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Parasite and Host both out of Taiwan


Parasite and Host both out of Taiwan

It’s the first time in science that bacterial genetics has been used to explain human migration, that is "This is the first paper where bacteria were specifically used for human migration patterns," says Prof. Mark Achtman, a geneticist at the University College Cork, in Ireland, while talking about his paper “The Peopling of the Pacific from a Bacterial Perspective”. The bacteria he used in his study is the human pathogen Helicobacter pylori, found in our guts and adhering to our inside 60,000 years ago since we left Africa.

There are two distinct groups of people which occupy all of the Pacific islands. The Melanesian had arrived as early as 50,000 years ago and dispersed in Australia, New Guinea and Solomon Islands. The Austronesian arrived much later at around 5,000 years ago and distributed over the rest of Pacific, even to the Indian Ocean. The discussion on the origin of Austronesian became a more complicated or controversial issue among geneticists, especially in the region of the Bismarck Archipelago, including Vanuatu, Tonga and Samoa. Since it neighbors the traditional Melanesia ranges of New Guinea and Solomon Islands, there are at least two theories about the origin of Austronesian, one is “Out of Taiwan”, another is “Out of Sundaland”. The theory “Out of Taiwan” had been mentioned 30 years ago by ANU archaeologist Peter Bellwood and is basically supported by linguistic and archaeological evidences, and has now become the mainstream on this subject.

The human gut bacteria Helicobacter pylori which Achtman used in this study, can be divided into two distinct strains in the bodies of Austronesian and Melanesian respectively. Strain hspMaori is found in the Austronesian and strain hpSahul is found in the Melanesian, and both strains are rarely found overlapped. This phenomenon may be due to the few contact between these two groups. In Achtman’s study, researchers collected 212 different bacterial population samples from the stomachs of Taiwanese and Australian aboriginals, highlanders from New Guinea, and Melanesians and Polynesians from New Caledonia. They compared these with samples from Europeans, Asians and the Pacific islanders. They found that the haplotypes from people's guts in Polynesia and islands from New Caledonia to Samoa were similar to the samples from aboriginal people in Taiwan. Therefore we can come to the conclusion both the parasite and its host came out of Taiwan together. In contrast, the counter theory of “Out of Sundaland” is not supported by the bacterial findings.

Another important aspect is the Taiwanese bacteria have more genetic diversity than other bacterial populations found in Polynesian, since the number of the population departed is always less than the population that stayed. This explanation can be used for linguistic findings also. The linguistic study of Austronesian had already found a similar phenomenon. There are 1200 languages that comprise the Austronesian language family which can be divided into 10 subgroups. Out of these, 9 subgroups are found in Taiwan. All the other languages spoken in the Pacific and Indian Oceans, belong to another subgroup. [Chart 1] The language diversity in Taiwan is depicting an interesting phenomenon, the population departed is always less than the population stayed, is suitable to explain the findings in both linguistics and genetics.

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Published at around the same time in 2009, Dr. Russell Gray’s paper on comparative linguistics for Austronesian languages also got a similar conclusion that supported the theory of “Out of Taiwan”. In “Language Phylogenies Reveal Expansion Pulses and Pauses in Pacific Settlement”, researchers use 210 vocabularies of 400 Austronesian languages to analyze with computational method and obtained the conclusion that “the language trees place the Austronesian origin in Taiwan approximately 5230 years ago”. Dr. Gray even mentioned the pauses and pulses during Austronesian migration; the know-how and vessel may be the decisive factors. The first expansion from Taiwan would be possible with the outrigger canoe and effective sailing techniques. The second pulse of migration might be with the more stable double-hulled canoes and advanced knowledge of astronomy for navigation to cover the even more bigger expanse of Pacific Ocean.

From the above two treatises of different disciplines, both have gotten the same conclusion and the theory of “Out of Taiwan”, after it was proposed by Peter Bellwood 30 years ago. It has received more and more supports from various disciplines not only the above two. Some examples include the distribution of paper mulberry trees in the Pacific, the archaeological findings of red-slipped pottery and jade artifact. Related papers and articles can be found in the links below.

Chart 1. Austronesian language family tree

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