You don't have to use something for what it was made for

Third, you don’t have to use something for what it was made for. The visual system was designed to recognise the physical world (objects, scenes) and social stimuli (faces, bodies) 1. But – once human culture had invented reading – each new generation of humans could then use the visual system to learn to read. This point has a second part: but if you use it for something different, it may not work perfectly. So, the visual system has been designed to recognise objects from whatever viewpoint: a coffee cup is a coffee cup if seen from the left, the right, or upside down. But in English, we asked children to learn that p, q, b, and d are all different letters, corresponding to different speech sounds. To the young child’s visual system, these all look like the same object (a round bit with a tail) viewed from different angles. It takes months, maybe years of learning to overcome the brain’s preference to interpret what it sees in terms of movable objects, and this is why children learning to read in English often mix up their b’s and d’s, and their 6’s and 9’s.

Lastly, when it comes to big changes in brain structure evolution always takes longer than you think. The brains of humans 5,000 years ago, even 50,000 years ago, looked pretty much the same as our brains now.

[1] I sometimes find myself talking about how evolution “designed” the brain. It’s a particular use of the word ‘design’. Think of it like this. Rummage around in the bottom of your kitchen drawer. There’s some stuff in there: paper clips, coins, a screw, a plastic button. Fill up the kitchen sink with water. Throw the stuff in the sink. Only the plastic button floats. The sink of water has selected the button from all the stuff you threw in. The water has designed the button as the best floating object. That’s what I mean by ‘designed’ when talking about evolution. Except for evolution, it’s not about floating, it’s about organisms surviving and reproducing.