Enta Geweorc
nhw posted that writers born between 1942 and 1951 are overrepresented in Hugo and Nebula awards, sparking a flurry of responses attempting to explain the decline of science fiction. I think the debate is mainly missing the fact that the Hugos and Nebulas have only been around for about fifty years, and the full range of a ten year cohort's output-from the first wunderkind born at the start of the ten years who wins an award at twenty five, to the grand old man born at the end who wins at seventy five-can easily span sixty years. Jack Williamson, of the 1902-11 cohort, won the Hugo and Nebula Best Novella awards in 2001 for "The Ultimate Earth" at the age of 93. Peter Beagle of the 1932-41 cohort won the best Novelette Hugo this year for "Two Hearts".
The Hugos didn't start to be awarded until 1953, and only 23 of them had been awarded (counting ties and collaborations) by 1964, the year before the Nebulas began. We can increase this to 35 by including twelve retro-Hugos. 334 Hugos and Nebulas have been awarded since 1965. The 1942-51 cohort are in that sweet spot where the Hugos and Nebulas in all four length categories (Short, Novelette, Novella, Novel) were available to be won at all stages in their careers, starting from 1965: the first award won by a member of the cohort was the 1965 Nebula for Best Novel, Babel-17 by Samuel R. Delany. The most recent is Connie Willis's Hugo for Best Novella, for "Inside Job".
"Younger" writers, i.e., those born after 1951, haven't had time to rack up the full number of awards possible for their cohort. If we had the Hugo and Nebula results from 2007-2047 available to us, the statistics might look a little different.
Edited to correct the "first Hugos in 1946" error. Thanks to timill