Friday, May 10, 2013

Trees and Waves in the Evolution of Culture

The 19th century thinkers who saw evolutionary processes in the biological world also saw them in culture. While evolutionary thinking about culture persisted well into the 20th century, it had become a minor theme, or less, in most of the humanities and social sciences by the second half of the century. Now, of course, there are concerted efforts to once again think culture as an evolutionary phenomenon.

There is thus a fair amount of biologically inspired work on language. But there are pitfalls there. Criticisms of the recent article on "ultraconserved" words is a case in point. More generally, it is useful to know, as Martin Lewis has written, that Linguistic Phylogenies Are Not the Same as Biological Phylogenies.
Linguistic evolution is only vaguely analogous to organic evolution for a variety of reasons, but a crucial factor is the fact that vastly less sharing occurs across biological lineages. We now know that genes can jump from one species to another, but the process is relatively rare; in this realm, change generally occurs as a result of random mutations acted upon by natural selection, not from the borrowing of elements from other species. When it comes to languages, however, sharing is ubiquitous. Languages are almost always borrowing words, and sometimes they adopt grammatical properties of other languages as well. At times, two completely unrelated languages essentially merge to create a hybrid tongue. To be sure, linguists are almost always able to determine which language contributed more elements and more basic structures, and hence should count as the parent tongue. (It should be noted that the use of the terms “parent” and “daughter” in relation to languages is misleading since, unlike in the biological realm, where individual organisms are discrete, the transition from “parent” to “daughter” language is always gradual.) When it comes to creole languages, however, such determinations are not always easy. In regard to grammar, different creoles of completely different parentage are often more similar to each other than they are to any of their source languages. In some instances of mixed languages, admixtures of vocabulary, grammar, and phonology run so deep that linguists abandon the quest for unambiguous classification. Cappadocian Greek, for example, is slotted by the Wikipedia into the seemingly impossible “Greek-Turkish” language family. Does Indo-European therefore encompass this language? Other sources, such as the Ethnologue, place this language in the Greek branch of the Indo-European family, but Turkish influences on Cappadocian Greek are pronounced: it has certain sounds that have been borrowed from Turkish, as well as vowel harmony; it has developed agglutinative inflectional morphology and lost (some) grammatical gender distinctions; and its basic word order is SOV. And Cappadocian Greek is by no means the only example of such a thoroughly “mixed language.” In the biological realm, in contrast, such mixtures are so obviously impossible that they have generated their own nonsense genre, as exemplified by Sara Ball’s delightful flip-book, Crocguphant.
I want to underline the point about creoles. Very different languaguages can, within less than a half-dozen generations, merge and form a new language which is quite unlike its parent languages. Creoles form where people speaking different languages find themselves in sustained interaction with one another, such as happened during the several centuries when European states colonized Africa, Asia, and the Americas. Creolization is thus common. 

Nor is such radical cultural mixing confined to language, a point I make in an old paper, Culture as an Evolutionary Arena (1996). American popular music is a good example. Here perhaps the strongest dynamic is that of the mixing of European and African musics, a dynamic that has now spread throughout the world. Jazz, rock and roll, and hip hop have spread everywhere, crossing with musical forms native to Asia, Latin American, Europe and Africa and bringing features of those musics back to America (and everywhere else).

Returning to language:
Linguistic family trees must therefore be taken as often showing lines of partial descent, unlike the phylogenetic diagrams of organic evolution. To gain a more complete understanding of linguistic relatedness, it is necessary to complement language families with other kinds of connections. The various languages of a Sprachbund, or a linguistic convergence area, for example, derive from different families, yet nonetheless come to share many features through long histories of mutual interaction.
Lewis goes on to suggest an alternative to phylogenetic trees:
A useful alternative to the linguistic tree is the so-called wave model, or Wellentheorie, originally devised to explain some of the characteristics of the Germanic languages that seemed to defy the phylogenetic approach. In wave theory, fluid dialect continua replace the stable, geographically bounded languages required by models predicated on direct descent from ancestral tongues. Here, innovations can occur at any points within a dialect continuum; such changes then spread outward in a circular manner, eventually dissipating as the distance from the innovation center increases. If a bundle of innovations substantially overlap and become entrenched, a new dialect, or even language, can be said to have emerged. But according to wave theory, such a “language” is still best viewed as an “impermanent collection of features at the intersections of multiple circles.”


  1. Actually borrowed genes are ubiquitous in nature. Sure it is relatively rarER in higher multicellular eukaryotes, but not absent. Viruses carry them in, so do bacteria and fungi. Some insects have absorbed parts of or entire bacterial genomes after long periods of mutualism. Lateral gene transfer is actually the norm for archaea and bacteria, and unicellular eukaryotes get about 50:50 for vertical and lateral.

  2. And I believe that hybridization is more common in multicellular plants than animals.