Evolutionary forces in language change depend on selective pressure, but also on random chance


A new interesting paper from Nature: Detecting evolutionary forces in language change, by Newberry, Ahern, Clark, and Plotkin (2017). Discovered via Science Daily.

The following are excerpts of materials related to the publication (written by Katherine Unger Baillie), from The University of Pennsylvania:

Examining substantial collections of annotated texts dating from the 12th to the 21st centuries, the researchers found that certain linguistic changes were guided by pressures analogous to natural selection — social, cognitive and other factors — while others seem to have occurred purely by happenstance.

“Linguists usually assume that when a change occurs in a language, there must have been a directional force that caused it,” said Joshua Plotkin, professor of biology in Penn’s School of Arts and Sciences and senior author on the paper. “Whereas we propose that languages can also change through random chance alone. An individual happens to hear one variant of a word as opposed to another and then is more likely to use it herself. Chance events like this can accumulate to produce substantial change over generations. Before we debate what psychological or social forces have caused a language to change, we must first ask whether there was any force at all.”

“One of the great early American linguists, Leonard Bloomfield, said that you can never see a language change, that the change is invisible,” said Robin Clark, a coauthor and professor of linguistics in Penn Arts and Sciences. “But now, because of the availability of these large corpora of texts, we can actually see it, in microscopic detail, and begin to understand the details of how change happened.”

One change is the regularization of past-tense verbs. Using the Corpus of Historical American English, comprised of more than 100,000 texts ranging from 1810 to 2009 that have been parsed and digitized — a database that includes more than 400 million words — the team searched for verbs where both regular and irregular past-tense forms were present, for example, “dived” and “dove” or “wed” and “wedded.”

“There is a vast literature and a lot of mythology on verb regularization and irregularization,” Clark said, “and a lot of people have claimed that the tendency is toward regularization. But what we found was quite different.”

Indeed, the analysis pointed to particular instances where it seems selective forces are driving irregularization. For example, while a swimmer 200 years ago might have “dived”, today we would say they “dove.” The shift towards using this irregular form coincided with the invention of cars and concomitant increase in use of the rhyming irregular verb “drive”/“drove.”

Despite finding selection acting on some verbs, “the vast majority of verbs we analyzed show no evidence of selection whatsoever,” Plotkin said.

The team recognized a pattern: random chance affects rare words more than common ones. When rarely-used verbs changed, that replacement was more likely to be due to chance. But when more common verbs switched forms, selection was more likely to be a factor driving the replacement.

The grammar of negating a sentence has changed from “Ic ne secge” (Beowulf, c. 900) to “Ic ne sege noht” (the Ormulum, c. 1100) to “I seye not” (Chaucer, c. 1400) to “I doe not say” (Shakespeare, c. 1600) before returning to the familiar “I don’t say” (Virginia Woolf, c. 1900). A team from Penn used massive digital libraries along with inference techniques from population genetics to quantify the forces responsible for language evolution, such as in Jespersen’s cycle of negation, depicted here. (c) Cherissa Dukelow, 2017, license information below

The authors also observed a role of random chance in grammatical change. The periphrastic “do,” as used in, “Do they say?” or “They do not say,” did not exist 800 years ago. Back in the 1400s, these sentiments would have been expressed as, “Say they?” or “They say not.”

Using the Penn Parsed Corpora of Historical English, which includes 7 million syntactically parsed words from 1,220 British English texts, the researchers found that the use of the periphrastic “do” emerged in two stages, first in questions (“Don’t they say?”) around the 1500s, and then roughly 200 years later in imperative and declarative statements (“They don’t say.”).

These manuscripts show changes from Old English (Beowulf) through Middle English (Trinity Homilies, Chaucer) to Early Modern English (Shakespeare’s First Folio). Penn researchers used large collections of digitized texts spanning the 12th to the 21st centuries to show that many language changes can be attributed to random chance alone. (c) Mitchell Newberry, 2017, license information below

While most linguists have assumed that such a distinctive grammatical feature must have been driven to dominance by some selective pressure, the Penn team’s analysis questions that assumption. They found that the first stage of the rising periphrastic “do” use is consistent with random chance. Only the second stage appears to have been driven by a selective pressure.

“It seems that, once ‘do’ was introduced in interrogative phrases, it randomly drifted to higher and higher frequency over time,” said Plotkin. “Then, once it became dominant in the question context, it was selected for in other contexts, the imperative and declarative, probably for reasons of grammatical consistency or cognitive ease.”

As the authors see it, it’s only natural that social-science fields like linguistics increasingly exchange knowledge and techniques with fields like statistics and biology.

“To an evolutionary biologist,” said Newberry, “it’s important that language is maintained through a process of copying language; people learn language by copying other people. That copying introduces minute variation, and those variants get propagated. Each change is an opportunity for a different copying rate, which is the basis for evolution as we know it.”

Featured image: copyrighted, modified from the Supplementary information of the article.

Image (c) Cherissa Dukelow, 2017, licensed under CC-BY-NC-SA 4.0 http://creativecommons.org/licenses/by-nc-sa/4.0/
Image (c) Mitchell Newberry, 2017, https://creativecommons.org/licenses/by-nc/4.0/, licensed under CC-BY-NC 4.0 (see materials at University of Pennsylvania for further sources).


WordPress Translation Plugin – now using Google Translation from and into Swedish, Finnish, Danish, Norwegian, Polish, Czech, Romanian, Bulgarian, Hindi, Arabic, Japanese, Chinese, etc.

The latest improvements added to the Indoeuropean Translator Widget have been included in the simpler WordPress Translation Plugin available in this personal blog.

It now includes links to automatic translations from and into all language pairs offered by Google Translation Engine, apart from other language pairs (from individual languages, like English or Spanish) into other online machine translators, viz Tranexp or Translendium.

Available language pairs now include English, Arabic, Bulgarian, Catalan*, Czech, Chinese (traditional/simplified), Welsh*, Danish, German, Greek, Spanish, Persian*, French, Hindi, Croatian, Icelandic*, Italian, Hebrew*, Latin*, Korean, Hungarian*, Dutch, Japanese, Norwegian (Bokmål), Polish, Portuguese (Brazilian Portuguese*), Romanian, Russian, Slovenian*, Serbian*, Swedish, Finnish, Tagalog*, Turkish* and Ukrainian*.

How ‘difficult’ (using Esperantist terms) is an inflected language like Proto-Indo-European for Europeans?

For native speakers of most modern Romance languages (apart from some reminiscence of the neuter case), Nordic (Germanic) languages, English, Dutch, or Bulgarian, it is usually considered “difficult” to learn an inflected language like Latin, German or Russian: cases are a priori felt as too strange, too “archaic”, too ‘foreign’ to the own system of expressing ideas. However, for a common German, Baltic, Slavic, Greek speaker, or for non-IE speakers of Basque or Uralic languages (Finnish, Hungarian, Estonian), cases are the only way to express common concepts and ideas, and it was also the common way of expression for speakers of older versions of those very uninflected languages, like Old English, Old Norse or Classical Latin; and their speakers didn’t consider their languages “difficult” …

Therefore, to use different cases is the normal way to express concepts that non-inflected languages express in different ways – i.e. not “more easily”, but “differently”. That’s the point Esperantism has lost in its struggle to convince the world of its “easiness”. In fact, the idea that cases are difficult is so impregnated in Esperantism, that some did create “an old version” [probably deemed “more difficult”] of Esperanto called Arcaicam Esperantom, as a fiction of evolution from an older language…

Thus, among the European population (more than 700 million inhabitants), just around 200 million speak non-inflected languages, while the rest use at least 4 cases to express every possible concept. Within the current EU, more or less half of its speakers speak an inflected language – like German, Polish, Czech, Greek, Lithuanian, Slovenian, or non-IE Hungarian, Finnish, etc. – as their mother tongue.

For example, the literal sentence “I go to-the-house” [not exactly the common expression “I go home” which is expressed differently in each language] would be said in Spanish “voy a-la-casa”, or in French “je vais a-la-maison”, in Italian “vado a-la-casa”, etc. Therefore, in an “easy conlang” for Western European speakers, say in something called Esperanto, a sentence like “io vo a-lo-haus” is apparently “easy”, because the syntactical structure is similar to those non-inflected languages.

NOTE: In fact, there are other interesting concepts behind the use of the obligatory subject before the verb in languages like English or Esperanto, that appears usually in those languages that have reduced the verbal system; therefore, the subject is necessary only in those languages whose verbal inflection becomes too simple to express an idea that must still be expressed some way – more or less like different combinations of prepositions and articles are often needed to substitute the lost nominal inflection, as we discuss here. In those ‘less innovative’ languages that retain a rich verbal system, the subject appears for some reason, as e.g. in Spanish “yo voy a la casa”, which must be expressed differently in innovative languages, using different linguistic resources, like e.g. Eng. “I myself go to the house” (or maybe “it’s me who…“), or French “moi, je vais a la maison”. Is that obligatory subject and ‘simplified’ verbal system of Esperanto “easier”, and therefore “better”…? I guess not. It’s just an imitation of French or English that Mr. Zamenhoff deemed “better” for his creation to succeed, given the relevance of those languages (and its speakers’ acceptance) back in 1900…

On the other hand, in German it would be “Ich gehe nach-Haus-e”, in Latin, it is “vado ad-domu-m”; in Polish “idę do-dom-u” etc. The use of declensions, if compared to uninflected languages, is usually made of just a simple change of “preposition+article” -> “declension” – or, in the ‘worst’ case (as it is shown here), by a “preposition+article” -> “preposition+declension”.

To sum up, can some languages be considered “more difficult” than others? Yes, indeed. If seen from a European point of view, some linguistic features are not easy to learn: the Arab writing system, Chinese unending kanjis, Sino-Tibetan or Vietnamese tones, etc. can cause headaches to [adult] speakers willing to learn them… Also, from an English, French or Spanish point of view, learning a language like Esperanto might seem “better” because of its apparent and equivocal “easiness”… But, between (a) all Indo-European speakers learning a non-inflected language like English [or ‘easy’ Esperanto], or (b) all Indo-European speakers learning an inflected one like Proto-Indo-European?; I guess there is no language “easier” than other, and therefore the “better” option should come from other rational considerations, not just faith in the absurd ramblings of an illuminated Polish ophthalmologist.

Therefore, the question remains still the same: why on earth should any European willing to speak a common language select an invented one (from the thousand “super easy” ones available) than a natural one, like the ancestor of most of their mother tongues, Proto-Indo-European?

New Version for Spanish Translation Plugin and Translator Widget Released

I don’t have a lot of time to post content on this blog, but at least there are some other WordPress-based websites I have to care of, and they usually include some type of a modified WordPress Translation Plugin.

The Spanish-Catalan translator link didn’t work right, and because of that I substituted it for another translation engine; a Spanish-Galician translator engine has also been added to the plugin, both from the Translendium engine. These two modifications are released with the new Spanish Translator Plugins dnghu_es_h and dnghu_es_v.

Because I have more than 5 (and more than 10) WordPress sites, and because I am used to work with widgets, I’ve finally developed the plugin into an easy-to-install Indo-European Translator Widget, which is actually more of the same code. If you are more used to widgets, or if you don’t need/want to place the translation links outside the sidebar, or if you just like the plug-and-play advantages of widgets, this might be your best option.

(I’ve tried to create a plugin account at WordPress.org for the widget, because now it’s not only about 10 lines of code, and new releases might be for security risks or other bugs – however, three weeks after requesting it, I haven’t received permission yet; I guess I’ll wait a little more and then publish it on the web – I just don’t want to upload things twice, or work more than necessary 🙂

It might seem paradoxial, as I’ve changed the plugin for the widget on this site, whilst in the widget’s site I’ll probably use the plugin: it’s a question of advantage balancing – and, in this very case, of the WordPress themes I’m using for each site.

Indeed, it remains the simplest possible code a non-professional like me could write, so you’ll probably be  able to modify and customise it if and when you want 😉