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In paleoanthropology, Out of Africa I is the first series of hominin expansions into Eurasia, which took place from 1.8 to 0.8 million years ago (Ma). Shortly before in Africa, ''Homo erectus'' had descended from the woodland-restricted ''Homo habilis''. ''H. erectus'', diverging from ''H. habilis'', adapted to the open grounds of the savannahs and arid landscapes, and later managed to expand out of East Africa, eventually into Eurasia. According to the recent African origin of modern humans hypothesis (''Out of Africa II''), anatomically modern humans started moving into Eurasia c. 100,000 years ago, replacing the early hominins they found there from the earlier migrations. (''Out of Africa'' usually means ''Out of Africa II'', the expansion of ''modern'' humans into Eurasia.) Early hominins moved out of Africa in at least three waves. Primitive chopper producers were first out by c. 1.8 Ma, followed by early Acheulean industries c. 1.4 Ma, and various cleaver-producing Acheulean groups around 0.8 Ma.〔Bar-Yosef, O. & Belfer-Cohen, A. (2001). From Africa to Eurasia — early dispersals. Quaternary International, 75(1), 19–28. doi:10.1016/S1040-6182(00)00074-4〕 Until the early 1980s, hominins were thought to have been restricted to the African continent in the Early Pleistocene, or until about 0.8 Ma; thus, archaeological efforts have been disproportionately focused on (East) Africa. Further, hominin migrations out of East Africa were probably rare in the Early Pleistocene, leaving a record of events broken in space and time.〔Lahr, M.M., 2010. “Saharan Corridors and Their Role in the Evolutionary Geography of ‘Out of Africa I’”. In: A. Baden et al. (Eds.), Out of Africa I: The First Hominin Colonization of Eurasia. Springer Netherlands, 27–46.〕 Archeological evidence does not fit simple theories on the whereabouts of the migration and is insufficient to support elaborate, even book-length, conjectures. ==Sites== The oldest hominin sites are in East Africa. The earliest evidence for retouched tools is from Kada Gona, Ethiopia, and dates back to 2.6 – 2.5 Ma in the very early Pleistocene. They might be the product of ''Australopithecus garhi'' or ''Paranthropus aethiopicus'', the two known hominins contemporary with the tools.〔Semaw, S. (2000). “The World’s Oldest Stone Artefacts from Gona, Ethiopia: Their Implications for Understanding Stone Technology and Patterns of Human Evolution Between 2·6–1·5 Million Years Ago”. Journal of Archaeological Science, 27(12), 1197–1214. doi:10.1006/jasc.1999.0592〕 ''Homo habilis'' is the first member of the ''Homo'' line and could have descended from the ''Australopithecus'' as early as 2.3 Ma; it is first attested in Lake Turkana, Kenya. ''Homo erectus'' seems to appear later, its earliest remains dating back to c. 1.9 – 1.6 Ma at Koobi Fora, Kenya.〔Van Arsdale, A. P. (2013) “Homo erectus - A Bigger, Smarter, Faster Hominin Lineage”. Nature Education Knowledge, 4(1):2.〕 The two species would have lived face to face in East Africa for nearly half a million years.〔Spoor, F., Leakey, M. G., Gathogo, P. N., Brown, F. H., Antón, S. C., McDougall, I., … Leakey, L. N. (2007). “Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya”. Nature, 448(7154), 688–91. doi:10.1038/nature05986〕 Well before ''Homo habilis'' disappeared (c. 1.4 Ma), ''Homo erectus'' had made it into Eurasia. The earliest well-dated Eurasian site is Dmanisi in Georgia, securely dated to 1.81 Ma.〔 A skull found at Dmanisi is evidence for caring for the old. The skull shows that this ''Homo erectus'' was advanced in age and had lost all but one tooth years before death, and it is perhaps unlikely that this hominid would have survived alone. It is however not certain that this is sufficient proof of caring – a partially paralysed chimpanzee at the Gombe reserve survived for years without help.〔Bauer, H. R. (1977). “Chimpanzee Bipedal Locomotion in the Gombe National Park, East Africa”. Primates, 18, 913–921.〕 Early Pleistocene sites in North Africa, the geographical intermediate of East Africa and Georgia, are in poor stratigraphic context. The earliest of the dated is Ain Hanech in northern Algeria (c. 1.8〔Sahnouni, M., Hadjois, D., van der Made, J., Derradji, A. Canals, A., Medig, M., Belahrech, H., Harichane, Z., and Rabhi, M. (2002). "Further research at the Oldowan site of Ain Hanech, North-eastern Algeria." Journal of Human Evolution 43(6): 925-937.〕 – 1.2 Ma〔Geraads, D., Raynal, J.-P., Eisenmann, V. (2004). The earliest occupation of North Africa: a reply to Sahnouni et al.(2002). Journal of Human Evolution 46, 751–761.〕), an Oldowan grade layer. It attests that early hominins have crossed the North African tracts, which are usually hot and dry. Hominins were part of the East African biome, and a flux in climate could have briefly expanded their environment, giving them the chance to move north. There is very little time between ''Homo erectus''’ apparent arrival in South Caucasus, and its probable arrival in East and Southeast Asia. There is evidence of hominins in Yuanmou, China, dating to 1.7 Ma and in Sangiran, on Java, Indonesia, from 1.66 Ma.〔Rightmire, G. P. (2001). Patterns of hominid evolution and dispersal in the Middle Pleistocene. Quaternary International, 75(1), 77–84. doi:10.1016/S1040-6182(00)00079-3〕 It appears hominins took longer to move into Europe, the earliest site being Barranco León in southeastern Spain dated to 1.4 Ma〔Toro-Moyano, I., Martínez-Navarro, B., Agustí, J., Souday, C., Bermúdez de Castro, J. M., Martinón-Torres, M., … Palmqvist, P. (2013). “The oldest human fossil in Europe, from Orce (Spain)”. Journal of human evolution, 65(1), 1–9. doi:10.1016/j.jhevol.2013.01.012〕 and a controversial Pirro Nord in Southern Italy, allegedly from 1.3 – 1.7 Ma.〔Arzarello, M., Marcolini, F., Pavia, G., Pavia, M., Petronio, C., Petrucci, M., … Sardella, R. (2007). “Evidence of earliest human occurrence in Europe: the site of Pirro Nord (Southern Italy)”. Die Naturwissenschaften, 94(2), 107–12. doi:10.1007/s00114-006-0173-3〕 In any case, by 1 Ma, hominins had settled in most of the Old World. However, it is hard to say whether settlement was continuous in Western Europe or if successive waves repopulated the territory in glacial interludes. Early Acheulean tools at Ubeidiya from 1.4 Ma〔Martínez-Navarro, B., Belmaker, M., & Bar-Yosef, O. (2009). “The large carnivores from ’Ubeidiya (early Pleistocene, Israel): biochronological and biogeographical implications”. Journal of human evolution, 56(5), 514–24. doi:10.1016/j.jhevol.2009.02.004〕 is weak evidence for a continuous settlement in the West, as successive waves out of Africa after then would likely have brought Acheulean technology to Western Europe. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Out of Africa I」の詳細全文を読む スポンサード リンク
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