The contribution of genetics and linguistics
Nothing could illustrate better the formidable contribution of archaeological science to the study of agricultural origins and dispersals than the first of the thematic chapters, on ‘archaeogenetics', by Martin Richards and his collaborators Maria Pala, Pedro Soares, and Gyaneshwer Chaubey (Chapter 2).
It provides an excellent introduction to the revolutionary collaborations between archaeologists and geneticists and their impact on the spatial and chronological mapping of specific lineages within a species. As early as the 1980s, genetic studies of modern populations, combining information on genealogies, the geographic distribution of lineages, and time depths from calculated mutation rates, began to unravel some of the key questions of prehistory on a truly global scale, including migrations that accounted for the spread of humans out of Africa and across continents. Archaeogenetic research on the Holocene has focused on the persistent questions about the diffusion of farming and herding, especially in Europe, where the combination of inferences from modern population genetic histories and the increasingly robust analysis of ancient DNA in human and animal bones and seeds from archaeological sites have completely retold the old Neolithic narrative. More broadly, the scientific evidence derived from genetic and morphological data emphasizes more than ever the continuous process of the agricultural revolution. In the past decade, along with studies of stable isotopes, archaeogenetics has constituted one of the most promising sources of information about the movements of recent humans and the changes in diet, plants, and animals that shaped their menus and lives.In Europe the model of ‘leapfrogging' colonization movements and assimilation by indigenous hunter-gatherers, taken as the most robust interpretation of current genetics studies, is in accord with current readings of the archaeological record there, as Alasdair Whittle describes in Chapter 22.
Europe is fortunate in having a growing data set of ancient DNA to compare and contrast with the modern data. Though interesting insights about domestication histories and dispersals have been drawn from genetic studies of present-day data from the Americas, Africa, and Southeast Asia, it is more difficult than commonly acknowledged to separate signals of Neolithic migrations from the many subsequent migrations of the last few thousand years. In the case of horse domestication processes on the Eurasian steppes, for example, quite apart from the effects of major historical events like the Mongol invasions, millions of horses were moved across the steppes during the course of the twentieth-century world wars and, especially, in the Soviet programme of agricultural collectivization in the 1920s and 1930s. As Chapter 2 concludes, the next phase of research needs to involve the systematic collection of ancient DNA for comparison with the models based on modern data sets.Chapter 3 takes up the more familiar shared ground of historical linguistics and archaeology, an intersection that emerged in the nineteenth century, and which Christopher Ehret and others have explored for the past three decades.[6] While archaeological evidence can reveal the material life of past communities, linguistics can also document the intangible transformations in technology and ideas. The potential for using language to understand change over time and across space has been mined particularly successfully from the African continent. Like the genetic studies of modern populations, historical linguistics produces a set of lineage relationships that can be interpreted in terms of patterns of historical transformations. The assumption is that when and where such changes took place may be detectable in modern language sets, given that established agricultural systems incorporate new vocabularies to express the technical processes of breeding, herding, and cultivation.
Ehret takes the reader through the processes of reconstructing ancestral protolanguages, which may be storehouses for early vocabularies related to agricultural practices. Since language history has been used to trace migrations of speakers, this evidence is also useful for locating origins and mapping the spread of agriculture. Thus it is argued that the dispersal of the proto-Niger- Congo family of speakers (sometimes called the ‘Bantu migration') eventually carried farming and herding from West and Central Africa eastwards and southwards across the continent, eventually supplanting many huntinggathering-fishing communities along the way. Ehret argues for the complementary nature of the two primary sources of evidence, linguistics and archaeology, and suggests new directions for an increasingly global view of the recovery of the origins and diffusion of agriculture. The arguments of linguistic studies are also discussed in several of the regional chapters, though it is clear that some of the earlier linguistic work made overly simplistic assumptions about agricultural origins and dispersals, given how archaeological research is showing that the development of agricultural systems couldIntroduction: a world with agriculture vary enormously in rates of change within as well as between regions and was not necessarily a one-way linear process as the linguistic models sometimes assumed.