In this second-to-last post on Indo-European origins and expansion, we turn once again to language diffusion, a cornerstone of the model employed by Bouckaert et al. A previous post asked whether languages actually spread by diffusion, arguing that the much more rapid process of advection is often more important. As was then pointed out, physical geographical factors, such as impassible mountains and fertile river corridors, guided such advectional movement. Today’s post considers language movement more generally—whether conceptualized as diffusion or advection—focusing more on the social than the natural environment.
A root error of Bouckaert et al. is regarding language expansion as a singular process. Actually, it can operate in two complete different modes: sometimes a language spreads with a group people, and sometimes it does so among different groups of people. To put it in most schematic terms, language movement occurs when a speaker moves from place A to neighboring place B, but it can also happen when a resident of A imparts his or her language to a resident of B. One process is basically demographic, the other conversional. In geohistorical terms, both forms of language expansion have been ubiquitous. They are generally meshed together in a complex manner, but sometimes one or the other process dominates. As they differ so fundamentally, it they could be realistically modeled in the same manner.
The clearest case of demographic expansion occurs when a single human group arrives on an uninhabited landmass and settles it. As the population expands in numbers and spreads geographically, its language will gradually differentiate into dialects and eventually into separate languages, as sub-populations pushing into new areas become socially separate and their forms of speech drift apart. Such linguistic differentiation could be arrested and reversed by state formation or the emergence of over-arching religious or other cultural institutions, but over the long span of the human past, divergence is usually the rule.
The settlement of Madagascar some 1,500 years ago is a prime example of such virgin-land expansion. Linguistic evidence confirms that the original Austronesian-speaking settlers arrived from Borneo in the Malay Archipelago. As their descendents spread over the mini-continent, their original language differentiated into dialects, some of which are regarded by linguistic splitters as separate languages (the Ethnologue lists ten). Later streams of migrants from the African mainland enhanced the island’s genetic diversity while introducing new linguistic elements, but the newcomers always adopted the language of the original settlers. As a result, all the indigenous forms of speech on Madagascar are very closely related, and are usually classified as variants of the single Malagasy macro-language.
Examples of the opposite process of conversional language expansion are common in today’s world. The process occurs whenever parents neglect to pass on their own mother tongue to their children, in favor of the language of one of their neighboring groups. Hundreds of languages have become endangered in over past generation alone by such changes in behavior. Most disappearing American Indian languages in the United States, for example, are in danger not because their populations are dying out or because their lands are being overrun by English speakers, but rather because decisions are made by parents to raise their children as English speakers.
Such processes of language abandonment and replacement are by no means limited to the modern world. A prime ancient example comes from the Philippine archipelago. Almost all Philippine languages belong to one branch of the Austronesian family, which is almost limited to the Philippines (see the map posted here). Such a pattern would seemingly indicate that the Philippines, like Madagascar, had been initially populated by a single group of settlers whose descendants subsequently spread over the archipelago as their language differentiated. But the actual demographic history of the Philippines was completely different. The original Austronesian settlers came to a land that had already been occupied by tens of thousands of years. Its indigenous* inhabitants were collectively called “Negritos” by Spanish authorities, a word meaning “small, dark-skinned people.” Their languages were undoubtedly unrelated to Austronesian, but we cannot say much beyond that. Although the Philippine indigenes have survived to this day, they abandoned their original tongues many centuries ago in favor of the Austronesian speech of the newcomers.
The social interactions between the Austronesian migrants and the indigenous inhabitants of the Philippines are poorly understood, but the key dynamics are evident. The newcomers were an agriculture people with much more highly developed technologies and forms of political integration than those held by the native foragers. The Austronesian migrants demographically overwhelmed most parts of the archipelago in short order, spreading their language(s) and well as their genes. Yet the indigenes held on in a number of rugged areas, particularly those characterized by heavy, year-round rainfall, such as the Sierra Madre Mountains of eastern Luzon** (in the winter dry season, the Sierra Madre catches rain from trade winds forced up-slope). From such redoubts, however, the indigenous foragers interacted extensively with their Austronesian neighbors, exchanging rain-forest products for agricultural and manufactured goods. Eventually, the languages of their trading partners fully “diffused” across their societies and then began to evolve in their own directions. Today, the several surviving “Negrito languages” are much more closely related to the 
languages of their neighbors than they are to each other. Strikingly similar processes have occurred elsewhere in the world. The most notable case is that of the “Pygmies” of central Africa, another group of diminutive, rainforest hunter-gatherers who long ago abandoned their own languages in favor of the tongues of their more numerous and powerful neighbors, in this case, languages in the Bantu sub-family of Niger-Congo.
The two cases explored above, Madagascar and northeastern Luzon, are best regarded as ends of a spectrum. Most examples of linguistic expansion involve both processes. When one language group expands it usually does so into the territory of a people speaking another language. As communication between natives and newcomers is essential, many individuals acquire a second language. Over time, such a process often leads to the linguistic conversion of the indigenous group—although advancing group are sometimes converted instead, in which case the language frontier retreats. Such encounters are generally accompanied by some conflict, as the native inhabitants typically resent the incursions of the newcomers, who in turn often use force to advance into new lands. To the extent that the indigenes are able to resist the settlers, they will delay the linguistic expansion. The effectiveness of any such resistance in turn depends on the relative numbers of the two groups and on their levels of political and technological development. Any realistic modeling of linguistic spread must take such factors into consideration.
Patterns of physical geographical play an important role here as well, as resistance by native inhabitants is usually more effective in areas of rough or otherwise difficult-to-traverse topography. In some cases, a particular climatic feature can stop language advance; the spreading Bantu-speakers, for example, encountered a firm barrier in the arid and Mediterranean climates of southwestern Africa, which precluded their faming practices and therefore created a refuge for peoples speaking Khoisan languages. Even the geometry of landmasses can play a role. As Anglo-Saxon speech spread across southern England, Celtic speakers were increasingly concentrated in the funnel-shaped peninsula of Cornwall, increasing their population density, shortening their defensive perimeter, and thereby enhancing their ability to resist the spread of English (further north, it was the rugged uplands of eastern Wales that afforded such protection). Yet again, all such features must also be taken into account by any effective attempt to model language spread.
The movement of one language group into the territory of another typically results in complex and variable linguistic interactions. Outcomes again depend heavily on relative numbers and different levels of technological and political development. When a large group of technically advanced people spreads over a landscape occupied by scant numbers of less technically advanced people, the linguistic impact can be minimal. As English advanced across Australia, for example, it picked up place names, animal designations, and words for unique landscape features (such as billabong) from Aboriginal languages, but not much more. But when two groups with more similar levels of development come into contact, much more intensive linguistic interactions typically result. Sometimes the linguistic substrates bequeathed by vanquished populations can be profound at both the grammatical and lexical levels, at other times they are of little significance, and occasionally they seem to be minor at first glance but turn out to be surprisingly important.***
When a language group moves into the lands of a different people, the initial linguistic development is often that of widespread bilingualism. If the newcomers are dominant, as they often are, the subjugated indigenes will find advantage in learning the new language, but even members of the dominant group sometimes acquire the native tongue. Gender relations typically play a crucial role here as well. Men from the more powerful group often take women from the subordinated people, insisting that their native wives learn their language. Such women do so imperfectly, often imposing upon it sounds, words, and grammatical patterns from their native tongue. When they pass down the transformed language of their husbands to their children, a certain degree of linguistic fusion results.
The preceding discussion only hints at the possible complexities involved in the linguistic interactions that occur when one language group pushes into the territory of another. Even so, it deeply challenges the diffusion model of Bouckaert et al. Rather than advancing by steady progression, an expanding language often moves forward in a spatially dispersed manner, as its speakers establish themselves as a dominant social stratum in a foreign land. Many members of the native population will learn the new language, but they will at first continue rearing their own children in their own tongue. After a number of generations of such bilingualism, most parents in the indigenous group may opt to acculturate their infants in their second languages rather than in their mother tongues. As a result, a language could “spread” almost instantaneously over fairly sizable areas. Over broader areas, however, such a process is likely to be patchy, with some areas “converting” much sooner than others.
A prime example of such uneven processes of language change comes from Anatolia. Most of the region was Greek-speaking in the 11th century when the Turkish influx began. By the 13th century most of Anatolia was firmly under Turkish rule, and by the middle of the 15th century Greek political power had vanished everywhere. Throughout this period, Turkish gradually supplanted Greek, but along both the Black Sea coast and that of the Aegean Sea, largely bilingual but primarily Greek-speaking communities persisted until the expulsions of the early 20th century. And as we saw in an earlier post, mixed “Turkish-Greek” forms of speech emerged in some areas.
A second major challenge to the diffusion model emerging from this analysis involves the unpredictability of language change when two (or more) linguistic communities come to occupy the same general territory. Although one might expect that the language of the dominant group would always prevail, that is obviously not the case—if it were, England would have switched to a Romance language after the Norman conquest, and Russia would have ended up with a North Germanic language of its Variangian rulers. Instead, England kept a Germanic tongue, and Russia—a Slavic one.
Interesting examples of the uncertain nature of language change after a successful invasion come from the Danubian grasslands of central and southeastern Europe. From the fourth century to the ninth century CE, this area experienced four major incursions by non-Indo-European-speaking, militarily dominant, pastoral peoples from the steppe zone to the east: those of the Huns, the Eurasian Avars, the Bulgars, and the Magyars. All four groups built empires of a sort, and all subjugated the much more numerous local inhabitants. The Huns and the Avars, however, disappeared within a century or so with little trace, linguistic or otherwise. The Bulgars, on the other hand, built a kingdom so powerful that vestiges of it survive to this day in the form of Bulgaria, but their Turkic tongue vanished long ago, failing to maintain itself in the heavily Slavic environment over which the Bulgars ruled. The Magyars, on the other hand, were able to firmly establish their language, which is spoken today by roughly 15 million people, even though the Magyars themselves were a relatively small group, substantially outnumbered by the peoples that they dominated.
Could one have predicted the fates of the Hunnic, Avar, Bulgar, and Magyar languages merely from the basic facts of their migrations, conquests, and state formations? I rather doubt it, as far too many contingencies were involved over long periods and broad territories. More to the point, could any such processes be successfully modeled as instances of linguistic diffusion? Here the answer must be a definitive “no.” Of course Bouckaert et al. would object here, as they rule out all episodes involving the “rapid” spread of a single language. Yet over the past several thousand years, the rapid spread of single languages has been the stuff of linguistic history over broad segments of the terrestrial globe. If such processes are ignored, nonsense necessarily results.
*The term “indigenous” becomes problematic wherever multiple waves of settlement have impacted a particular place. The term is used here in the relative sense, referring simply to groups that predated other groups with which they are compared.
**Intriguingly, the most rugged area of northern Luzon, the Cordillera Central, did not serve as a refuge for the indigenous hunter-gatherers, as all of its recorded ethno-linguistic groups are descended from the Austronesian migrants. The Cordillera, the site of my own doctoral research, is an usual area in many respects, as it was historically characterized by higher population densities than those found in the adjacent lowlands to the east; dense populations, in turn, necessitated the construction of some of the world’s most elaborate agricultural terraces (see the photo to the left). In all likelihood, such high population density in the mountains resulted from Spanish pressure; residents of northern Luzon who did not want to submit to Spanish rule and forced Christianization fled to the uplands, where they had to build terraces in order to survive. Prior to this influx, small numbers of “Negritos” may have lived in parts of the Cordillera.
***Intriguingly, substrate influences that seem insignificant at first glance can actually turn out to be important. For decades, linguists looked for Celtic influences on English in the wrong places and thus could not find them; even such a recent, authoritative text as Baugh and Cable’s A History of the English Language (1993) states that, “Outside of place-names the influence of Celtic upon the English language is almost negligible” (p. 85). Currently, however, many of the linguistic peculiarities of English are being attributed to the Celts. These include the do-support construction (where do is required in questions and for negation), the diphthongization of long vowels (possibly, the first push that started the chain reaction of the Great Vowel Shift), expressing possession inside noun phrases, using the same –self items for reflexives (“John cut himself”) and intensifiers (“The president himself will visit”), using the same verb forms for both causative structures (“I broke the vase”) and inchoative ones (“The vase broke”), and the it-cleft (“It was a car that he bought”).
). Labor demands during harvest season, moreover, restrict crop size. But prices were high in the early years, and if few growers became rich, many made a comfortable living. More than a few maintained a migratory existence, sojourning in Mexico or Costa Rica during the rainy season and returning to Mendocino in the spring. Many others, however, merely grew a few plants to supplement incomes earned in the formal sector. I have taught several students from backwoods Mendocino backgrounds at Stanford University, and when asked what their parents do for a living, the response is generally on the lines of, “my mother is a teacher/nurse/county employee, and my father, well, he, um, well, he …”