"I had better say something here about this question of age, since it is particularly important for mathematicians. No mathematician should ever allow himself to forget that mathematics, more than any other art or science, is a young man's game. ... I do not know an instance of a major mathematical advance initiated by a man past fifty. If a man of mature age loses interest in and abandons mathematics, the loss is not likely to be very serious either for mathematics or for himself."
According to at least one source, Yitang Zhang, conveyor of the recent much-heralded 'bounded gap' proof for prime numbers, is in his 50's.
A number of general press pieces continue to follow the Zhang story, pretty much re-hashing the same information already released. RJ Lipton has added a little more added thought (if you're prepared for some deeper math) at his "Gödel's Last Letter…" blog here:
He includes several links as well, including one that led me to an old MathOverflow thread on "Major mathematical advances past fifty" which begins with the above quote... before offering an array of counter-examples:
…. a possibly interesting/encouraging read for some of us, of a certain age. ;-)