In the mid nineteenth century, organismal evolution might have been controversial, but the idea of linguistic evolution was not, despite the fact that a literal interpretation of the Bible would seem to rule it out.
Because any literate person could pick up Chaucer's Canterbury Tales and see that the English language (not to mention others) had changed through time.
How do these changes occur?
|"The man"||Se man||þa mannas|
|"The book"||Seo boc||þa boca|
|"The ship"||þaet scip||þa scipu|
|"The man"||Madhr inn||menn inir|
|"The book"||Bok in||boekr inar|
|"The ship"||Skip it||skip in|
The actual roots of the words are very similar, but the grammars are different. All that is needed to make these languages mutually intelligible is to simplify their grammars. In England, that is what happened.
All of this happens in historical time and is often noticible in the span of a human lifetime. No big surprise, therefore, that scholars whose profession had witnessed the breakup of Latin into the Romance Lanugages thought of linguistic change in evolutionary terms, long before the idea was brought to biology. Indeed, people had long noted the similarities in languages. E.G.:
Babelists: And yet, from Classical Era to the mid 18th century, scholars essentially bought the "Babelist" idea that one of the known languages was the Mother Tongue from which others were derived. Typically they favored prestigious languages such as Hebrew, Classical Arabic, or Ancient Greek. Of course, by identifying the "Mother Tongue" they also hoped to see which nations were "getting it wrong."
Sir William Jones 1786: The breakthrough was the work of an administrator in the British Raj, Sir William Jones. A polyglot, he was familiar with 28 languages, of which we spoke English, Latin, Ancient Greek, Farsi, Arabic, and Sanskrit very well (despite three of them being "dead" languages). His big contribution came from his study of Sanskrit, the ancient language of the Vedas - the oldest Hindu scriptures. He noted, in this Asian language, an odd similarity to the languages of Europe. He wrote:
"The Sanskrit language, whatever be its antiquity, is of a wonderful structure, more perfect than the Greek, more copious than the Latin, and more exquitely refined than either, yet bearing to both of them a stronger affinity, both in the roots of verbs and in the forms of grammar, than could possibly have been produced by accident; so strong indeed, that no philologer could examine them all three, without believing them to have sprung from some common source, which, perhaps, no longer exists; there is similar reason, though not quite so forcible, for supposing that both the Gothick and the Celtick, though blended with a very different idiom, had the same origin wth the Sanskrit, and the old Persian might be added to the same family."
(Italics are mine - JM)
Jones made two remarkable innovations:
This table shows the basic similarities. Note the last two languages, Arabic and Hebrew, were not mentioned by Jones and are quite different:
Jones' hypothetical mother tongue is known today as Proto-Indo-European. Most, (but not all) of the languages of Europe and Northern India are descended form it. This group is called Indo-European
Within it are sub-groups consisting of descendants of intermediate common ancestors. E.G.:
|2. Ancient Greek||Pente||Ikhthos|
|5. Welsh||Pump (pronounced "pimp")||Pysg (pronounced "pisg"|
|6. Old Norse||Fimm||Fiskr||7. German||Fünf||Fisch (pronounced "fish")|
|8. Anglo-Saxon||Fif||Fisc (pronounced "fish")|
All of the languages in this table are Indo-European. This list shows a key derived feature of the Germanic languages (6 - 8), a subgroup of Indo-European, - a tendency to replace a "P" with an "F". This innovation was presumably present in the common ancestor of Germanic languages but not in Proto-Indo-European.
So, languages can be grouped in an internested heirarchy based on recency of common ancestry.
When was Proto-Indo-European spoken?
Language change is not clocklike. Rates vary with social circumstances and status of communications media.
Nevertheless, we can tell, in a general sense how long ago the mother tongue of a language group was spoken based on the diversity of variations of a given word. In the case of the IE languages, it's roughly 5000 years. Where was Proto-Indo-European spoken?
Good question. There are two major hypotheses:
The Moral: Because languages evolve in a branching pattern, we can use the same cladistic techniques to recover their histories that we would use on organisms.