Tracking Austronesian Expansion Into the Pacific Via the Paper Mulberry Plant Elizabeth A
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COMMENTARY Tracking Austronesian expansion into the Pacific via the paper mulberry plant Elizabeth A. Matisoo-Smitha,b,1 banana, taro, breadfruit, and sugarcane, have aDepartment of Anatomy, University of Otago, Dunedin 9054, New Zealand; and bAllan Near Oceanic origins, whereas the sweet potato Wilson Centre for Molecular Ecology and Evolution, University of Otago, Dunedin 9054, and the bottle gourd are of South American New Zealand origin. Thus, the results presented by Chang et al. (6), indicating that the most common variant of paper mulberry found in the Pacific, One of the strategies the ancestors of Pacific with the Lapita Cultural Complex (1). The and the one most likely introduced by the early peoples used for successful settlement of the Lapita culture first appears in the Bismarck colonists, has a clear Taiwanese origin, are sig- islands of the Pacific Ocean was the concept Archipelago some 3400 years before present nificant, providing (to my knowledge) the first of transported landscapes (1). Pacific peoples (BP) and rapidly spreads into the previously direct genetic link between Taiwan and one of carried their culturally and economically im- uninhabited islands of Remote Oceania, the Pacific commensal species. portant plants and animals in their coloniz- reaching Tonga and Samoa, on the edge of Native to Asia, including Taiwan, paper ing canoes and introduced these species to thePolynesianTrianglebyabout2900BP(7). mulberry is a dioecious plant (plants are the islands they settled, which were relatively It is generally accepted that the Lapita culture either male or female) that gets its common impoverished in terms of terrestrial re- is an extension of the Neolithic expansion sources. It has been demonstrated that of Austronesian-speaking peoples through namefromthefactthatitwasusedinChina phylogeographic analyses of these plants and Island Southeast Asia, from the Austronesian and Japan to make paper. In the Pacific, animals can serve as proxies for reconstructing homeland in Taiwan (8–11). Migration to and paper mulberry was an extremely important the pathways of colonizing canoes, and thus settlement of the rest of the Polynesian Tri- plant used for producing barkcloth or tapa, trace the movement of Pacific peoples and angle did not begin until some 1,700 years which was not only used for clothing, but for identify their likely origins. This “commensal after the colonization of Samoa and Tonga, ceremonial artifacts and as an important approach” to tracking the movement of pre- with settlement of Aotearoa/New Zealand indicator of wealth in gift exchange, still seen historic Pacific peoples has to date focused around 730 BP, marking the end of Austro- today in places like Tonga. Tapa production primarily on the animals transported by Pa- nesian expansion into the Pacific (Fig. 1). Al- diminished in many Pacific cultures with the cific colonists, including the Pacific rat (2, 3), though Taiwan has been identified as the introduction of European woven cloth, and pigs (4), and chickens (5). In PNAS, Chang homeland of the Austronesian languages, all as a result, so did the cultivation of paper et al. (6) now present genetic analyses of one previous commensal animal studies indicate mulberry. Barkcloth is produced by beating of the important plant species carried into origins and migration pathways that do not the inner bark of various trees, but most and across the Pacific in colonizing canoes, include Taiwan, suggesting a complex history commonly the paper mulberry, into a thin, with their study of the paper mulberry forthevariouscomponentsofAustronesian pliable, felt-like fabric. Evidence of wooden (Broussonetia papyrifera). and Lapita cultures. Most of the economically tapa beaters have been found in an early, The settlement of the Remote Pacific has important plant species introduced to Remote waterlogged site in East Polynesia, indicating been associated and identified archaeologically Oceanic islands during prehistory, such as it was clearly important for the first colonists (12). These artifacts link the tradition to early Austronesian cultures in Island Southeast Asia and on the mainland, where the earliest stone barkcloth beater has been found in Guangxi, Southern China, and dates to around 8000 BP (13). To identify the geographic origins of paper mulberry and reconstruct its spread through Island Southeast Asia and into the Pacific, Chang et al. (6) studied genetic variation in a 1,233-bp region of the chloroplast DNA Author contributions: E.A.M.-S. wrote the paper. Conflict of interest statement: E.A.M.-S. was a principal investigator (PI) on a project with Dr. Andrea Seelenfreund. The Marsden grant was awarded to E.A.M.-S. in 2009 and ran through 2012. E.A.M.-S. was the identified PI, and Dr. Andrea Seelenfreund was an associate investigator. The project was for archaeological investigations and DNA analyses of human remains from Isla Mocha, Chile. Fig. 1. Map showing the direction of Austronesian expansion from Taiwan and likely timing of expansion into the Pacific. Dates are expressed in years before present (BP) and are based on current archaeological evidence. The dotted See companion article on page 13537. line separates Near Oceania and Remote Oceania. Adapted from ref. 20, with permission from Elsevier. 1Email: [email protected]. 13432–13433 | PNAS | November 3, 2015 | vol. 112 | no. 44 www.pnas.org/cgi/doi/10.1073/pnas.1518576112 Downloaded by guest on September 23, 2021 (cpDNA), which, like mtDNA in humans, is the distribution of this haplotype would introduction history is indicated for Near COMMENTARY maternally inherited. A total of 604 samples be totally consistent with the expansion of Oceania, and further sampling in both Near of paper mulberry were collected from south Austronesian languages. Oceania, particularly locations in the Bismarck China, Cambodia, Vietnam, Thailand, Japan, The fact that a single haplotype, cp-17, is Archipelago (locations with evidence of Lapita Taiwan, the Philippines, Sulawesi, the Solomon dominant across the vast region of Polynesia settlement) and investigations into the distri- Islands, Fiji, and several islands in Polynesia. is consistent with suggestions that Polynesian bution and genetic origins of paper mulberry After sequencing, a total of 48 haplotypes, varieties consist of only male plants that are plants in Vanuatu and New Caledonia will be or distinct lineages, were identified, 31 of clonally propagated (14, 15) and strongly most interesting. Such information would which were shared. One haplotype, desig- supports that they did not disperse naturally help to determine whether paper mulberry nated cp-20, was found throughout the na- was likely introduced by Lapita colonists tive range (southern China, Taiwan, Chang et al. now pre- or if the introduction of cp-17 to Polynesia Vietnam, Cambodia, and Thailand) and was sent genetic analyses of may have been the result of a post-Lapita identified as the likely ancestral type. As might introduction possibly directly from cp-17 be expected, samples collected in this native one of the important harboring locations in Island Southeast Asia range also showed the greatest cpDNA var- plant species carried (either Taiwan or Sulawesi) or via Micronesia iation, with 27 haplotypes identified from into and across the (16). Previous studies of commensal species China, 20 of which were exclusively found such as the Pacific rat (17) and Pacific dogs there. Another five haplotypes were found Pacific in colonizing (18) have demonstrated the need for specific, in Indochina (Vietnam, Cambodia, and canoes, with their study targeted sampling and full analysis of archae- Thailand). Interestingly, the comparatively of the paper mulberry. ological dates and distributions of commensal small island of Taiwan harbored 19 haplo- species that can reveal erroneous assump- types, 16 of which were endemic. but were transported intentionally by hu- tions and errors in our interpretations of The Taiwanese samples showed surprising mans. This form of propagation may also phylogeographic patterns and reconstruc- geographic structuring, with different lineages explain the possible loss of the species in tions of prehistoric human dispersals in the found in the north, the east, and southern/ particular locations when barkcloth manu- Pacific made based on limited sampling. The central parts of the island. The haplotypes facture is abandoned. application of ancient DNA methods to iden- found in the north of the island, particularly Chang et al. (6) have contributed signifi- tify the haplotypes in pre-European samples cp-1, were shared with samples from the east cantly to our understanding of Neolithic ex- and artifacts made of tapa (19) will also assist coast region of the mainland of China, and pansions from the mainland of China to in clarifying or confirming these interpreta- were believed to have been introduced from Taiwan and the subsequent Austronesian mi- tions from modern and historic samples and there during the early phase of Austronesian grations through Island Southeast Asia and present exciting opportunities. expansions to the island dating between 8000 into the Pacific. The clear Taiwanese origins and 6000 BP (6). These northern varieties of cp-17, the likely lineage introduced to ACKNOWLEDGMENTS. I thank Dr. Ceridwen Fraser, Australian National University, for the base map used in were not introduced further south, where Polynesia by early Polynesian colonists, Fig. 1, which was modified by Robbie McFee from the the endemic Taiwanese lineages are found. is most exciting. A much more complex Department of Anatomy, University of Otago. The most common variant found in the Pacific, cp-17, has a clear south/central Taiwanese origin. Haplotype cp-17 is the 1 Kirch PV (2000) On the Road of the Winds: An Archaeological 11 Gray RD, Drummond AJ, Greenhill SJ (2009) Language only lineage found in Sulawesi, Fiji, and in all History of the Pacific Islands before European Contact (Univ of phylogenies reveal expansion pulses and pauses in Pacific settlement. of the Polynesian Islands sampled (Samoa, California Press, Berkeley, CA). Science 323(5913):479–483. 2 Matisoo-Smith E, et al.