The current issue of the Economist has a special section on lifelong learning - a paragraph to ponder:
"Fortunately, there is some good news to go with the bad. Psychologists distinguish between “fluid intelligence”, which is the ability to solve new problems, and “crystallised intelligence”, which roughly equates to an individual’s stock of accumulated knowledge. These reserves of knowledge continue to increase with age: people’s performance on vocabulary and general-knowledge tests keeps improving into their 70s. And experience can often compensate for cognitive decline. In an old but instructive study of typists ranging in age from 19 to 72, older workers typed just as fast as younger ones, even though their tapping speed was slower. They achieved this by looking further ahead in the text, which allowed them to keep going more smoothly.
What does all this mean for a lifetime of continuous learning? It is encouraging so long as people are learning new tricks in familiar fields. “If learning can be assimilated into an existing knowledge base, advantage tilts to the old,” says Mr Salthouse. But moving older workers into an entirely new area of knowledge is less likely to go well."