why johnny can read but, can’t track a wolverine

November 24, 2009

Johnny can’t track the dog that poops in your yard; the deer that eat your apples, let alone a wolverine because the part of his brain used for tracking critters has been co-opted so that he can read.

I would like to feed your fingertips to the wolverines

CultureLab a science news blog : how our brains learned to read.

Today we are readers. Evidence suggests that reading – which depends on an alphabet, writing materials, papyrus and such – is only about 5000 years old. The brain in its modern form is about 200,000 years old, yet brain imaging shows reading taking place in the same way and in the same place in all brains. To within a few millimetres, human brains share a reading hotspot – what Stanislas Dehaene calls the “letterbox” – on the bottom of the left hemisphere.

Dehaene builds his clear and interesting book around this “reading paradox,” which is really more puzzle than paradox. It is standard procedure in cognitive neuroscience to assume that a brain area dedicated to a particular function – especially when it is universal – is an adaptation that evolved to serve a function related to reproductive success. The letterbox, however, cannot be an adaptation because reading is an utterly recent invention, unlike neurological abilities for language and socialising that were around long enough to have evolved. What’s more, the letterbox does not ride on top of areas used for speech. Instead, it must be an “exaptation”: a brain area that evolved to do one thing but has been co-opted to do another.


posting by jim


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