John McWhorter’s The Power of Babel: A Natural History of Language is a lively, discursive, readable look at how language changes. I particularly recommend it to SF and fantasy novelists looking for worldbuilding information, but think it has a lot to offer any reader who just thinks language is cool.
As the subtitle suggests, McWhorter is looking at language change in ways very similar to those of biologists looking at the evolution of life—though he takes pains to stress both the limits of the analogy and the lack of a “goal” for language change. He starts with the first language and the small-scale mechanisms that turned it into thousands and thousands of languages, such as sound changes and the creation of grammatical rules. He then looks at what happens when different languages encounter each other (with a side trip into language, dialect, and how the line between the two is essentially cultural), or when languages develop mostly in isolation, or when they get enshrined as standard written forms. He concludes with a look at language extinction and the prospects for language revival movements (with an epilogue on the claims that words from the world’s first language have been reconstructed).
The book is full of fascinating tidbits about world languages: some languages have sixteen genders for nouns; or lack verb tenses; or require you, as a matter of grammar, to specify how you know something; or change initial consonants of nouns based on the preceding pronoun. The twenty most popular languages are spoken by a full ninety-six percent of the world’s population. One Australian language, Jingulu, has just three verbs: come, go, and do. And so on.
The book is also full of digressions (usually on pop culture, a few of which have already dated poorly) and other authorial asides, which I found largely entertaining, but I can see that your tolerance may vary. For instance, in discussing the transition between treating Italian as a village dialect of Latin and a noble language in its own right, he notes that
Dante, afflicted with that queer medieval southern European malady called courtly love, in 1293 dedicated a volume of poems to his adored Beatrice, who combined two traits unusual in a dedicatee of love poetry—namely, having never been touched in by the author at any point in her life and being dead.
Or in discussing bits of leftover “junk” from prior days, he observes:
It’s like Charlie Brown. Charlie Brown is a bald child. Did you ever think about that? Charlie Brown is an eight-year-old who has virtually no hair on his head! . . .
The reason Charlie Brown has no hair is that, until roughly the mid-1960s, in comics and cartoons baldness was a kind of established signifier for dopiness—when someone drew a guy as bald, it meant something specific. . . .
. . . By the end of the run in 1999, Peanuts was only faintly recognizable as the strip that had debuted in 1950. But throughout, Charlie Brown remained bald, as a reflexive remnant of an earlier meaning now bleached out and lost. Languages are chock-full of Charlie Brown heads.8
8. Never again will that sequence of words be used in the English language.
(As that excerpt suggests, there are a good number of footnotes, though many of them are in the more traditional vein of exceptions or providing additional information.)
I skimmed this quickly, because I’d already listened to an audio lecture series taught by McWhorter. If you also have already listened to that, I don’t think you need to read the book: the content is very similar, and indeed the lecture series covers a few more topics. I slightly prefer the lecture series because I have a very difficult time “hearing” things on the page, and thus all the discussion of pronunciations in the book go right past me, though I did find the lecture series dragged slightly in the middle. In either format, though, I very much enjoyed the content and highly recommend it.