In this chapter we examine some assumptions necessary for recognizing the existence of prehistoric migrations, using data from various disciplines and comparing their perspectives. Genes, languages and material cultures all contribute to our understanding of the human past, yet the data they yield can often be incomplete and ambiguous. On the one hand, the migration of a human population into an uninhabited landscape can provide a historical situation in which genes, languages and cultures moved in relative cohesion. Immigration into a previously settled landscape, on the other hand, can be expected to have led to situations of more complex interaction and admixture between populations of different origin.
Significant migrations that lead to permanent settlement into new territory will always leave a signature. Our problem is to recognize that signature. We can expect that with any significant level of migration there will be visible changes in language, material culture and biology, even if there is a considerable amount of admixture between indigenous and immigrating populations.
Are any signatures of ancient migration likely to be clear and unambiguous? Archaeologists, comparative linguists, geneticists, biological anthropologists and ethnologists are all able to consider this question. They must also be willing to consider it in a cross-disciplinary collaborative framework, triangulating across the borders of their specializations. This is a concept used to great effect by archaeologists Patrick Kirch and Roger Green (2001:42) in their detailed reconstruction of ancient Polynesian society:
We seek to develop a triangulation m. ethod in which the subdisciplines of historical linguistics, archaeology, comparative ethnology, and biological anthropology independently contribute their data and assessments to the common objective of historical reconstruction.
Kirch and Green also point out that prehistorians work with 'polygons of error' rather than the precise intersection points of real surveyors, but the triangulation metaphor is still very apt.
First Migrants: Ancient Migration in Global Perspective, First Edition. Peter Bellwood. © Peter Bellwood. Published 2013 by John Wiley & Sons, Ltd.
The existence of polygons of error rather than precise intersections is the main reason why biology, language and culture do not always covary in unison. People procreate and contribute 50% of their genes to each offspring, but a male and female from different ethnolinguistic communities do not create a new language from 50% of the linguistic resources of each of them drawn at random, or build a house split down the middle to reflect their separate architectural traditions. This is partly why, if we travel in Africa, Southeast Asia and the western Pacific, even Europe and India, we find millions of people who speak closely related languages, but who are as different in biological appearance as western Europeans and northern Indians (Indo-European speakers), Melanesians and Filipinos (Austronesian speakers), or Iraqis and Ethiopians (Afroasiatic speakers). There is nothing terribly mysterious about all of this.
World History
