Julia Cresswell - Oxford Dictionary of Word Origins (3rd Edition)

It is well established that English has an unusually large vocabulary. This is partly because its history has exposed the language to an unusually large number of influences, and partly because it has never been slow to borrow from any language it meets. Although there are borrowings from many exotic languages, the majority of words in English have come from one of the large number of languages that belong to the Indo-European group, as English itself does. This is the dominant family of languages in Europe and Western Asia, all of which are descended from a hypothetical language called Proto-Indo-European. Who the original Indo-Europeans were we do not know. The majority of scholars would probably say that they were a people living somewhere in the region of the Black Sea approximately 6000 years ago, but views vary widely both as to when and where they lived. What we do know is that their language spread, changing all the while. How and why it spread are again hotly debated, but speakers of the language group spread as far east as western China, south into India, and west as far as Ireland, before the languages were exported to other continents at a later date.

It may seem impossible that Irish, English, Greek, Persian, and Hindi are all related, but they are indeed all descended from Proto-Indo-European. The secret behind discovering the links lies in the study of early forms of the languages and of the way in which sounds change in language, combined with careful comparison of the languages. Of these, the most important for our purposes is sound change. The way that a language is pronounced is constantly changing, although we may not be aware of it. Today we are lucky, because we have sound recordings stretching back over 100 years, and can hear for ourselves how odd someone speaking only 50 years ago sounds today. We are so used to the idea of a standard written language that it is easy to forget how much variation there is in the sounds of the spoken English we hear today. Those who want to check this out for themselves will find the British Library website has an excellent collection of recordings.

The brain has an extraordinary ability to recognize the same words in the widely different sounds of English spoken, say, in Mumbai, Melbourne, Alabama, and Glasgow. Over time which of these varying sounds becomes the generally accepted one varies. This is the key to one of the ways sounds in speech changethere is constant variety all around us, but we can usually ignore it. If what we think of as the standard form changes, it can eventually lead to a change in the written form. Speakers of British English can hear for themselves how this process works. One of the changes that is taking place in English at the moment is a change in the sound written th. Th is actually the symbol for two closely related soundsthat in