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Origin and dispersal of the coconut

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The origin and inter-continental dispersal of the coconut have been debated by scientists, as the species is widespread and has a complex history. It evolved in the central Indo-Pacific. It was domesticated by Austronesian peoples in Island Southeast Asia and spread during the Neolithic via their seaborne migrations as far east as the Pacific Islands, and as far west as Madagascar and the Comoros. The species played a critical role in the long sea voyages of Austronesians by providing a portable source of food and water, as well as building materials for Austronesian outrigger boats. Coconuts were spread in historic times along the coasts of the Indian and Atlantic Oceans by South Asian, Arab, and European sailors. Based on these separate introductions, coconut populations can still be divided into Pacific coconuts and Indo-Atlantic coconuts. The Indo-Atlantic type was introduced to the Americas during the colonial era in the Columbian exchange, while Austronesian sailors appear to have introduced Pacific coconuts to Panama in pre-Columbian times.

Center of origin

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There have been two major viewpoints on the origins of the genus Cocos: one in the Indo-Pacific, the other in South America.[1][2] Modern genetic studies have identified the center of origin of the coconut as being the Central Indo-Pacific, the region between western Southeast Asia and Melanesia, where the species has its greatest genetic diversity.[3][4][5][6]

Two other lines of evidence support a Central Indo-Pacific origin: linguistic[7] and ecological:[8]

  • Linguistic evidence is provided by similarities of the local names in the Austronesian region. For example, the Polynesian and Melanesian term niu; Tagalog and Chamorro term niyog; and the Malay word nyiur or nyior.[7][9]
  • Ecological evidence for a Central Indo-Pacific origin includes the Indo-Pacific native range of the coconut crab; and the higher amounts of C. nucifera-specific insect pests in the region (90%) in comparison to the Americas (20%), and Africa (4%).[8]

Dispersal by Austronesian peoples

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See also: Domesticated plants and animals of Austronesia, Austronesian peoples, and Genomics of domestication

The cultivation and spread of the coconut was closely tied to the early migrations of the Austronesian peoples who carried coconuts as canoe plants to the islands they settled.[5][6][10][11]

Map of the Pacific and Indian oceans
Chronological dispersal of Austronesian peoples across the Indo-Pacific[12][13]
Geographical distributions of Indo-Atlantic and Pacific coconut subpopulations and their genetic composition[6]
Inferred historical introduction of coconuts from the original centers of diversity in the Indian subcontinent and Island Southeast Asia[6][14][11]

The coconut played a critical role in the migrations of the Austronesian peoples. They provided a portable source of both food and water, allowing Austronesians to survive long sea voyages to colonize new islands as well as establish long-range trade routes. Based on linguistic evidence, the absence of words for coconut in the Taiwanese Austronesian languages makes it likely that the Austronesian coconut culture developed only after Austronesians started colonizing the Philippine islands. The importance of the coconut in Austronesian cultures is evidenced by shared terminology of even very specific parts and uses of coconuts, which were carried outwards from the Philippines during the Austronesian migrations.[6][8] Indo-Atlantic type coconuts were later spread by Arab and South Asian traders along the Indian Ocean basin, resulting in limited admixture with Pacific coconuts introduced earlier to Madagascar and the Comoros via the ancient Austronesian maritime trade network.[6]

Proposed natural intercontinental dispersal

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Coconut fruit in the wild is light, buoyant, and highly water resistant. It has been claimed that they evolved to disperse significant distances via marine currents.[15] C.H. Edmondson stated in 1941, on the basis of an extremely small sample, that coconuts can travel 110 days, or 5,000 km (3,000 mi), by sea and still be able to germinate.[16] The claim is disputed.[17] Thor Heyerdahl, based on his experience crossing the Pacific Ocean on a raft, stated that while the nuts he kept dry survived the crossing, those below deck that became wet were all ruined by salt water, and that nuts started to germinate after 70 days.[18]

The 2014 coral atoll origin hypothesis proposed that the coconut had dispersed in an island hopping fashion using the small, sometimes transient, coral atolls. It noted that by using these small atolls, the species could easily island-hop. Over the course of evolutionary time-scales the shifting atolls would have shortened the paths of colonization, meaning that any one coconut would not have to travel very far to find new land.[19]

Drift models based on wind and ocean currents have shown that coconuts could not have drifted across the Pacific unaided.[17] If they were naturally distributed and had been in the Pacific for a thousand years or so, then we would expect the eastern shore of Australia, with its own islands sheltered by the Great Barrier Reef, to have been thick with coconut palms: the currents were directly into, and down along this coast. However, both James Cook and William Bligh (put adrift after the Bounty mutiny) found no sign of the nuts along this 2,000 km (1,200 mi) stretch when he needed water for his crew.[20]

These drift models thus provide substantial circumstantial evidence that Austronesian voyagers were involved in deliberately carrying coconuts across the Pacific Ocean and that the species could not have dispersed worldwide without human agency. More recently, genomic analysis of cultivated coconut has shed light on the movement. However, admixture, the transfer of genetic material, evidently occurred between the two populations. Admixture has been limited to Madagascar and coastal east Africa, excluding the Seychelles. This pattern coincides with the known trade routes of Austronesian sailors. Additionally, a genetically distinct subpopulation of coconut on the Pacific coast of Latin America has undergone a genetic bottleneck resulting from a founder effect; its ancestral population is the Pacific coconut from the Philippines. This, together with their use of the South American sweet potato, suggests that Austronesian peoples may have sailed as far east as the Americas.[21] In the Hawaiian Islands, the coconut is regarded as a Polynesian introduction.[22]

Pacific and Indo-Atlantic populations

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A genomic study in 2011 identified two highly differentiated populations of coconuts, one originating from Island Southeast Asia (the Pacific group) and the other from the southern margins of the Indian subcontinent (the Indo-Atlantic group). The Pacific group is the only one to display clear genetic and phenotypic indications that they were domesticated; including dwarf habit, self-pollination, and the round niu vai fruit morphology with larger endosperm-to-husk ratios. The distribution of the Pacific coconuts correspond to regions settled by Austronesian voyagers indicating that its spread was largely the result of human introductions. It is most strikingly displayed in Madagascar, an island settled by Austronesian sailors at around 2000 to 1500 BP. The coconut populations on the island show genetic admixture between the two subpopulations indicating that Pacific coconuts were first brought by the Austronesian settlers, which then interbred with the later Indo-Atlantic coconuts brought by Europeans from India.[6][10]

Boat on ocean
A wa'a kaulua (double-hulled canoe) from Hawaii. Catamarans were one of the early technological innovations of Austronesian peoples that allowed them to colonize the islands of the Indo-Pacific and introduce coconuts and other canoe plants along their migration routes.[23][24][25]

Genetic studies of coconuts have confirmed pre-Columbian populations of coconuts in Panama. However, it is not native, and displays a genetic bottleneck resulting from a founder effect. A study in 2008 showed that the coconuts in the Americas are genetically closest related to the coconuts in the Philippines, and not to any other nearby coconut populations (including Polynesia). Such an origin indicates that the coconuts were not introduced naturally, such as by sea currents. The researchers concluded that it was brought by early Austronesian sailors to the Americas from at least 2,250 BP, and may be proof of pre-Columbian contact between Austronesian cultures and South American cultures. It is further strengthened by other similar botanical evidence of contact, like the pre-colonial presence of sweet potato in Oceanian cultures.[5][11][17] During the colonial era, Pacific coconuts were further introduced to Mexico from the Spanish East Indies via the Manila galleons.[6]

In contrast to the Pacific coconuts, Indo-Atlantic coconuts were largely spread by Arab and Persian traders into the East African coast. Indo-Atlantic coconuts were introduced into the Atlantic Ocean by Portuguese ships from their colonies in coastal India and Sri Lanka; first introduced to coastal West Africa, then onwards into the Caribbean and the east coast of Brazil. All of these introductions are within the last few centuries, relatively recent in comparison to the spread of Pacific coconuts.[6]

Coconuts today can be grouped into two highly genetically distinct subpopulations: the Indo-Atlantic group originating from southern India and nearby regions (including Sri Lanka, the Laccadives, and the Maldives); and the Pacific group originating from the region between maritime Southeast Asia and Melanesia. Linguistic, archaeological, and genetic evidence all point to the early domestication of Pacific coconuts by the Austronesian peoples in maritime Southeast Asia during the Austronesian expansion (c. 3000 to 1500 BCE). Although archaeological remains dating to 1000 to 500 BCE suggest that the Indo-Atlantic coconuts were later independently cultivated by the Dravidian peoples, only Pacific coconuts show clear signs of domestication traits like dwarf habits, self-pollination, and rounded fruits. Indo-Atlantic coconuts, in contrast, all have the ancestral traits of tall habits and elongated triangular fruits.[8][6][5][26]

Specimens have been found in the Caribbean and the Atlantic coasts of Africa and South America for less than 500 years (the Caribbean native inhabitants do not have a dialect term for them, but use the Portuguese name), but evidence of their presence on the Pacific coast of South America antedates Columbus's arrival in the Americas.[3]

  • Indo-Atlantic coconut from eastern India with the elongated triangular niu kafa-type fruits
    Indo-Atlantic coconut from eastern India with the elongated triangular niu kafa-type fruits
  • Domesticated Pacific coconut from the Philippines with bright yellow rounded niu vai-type fruits and a slow-growing dwarf habit
    Domesticated Pacific coconut from the Philippines with bright yellow rounded niu vai-type fruits and a slow-growing dwarf habit
  • Coconut trees on a beach in Samoa
    Coconut trees on a beach in Samoa
  • Coconut germinating on Punaluʻu Beach on the island of Hawaiʻi
    Coconut germinating on Punaluʻu Beach on the island of Hawaiʻi

References

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  1. ^ Srivastava, Rashmi; Srivastava, Gaurav (2014). "Fossil fruit of Cocos L. (Arecaceae) from Maastrichtian-Danian sediments of central India and its phytogeographical significance". Acta Palaeobotanica. 54 (1): 67–75. doi:10.2478/acpa-2014-0003.
  2. ^ Nayar, N. Madhavan (2016). The Coconut: Phylogeny, Origins, and Spread. Academic Press. pp. 51–66. ISBN 978-0-12-809779-3.
  3. ^ a b Vollmann, Johann; Rajcan, Istvan (2009-09-18). Oil Crops. Springer Science & Business Media. pp. 370–372. ISBN 978-0-387-77594-4.
  4. ^ Elevitch, C.R., ed. (April 2006). "Cocos nucifera (coconut), version 2.1". Species Profiles for Pacific Island Agroforestry (PDF). Hōlualoa, Hawaii: Permanent Agriculture Resources. Archived (PDF) from the original on October 20, 2013. Retrieved 22 December 2016.
  5. ^ a b c d Baudouin, Luc; Lebrun, Patricia (26 July 2008). "Coconut (Cocos nucifera L.) DNA studies support the hypothesis of an ancient Austronesian migration from Southeast Asia to America". Genetic Resources and Crop Evolution. 56 (2): 257–262. doi:10.1007/s10722-008-9362-6. S2CID 19529408.
  6. ^ a b c d e f g h i j Gunn, Bee F.; Baudouin, Luc; Olsen, Kenneth M.; Ingvarsson, Pär K. (22 June 2011). "Independent Origins of Cultivated Coconut (Cocos nucifera L.) in the Old World Tropics". PLOS ONE. 6 (6) e21143. Bibcode:2011PLoSO...621143G. doi:10.1371/journal.pone.0021143. PMC 3120816. PMID 21731660.
  7. ^ a b Ahuja, SC; Ahuja, Siddharta; Ahuja, Uma (2014). "Coconut – History, Uses, and Folklore" (PDF). Asian Agri-History. 18 (3): 223. Archived from the original (PDF) on August 10, 2017. Retrieved 3 January 2017.
  8. ^ a b c d Lew, Christopher. "Tracing the origin of the coconut (Cocos nucifera L.)" (PDF). Prized Writing 2018–2019. University of California, Davis: 143–157. Archived from the original (PDF) on June 23, 2021. Retrieved April 22, 2021.
  9. ^ Elevitch, Craig R., ed. (2006). Traditional trees of Pacific Islands: their culture, environment, and use. forewords by Isabella Aiona Abbott and Roger R.B. Leakey (1st ed.). Hōlualoa, Hawaii: Permanent Agriculture Resources. ISBN 978-0-9702544-5-0.
  10. ^ a b Crowther, Alison; Lucas, Leilani; Helm, Richard; Horton, Mark; Shipton, Ceri; et al. (14 June 2016). "Ancient crops provide first archaeological signature of the westward Austronesian expansion". PNAS. 113 (24): 6635–6640. Bibcode:2016PNAS..113.6635C. doi:10.1073/pnas.1522714113. PMC 4914162. PMID 27247383.
  11. ^ a b c Brouwers, Lucas (1 August 2011). "Coconuts: not indigenous, but quite at home nevertheless". Scientific American. Retrieved 10 January 2019.
  12. ^ Chambers, Geoff (2013). "Genetics and the Origins of the Polynesians". eLS. John Wiley & Sons, Inc. doi:10.1002/9780470015902.a0020808.pub2. ISBN 978-0-470-01617-6.
  13. ^ Blench, Roger (2009). "Remapping the Austronesian expansion" (PDF). In Evans, Bethwyn (ed.). Discovering History Through Language: Papers in Honour of Malcolm Ross. Pacific Linguistics. ISBN 978-0-85883-605-1.
  14. ^ Lutz, Diana (24 June 2011). "Deep history of coconuts decoded". The Source. Retrieved 10 January 2019.
  15. ^ Foale, Mike. (2003). The Coconut Odyssey – the bounteous possibilities of the tree of life Archived March 30, 2011, at the Wayback Machine. Australian Centre for International Agricultural Research Archived March 18, 2009, at the Wayback Machine. Retrieved May 30, 2009.
  16. ^ Edmondson, C.H. (1941). "Viability of coconut seeds after floating in sea". Bernice P. Bishop Museum Occasional Papers. 16: 293–304.
  17. ^ a b c Ward, R. G.; Brookfield, M. (1992). "Special Paper: the dispersal of the coconut: did it float or was it carried to Panama?". Journal of Biogeography. 19 (5): 467–480. Bibcode:1992JBiog..19..467W. doi:10.2307/2845766. JSTOR 2845766.
  18. ^ Heyerdahl, Thor. (1950) Kon-Tiki: Across the Pacific by Raft. Mattituck: Amereon House. 240 p.
  19. ^ Harries, Hugh C.; Clement, Charles R. (2014). "Long-distance dispersal of the coconut palm by migration within the coral atoll ecosystem". Annals of Botany. 113 (4): 565–570. doi:10.1093/aob/mct293. PMC 3936586. PMID 24368197.
  20. ^ "William Bligh's Logbook". State Library of New South Wales. Archived from the original on October 26, 2016. Retrieved October 26, 2016.
  21. ^ Gunn, Bee; Luc Baudouin; Kenneth M. Olsen (2011). "Independent Origins of Cultivated Coconut (Cocos nucifera L.) in the Old World Tropics". PLOS One. 6 (6) e21143. Bibcode:2011PLoSO...621143G. doi:10.1371/journal.pone.0021143. PMC 3120816. PMID 21731660.
  22. ^ Elzebroek, A. T. G. (2008). Guide to Cultivated Plants. CABI. pp. 186–192. ISBN 978-1-84593-356-2.
  23. ^ Mahdi, Waruno (1999). "The Dispersal of Austronesian boat forms in the Indian Ocean". In Blench, Roger; Spriggs, Matthew (eds.). Archaeology and Language III: Artefacts languages, and texts. One World Archaeology. Vol. 34. Routledge. pp. 144–179. ISBN 978-0-415-10054-0.
  24. ^ Doran, Edwin B. (1981). Wangka: Austronesian Canoe Origins. Texas A&M University Press. ISBN 978-0-89096-107-0.
  25. ^ Johns, D. A.; Irwin, G. J.; Sung, Y. K. (29 September 2014). "An early sophisticated East Polynesian voyaging canoe discovered on New Zealand's coast". Proceedings of the National Academy of Sciences. 111 (41): 14728–14733. Bibcode:2014PNAS..11114728J. doi:10.1073/pnas.1408491111. PMC 4205625. PMID 25267657.
  26. ^ "Deep history of coconuts decoded: Origins of cultivation, ancient trade routes, and colonization of the Americas". ScienceDaily. Washington University in St. Louis. 24 June 2011. Retrieved 22 April 2021.
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