Peter Watts recalls a study in which an adult had a brain scan and was found to have almost no brain at all. The skull was filled with cerebrospinal fluid except for a thin layer of brain tissue around the edges. This person had an undiagnosed case of hydrocephalus that left him with a cavernous hole in the middle of his head. Yet he had an IQ of 126 and a math degree.
It happens occasionally. Someone grows up to become a construction worker or a schoolteacher, before learning that they should have been a rutabaga instead. Lewin’s paper reports that one out of ten hydrocephalus cases are so extreme that cerebrospinal fluid fills 95% of the cranium. Anyone whose brain fits into the remaining 5% should be nothing short of vegetative; yet apparently, fully half have IQs over 100. (Why, here’s another example from 2007; and yet another. Let’s call them VBNs, or “Virtual No-Brainers”)
What makes the difference between those who are fully functional and those who aren’t? Watts gives us a few ways the brain might work around such damage, some which have been debunked, and some that have never been adequately studied. What is unsettling is the thought of how many people never need a brain scan and go their entire lives not knowing they have none. Do you know for sure that you have a brain? -via Metafilter
(Image credit: Oliveira, et al 2012)