Advances in glottochronology

Question

I have read some old works on lexicostatistics and glottochronology, like Swadesh's original articles or this work, where using Swadesh's basic assumptions the author obtains a temporal estimation for the separation between two Mexican languages. However, I am aware that later the theory received a lot of criticism for its too radically simplified assumptions, which led to some absurd results (a summary can be found here). These assumptions basically boil down to:
(1) Assume a core of relatively stable words.
(2) Assume the "replacement" rate in the core of stable words is approximately constant across languages.

My question is: What is the status of lexicostatistics/glottochronology in current research in linguistics? Is it completely disregarded, or are there more modern improvements that make this theory useful? I ask as a complete stranger to linguistics. A different but closely related question: In glottochronology, starting with Swadesh's lists, as far as I know, all that is taken into account are the proportion of cognates. However, given known cognates, could the amount of phonetic changes be used too to estimate the temporal distance? This, if possible, could be one of the improvements that I mentioned above. I ask this motivated partly by this article, in which they study models for the probability of sound change and their role in the reconstruction of proto-languages, but they do not mention anything about glottochronology.

Answer 1

(This was going to be a comment but it got too long. I hope it is useful nonetheless.)

I can speak for Austroasiatic linguistics (a fairly large family with a small core of researchers actively working on reconstruction). The consensus in the field is that glottochronological estimates are outdated and not particularly useful. In current presentations, Bayesian computational phylogenetic analyses are often referred to as useful benchmarks instead. They are often used to support other analyses (e.g. my archaeological evidence / genetic evidence / phonological reconstruction suggests that speakers of these two languages lived here at time n and then diverged by time n+1, and here's my computational phylogenetic analysis which roughly agrees). One advantage of these analyses is that they can incorporate known facts, such as the fact that two languages had definitely diverged by a certain date. They can also incorporate assumptions about differing rates of change in different sub-branches, and much else.

I assume things are similar in other language families. The modelling papers usually get a lot of press when they come out. The last big one that interested me was Sagart et al 2019 in PNAS, on Sino-Tibetan.

Answer 2

There are several approaches of these word-lists.
Some people like J. Greenberg deemed them practical, but attached no extra value to them.
Some others assign them more methodological values than just being practical.
Among present-day comparatists, only the Moscow School still "believes" in that kind of word-lists and calculations. Most linguists normally consider them close to worthless.
As a rule, my own opinion is that human intelligence and hard work cannot be replaced by automated processes.
Apart from the fact that "stability" can only be a relative feature, and apart from the known fact that rates of change and replacement are highly unstable, (Icelandic is fairly stable, Armenian is full of Iranian words, etc), another problem is that languages often have more than one word to express a given concept or realia.
Besides, inside a given family, dialects and languages often have different words, all of which may in fact be inherited.
So people who use word-lists are compelled to choose among all that complexity only one word, in so doing they are creating artificially simple word-lists.
It can also be noted that these word-lists as they exist do not necessarily include the words that are most interesting from a comparative point of view. For example, none includes the word "lip", which is nevertheless highly revealing.

Answer 3

One of the core assumptions of lexicostatistics, the constant word replacement rate, was questioned be Daniel Nettle (1999) who suggests different rates of language evolution depending on the size of the speech community. Language in small (and small means really small here) speech communities changes faster than in larger ones.