The fact that adults find it harder to learn musical instruments than children points to a second type of mental loss with age — a reduction in learning capacity. The parts of the brain known as the temporal lobes control new learning, and are particularly vulnerable to the effects of ageing. This means that, as we get older, we take longer to learn a new language, are slower to master new routines and technologies at work, and we have to rely more on diaries and other mental aids.