Simon J. Greenhill and Russell D. Gray.

The shape and the fabric of human cultural history is the focus of two long-standing debates in linguistics and anthropology. The first concerns the extent to which human history is tree-like (its shape), and the second concerns the unity of that history (its fabric). Proponents of cultural phylogenetics are often accused of assuming that human history has been both highly tree-like and consisting of tightly linked lineages. Critics have pointed out obvious exceptions to these assumptions. Instead of a priori dichotomous disputes about the validity of cultural phylogenetics, we suggest that the debate is better conceptualized as involving positions along continuous dimensions. The challenge for empirical research is, therefore, to determine where particular aspects of culture lie on these dimensions. We discuss the ability of current computational methods derived from evolutionary biology to address these questions. These methods are then used to compare the extent to which lexical evolution is tree-like in different parts of the world and to evaluate the coherence of cultural and linguistic lineages.

The last few years have seen a wave of new computational phylogenetic approaches entering historical linguistics. The application of these computational methods to linguistics is perhaps “one of the most vibrant contemporary streams of comparative linguistics”. Whilst linguistics is not unfamiliar with computational methods, these new methods go far beyond the simplistic and flawed analyses of lexicostatistics or glottochronology. The new approaches have great potential for illuminating long-standing questions about language subgrouping and human prehistory, for exploring how different aspects of languages change and evolve over time, and for investigating the co-evolution of language structures. In this talk I will discuss some of my recent work on these issues.

Many papers about language subgrouping make the argument that if a word form is present in two language subgroups, then it probably reflects their common proto-language. This fairly reasonable assumption has taken center-stage in the reconstruction of Proto-Central-Pacific and Proto-Oceanic, and subsequent inferences about these respective societies. In this talk I will introduce a method that calculates the actual probability that a given form reflects the proto-language. This method builds on the linguistic comparative method, and provides a powerful tool for testing and confirming reconstructions in a probabilistic framework.

Languages are the archives of history. Their elements – such as lexicon and grammar – carry historical signal about the people who spoke these languages and their cultures. Biologists have developed a powerful set of statistical phylogenetic methods for answering questions about human prehistory using genetic data. Information from language, however, holds far greater potential for understanding our past. In this talk I will discuss some of the work I have been doing to apply phylogenetic methods to languages. I will first use these methods to test between hypotheses about the settlement of the Pacific, and to reveal some striking patterns of cultural and linguistic change.

Languages are the archives of history. Their elements – such as lexicon and grammar – carry historical signal about the people who spoke these languages and their cultures. Biologists have developed a powerful set of statistical phylogenetic methods for answering questions about human prehistory using genetic data. Information from language, however, holds far greater potential for understanding our past. In this talk I will discuss some of the work I have been doing to apply phylogenetic methods to languages. I will first use these methods to test between hypotheses about the settlement of the Pacific, and to reveal some striking patterns of cultural change. I will then discuss how phylogenetic methods can integrate with the comparative method to help explore issues like language subgrouping, inference of proto-languages, and linguistic paleontology.

The basic comparative data on the languages of the world is often widely dispersed in hard to obtain sources. Here we outline how our Austronesian Basic Vocabulary Database (ABVD) helps remedy this situation by collating wordlists from over 550 languages into one web-accessible database. We describe the technology underlying the ABVD and discuss the benefits that a “bioinformatic” approach to data and databases can provide.

The settlement of the Pacific is one of the great chapters of human history. This region was settled by the Austronesian people during the last 10,000 years, eventually encompassing the region from Taiwan, to Hawaii, Easter Island (Rapanui), New Zealand, and Madagascar. Along the way, these people carried with them a distinctive “Lapita” culture and one of the largest language families in the world. There are two competing scenarios for this Austronesian expansion: either a rapid tree-like spread from Taiwan beginning around 6000 BP, or an expansion from a deeper Island South-East Asia origin around 17,000 BP. Over the last few years we have built a large comparative database of linguistic information from these languages and have begun using phylogenetic methods to explore Austronesian origins. The results of some phylogenetic analyses on 400 of these languages will be presented, along with what these results tell us about Pacific prehistory.

Phylogenetic tree thinking is beginning to revolutionise studies of linguistic and cultural evolution. However, linguistic and cultural traits are easily transmitted horizontally (“borrowed”) between cultures. Indeed, well over 95% of the words in the Oxford English Dictionary aren’t English. A loud and persistent debate has centered around the issue of borrowing and whether it invalidates cultural phylogenies or not. Here, we use a natural model of linguistic evolution to simulate borrowing between languages. The results show that tree topologies constructed with Bayesian phylogenetic methods are relatively robust to the effects of realistic levels of borrowing. Inferences about time depth are slightly less robust.

Nombre de données linguistiques essentielles recueillies au fil des ans dorment dans des placards et ne sont pas accessibles à la communauté linguistique ou au public intéressé. Nous (Gray & Greenhill) exploitons ces données pour reconstruire des arbres phylogénétiques des langues à l’aide des méthodes informatiques utilisées en biologie de l’évolution et pour vérifier ainsi les hypothèses émises sur le peuplement du Pacifique. Dans cette optique, nous avons informatisé une grande quantité de données lexicales et construit une base de données à grande échelle. Nous avons débuté avec le vocabulaire fourni par les listes de Swadesh rassemblées par Blust ces dernières vingt années ; notre base s’est ensuite enrichie grâce aux données de nombreux linguistes ou de publications. On peut consulter la base de données de vocabulaire austronésien (Austronesian Basic Vocabulary Database) à l’adresse suivante: http://language.psy.auckland.ac.nz. Actuellement, cette base concerne 481 langues, pour un total de plus de 100 000 entrées. Nous présenterons quelques-unes des techniques requises pour construire une telle base et nous évoquerons l’intéret qu’il y a à mettre à disposition sur internet ces données pour des recherches en collaboration. Pour terminer, nous exposerons nos projets d’extension et de consolidation de cette base de données, en invitant les chercheurs à nous fournir de nouvelles données. Au cours de notre communication, nous mentionnerons quelques résultats issus de nos dernières analyses.

..or in English:

Much of the valuable linguistic data that has been collected over the years is languishing in filing cabinets and is not immediately available to linguists and interested members of the public. We (Gray & Greenhill) are using this data to construct phylogenetic trees with computational methods adopted from evolutionary biology to test hypotheses about Pacific settlement. As part of this project we have “computerised” a large amount of lexical data, and constructed a large scale comparative database of this vocabulary. This data began with a collection of Swadesh lists collected by Blust over the last 20 years, and has been supplemented with lists from many other linguists and published resources. This Austronesian Basic Vocabulary Database is available on the internet at http://language.psy.auckland.ac.nz, and currently has word lists from 481 languages, for a total of over 100,000 entries. We shall describe some of the technologies required to build a repository such as this, and talk about the benefits of releasing data onto the internet for collaborative purposes. Finally, we will discuss our plans for expansion and consolidation of this database and make a special plea for more data. A few results from our recent analyses will be presented along the way.

Greenhill, S.J. & R.D. Gray

Department of Psychology, University of Auckland, New Zealand;

This is the abstract of a talk I gave at Doom ’07 – The Annual New Zealand Phylogenetics Meeting at Whakapapa, New Zealand.

The settlement of the Pacific is one of the greatest population movements in the last 10,000 years, and lead to the settlement of the region bounded by Taiwan, Hawaii, Easter Island (Rapanui), New Zealand, and Madagascar. This Austronesian expansion brought with it (and developed along the way) a distinctive Lapita cultural complex and what has become the largest language family in the world, with over 1,000 languages.

There are a number of scenarios describing this Austronesian expansion as either a rapid tree-like spread from Taiwan beginning around 6000 BP, or expansion from a deeper Island South-East Asia origin around 13,000 BP. Over the last few years we have built a large comparative database of linguistic information from these languages (Austronesian Basic Vocabulary Database) and have begun using phylogenetic methods on it.

We will present results from some large analyses of lexical data from over 300 languages, and demonstrate the power of this data at resolving these questions.

A picture from Google Earth, showing the Austronesian words meaning “hand”. Data from the Austronesian Basic Vocabulary Database