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Evolution had no time to build reading
A region too new
Some brain regions, like those specialized for faces, have a long evolutionary history. The visual word form area, typically on the left in most people, recognizes letters and words. Brain evolution ran for a long time before written language existed, so this region cannot be hardwired as something evolved for the job.
Wired before reading
In preverbal infants who cannot read yet, the region that will later process words is already wired up to other brain regions in a way that predisposes it to do the right computations. Experience then repurposes that preset connectivity to recognize words once a child learns to read.
Faces work the same way
Face processing works as a mixture too. Something is in the brain at birth that does not depend on experience, and normal maturation and development shape it from there. Imaging studies of babies, such as those by Rebecca Saxe at MIT, track how the face system develops. At birth the response is crude, and it becomes much more refined and granular through experience.
How can old brain tissue learn a new skill?
Neuroscientist Stanislas Dehaene proposed the neuronal recycling hypothesis, in which cultural inventions like reading take over cortical regions whose existing wiring already suits the job. The visual word form area sits next to regions that recognize objects and faces, and it handles the line junctions and contours that letters are made of. Dehaene noted that writing systems around the world use shapes common in natural scenes, such as T and Y junctions. Scripts evolved to fit what the visual system was already good at.
How recent is writing compared with the human brain?
Modern humans appeared roughly three hundred thousand years ago, based on fossils from Jebel Irhoud in Morocco. The earliest known writing, the cuneiform of Sumer in Mesopotamia, dates to around 3200 BCE. Alphabets came much later, with the earliest examples about 1800 BCE. Mass literacy became common only in the last few centuries.
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