Abstract:

Diploic veins are a complex vascular network within the cranial wall, playing a significant role in human cranial blood circulation. Since their discovery in the early 18th century, research on this structure has been limited by the traditional dissection methods, leaving many questions unresolved regarding their morphological variations, functions, and implications for human evolution. Recent advances in CT and MR imaging and newly-developed 3D reconstruction techniques have overcome previous bottlenecks, which can detect the morphological details of these vascular structures. New studies have revealed that traditional classifications of diploic veins lack broad applicability, while also redefining their distribution areas and patterns and identifying functional roles in cerebrospinal fluid circulation and cerebral thermoregulation, which may be essential to human brain physiology. Research on hominin fossils has further highlighted interspecific differences in diploic veins, offering potential applications in future taxonomical discussions. The current evidence indicates that the diploic vascular pattern can identify Neanderthal cranial fossils from other Homo species, and it also help differentiate non-human primates from hominins. Additionally, diploic veins may have contributed to human brain evolution, with possible links to brain volume and regional endocast morphology. To clarify the mechanism behind the variation and evolution, further studies are warranted to investigate the diploic vascular morphology and physiology in large extant human populations and also in hominin fossils. This paper reviews the history of diploic vein research and synthesizes recent advancements, summarizing methodologies, technical challenges, and future directions to promote further studies in this field.

Key words: hominins, Micro-CT, 3D reconstruction, brain evolution, taxonomy