Hi Daniel. Parrots don't learn to talk in the wild, but only when domestication improves their quality of life and leaves them time to think about such things. This is why there is no activity on your graph before the 1950s.And little activity until the mid-1970s. That '74 recession changed everything.Very effective, that 150 years of inactivity.Art
Very interesting idea, Arthurian. (And welcome to the blog, btw -- don't think I've seen you comment before).It would indeed seem like there was a shock to bourgeois ideology sometime in the 60s and 70s. However, I am afraid that without some international data (case of Britain?) it's hard to find the pulse on this one.