Phrenology, the study of the conformation of the skull as indicative of mental faculties and traits of character, enjoyed great popular appeal well into the 20th century.
The system of Franz-Joseph Gall (German physician,1758-1828)was constructed by a method of pure empiricism. Some of the traits that he presumed to detect were "criminal." Lombroso tried to discern a possible relationship between criminal psychopathology and physical or constitutional defects. Among these anomalies, which he termed stigmata, were various unusual skull sizes and asymmetries of the facial bones