[Ontogeny and phylogeny of the skull]

Ontogeny of the skull is primarily determined by genetic factors and is modified during development by environmental factors. The shape of the skull and the direction of its development during intrauterine life are determined by the requirements of the growing brain. After birth, the most important role in modifying the shape of the skull is played by large forces from the stomatognathic system. The development of the cranium is fastest during fetal life; at birth, its size is 65% of its final value. After birth, changes in the shape of the skull take place at a slower pace and coincide with eruption of deciduous and permanent teeth, to a lesser degree with formation of the cervical lordosis and other curvatures of the vertebral column. A significant difference has been revealed between times when the skull reaches its final shape and size; adult shape is achieved first. The shape of the human skull has not been constant. Many changes over centuries favored evolution of the neurocranium and involution of the splanchnocranium. They have been provoked by new dietary habits, erect position of the body, alterations and development of the central nervous system, and locomotion type. The dominating features of contemporary man include a reduced splanchnocranium, micrognathia, and retroposition of the mandible. Our studies on medieval and contemporary material have confirmed the narrowing of the face together with shortening and lowering of the skull.