Pacific Bananas: Complex Origins, Multiple Dispersals?

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ABSTRACT

This paper reviews recent genetic evidence for the origins of the traditional cultivated bananas of the Pacific, and shows that they are unexpectedly complex. Current assumption of their prevailing west-to-east spread from Southeast Asia into the Pacific thus needs modification. Although bananas are widely assumed to have been part of the set of crops transported to Polynesia at first settlement, the linguistic evidence on which this is based underestimates the diversity of bananas in the New Guinea region and is suspect. Archaeological evidence of bananas is so far very tenuous. Recent genetic evidence of the parentage of most groups of cultivated bananas shows that the primary step toward edibility occurred in the Philippines-New Guinea region. Early movements westward across Island Southeast Asia must have occurred, and the complexity of hybrids makes regionally dispersed development likely. There is no demonstrable link with Taiwan or the adjacent coast of China. There is no evidence that the genetically distinct lineages of bananas found in Polynesia were brought together in the putatively ancestral Lapita crop assemblage of the northern New Guinea region. The complex phylogeny of the cultivated Pacific bananas may thus suggest multiple prehistoric introductions of bananas to Polynesia. If bananas were part of the founding set of crops of Remote Oceania, the question "which bananas?" is currently unanswered. KEYWORDS: Indo-Pacific migration and colonization; banana domestication, taxonomy, and genetics; Pacific plantains, Fe'i bananas, New Guinea archaeobotany, banana phytoliths.

BANANAS, all of which belong to genus Musa in the family Musaceae, have been accepted as part of the pre-European suite of Oceanic cultivated plants since the first published descriptions of Pacific peoples (Barrau 1962, 1965; Merrill 1954; Yen 1991). Although they are among the most thoroughly investigated of Oceanic staple food plants (Yen 1973:69-70), the classification and nomenclature of Pacific cultivated bananas continue to be confused and confusing, even though the characteristics that distinguish them from bananas elsewhere were explained in the classic studies of Simmonds (1959, 1962). Now that biomolecular analyses are revising the phylogeny of bananas, and their prehistory is beginning to be investigated directly by archaeobotanical analyses, Pacific bananas warrant review.

Two groups of cultivated bananas have long been distinguished in the Pacific, each belonging to a separate section of genus Musa. The Fe'i bananas probably originated in the New Guinea area. Formerly important in Tahiti but generally rare, they are not found outside the Pacific. The other Pacific cultivars belong in a second section of the genus, along with all other cultivated bananas including the common commercial ones. It was believed until recently that cultivars belonging to this more widespread section were introduced to the New Guinea region from the west. Biomolecular evidence has now established that Pacific cultivars of this section form a genetically distinctive group, also with New Guinea parentage (Carreel et al. 1994, 2002; Kennedy in press; Lebot 1999; Lebot et al. 1993, 1994). This group is now known as the Pacific plantains.

Although Pacific domesticated bananas are notable for their imputed antiquity as well as distinctiveness, they have only recently begun to be investigated archaeologically. In Polynesia, there are leaf fragments from Tangatatau rockshelter, Mangaia, Cook Islands (Kirch et al. 1995), and Henderson Island (Weisler 1997), and probable phytoliths from Easter Island (Cummings 1998). These remains are identified only as genus Musa. In the more complex phytolith record from the Kuk site in the Highlands of New Guinea, several Musaceae taxa are distinguished, to the successive taxonomic levels of genus, section, species and subspecies. Bananas were present there by 10,000 B.P., and were cultivated by about 7000 B. …