To earn their licence, London cab drivers memorize some 25,000 streets. Eleanor Maguire found that the rear part of their hippocampus, involved in navigation, is larger than average. Following trainees over several years, she saw it grow in those who qualified. The adult brain physically reshapes itself with use.
Remembering is not replaying a recording — it is rebuilding. Each time you recall a memory, it becomes temporarily malleable and can be altered before being stored again. That is why two people can sincerely remember the same event… differently.
In 2003, Johnson and Goldstein compared European countries. Where you must tick a box to become a donor, consent rates ranged from 4% to 28%. Where you're a donor by default unless you opt out, they topped 85%. People aren't more generous on one side; most simply stick with whatever option was chosen for them.