The rise and fall of the third chimpanzee

To take an example, if the word meaning 'sheep' were totally different in each modern Indo-European language branch, we could conclude nothing about the word for 'sheep' in the mother tongue. But if the word were similar in several branches, especially in ones as geographically distant as Indo-Iranian and Celtic, we might infer that the various branches had wherited the same root from the mother tongue. By knowing what sound shifts have taken place among the various daughter tongues, we could even reconstruct the form of the word root in the mother tongue.

A SHEEP IS A SHEEP IS A SHEEP

In many modern Indo-European languages, as well as in some ancient ones that we know from preserved writings, the words meaning 'sheep' are quite similar. These words must have been derived from an ancestral form that is inferred to have been owis and that was used in proto-Indo-European (PIE), the unwritten mother tongue.

As the figure above shows, the words for 'sheep' in many Indo-European languages from India to Ireland really are very similar: avis, hawis, ovis, ois, oi, etc. The modern English 'sheep' is obviously from a different root, but English retains the original root in the word 'ewe'. Consideration of the sound shifts that the various Indo-European languages have undergone suggests that the original form was owis.

HONOURABLE ROOT, DISHONOURABLE WORD

Just as in the case of words for 'sheep', the words that mean 'to fart loudly' are similar among many written Indo-European languages. This suggests an ancestral form perd, used in proto- Indo-European (PIE), the unwritten mother tongue.

Naturally, the same word root shared among several daughter languages does not automatically prove shared inheritance from the mother tongue. The word could also have spread later from one daughter language to another. Archaeologists sceptical of linguists' attempts to reconstruct mother tongues love to cite words like 'Coca-Cola', shared among many modern European languages. The archaeologists claim that linguists would absurdly attribute 'Coca-Cola' to the mother tongue of thousands of years ago. In fact, 'Coca-Cola' illustrates how linguists weed out recent borrowings from old inheritances: the word is obviously foreign ('coca' is actually from a Peruvian Indian word, 'cola' West African), and it does not exhibit the same sound shifts among languages as do old Indo-European roots (in German it is still 'Coca-Cola', not Kocherkohler). By such methods, linguists have been able to reconstruct much of the grammar and nearly 2,000 word roots of the mother tongue, termed proto-Indo-European but usually abbreviated as PIE. That is not to say that all words in modern Indo-European languages are descended from 'IE: most are not, because there have been so many new inventions or borrowings (like the root 'sheep' replacing the old PIE root owis in English). Our inherited PIE roots tend to be words for human universals that people surely were already naming thousands of years ago: words for the numbers and human relationships (as in the table on page 226); words for body parts and functions; and ubiquitous objects or concepts like 'sky', 'night', 'summer', and 'cold'. Among the human universals thus reconstructed are such homely acts as 'to break wind', with two distinct roots in PIE depending on whether one does it loudly or softly. The root for doing it loudly (PIE perd) gave rise to a series of similar words in modern Indo-European languages (perdet, pardate, etc.)— including English 'fart' (see figure on page 235, and sample text on pages 248—9). So far, we have seen how linguists have been able to extract, from written languages, evidence of a pre-literate mother tongue and steamroller. The obvious next questions are: when was PIE spoken, where was it spoken, and how was it able to overwhelm so many other languages? Let's begin with the matter of'when', another seemingly impossible question. It is bad enough that we have to infer the words of an unwritten language; how on earth do we determine when it was spoken?

We can at least start to narrow down the possibilities, by examining the oldest written samples of Indo- European languages. For a long time, the oldest samples that scholars could identify were Iranian texts of around 1000-800 BC, and Sanskrit texts probably composed around 1200–1000 BC but written down later. Texts of a Mesopotamian kingdom called Mitanni, written in a non-Indo-European language but containing some words obviously borrowed from a language related to Sanskrit, push the proven existence of Sanskrit-like languages back to nearly 1500 BC. The next breakthrough was the late-nineteenth-century discovery of a mass of ancient Egyptian diplomatic correspondence. Most of it was written in a Semitic language, but two letters in an unknown language remained a mystery until excavations in Turkey uncovered thousands of tablets in the same tongue. The tablets proved to be the archives of a kingdom that thrived between 1650 and 1200 BC and that we now refer to by the biblical name 'Hittite'. In 1917 scholars were astonished by the announcement that the Hittite language proved on deciphering to belong to a previously unknown, very distinctive and archaic, now-vanished branch of the Indo- European family, termed Anatolian. Some obviously Hittite-like names mentioned in earlier letters of Assyrian merchants at a trading post near the Hittite capital's future site push the detective trail back to nearly 1900 BC. This remains our first direct evidence for the existence of any Indo-European language.

Thus, as of 1917, two Indo-European branches—Anatolian and Indo-Iranian—had been shown to exist by around 1900 and 1500 BC, respectively. A third early branch was established in 1952, when the young British cryptographer, Michael Ventris, showed that the so-called Linear B writing of Crete and Greece, which had resisted deciphering since its discovery around 1900, was an early form of the Greek language. Those Linear B tablets date to around 1300 BC. But Hittite, Sanskrit, and early Greek are very different from each other, certainly more so than are modern French and Spanish, which diverged over a thousand years ago. That suggests that the Hittite, Sanskrit, and Greek branches must have split off from PIE by 2500 BC or earlier. How much earlier do the differences between those branches imply? How can we obtain a calibration factor that converts 'percentage difference between languages' into 'time since the languages began to diverge'? Some linguists use the rate of word change in historically documented, written languages, like the changes from Anglo-Saxon to Chaucer's English to Modern English. These calculations, which belong to a science called glottochronology (or chronology of languages), yield the rule of thumb that languages replace about twenty per cent of their basic vocabulary every thousand years.

Most scholars reject glottochronology calculations, on the grounds that word replacement rates must vary with social circumstances and with the particular words themselves. However, the same scholars are generally still willing to make a seat-of-the-pants estimate. The usual conclusion from either glottochronology or pants' seats is that PIE may have started to break up by 3000 BC, surely by 2500 BC, and not before 5000 BC.

There is still another, completely independent approach to the dating problem—the science termed linguistic paleontology. Just as paleontologists try to discover what the past was like by looking for relics buried in the ground, linguistic paleontologists do it by looking for relics buried in languages.

To understand how this works, recall that linguists have reconstructed nearly 2,000 words of PIE vocabulary. It is not surprising that these include words like 'brother' and 'sky', which must have existed and been named since the dawn of human language. But PIE should not have had a word for 'gun', since guns were not invented until about 1300 AD, long after PIE-speakers had already scattered to speak distinct languages in Turkey and India. In fact, the word for 'gun' uses different roots in different Indo-European languages: 'gun' in English, fusil in French, ruzhyo in Russian, and so on. The reason is obvious: different languages could not possibly have inherited the same root for 'gun' from PIE, and they each had to invent or borrow their own word when guns were invented.

The gun example suggests that we should take a series of inventions whose dates we know, and see which of those do and which do not have reconstructed names in PIE. Anything—like gun—that was invented after PIE began to break up should not have a reconstructed name. Anything—like brother—that was invented or known before the break-up might have a name. (It does not have to have a name, because plenty of PIE words have surely become lost. We know the PIE words for 'eye' and 'eyebrow' but not'eyelid', although PIE speakers must have had eyelids.) Perhaps the earliest major developments without PIE names are battle chariots, which became widespread between 2000 and 1500 BC, and iron, whose use became important between 1200 and 1000 BC. The lack of PIE terms for these relatively late inventions does not surprise us, since the distinctness of Hittite had already convinced us that PIE broke up long before 2000