So I recently read a book called "Historical Linguistics" (3rd edition), by Winfred P. Lehmann - a pretty textbooky title, if you ask me - which talks about the way that languages tend to change over time, and the way that modern scholars investigate this change. There's a strong emphasis on methodology in this book, I should make clear; but there are enough historical examples from actual data that I felt like I learned some interesting historical content as well - particularly from the regions I'm currently interested in most, which are the various parts of Europe (although there is a significant amount of content from India as well) - and I feel like I learned a lot from the book.
The textbook that I read
What are the "Indo-European" languages?
My interest in these regions is part of what inspired me to get this book, because what seems to distinguish this book most from the many other textbooks on the subject is its extensive focus on what linguists today call the "Indo-European languages" - or the languages of the broad family extending from India to Europe (hence the name). Fellow English speakers might take note that this particular family is the one that English is considered to be a part of, since the Germanic languages (including English) - along with the Romance languages, Slavic languages, Hellenic languages, and many others - are all considered to be part of a larger "Indo-European" family tree; with each of these familiar groups being branches of the larger tree. Thus, English is considered to be in the Germanic branch of the larger Indo-European tree.
Indo-European family tree
Most of the languages of Europe are "Indo-European"
Europeans long suspected that they had much in common with each other both culturally and linguistically, and tended since Roman times to group themselves together into the predominantly Christian West - a broad cultural grouping that had strong cultural and social ties to each other, even during periods of religious (and other) warfare; and which was believed by many Europeans to be superior to all the groups outside of this "Western world." But despite the overt racism and religious bigotry that characterized many aspects of how many of them saw these social ties, some of the other aspects of the European account - such as there being a relatively recent common heritage for most of the nations of Christian Europe - were actually correct, as it turned out; and later evidence would make clear that most of the languages of that part of the world (including some of the most widely spoken languages there) were indeed a part of the larger Indo-European family.
Official of the East India Company (1760's), which ruled India
for the British when this linguistic link was discovered there
Many of the languages of India are also "Indo-European"
But the Indian part of this family (as implied by the "Indo-" in "Indo-European") was not recognized to be a part of this larger family until much later, when European scholars visiting India began to be aware of similarities between some of the local Indian languages, and many of the languages back home. Some of the people back home were scandalized by the claim of linguistic ties between Europe and the peoples of India (whom they viewed to be inferior, and whose religions and race they so often misunderstood). Nonetheless, the linguistic evidence continued to pile up for there being a relatively recent common ancestor for these various languages. Furthermore, the British philologist Sir William Jones gave an address to the Asiatic Society of Bengal in 1786, where he proposed a common origin for the classical languages of Europe (like Latin and Greek), and the classical language of India known to us as "Sanskrit." This turned out to be correct, and the modern discipline of historical linguistics is often considered to have begun with this address to the Asiatic Society. Later generations of linguists would add Indian languages like Hindi, Urdu, and Bengali to the list of Indo-European languages (all correct additions), while some of the languages associated with the "Christian West" - such as Finnish, Estonian, and Hungarian - became gradually to be seen as not actually a part of the larger Indo-European family, but as parts of separate families (in the case of these three languages, the "Uralic" family). This also turned out to be correct, as it turned out; and the irony of the linguistic evidence here continues to surprise many outside of linguistics today.
Sir William Jones, the British philologist mentioned above
The idea that languages descend from other languages is not (by itself) controversial ...
I should mention that the idea of languages descending from other languages is not (by itself) controversial, since creationists and evolutionists alike agree that considerable linguistic change has happened within the universally-accepted timeline of humanity - for example, the modern Romance languages of Spanish, French, Italian, and Portuguese descending from the common ancestral language of Latin. There is universally acknowledged evidence of a documented linguistic change, as any English speaker who's tried to read Shakespeare or the King James Bible will recognize (their English being quite different from our own).
... but the early date for "Proto-Indo-European" sometimes is
But as one goes further back into the timeline that mainstream linguists put forward for the history of languages, one comes face-to-face with controversies about the age of the earth (and specifically human beings), since much of the field of linguistics today extends its chronology back into the periods where the existence of an earth (and a human species) is disputed by creationists. This post will not attempt to settle these controversies (or even enter them), since evolutionists and creationists alike agree that the later part of the history of the "Proto-Indo-Europeans" (and all the languages descended from theirs) is within the last six thousand years. Thus, it is well within the timeline universally acknowledged by both sides as true human history; and the controversies about the existence of a longer human history prior to that have minimal (if any) relevance to our current discussion. (If I ever feel like it later, I might address such issues in a future post; but given that I have no training in the natural sciences, I do not feel qualified to give expert opinion on it; and will instead leave the public commentary on such issues to others.)
The first verses of Homer's Iliad in the original Greek, among the earliest texts written in the Greek alphabet
Reconstructing the "Proto-Indo-European" language
Going back to the Indo-European language family, the author of this book that I read is a true expert in the Indo-European languages, and he was actually involved in the reconstruction of the now-gone "proto-language" for the Indo-European family. There are no written records of the proto-language itself, but there are extensive written records for most of the living descendants of this language (and even for some of the dead ones); and the broader Indo-European language family has a documented history that is more extensive than any other broad family of languages; although it is one of three broad families to have written histories extending over three thousand years. The others, in case you're wondering, are the Afro-Asiatic language family (which includes the Semitic languages of Hebrew and Arabic), and the Sino-Tibetan language family (which includes all the varieties of Chinese).
The Rig Veda, an ancient Hindu text in Sanskrit which is also of considerable interest to historical linguists
This book is not an actual history of the Indo-European languages, but a book about methodology ...
Although this book has occasional examples from languages outside of this "Indo-European" family - usually when there are no examples to be found of his current topic in Indo-European languages, or when the earliest research on that particular chapter's subject was done in an outside language - the book's focus is still almost exclusively on the Indo-European languages. As I said, this focus was part of what attracted me to this book to begin with; since my current interests lie mainly in the various languages of Europe - and to a lesser extent, the languages of India as well - and I wanted a book focused as much as possible on the subjects that interested me most. Nonetheless, this book is not to be interpreted as an actual history of the Indo-European languages - although extensive examples are used from this family, these historical examples are not the focus of the book. Rather, the focus is on the methodologies and analytical tools used to investigate these (and other) families, and on the mechanisms of how these (and all other) languages change over time.
Tablet with Linear B script, the earliest form of Greek writing (predating the Iliad and the Odyssey by centuries)
Using data from Indo-European languages to test theories about language change
I should note that because the Indo-European languages are much better-documented than any other language family, there is much more data to be used from this family than from any other; and so they provided an ideal laboratory for historical linguists to test their theories of language change. The knowledge gained in the investigation of these languages has since been applied to other language families as well; and the techniques tried-and-tested in the families with abundant data have also yielded useful results for the families with less abundant (and even scarce) data. But although some of the other major language families - such as the language family including Arabic, or the separate one including Chinese - each have some branches that have been documented extensively, each one also has many other branches that have not been documented so thoroughly; and so similar reconstructions on the proto-languages in these families will have to wait until better data are gathered on these other needed branches. Hopefully in the future, though, similar reconstructions for these language families (and many others) may be a real possibility, that will come within the reach of linguistic science.
The book I read at Amazon
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