Historical linguistics, also called Diachronic Linguistics, the branch of linguistics concerned with the study of phonological, grammatical, and semantic changes, the reconstruction of earlier stages of languages, and the discovery and application of the methods by which genetic relationships among languages can be demonstrated. According to dictionary.com, Historical linguistics is the branch of linguistics which deals with the history and development of languages. Also it can be defined as the branch of linguistics that focuses on the interconnection between different languages in the word and, or their historical development.
Historical linguistics had its roots in the etymological speculations of classical and medieval times, in the comparative study of Greek and Latin developed during the Renaissance and in the speculations of scholars as to the language from which the other languages of the world were descended. It was only in the 19th century, however, that more scientific methods of language comparison and sufficient data on the early Indo-European languages combined to establish the principles now used by historical linguists.
Historical linguistics has existed as a scholarly discipline for over 200 years, Trask, R.L (1996) and it was the first branch of linguistics to be placed on a firm footing, none the less, it is of present one of the liveliest and most engaging area of linguistics.
THE HISTORY OF LANGUAGE
There are over 5,000 distinct human languages in the world. One very basic question is how did they all get there? One of the greatest mysteries that has confronted ma has been that of the origin of a language, a topic on which there has been much speculation. Many of us are familiar with the stories in the genesis concerning the giving of names by a deity and the diffusion of different tongs following the destruction of the tower of Babel. At times, theorists with an inclination towards experimentation have even gone so far as to try to recreate the conditions which they consider necessary for the origin of language. Herodotus, the Greek historian, tells how the ancient Egyptian king PSametichus raised two children in complete isolation from human speech to see what language they would naturally speak, Wardhaugh, R (1972) It's hard to imagine a cultural phenomenon that's more important than the development of language. And yet no human attribute offers less conclusive evidence regarding its origins. The absence of such evidence certainly hasn't discouraged speculation about the origins of language. Over the centuries, many theories have been put forward--and just about all of them have been challenged, discounted, and often ridiculed. Each theory accounts for only a small part of what we know about language. Different scholars have been speculating the origin of language by demonstrating different theories of language. The following are the theories;
The Bow-Wow Theory
According to this theory, language began when our ancestors started imitating the natural sounds around them. The first speech was onomatopoeic--marked by echoic words such asmoo, meow, splash, cuckoo, and bang.
Weakness of the theory
Relatively few words are onomatopoeic, and these words vary from one language to another. For instance, a dog's bark is heard as au au in Brazil, ham ham in Albania, and wang, wang in China. In addition, many onomatopoeic words are of recent origin, and not all are derived from natural sounds.
The Ding-Dong Theory
This theory, favored by Plato and Pythagoras, maintains that speech arose in response to the essential qualities of objects in the environment. The original sounds people made were supposedly in harmony with the world around them.
Weakness of the theory
Apart from some rare instances of sound symbolism, there's no persuasive evidence, in any language, of an innate connection between sound and meaning.
The La-La Theory