Sundaland is a biogeographical region of Southeastern Asia which encompasses the Sunda shelf, the part of the Asian continental shelf that was exposed during the last ice age. The last glacial period, popularly known as the Ice Age, was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 12,000 years ago. It included the Malay Peninsula on the Asian mainland, as well as the large islands of Borneo, Java, and Sumatra and their surrounding islands. The eastern boundary of Sundaland is the Wallace Line, identified by Alfred Russel Wallace as the eastern boundary of the range of Asia's land mammal fauna, and thus the boundary of the Indomalaya and Australasia ecozones. The islands east of the Wallace line are known as Wallacea, and are considered part of Australasia.
The South China Sea and adjoining landmasses had been investigated by scientists such as Molengraaff and Umbgrove, who had postulated ancient, now submerged, drainage systems. These were mapped by Tjia in 1980 and described in greater detail by Emmel and Curray in 1982 complete with river deltas, floodplains and backswamps. The ecology of the exposed Sunda shelf has been investigated by analyzing cores drilled into the ocean bed. The pollens found in the cores have revealed a complex ecosystem that changed over time. The flooding of Sundaland separated species that had once shared the same environment such as the river threadfin (Polydactylus macrophthalmus, Bleeker 1858), that had once thrived in a river system now called "North Sunda River" or "Molengraaff river". The fish is now found in the Kapuas River on the island of Borneo, and in the Musi and Batanghari rivers in Sumatra.
Previously, humans were believed to have migrated southward, from the East Asia mainland to Taiwan and then to the rest of Maritime Southeast Asia. However, recent findings point to the submerged Sundaland as the probable cradle of Asian population: thus the "Out of Sundaland" theory.
A study from Leeds University and published in Molecular Biology and Evolution, examining mitochondrial DNA lineages, suggested that humans had been occupying the islands of Southeast Asia for a longer period than previously believed. Population dispersals seem to have occurred at the same time as sea levels rose, which may have resulted in migrations from the Philippine Islands to as far north as Taiwan within the last 10,000 years. The population migrations were most likely to have been driven by climate change — the effects of the drowning of an ancient continent. Rising sea levels in three massive pulses may have caused flooding and the submerging of the Sunda continent, creating the Java and South China Seas and the thousands of islands that make up Indonesia and the Philippines today.
A 2009 genetic study published by the 2009 Human Genome Organization Pan-Asian SNP Consortium found that Asia was originally settled by humans via a single southern route. The migration came from Africa via India, into Southeast Asia and what are now islands in the Pacific, and then later up to the eastern and northern Asian mainland.
Genetic similarities were found between populations throughout Asia and an increase in genetic diversity from northern to southern latitudes. Although the Chinese population is very large, it has less variation than the smaller number of individuals living in Southeast Asia, because the Chinese expansion occurred very recently, following the development of rice agriculture — within only the last 10,000 years.
Oppenheimer locates the origin of the Austronesians in Sundaland and its upper regions. Genetic research reported in 2008 indicates that the islands which are the remnants of Sundaland were likely populated as early as 50,000 years ago, contrary to a previous hypothesis[by whom?] that they were populated as late as 10,000 years ago from Taiwan.[dubious ]
From the standpoint of historical linguistics, the home of the Austronesian languages is the main island of Taiwan, also known as Formosa; on this island the deepest divisions in Austronesian are found, among the families of the native Formosan languages.
The islands of Sundaland rest on an extension of Asia's shallow continental shelf, called the Sunda shelf. During the ice ages, sea levels were lower and all of Sundaland was an extension of the Asian continent.
As a result, the islands of Sundaland are home to many Asian mammals including elephants, monkeys, apes, tigers, tapirs, and rhinoceros. The Wallace Line, which includes the Lombok Strait between Bali and Lombok, and the Makassar Strait between Borneo and Sulawesi, together mark the end of the Asian continental shelf, and the islands of Wallacea are separated from Asia and from Australia and New Guinea by deep ocean.
Botanists often include Sundaland, the adjacent Philippines, Wallacea and New Guinea in a single Floristic province of Malesia, based on similarities in their flora, which is predominantly of Asian origin.
Ecoregions of Sundaland
- Borneo lowland rain forests (Borneo)
- Borneo montane rain forests (Borneo)
- Borneo peat swamp forests (Borneo)
- Eastern Java–Bali montane rain forests (Bali, Java)
- Eastern Java–Bali rain forests (Bali, Java)
- Mentawai Islands rain forests (Mentawai Islands)
- Peninsular Malaysian montane rain forests (Malay peninsula)
- Peninsular Malaysian peat swamp forests (Malay peninsula)
- Peninsular Malaysian rain forests (Anambas Islands, Malay peninsula)
- Southwest Borneo freshwater swamp forests (Borneo)
- Sumatran freshwater swamp forests (Sumatra)
- Sumatran lowland rain forests (Sumatra, Nias, Bangka Island)
- Sumatran montane rain forests (Sumatra)
- Sumatran peat swamp forests (Sumatra)
- Sundaland heath forests (Indonesia)
- Western Java montane rain forests (Java)
- Western Java rain forests (Java)
Notes and references
- The physical geography of Southeast Asia by Avijit Gupta, 2005, ISBN 0-19-924802-8 , page 403
- Till Hanebuth, Karl Stattegger and Pieter M. Grootes, "Rapid Flooding of the Sunda Shelf: A Late-Glacial Sea-Level Record", Science 288 12 May 2000:1033–35.
- Distributation of the River Threadfin
- Dr. Martin Richards. "Climate Change and Postglacial Human Dispersals in Southeast Asia". Oxford Journals. Retrieved 2010.
- Press release: Agency for Science, Technology and Research (A*STAR), Singapore (2009-12-10). "Genetic ancestry highly correlated with ethnic and linguistic groups in Asia". Retrieved 2012-06-14.
Paper: The HUGO Pan-Asian SNP Consortium (2009-12-11). "Mapping Human Genetic Diversity in Asia". Science 326 (5959): 1541–1545. doi:10.1126/science.1177074. PMID 20007900.
- Oppenheimer 1999
- New research forces U-turn in population migration theory
Selected faunal references in Borneo
- Abdullah MT. 2003. Biogeography and variation of Cynopterus brachyotis in Southeast Asia. PhD thesis. The University of Queensland, St Lucia, Australia.
- Corbet, GB, Hill JE. 1992. The mammals of the Indomalayan region: a systematic review. Oxford University Press, Oxford.
- Hall LS, Gordon G. Grigg, Craig Moritz, Besar Ketol, Isa Sait, Wahab Marni, Abdullah MT. 2004. Biogeography of fruit bats in Southeast Asia. Sarawak Museum Journal LX(81):191–284.
- Karim, C., A.A. Tuen, Abdullah MT. 2004. Mammals. Sarawak Museum Journal Special Issue No. 6. 80: 221—234.
- Mohd. Azlan J., Ibnu Maryanto, Agus P. Kartono, Abdullah MT. 2003 Diversity, Relative Abundance and Conservation of Chiropterans in Kayan Mentarang National Park, East Kalimantan, Indonesia. Sarawak Museum Journal 79: 251–265.
- Hall LS, Richards GC, Abdullah MT. 2002. The bats of Niah National Park, Sarawak. Sarawak Museum Journal. 78: 255–282.
- Wilson DE, Reeder DM. 2005. Mammal species of the world. Smithsonian Institution Press, Washington DC.
- Austronesian languages
- Banda Arc
- Father Tongue hypothesis
- Islands of Indonesia
- Oceanic trench
- Plate tectonic
- Sunda Arc
- Sunda Islands
- Sunda Trench
- Animation of Sundaland submersion
- Conservation International: Sundaland
- Review of Oppenheimer's Eden in the East, about Sundaland