Mark Pagel, a coauthor of
Ultraconserved words point to deep language ancestry across Eurasia | PNAS has coauthored some other interesting papers.
Dominant words rise to the top by positive frequency-dependent selection | PNAS - from wanting to use words that others use.
Frequency of word-use predicts rates of lexical evolution throughout Indo-European history | Nature - looking at English, Spanish, Russian, and Modern Greek, using text corpora with 20 to 100 million words each.
Their written histories:
- English: 1,300 years (Old English)
- Spanish: 2,300 years (Old Latin)
- Russian: 900 years (Old East Slavic)
- Greek: 3,400 years (Mycenaean Greek), 2,800 years (Homeric Greek)
Their ancestors diverged with the spread of the Corded Ware culture in Northern Europe, around 5,000 years ago.
Noting that IE langs' words for tail is very variable - English "tail", German Schwanz, French queue, Greek oura - while their words all come from a single protoform, *dwô.
Figure 1a shows the inferred distribution of rate estimates, where we observe a roughly 100-fold variation in rates of lexical evolution among the meanings. At the slow end of the distribution, the rates predict zero to one cognate replacements per 10,000 years for words such as ‘two’, ‘who’, ‘tongue’, ‘night’, ‘one’ and ‘to die’. By comparison, for the faster evolving words such as ‘dirty’, ‘to turn’, ‘to stab’ and ‘guts’, we predict up to nine cognate replacements in the same time period.
Thus confirming Aharon Dolgopolsky's results.
Figure 2 shows that the distribution of word-use frequencies in each language is highly skewed, such that most words are used relatively infrequently (fewer than 100 times per million words), with a small number of frequently used words (as
often as 35,000 times per million words) accounting for most speech. Word-use frequencies are highly correlated among the four languages (0.78 < r < 0.89, mean r = 0.84; Supplementary Fig. 2),showing that words used at a high frequency in one language tend to be used at a high frequency in the other languages.
The authors suggest that these frequencies have been very stable over the history of Indo-European. But there is a confounding factor. All four corpora are likely of present-day and relatively recent texts, and living in present-day society may account for this similarity.
There is a good check: find these results for literature from the past. One won't get as good a sample size, but one should be able to get enough to find overall trends. However, a problem may be limited subject matter. The oldest continually-transmitted work of literature is the Rig Veda, and that is a big collection of hymns. The oldest Greek texts are Linear B tablets, and those are all bookkeeping records. Etc.
The authors found a negative correlation between rate of use and rate of change. Since some parts of speech are used more than others, so they split the words up by part of speech. "To examine this effect, we categorized meanings as either nouns, adjectives, verbs, pronouns, numbers, conjunctions, prepositions or special adverbs (‘what’, ‘when’, ‘where’, ‘how’,‘here’, ‘there’ and ‘not’)"
What they found: "For a given frequency of meaning-use, prepositions and conjunctions evolve most quickly, followed by progressively slower evolution for adjectives, verbs, nouns, special adverbs, pronouns and finally numbers."
Also, "The generality of this influence is suggested in the finding that estimates of the rate of lexical replacement in Indo-European languages are correlated with rate estimates in Bantu, Cushitic and Malayo-Polynesian."
Then on language change in general. "One is that we expect languages to diverge in the least frequently used parts of their vocabularies. This may mean that languages retain mutual intelligibility far longer than expected from simple uniform rates models of linguistic divergence."
One can check such estimates with almost mutually intelligible languages like Spanish and Italian, Russian and Ukrainian, etc.
