Reading in the Brain

Our ability to read brings us face-to-face with the singularity of the human brain.

the literate brain contains specialized cortical mechanisms that are exquisitely attuned to the recognition of written words.

writing was born only fifty-four hundred years ago in the Fertile Crescent, and the alphabet itself is only thirty-eight hundred years old.

Evolution thus did not have the time to develop specialized reading circuits in Homo sapiens.

Nothing in our evolution could have prepared us to absorb language through vision. Yet brain imaging demonstrates that the adult brain contains fixed circuitry exquisitely attuned to reading.

In his Natural Theology (1802), he imagined that in a deserted heath, a watch was found on the ground, complete with its intricate inner workings clearly designed to measure time. Wouldn’t it provide, he argued, clear proof that there is an intelligent clockmaker, a designer who purposely created the watch? Similarly, Paley maintained that the intricate devices that we find in living organisms, such as the astonishing mechanisms of the eye, prove that nature is the work of a divine watchmaker.

Charles Darwin famously refuted Paley by showing how blind natural selection can produce highly organized structures. Even if biological organisms at first glance seem designed for a specific purpose, closer examination reveals that their organization falls short of the perfection that one would expect from an omnipotent architect.

Time was simply too short for evolution to design specialized reading circuits. How, then, did our primate brain learn to read? Our cortex is the outcome of millions of years of evolution in a world without writing—why can it adapt to the specific challenges posed by written word recognition?

the human brain should be compared to a blank slate that progressively absorbs the imprint of man’s natural and cultural environment through the five senses.

All over the world, the same brain regions activate to decode a written word. Whether in French or in Chinese, learning to read necessarily goes through a genetically constrained circuit.

the “neuronal recycling” hypothesis. According to this view, human brain architecture obeys strong genetic constraints, but some circuits have evolved to tolerate a fringe of variability.

The uniqueness of our species may arise from a combination of two factors: a theory of mind (the ability to imagine the mind of others) and a conscious global workspace (an internal buffer where an infinite variety of ideas can be recombined).

Two major parallel processing routes eventually come into play: the phonological route, which converts letters into speech sounds, and the lexical route, which gives access to a mental dictionary of word meanings.