Historical linguistics, also known as philology, is the study of how a language develops into its present form. This can include changes from older versions of the language in speech and grammar, or the diachronic variation of language, as well as the etymology of loanwords and neologisms. Changes due to influence from other languages are called external change; those not caused by exogenetic factors are called internal change.
For a long time, people knew that languages could evolve into new languages, based on the development of Latin into Vulgate Latin, and thence into the Romance languages, including French, Spanish, Portuguese, Italian and Romanian. However, the field of historical linguistics is relatively new, dating back to the 19th century.
Traditionally historical linguistics has attempted to reconstruct ancestor languages via the process of the comparative method. The comparative method attempts to find regular sound changes between languages. Comparative reconstruction is based on several principles, including:
- Majority principle: If, in a group of cognates (words in different languages of the same origin), most of the words share a certain feature, then that feature was probably present in the older language.
- Most natural development principle: Some types of linguistic change are more common than others. For example:
- Stops become fricatives.
- Vowels at the ends of words disappear,
- Consonants at the ends of words go from voiced to voiceless.
- Consonants between two vowels go from voiceless to voiced.
Consider this example of the Chinese word 澤, 'swamp', or the 'ze' in 'Mao Zedong':
|Modern Standard Mandarin (Putonghua)||Ze|
Note that the 'h' ending in Zah is a glottal stop, and the 'z's are unaspirated voiceless alveolar affricates. By the majority principle, we can conclude that the original word probably started with 'z' and ended with 'k'.
In general, the majority principle is preferred in reconstruction only in the absence of other lines of evidence. It is possible for several dialects or descendent languages to share innovations not present in the proto-language either by chance, or by innovative dialects splitting to create more dialects sharing its innovations. For example, we find that several dialects of English have a phonological rule that coda r sounds are deleted: in received pronunciation, the word "butter" is pronounced /ˈbʌ.tə/ (butt-ah). We find the same is true for the majority of English dialects:
|General American English||/ˈbʌ.təɹ/ (butter)|
|Received Pronunciation||/ˈbʌ.tə/ (buttah)|
|New Zealand English||/ˈbʌ.tə/ (buttah)|
|South African English||/ˈbʌ.tə/ (buttah)|
From this data, by the majority principle, we might conclude that the original pronunciation lacked the r sound, which was added in American English. However, RP, NZ, and SA English are all descended from 19th century British English, which in fact underwent an r-deletion sound change, which was inherited by all its daughter dialects, whereas American English preserves the older form, having split from British English prior to the sound change.
Sound changes are an important part of historical linguistics. There are several types of this:
- Metathesis: Two sounds in a word are reversed, e.g. nuclear → newkiller.
- Epenthesis: A sound is added to the middle of a word, e.g. Latin tremulare → French trembler
- Prothesis: A sound is added to the beginning of a word, e.g. Latin schola → French école
- Assimilation: A sound becomes closer to a nearby sound, e.g. Latin octo → Italian otto
- Lenition: Making a consonant more sonorous, e.g. Latin vita → Spanish vida
Grimm's Law is one of the most famous sound shifts. It was the first systematic sound shifts discovered, and changed the course of historical linguistics forever. It describes how Proto-Indo-European, the language that evolved into Sanskrit, Latin, Greek and the Germanic languages (English, German, Dutch...), became Proto-Germanic, the common ancestor of the Germanic languages.
It consists of three parts which form consecutive phases in the sense of a chain shift. The phases are usually constructed as follows:
- Proto-Indo-European voiceless stops change into voiceless fricatives.
- Proto-Indo-European voiced stops become voiceless stops.
- Proto-Indo-European voiced aspirated stops become voiced stops or fricatives (as allophones).
This chain shift can be abstractly represented as:
- bʰ > b > p > ɸ
- dʰ > d > t > θ
- gʰ > g > k > x
- gʷʰ > gʷ > kʷ > xʷ
Here each sound moves one position to the right to take on its new sound value. ɸ is the voiceless bilabial fricative, and x is the voiceless velar fricative. 'w' indicates labialised.
Syntactic changes are often found in historical linguistics as well. Consider the follow comparison between Classical Chinese and its Putonghua translation (note that the transcription used Putonghua pronunciations):
Wu shui yu gui
I whom with return
Wo he shui yiqi guiqu
I with whom together return
In the former sentence, movement has occurred: with moved from before whom to after it. This cannot occur in Putonghua and is an example of syntactic change.
Borrowing is the process of taking a word from one language and incorporating it into the lexicon of another. For example, English borrowed forte from Italian, faux pas from French, ketchup from Chinese, palaver from Portuguese and so on. A special type of borrowing is 'calque, in which we directly translate the elements of a word from the source language to the target language. A famous example is the word skyscraper, which was translated into various languages such as the French gratte-ciel or scrape-sky.
A neologism is a new word. It can be formed by coinage, in which people actually create a word. An example of this is canola, which is genetically modified rapeseed, and nylon. Words like nylon are called eponyms as they are derived from the name of a place or person; in this case, New York and London.
Semantic change occurs when the meaning of a word or morpheme changes. There are multiple theories of semantic change. Several of the processes in semantic change are:
- Narrowing: The word's sense goes from broad to narrow. In Classical Chinese, qizi referred to the wife and children; it refers only to the wife in Putonghua.
- Widening: The word's sense goes from narrow to broad. In Classical Chinese, jiang and he referred to the Chang Jiang and Huang He (i.e. the Yangtze and Yellow Rivers), but are now generic terms for river.
- Metonymy: Sometimes, a word's sense can change by metonymy, e.g. the Chinese word sheji, which used to refer to the gods of the land and the grains. As ancient kings would worship these gods, the word later gained the sense of nation.
- Synecdoche: Sometimes, a word's sense can shift from a part to the whole. For example, the Chinese word ji used to refer to the final month of each season, but now means season.
- Metaphor: Sometimes, a word's sense can change by metaphor, e.g. broadcast, which used to mean spread seeds, but now means transmit information.
- Hyperbole: The word's sense goes from weak to strong. For example, kill used to mean torment, but now means slaughter.
- Meiosis: The word's sense goes from strong to weak. For example, astound used to mean strike with thunder, but now means surprise strongly.
Some words may go through several of these change. For example, ji originally meant the smallest child of a family. This meaning extended to the final month of a season by metaphor. Then it extended to season by synecdoche. Later, it extended to mean period of time by broadening.
A new method of historical linguistics was developed by Joseph Greenberg, called mass comparison. The method remains controversial. Most of the language families Greenberg constructed are not accepted by the majority of linguists; however, Afro-Asiatic and Niger-Congo have been almost wholly accepted, and Nilo-Saharan has been accepted with some reservations, many linguists splitting off groups.
The principle of mass comparison is that languages generally don't borrow very basic vocabulary, such as pronouns, though there are examples of borrowing in mixed languages. As such, he looks for general similarities, which supposing that words can have semantic shift.