No. 15: Spring 1981
John Lorber, a British neurologist, has studied many cases of hydrocephalus (water on the brain) and concluded that the loss of nearly all of the cerebral cortex (the brain's convoluted outer layer) does not necessarily lead to mental impairment. He cites the case of a student at Sheffield University, who has an IQ of 126 and won first-class honors in mathematics. Yet, this boy has virtually no brain; his cortex measures only a millimeter or so thick compared to the normal 4.5 centimeters.
Although the deeper brain structures may carry on much of the body's work, the cortex is supposed to be a late evolutionary development that gave humans their vaunted mental powers and superiority over the other animals. If the cortex can be removed with little mental impairment, what is it for in the first place?
(Lewin, Roger; "Is Your Brain Really Necessary?" Science, 210:1232, 1980.) Comment. Brain size, then, may mean nothing in comparing ancient and modern human skulls or human brain capacity with those of animals! Where is the seat of intelligence?
|In some cases of hydrocephalus, the cortex is only paper-thin, but little mental impairments is apparent.|