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Wired to Read

Brain researchers in France, Belgium, Portugal, and Brazil have been working on the puzzle of how the human brain re-purposes itself to enable us to read. The mystery is that reading is one of those complex skills that emerged in an evolutionary blink of the eye, in the Middle East about 5,000 years ago. It is also a skill reserved until the last two centuries for a very small percentage of humanity. That’s a strong circumstantial case that to read we must be appropriating parts of the brain that evolved for other purposes and re-wiring them to make sense of written language.

The international team of neuroscientists, led by Stanislas Dehaene at the Institut National de la Santé et de la Recherche Médicale in Gif-sur-Yvette, France, reports its work in a recent issue of the journal Science, in “How Learning to Read Changes the Cortial Networks for Vision and Language.”

I grant myself the license of an academic blogger to mention this. I am an anthropologist and some members of my profession indeed possess the expertise to read material like this with deep understanding—but I am not among them. I am rather, a member of the American Association for the Advancement of Science who pages through the issues of Science and dips into the daily news alerts humbled at every turn by the vast expanse of my ignorance. Still, I keep reading. Even though I don’t understand the details, I like being a witness. And scientific reports often seem like a glimpse of something bigger.

Professor Dehaene has a talent for finding interesting problems and coming up with intriguing evidence. He has published work on how the human brain manages mathematics, which would seem to be an even more implausible re-purposing of the cerebral equipment given to us by our species’ long stay in the world of hunting and foraging.

Dehaene and his colleagues recruited volunteers in three groups: people who became literate in childhood, people who learned to read as adults, and illiterates. They then used brain imaging to find the ways in which literate and illiterate brains differ. As Science summarizes it, “the junction of the left occipital and temporal lobes of the brain” and “parts of the left temporal lobe that respond to spoken language” differ between literate and illiterate brains. When something gets “repurposed,” it stands to reason that the original purpose might not be served quite so well. Does literacy bring tradeoffs?

Maybe. If you learn to read as a child, the part of the occipital-temporal cortex that recognizes human faces is smaller than it is in people who learn to read later or who remain illiterate. Dehaene and his colleagues don’t yet know whether the difference in size translates into a degradation of ability.

But I’ll offer an anthropological hunch that the answer is yes. And as this is a blog and I bear no responsibility for wild scientific hypotheses, I’ll go further. Anthropologists who have worked with non-literate people often reported what seem levels of observational ability that would be highly unusual in the West. This usually gets explained as a matter of culture: if you grow up in a culture where making fine discriminations about something is a condition of success, naturally you get good at it. Think of hunters tracking game or sailors “reading” the ocean. But it may well be that a brain that hasn’t been partly usurped by learning to read has a much better shot at getting good at a variety of tasks that involve special kinds of recognizing.

There is also strong evidence of evolutionary co-development of fine motor control over the hands, visual control, and the parts of the brain involved in language. Some evidence points to hand sign language as our first language.  Rudimentary signing emerges spontaneously in most children, for example, before they can speak. And our right or left handedness corresponds with the brain localization of language. All of this is reason to wonder whether literacy poses some other not-yet-recognized taxes on dexterity and coordination.

Be that as it may, Dehaene has reminded us of the wonderful strangeness of literacy. Learning to read enables us to connect with the dead and with generations to come, to obliterate social and physical distance, to stop speech in its tracks and think, to experience worlds we will never see. But that enormous liberation just might come at a price paid in subtle diminishments to our direct experience of the world. We academics of course treat literacy as all gain and no loss. If we are wrong about that will it make a difference in how we view education?

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