Is language evolution grinding to a halt?: Exploring the life and death of words in English fiction

The Google Books corpus, derived from millions of books in a range of major languages, would seem to offer many possibilities for research into cultural, social, and linguistic evolution. In a previous work, we found that the 2009 and 2012 versions of the unfiltered English data set as well as the 2009 version of the English Fiction data set are all heavily saturated with scientific and medical literature, rendering them unsuitable for rigorous analysis. By contrast, the 2012 version of English Fiction appeared to be uncompromised, and we use this data set to explore language dynamics for English from 1820--2000. We critique a previous method for measuring birth and death rates of words, and provide a robust, principled to examining the volume of word flux across various relative frequency usage thresholds. We use the contributions to the Jensen-Shannon divergence of words crossing thresholds between consecutive decades to illuminate the major driving factors behind the flux. We find that while individual word usage may vary greatly, the overall statistical structure of the language appears to remain fairly stable. We also find indications that scholarly works about fiction are strongly represented in the 2012 English Fiction corpus, and suggest that a future revision of the corpus should attempt to separate critical works from fiction itself.