Brain evolution in the human genus is associated with a definite increase in metabolic expenditure. Currently, there is no agreement on the existence of specific cooling mechanisms in Homo sapiens to balance the heat production related to such high metabolic rates. At the same time there is little information on the thermoregulatory biology of the brain mass in our own species. Cortical and meningeal vessels have been hypothesised to have a functional role in this sense, as suggested by anatomical differences among fossil hominids. Here, we present a model to analyze heat dispersion on fossil endocasts, as function of brain geometry and basic physical properties associated with heat conduction. Combining digital imaging and numerical integration techniques, we used the heat equation to quantify heat dynamics on the surface of fossil endocasts, dividing the space in a three dimensional cubic lattice. After CT-based endocasts reconstruction and voxel-based 3D model rendering, we find numerically the stationary heat distribution on the regular lattice defined by the voxels. Although this study rely only on raw geometry without considering further anatomical or histological elements, some differences between modern humans, Neandertals, and Australopithecines merits attention. Advantages and limits of the method are discussed accordingly.