Phrenology

Phrenology is the formal practice of assigning personality traits to individual people on the basis of the contour of their skulls and facial features. "The founder of phrenology was Franz Joseph Gall (1785–1828), a physician from Vienna and a very capable neuroanatomist(reference for quote: Stone JL. Mark Twain on phrenology. [Biography. Historical Article. Journal Article] Neurosurgery. 53(6):1414-6; discussion 1416-7, 2003 Dec. UI: 14633308). He had a theoretical view that in and of itself was plausible, that if the human brain had areas within it that were responsible for specific mental functions, that the relative power of these functions correlated with the size and development of the regions, and that the outer contour of skull was physical evidence of the size of those regions.

The acceptance of phrenology was helped by the presence of physical characteristics that were common to families and ethnic groups and could be correlated to generally held notions about those groups.