Pierre Paul Broca (1824–1880) identified an area of the brain responsible for speech production in 1861. Having observed a patient who could not speak except for the meaningless utterance of “tan, tan,” Broca examined the brain of the individual upon his death. Broca determined the patient was missing a section of the frontal lobe from the cerebral hemisphere. Broca continued to examine the brains of individuals with a lack of speech and found they all lacked the same area of the brain.
There is still an ongoing debate about how to measure intelligence and whether inherited traits or the environment affect learning abilities more. (© iStockphoto.com/LisaFX Photographic Designs.)