Cladistic and reticulate processes in language change and diversification Sarah Grey Thomason University of Michigan January 2002 1. Introduction. This paper explores some of the ways in which linguistic evidence can contribute to the effort to discover and understand the interweaving of linguistic, cultural, and genetic change. I will begin by discussing the historical linguist's concept of language families, focusing on the problem of `synchronizing the clocks' (John Moore, this volume) that represent different dating techniques in historical linguistics, archaeology, and genetics ( 2). Section 3 surveys the most extreme outcomes of language contact and attempts to x provide answers, from a linguist's viewpoint, to two questions posed by William Durham (this volume). First, can one predict when ethnogenesis will come about through cladistic development and when it will come about via amalgamation, or reticulate development? And second, a question about tempo and mode: does linguistic change and diversification happen gradually, through `insensibly fine gradations', or abruptly via punctuated equilib- rium? Section 4 then addresses (very tentatively) the prospects for using linguistic evidence in conjunction with evidence from other branches of anthropology, especially genetics, to achieve a unified picture of population origins. Throughout the paper, most of my examples will be drawn from the New World. My main conclusion will be that cladistic development is by far the most common route to language genesis, with reticulate origin a distant second: when different languages come into contact, amalgamation of the languages does sometimes occur, but it rarely results in a stable mixed language that becomes a community's primary medium of communication. The reasons for the low probability of amalgamation are social, not linguistic. A related conclusion is that punctuated equilibrium, though it could be invoked frequently (if rather trivially) in describing specific linguistic changes, is probably not an important factor in the split of a parent language into two or more daughter languages to form a language family. Language splits probably proceed much more often by insensibly fine gradations. (But here the `probably' hedge is needed, for reasons I'll explain later on.) 2. Estimating time depths for language families. In the elaborate biologi- cal metaphor used by historical linguistics since the nineteenth century, a language family consists of a single parent language and a set of one or more descendent languages, which are changed later forms of the earlier parent language. The parent language is called a proto-language if it is unattested (literally, prehistoric), and its descendants are its daughter languages. The members of a language family, parent and daughters, are said to be genet- ically related. Crucially, parent and daughter languages do not co-exist as contemporary living languages. That is, while it is certainly possible for a parent language to live on in written or even limited spoken form after its split into two or more daughter languages, it will not continue as the major language of any speech community, and it is unlikely to be learned as a first language by children. Latin is the most famous example of a parent lan- guage that survived its historical split into several daughter languages (the modern Romance languages): it continued to be used as a (or the) major language of European diplomacy long after its descendants replaced it as major languages of speech communities. Sanskrit is another example|a more typical one, because its continuing cultural importance was due to its status as the language of a major religion. Language families vary greatly in size and complexity. At one extreme, a few of the world's language families are enormous and complex, with hundreds of member languages. The two most spectacular examples are Niger-Congo in sub-Saharan Africa and Austronesian in Oceania and parts of southeast Asia, but the Indo-European family, with far fewer lan- guages but with worldwide distribution (thanks primarily to colonialism), is of even greater importance in the international ecology of languages. At the other extreme, a non-trivial number of languages, e.g. Basque in western Europe and Burushaski in Pakistan, constitute one-member language families, as far as we can tell (at least at present): they are certainly descended from earlier parent languages, but their respective parents apparently underwent no splits, each developing instead in a straight-line fashion into a single isolated modern language. In other words, language split is not inevitable: whether or not splits will occur is a function of non-linguistic factors such as the amount of territory occupied by a language's speakers. Complexity in a language family is represented by branching in the metaphorical family tree, with subgroups clustering together on separate branches and often branching in 2 their turn into sub-subgroups, and so on. Historical linguists reconstruct cladistic (tree-forming) processes of language split and di- versification by means of a powerful methodology known simply as the Comparative Method. This method enables us to establish the fact of linguistic relationship by showing systematic sound/meaning correspondences in a particular set of languages, correspondences that are too numerous and too interlocking to be plausibly assigned to the operation of mere coinci- dence. The method also permits the reconstruction of parts of the proto-language's lexical, phonological, and morphological structure, and to a lesser extent its syntactic structure; in fact, most historical linguists would insist that establishing genetic relationship requires showing that reconstruction is possible in all the major components of a language's structure. Distinguishing the results of reticulate processes from the results of cladistic processes can be problematic in cases of languages that, if related at all, are only very distantly related. At shallower time depths (say, 8,000-10,000 years), the Comparative Method makes it possible to identify borrowed material that has been incorporated into one or more of the languages being compared. An occasional loanword or borrowed syntactic pattern may certainly es- cape detection. But if a language with two or more fairly closely related sister languages has borrowed extensively from another language, the borrowed items will be flagged as un- analyzable residue by the Comparative Method. The only exception to this generalization would be a case of extensive borrowing from a closely-related language; in such cases, the foreign material could in fact disrupt application of the Comparative Method|though that fact itself would be flagged by the methodology. Several such cases have been proposed from different parts of the world, especially in the Pacific, but the jury is still out on whether those instances actually do prevent successful application of the Comparative Method. The 8,000-10,000-year time depth is very, very rough and tentative, and this brings us to the problem of determining how long ago two or more related languages split off from their common parent. First the bad news: the only sure way of establishing the time depth for any language family is to have the initial split, and (if any) all subsequent splits as well, documented in datable texts. This would require dated documents written or inscribed in the parent language and in all the daughter languages. Unfortunately, such cases are vanishingly rare. There's Latin, which (though not precisely in its most widely preserved written form) 3 is the ancestor of the Romance languages; there's literary Old English, which is close to the ancestor of most of the Modern English dialects (there are a few kinks in the line from Old English to Modern English); there's Classical Arabic, which is sort of the ancestor of the Modern Arabic dialects; there's Sanskrit, which is close to the ancestor of the Modern Indic languages; and there are a very few others in the Old World and perhaps one or two in the New World. Chinese has the oldest continuous literary tradition of all the world's living languages|the earliest known Chinese writing dates from the Shang dynasty (1766-1123? BCE)|but even aside from the fact that the ancient writing system is very conservative and tends to conceal dialect divergence, the emergence of the several different Modern Chinese languages was fairly recent. Egyptian, now dead, also had a very long written tradition (3200 BCE-1700 CE), but it remained a unitary tradition (no splits and thus only one daughter language at each stage), so it's useless for the investigation of documented language splits. In practice, almost all of our precise information about time depths comes from a few branches of the large Indo-European (IE) family. Of all the hundreds of language families in the world, IE is by far the best understood historically, partly because it has received by far the most attention from historical linguists for the past century and a half and partly because it is so well documented, with attestations from several of its ten branches dating from before the turn of the common era. Now the good news, or at least the semi-good news: historical linguists do have ways of compensating for the distressing paucity of real-time data on language splits. The first step, always, is to work intensively on a group of related languages (after demonstrating that they are related) to get a feel for how closely related they are. Basic vocabulary can be compared and lexical closeness can be calculated. Grammatical closeness can only be judged impressionistically, but a historical linguist with solid training and experience in Indo-European can provide reasonable support for an estimate of grammatical closeness in another language family by comparison to one or more branches of Indo-European. In other words, Indo-European is usually used as the rough measuring stick for estimating closeness of relationship.