Toba catastrophe theory
Toba eruption theory | |
---|---|
Volcano | Toba Caldera Complex |
Date | c. 74,000 years BP |
Location | Sumatra, Indonesia 2°41′04″N 98°52′32″E / 2.6845°N 98.8756°E |
VEI | 8 |
Impact | Impact disputed |
Deaths | (Potentially) almost all of humanity, leaving around 3,000–10,000 humans left on the planet |
Lake Toba is the resulting crater lake |
The Toba eruption (sometimes called the Toba supereruption or the Youngest Toba eruption) was a
History
In 1972, an analysis of human hemoglobins found very few variants, and to account for the low frequency of variation human population must had been as low as a few thousand until very recently.[9] More genetic studies confirmed an effective population on the order of 10,000 for much of human history.[10][11] Subsequent research on the differences in human mitochondrial DNA sequences dated a rapid growth from a small effective population size of 1,000 to 10,000, sometime between 35,000 and 65,000 years ago.[12][13][14]
The large magnitude of Toba eruption has been known since 1939, and various techniques dated the timing of the event to 73,000 to 75,000 years ago.[15] A study published in 1993 suggested that the eruption accelerated climate and environmental transition from the last interglacial period MIS-5 to the last glacial period MIS-4.[16]
In 1993, science journalist Ann Gibbons posited that population growth was suppressed by the cold climate of the last Pleistocene Ice Age, possibly exacerbated by the Toba eruption. The subsequent explosive human expansion was believed to be the result of the end of the ice age.[17] Geologist Michael R. Rampino of New York University and volcanologist Stephen Self of the University of Hawaiʻi at Mānoa supported her theory.[18] In 1998, anthropologist Stanley H. Ambrose of the University of Illinois Urbana-Champaign hypothesized that the Toba eruption caused a human population crash, and the low population size was sustained by the global glacial condition of MIS-4 until the climate eventually transitioned to the warmer condition of MIS-3 about 60,000 years ago, during which rapid human population expansion occurred.[2]
Toba eruption
The most recent estimate of eruptive volume is 3,800 km3 (910 cu mi)
The most recent two high-precision argon–argon datings dated the eruption to 73,880 ± 320[31] and 73,700 ± 300 years ago.[32] Five distinct magma bodies were activated within a few centuries before the eruption.[33][34] The implied prevailing wind from the ash distribution is consistent with the eruption occurred during summer.[25] The eruption commenced with small and limited air-fall and was directly followed by the main phase of ignimbrite flows.[22] The ignimbrite phase is characterized by low eruption fountain,[35] but co-ignimbrite column developed on top of pyroclastic flows reached a height of 32 km (20 mi).[36] The entire eruption was likely continuous without major break and may have only lasted 9 to 14 days.[15] Petrological constrains on sulfur emission yielded a wide range from 1013 to 1015 g, depending on the existence of excess gas in the Toba magma chamber.[37][38]
Climatic effects
By analyzing climate proxies and simulating climate forcing, researchers can gain insights into the immediate climatic effects of the Toba eruption. However, there are limitations to both methods. In sedimentary records where the Toba tuff does not serve as a marker horizon, it cannot indicate the exact section that records the environmental conditions immediately after the eruption. Meanwhile, in sedimentary records that do have the Toba tuff as a marker horizon, the sedimentation rate may be too low to capture the short-term climatic effects of the eruption.[39][40] On the other hand, results of climate models entirely depend on the volatile budget of erupted magma, hence varies accordingly to the assumed volatile budget.
Climate proxy
The Toba tephra layer in marine sediments coincides with the δ18O MIS 5a to 4 boundary, marking a climatic transition from warm to cold caused by a change in ocean circulation and a drop in atmospheric CO2 concentration, also known as the Dansgaard-Oeschger event. Geologist Michael R. Rampino and volcanologist Stephen Self hypothesized that Toba eruption accelerated this shift.[16][41] Testing this hypothesis required higher resolution sedimentary records.
Two marine sediment cores Toba marker horizon retrieved[clarification needed] from the Northern Indian Ocean and the South China Sea either showed no pronounced cooling or a 0.8–1.0 °C (1.4–1.8 °F) cooling in the centuries following eruption.[42][43] The core resolution[clarification needed] was insufficient to ascertain that the cooling was caused by the Toba eruption since the two events could be decades or centuries apart in the core.[39] However, a severe cooling of only a few years is not expected to appear in these sediment records of centennial resolution.[43] Nonetheless, the marine sedimentary records indicate that Toba had only a minor effect on the time scales longer than a century.[43][39]
In Greenland ice cores, a large sulfate spike that appeared between Dansgaard–Oeschger event 19 and 20 was possibly related to Toba eruption. The δ18O values of the ice cores indicate a 1,000-year cooling event immediately following the sulfate signal.[44] However, high-resolution δ18O excluded the possibility of a more-than-a-century-long cooling impact of the eruption and ruled out that Toba triggered the cooling as it was already underway.[45][46]
Insufficient resolution in marine sediments bearing the Toba tuff has hindered the assessment of any short-term effects that may have lasted for less than a century.[47]
In 2013, a microscopic layer of Toba ash was reported in sediments of Lake Malawi. Together with the high sedimentation rate of the lake and Toba marker horizon, several team have reconstructed the local environment after Toba eruption at subdecadal resolution of ~6–9 years. The sediments in core display no clear evidence of cooling and no unusual deviations in concentrations of climate-sensitive ecological indicators. These results imply that the duration of the Toba cooling must have been either briefer than the sampling resolution of ~6–9 years or too small in magnitude in East Africa.[5][47][48][49]
Climate modeling
The mass of sulfurous gases emitted during Toba eruption is a crucial parameter when modeling its climatic effects.
Assuming an emission of 1.7 billion tonnes (1.9 billion short tons) of
In a 2021 study, two other emission scenarios, 0.2 billion tonnes (0.22 billion short tons) and 2 billion tonnes (2.2 billion short tons) of
Petrological studies of Toba magma constrained that the mass of
Genetic bottleneck hypothesis
Genetic bottleneck in humans
The Toba eruption has been associated with a
Proponents of the genetic bottleneck theory (including Robock) suggest that the Toba eruption resulted in a global ecological disaster, including destruction of vegetation along with severe drought in the
Other research has cast doubt on an association between the Toba Caldera Complex and a genetic bottleneck. For example, ancient stone tools at the Jurreru Valley in southern India were found above and below a thick layer of ash from the Toba eruption and were very similar across these layers, suggesting that the dust clouds from the eruption did not wipe out this local population.[64][65][66] However, another site in India, the Middle Son Valley, exhibits evidence of a major population decline and it has been suggested that the abundant springs of the Jurreru Valley may have offered its inhabitants unique protection.[67] Additional archaeological evidence from southern and northern India also suggests a lack of evidence for effects of the eruption on local populations, causing the authors of the study to conclude, "many forms of life survived the supereruption, contrary to other research which has suggested significant animal extinctions and genetic bottlenecks".[68] However, some researchers have questioned the techniques utilized to date artifacts to the period subsequent to the Toba supervolcano.[69] The Toba Catastrophe also coincides with the disappearance of the Skhul and Qafzeh hominins.[70] Evidence from pollen analysis has suggested prolonged deforestation in South Asia, and some researchers have suggested that the Toba eruption may have forced humans to adopt new adaptive strategies, which may have permitted them to replace Neanderthals and "other archaic human species".[71][72]
Additional caveats include difficulties in estimating the global and regional climatic effects of the eruption and lack of conclusive evidence for the eruption preceding the crash.
Genetic bottlenecks in other mammals
Some evidence indicates population crashes of other animals after the Toba eruption. The populations of the Eastern African chimpanzee,[75] Bornean orangutan,[76] central Indian macaque,[77] cheetah and tiger,[78] all recovered from very small populations around 70,000–55,000 years ago.
Migration after Toba
The exact geographic distribution of anatomically modern human populations at the time of the eruption is not known, and surviving populations may have lived in Africa and subsequently migrated to other parts of the world. Analyses of mitochondrial DNA have estimated that the major migration from Africa occurred 60,000–70,000 years ago,[79] consistent with dating of the Toba eruption to about 75,000 years ago.[citation needed]
See also
- Early human migrations – Spread of humans from Africa through the world
- Most recent common ancestor – Most recent individual from which all organisms in a group are directly descended
- Quaternary extinction event– Extinctions of large mammals in the Late Pleistocene
- Recent African origin of modern humans – "Out of Africa" theory of the early migration of humans
- Timeline of volcanism on Earth
- Wallace Line – Line separating Asian and Australian fauna
Citations and notes
- ^ "Surprisingly, Humanity Survived the Super-volcano 74,000 Years Ago". Haaretz.
- ^ a b Ambrose 1998.
- ^ Michael R. Rampino, Stanley H. Ambrose, 2000. "Volcanic winter in the Garden of Eden: The Toba supereruption and the late Pleistocene human population crash", Volcanic Hazards and Disasters in Human Antiquity, Floyd W. McCoy, Grant Heiken
- ^ "Toba super-volcano catastrophe idea 'dismissed'". BBC News. 30 April 2013. Retrieved 2017-01-08.
- Choi, Charles Q. (2013-04-29). "Toba Supervolcano Not to Blame for Humanity's Near-Extinction". Livescience.com. Retrieved 2017-01-08.
- ^ PMID 29477183.
- S2CID 225418492.
- ^ Hawks, John (9 February 2018). "The so-called Toba bottleneck didn't happen". john hawks weblog.
- S2CID 246416256.
- ISSN 1469-5073.
- ISSN 1537-1719.
- ISSN 1943-2631.
- ISSN 0011-3204.
- S2CID 29309837.
- ISSN 0018-7143.
- ^ S2CID 128626019.
- ^ S2CID 4322781.
- ^ Gibbons 1993.
- PMID 8266085.
- ^ .
- Bibcode:2019AGUFM.V51H0141S.
- ISSN 1432-0819.
- ^ ISSN 1040-6182.
- ISSN 1040-6182.
- ISSN 0305-8719.
- ^ ISSN 0091-7613.
- ISSN 0025-3227.
- ISSN 1476-4687.
- ISSN 1476-4687.
- PMID 23630269.
- ISSN 1476-4687.
- PMID 23112159.
- ISSN 1871-1014.
- ISSN 0267-8179.
- ISSN 0010-7999.
- ISSN 1460-2415.
- ISSN 1476-4687.
- ^ .
- ^ Scaillet, Bruno; Luhr, James F.; Carroll, Michael R. (2003), "Petrological and volcanological constraints on volcanic sulfur emissions to the atmosphere", Volcanism and the Earth's Atmosphere, Washington, D. C.: American Geophysical Union, pp. 11–40, retrieved 2024-04-25
- ^ a b c Oppenheimer 2002.
- S2CID 128903263.
- S2CID 129546088.
- S2CID 128903263.
- ^ S2CID 129838182.
- .
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- ^ S2CID 239203480.
- ^ PMID 23630269.
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- .
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- ^ Gibbons 1993, p. 27
- ^ Rampino & Self 1993a
- ^ Ambrose 1998, passim; Gibbons 1993, p. 27; McGuire 2007, pp. 127–128; Rampino & Ambrose 2000, pp. 78–80; Rampino & Self 1993b, pp. 1955.
- ^ Ambrose 1998; Rampino & Ambrose 2000, pp. 71, 80.
- ^ "Science & Nature – Horizon – Supervolcanoes". BBC.co.uk. Retrieved 2015-03-28.
- ^ "When humans faced extinction". BBC. 2003-06-09. Retrieved 2007-01-05.
- ^ M.R Rampino and S.Self, Nature 359, 50 (1992)
- ^ Robock & others 2009.
- ^ Rampino & Ambrose 2000, p. 80.
- ^ Ambrose 1998, pp. 623–651.
- ^ "Mount Toba Eruption – Ancient Humans Unscathed, Study Claims". Anthropology.net. 6 July 2007. Archived from the original on 2008-01-11. Retrieved 2008-04-20.
- from the original on December 7, 2008.
- ^ John Hawks (5 July 2007). "At last, the death of the Toba bottleneck". john hawks weblog.
- ^ Jones, Sacha. (2012). Local- and Regional-scale Impacts of the ~74 ka Toba Supervolcanic Eruption on Hominin Population and Habitats in India. Quaternary International 258: 100-118.
- ^ See also "Newly Discovered Archaeological Sites in India Reveals Ancient Life before Toba". Anthropology.net. 25 February 2010. Archived from the original on 22 July 2011. Retrieved 28 February 2010.
- ^ National Geographic- Did early humans in India survive a supervolcano?
- ^ Shea, John. (2008). Transitions or Turnovers? Climatically-forced Extinctions of Homo sapiens and Neanderthals in the East Mediterranean Levant. Quaternary Science Reviews 27: 2253-2270.
- ^ "Supervolcano Eruption In Sumatra Deforested India 73,000 Years ago". ScienceDaily. 24 November 2009.
- ^ Williams & others 2009.
- ^ Oppenheimer 2002, pp. 1605, 1606.
- ^ See Huff & others 2010, p.6; Gibbons 2010.
- ^ Goldberg 1996
- ^ Steiper 2006
- ^ Hernandez & others 2007
- ^ Luo & others 2004
- ^ "New 'Molecular Clock' Aids Dating Of Human Migration History". ScienceDaily. 22 June 2009. Retrieved 2009-06-30.
References
- Ambrose, Stanley H. (1998). "Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans". PMID 9650103.
- Chesner, C.A.; Westgate, J.A.; Rose, W.I.; Drake, R.; Deino, A. (March 1991). "Eruptive History of Earth's Largest Quaternary caldera (Toba, Indonesia) Clarified" (PDF). Geology. 19 (3): 200–203. .
- Gibbons, Ann (1 October 1993). "Pleistocene Population Explosions". Science. 262 (5130): 27–28. PMID 17742951.
- Gibbons, Ann (19 January 2010). "Human Ancestors Were an Endangered Species". ScienceNow.
- Goldberg, T.L. (1996). "Genetics and biogeography of East African chimpanzees (Pan troglodytes schweinfurthii)" (PhD). Harvard University, unpublished.
- Hernandez, R.D.; Hubisz, M.J.; Wheeler, D.A.; Smith, D.G.; Ferguson, B.; et al. (2007). "Demographic histories and patterns of linkage disequilibrium in Chinese and Indian Rhesus macaques". Science. 316 (5822): 240–243. PMID 17431170.
- Huff, Chad. D; Xing, Jinchuan; Rogers, Alan R.; Witherspoon, David; Jorde, Lynn B. (19 January 2010). "Mobile Elements Reveal Small Population Size in the Ancient Ancestors of Homo Sapiens". Proceedings of the National Academy of Sciences. 107 (5): 2147–2152. PMID 20133859.
- Jones, S. C. (2007). "The Toba Supervolcanic Eruption: Tephra-Fall Deposits in India and Paleoanthropological Implications". In Petraglia, M. D.; Allchin, B. (eds.). The Evolution and History of Human Populations in South Asia. Springer. pp. 173–200. ISBN 978-1-4020-5561-4.
- Luo, S.-J.; Kim, J.-H.; Johnson, W.E.; Van der Walt, J.; Martenson, J.; et al. (2004). "Phylogeography and genetic ancestry of tigers (Panthera tigris)". PLOS Biology. 2 (12): 2275–2293. PMID 15583716.
- Luo, Shu-Jin; Zhang, Yue; Johnson, Warren E.; Miao, Lin; Martelli, Paolo; et al. (2014). "Sympatric Asian felid phylogeography reveals a major Indochinese-Sundaic divergence". Molecular Ecology. 23 (8): 2072–2092. S2CID 40030155.
- McGuire, W.J. (2007). "The GGE Threat: Facing and Coping with Global Geophysical Events". In Bobrowsky, Peter T.; Rickman, Hans (eds.). Comet/Asteroid Impacts and Human Society: an Interdisciplinary Approach. Springer. pp. 123–141. ISBN 978-3-540-32709-7.
- Ninkovich, D.; N.J. Shackleton; A.A. Abdel-Monem; J.D. Obradovich; G. Izett (7 December 1978). "K−Ar age of the late Pleistocene eruption of Toba, north Sumatra". Nature. 276 (5688): 574–577. S2CID 4364788.
- Oppenheimer, Clive (August 2002), "Limited global change due to largest known Quaternary eruption, Toba ≈74 kyr BP?", Quaternary Science Reviews, 21 (14–15): 1593–1609,
- Petraglia, M.; Korisettar, R.; Boivin, N.; Clarkson, C.; Ditchfield, P.; et al. (6 July 2007). "Middle Paleolithic Assemblages from the Indian Subcontinent Before and After the Toba Super-eruption" (PDF). Science. 317 (5834): 114–116. S2CID 20380351.
- Rampino, M. R.; Ambrose, S. H. (2000). "Volcanic winter in the Garden of Eden: The Toba supereruption and the late Pleistocene human population crash". In McCoy, F. W.; Heiken, G. (eds.). Volcanic Hazards and Disasters in Human Antiquity. Boulder, Colorado: Geological Society of America Special Paper 345. ISBN 0-8137-2345-0.
- Rampino, Michael R.; Self, Stephen (2 September 1992). "Volcanic Winter and Accelerated Glaciation following the Toba Super-eruption" (PDF). Nature. 359 (6390): 50–52. S2CID 4322781. Archived from the original(PDF) on 20 October 2011.
- Rampino, Michael R.; Self, Stephen (1993). "Climate–Volcanism Feedback and the Toba Eruption of ~74,000 Years ago" (PDF). Quaternary Research. 40 (3): 269–280. S2CID 129546088. Archived from the original(PDF) on 2011-10-21.
- Rampino, Michael R.; Self, Stephen (24 December 1993). "Bottleneck in the Human Evolution and the Toba Eruption". Science. 262 (5142): 1955. PMID 8266085.
- Robock, A.; Ammann, C.M.; Oman, L.; Shindell, D.; Levis, S.; Stenchikov, G. (2009). "Did the Toba Volcanic Eruption of ~74k BP Produce Widespread Glaciation?". .
- Rose, W.I.; Chesner, C.A. (October 1987). "Dispersal of Ash in the Great Toba Eruption, 75 ka" (PDF). Geology. 15 (10): 913–917. .
- Self, Stephen; Blake, Stephen (February 2008). "Consequences of Explosive Supereruptions". Elements. 4 (1): 41–46. .
- Steiper, M.E. (2006). "Population history, biogeography, and taxonomy of orangutans (Genus: Pongo) based on a population genetic meta-analysis of multiple loci". Journal of Human Evolution. 50 (5): 509–522. PMID 16472840.
- Thalman, O.; Fisher, A.; Lankester, F.; Pääbo, S.; Vigilant, L. (2007). "The complex history of gorillas: insights from genomic data". Molecular Biology and Evolution. 24: 146–158. PMID 17065595.
- Williams, Martin A.J.; Stanley H. Ambrose; Sander van der Kaars; Carsten Ruehlemann; Umesh Chattopadhyaya; Jagannath Pal; Parth R. Chauhan (30 December 2009). "Environmental impact of the 73 ka Toba super-eruption in South Asia". Palaeogeography, Palaeoclimatology, Palaeoecology. 284 (3–4). Elsevier: 295–314. .
- Zielinski, G.A.; Mayewski, P.A.; Meeker, L.D.; Whitlow, S.; Twickler, M.S.; Taylor, K. (1996). "Potential Atmospheric Impact of the Toba Mega-Eruption ~71,000 years ago" (PDF). Geophysical Research Letters. 23 (8): 837–840. doi:10.1029/96GL00706. Archived from the original(PDF) on July 18, 2011.
Further reading
- OCLC 1020313538.
External links
- Population Bottlenecks and Volcanic Winter
- "Toba Volcano by George Weber". Archived from the original on April 22, 2011. Retrieved June 1, 2006.
- "The proper study of mankind" – Article in The Economist
- Homepage of Professor Stanley H. Ambrose, including bibliographic information on the two papers he has published on the Toba catastrophe theory
- Mount Toba: Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans by Professor Stanley H. Ambrose, Department of Anthropology, University Of Illinois, Urbana, USA; Extract from "Journal of Human Evolution" [1998] 34, 623–651
- Journey of Mankind by The Bradshaw Foundation – includes discussion on Toba eruption, DNA and human migrations
- Geography Predicts Human Genetic Diversity ScienceDaily (Mar. 17, 2005) – By analyzing the relationship between the geographic location of current human populations in relation to East Africa and the genetic variability within these populations, researchers have found new evidence for an African origin of modern humans.
- Out of Africa – Bacteria, As Well: Homo Sapiens And H. Pylori Jointly Spread Across The Globe ScienceDaily (Feb. 16, 2007) – When man made his way out of Africa some 60,000 years ago to populate the world, he was not alone: He was accompanied by the bacterium Helicobacter pylori...; illus. migration map.
- Magma 'Pancakes' May Have Fueled Toba Supervolcano
- Youtube video "Stone Age Apocalypse"