Reconsidering Austronesian Homeland and Dispersal Models using Genetic and Morphological Signatures of Domestic Animals

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The invention and spread of farming around the world was one of the most important events in human history, and it continues to shape our existence today. Understanding this process is one of the keys to understanding human civilization, yet despite decades of study, fundamental questions regarding why, where and how it occurred, and what were its early consequences for humankind remain unanswered. The bones of early domestic animals and their wild ancestors are commonly found at archaeological sites and they hold important clues to many of these questions. New scientific techniques including the use of genetics and statistical analyses of the shapes of these ancient bones are beginning to provide unique insights into the biology of the domestication process itself, as well as new ways of tracking its spread as farmers moved into new areas. One of the most momentous journeys made by early farmers was firstly from mainland East Asia into Island Southeast Asia, and then into the Pacific. This movement is traditionally thought to have begun by a linguistically related group known as the Austronesians. Evidence from studies of languages, pottery, and human gut bacteria suggest that farmers in Taiwan began heading south, reaching the Philippines before continuing on towards the island of New Guinea. From there, a culturally distinct group known as Lapita headed east into the Pacific. These were the ancestors of the Polynesians who went onto colonize the most remote islands on Earth. When farmers migrate, they take with them not just their agricultural tools and their plants, but also their domestic animals as well. When we investigated the genetic signatures of archaeological pigs throughout Island Southeast Asia, we expected the evidence to show that the route pigs took to reach the Pacific mirrored that of the humans. After all, pigs could not have swum across the open ocean to reach the islands of West Polynesia. What we found, however, strongly suggested that the pigs associated with the Lapita expansion did not come from Taiwan, as the people seem to have, but originated instead in Vietnam, then travelling along the islands of Sumatra and Java before reaching New Guinea. The assumption at the heart of the Out-of-Taiwan model holds that all of the individual elements of the farming package first originated in Taiwan, and that each of the elements should tell the same story. The contradiction between the pig data and the human evidence implies that the story of the Pacific colonization was a great deal more complex than previously imagined. By adding to and extending our previous work on pigs to include dogs and chickens, we plan to unravel these complexities. We will start by examining archaeological remains from sites across the region from two different perspectives. By employing newly developed techniques to quantify shape changes (called geometric morphometrics), we will be able to identify diagnostic signatures that will enable us to pinpoint the origins of the ancestors of the examined sample. In addition, we will extract DNA from the archaeological material and compare the genetic sequences with a global database. The combination of these techniques will also us not only to acquire two different kinds of data from the same specimen, but also to compare the evidence from each and trace the signatures through time space. We will also collect and analyze modern pig, dog, and chicken samples from throughout the region to ascertain their genetic diversity. This element of the study will enable us to ask questions about the relationships between modern and ancient specimens, and the degree of hybridization between different waves of incoming domestic animals. Overall we aim to reconstruct a detailed map of the migration of early farmers into the Pacific, allowing us to obtain answers to a series of longstanding questions, and insights into the origins of agriculture, human migration, and civilization.