Now the Hugos have been awarded at Denvention, it's time for the annual moaning about the ageing of science fiction. Using nhw's data, I graphed the birth dates of Hugo and Nebula winners before, and I've graphed the median ages here:
Again, I'm not seeing much to suggest the end is nigh. Median ages have risen before, and fallen before. I think the shocking statistic that only two awards have gone to writers born after 1970 (Tim Pratt and Elizabeth Bear who won the last two years' short story Hugos) is mainly a coincidence of threshold number: the upward trend in ages has happened to parallel the line of constant age, reflecting a delay in the appearance of the 1970s birth group for a few years longer than expected.
To me the big event is the collapse in the number of older writers represented at the novel length in the 80s, when the age range of Hugo and Nebula winners narrowed dramatically. The median ages have been climbing again from that low, as those young 80s writers grow older while continuing to win awards, and the younger writers are not coming in at a rate of exactly one year per year. That can change quickly: as the financial salesmen say "the market may go down as well as up".