London is a crazy mixed-up city, navigation-wise. It's so hard find your way around that when taxi-drivers learn to, they say they've Acquired The Knowledge. And now scientists say The Knowledge actually changes drivers' brains.
It's the latest evidence that adult brains can evolve and change to learn new things. Until the 1970s and '80s, scientists believed our brains were mostly fixed, and that only during a critical period of childhood could our neurons grow and make new connections. But a growing body of evidence shows that even adults can improve their gray matter.
MRIs first showed that London taxi drivers' hippocampi were larger than normal in 2000. But it was always possible that this was not cause and effect. Perhaps drivers who could pass the three to four year driver training—which includes memorizing a labyrinth of 25,000 streets within London's 10-kilometer radius including thousands of tourist attractions—already had more gray matter and that's what helped them pass their tests.
But now, Neuroscientist Eleanor Maguire of University College London has answered the chicken and egg question by comparing taxi drivers to normal folks and following them over four years. Drivers who had completed their training and passed their tests did better on memory tasks than those who failed as well as the control group.
It's hope for adults who want to learn how to play the fiddle or learn Cantonese! But be hopeful only if you're willing to put in the equivalent of five years memorizing the labyrinthian throughfares of London to learn your new skill.