Did you ever notice the shape of your own skull? Try running your fingers along your scalp. You'll find bumps and ridges and planes. The human skull is anything but round!
Not so long ago it was believed that the bumps you had on your skull indicated what kind of person you were. A discerning doctor, it was believed, could "read" the shape of someone's brain by carefully examining their head. For example, if you had a large bump behind the ear, that indicated a significant sexual appetite. A bump over the eyes indicated an appreciation of music, and so on. This theory was pioneered by an early 19th-century researcher named Franz Joseph Gall, and was known as Phrenology.
For a little while Phrenology was all the rage. Later phrenologists made painstaking maps of the head, finding bumps for such things as Hope, Conscientiousness and Spirituality.
As it turned out, Phrenology was incorrect. There is no relation at all between bumps on the head and personality. Phrenology fell into disrepute and Gall became something of an embarrassment to 19th century science.
We shouldn't be so hasty to laugh. No, bumps on the skull don't correspond to aspects of the personality, but different areas of the brain underneath do indeed control different mental functions. A modern day neurologist wouldn't use broad terms such as Conscientiousness or Hope, but there are brain centers associated with musical ability and sexual behavior.
While his name has become associated with a wrong idea, Gall was one of the first researchers to suggest that different parts of the brain do different things.