Frontal sinuses and human evolution

The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranialvault and close to the brain. Despite a long history of study, understanding of their origin and variation throughevolution is limited. This work compares most hominin species’ holotypes and other key individuals with extanthominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimen-sions based on a simple and reproducible methodology. We also observed a covariation between the size andshape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance ofHomo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directlyaffected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demon-strate their substantial potential for discussions of the evolutionary relationships between hominin species.