Bananas (Musa spp) are a tropical crop, and a staple in the wet tropic areas of Africa, the Americas, mainland and island Southeast Asia, South Asia, Melanesia and the Pacific islands. Perhaps 87% of the total bananas consumed worldwide today are locally consumed; the rest is distributed outisde of the wet tropical regions in which they are grown. Today there are hundreds of fully domesticated banana varieties, and an uncertain number are still in various stages of domestication: that is to say, they still are inter-fertile with wild populations.
Bananas are basically giant herbs, rather than trees, and there are approximately 50 species in the Musa genus, which includes the edible forms of bananas and plantains. The genus is split into four or five sections, based on the number of chromosomes in the plant, and the region where they are found. Furthermore, over a thousand different types of cultivars of bananas and plantains are recognized today. The different varieties are characterized by wide differences in peel color and thickness, flavor, fruit size, and resistance to disease. The bright yellow one found most frequently in western markets is called the Cavendish.
Bananas produce vegetative suckers at the base of the plant which can be removed and planted separately. Bananas are planted at a typical density of between 1500-2500 plants per square hectare. Between 9-14 months after planting, each plant produces some 20-40 kilograms of fruit. After the harvest, the plant is cut down, and one sucker is allowed to grow up to produce the next crop.
Studying Banana History
Bananas are difficult to study archaeologically, and so the domestication history was unknowable until recently. Banana pollen, seeds and pseudostem impressions are quite rare or absent at archaeological sites, and much of the recent research has been focused on the relatively new technologies associated with opal phytoliths, basically silicon copies of cells created by the plant itself.
Banana phytoliths are uniquely shaped: they are volcaniform, shaped like little volcanoes with a flat crater at the top. There are differences in the phytoliths between varieties of bananas; but variations between wild and domesticated versions are not as yet definitive, so additional forms of research need to be used to fully understand banana domestication.
Genetics and linguistic studies also help in understanding banana history. Diploid and triploid forms of bananas have been identified, and their distribution throughout the world is a key piece of evidence. In addition, linguistic studies of local terms for bananas support the notion of the spread of the banana away from its point of origin: island southeast Asia.
Banana Domestication and Dispersal
Exploitation of early wild forms of bananas has been noted at the Beli-Lena site of Sri Lanka by c 11,500-13,500 BP, Gua Chwawas in Malaysia by 10,700 BP, and Poyang Lake, China by 11,500 BP. Kuk Swamp, in Papua New Guinea, so far the earliest unequivocal evidence for banana cultivation, had wild bananas there throughout the Holocene, and banana phytoliths are associated with the earliest human occupations at Kuk Swamp, between ~10,220-9910 cal BP.
Bananas have been cultivated and hybridized a number of times over several thousand years, so we'll concentrate on the original domestication, and leave the hybridization to botanists. All edible bananas today are hybridized from Musa acuminata (diploid) or M. acuminata crossed with M. balbisiana (triploid). Today, M. acuminata is found throughout mainland and island southeast Asia including the eastern half of the Indian subcontinent; M. balbisiana is mostly found in mainland southeast Asia. Genetic changes from M. acuminata created by the domestication process include the suppression of seeds and the development of parthenocarpy: the ability of humans to create a new crop without the need for fertilization.
Archaeological evidence from the Kuk Swamp of the highlands of New Guinea indicates that bananas were deliberately planted by at least as long ago as 5000-4490 BC (6950-6440 cal BP). Additional evidence indicates that Musa acuminata ssp banksii F. Muell was dispersed out of New Guinea and introduced into eastern Africa by ~3000 BC (Munsa and Nkang), and into south Asia (the Harappan site of Kot Diji) by 2500 cal BC, and probably earlier.
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The earliest banana evidence found in Africa is from Munsa, a site in Uganda dated to 3220 cal BC, although there are problems with the stratigraphy and chronology. The earliest well-supported evidence is at Nkang, a site located in southern Cameroon, which contained banana phytoliths dated between 2,750 to 2,100 BP.
Like coconuts, bananas were most widely spread as a result of the sea exploration of the Pacific by Lapita peoples ca 3000 BP, of extensive trade voyages throughout the Indian Ocean by Arab traders, and of exploration of the Americas by Europeans.
Sources
Much of Volume 7 of the Ethnobotany Research & Applications is dedicated to banana research, and it is all free to download.
This glossary entry is a part of the guide to Plant Domestication, and the Dictionary of Archaeology.
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De Langhe E, Vrydaghs L, de Maret P, Perrier X, and Denham T. 2009. Why Bananas Matter: An introduction to the history of banana domestication. Ethnobotany Research & Applications 7:165-177. Open Access
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Perrier X, De Langhe E, Donohue M, Lentfer C, Vrydaghs L, Bakry F, Carreel F, Hippolyte I, Horry J-P, Jenny C et al. 2011. Multidisciplinary perspectives on banana (Musa spp.) domestication. Proceedings of the National Academy of Sciences Early Edition.
