Olorgesailie

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The landscape of the Olorgesailie Basin, 1993
Olorgesailie Basin: A collection of stone utensils

Olorgesailie is the name of an archaeological and paleoanthropological site in southern Kenya , almost 70 kilometers southwest of Nairobi . The site is located in the eponymous Olorgesailie Basin , a depression partially filled with sediment that is part of the East African Trench . Olorgesailie is known in specialist circles as the location of numerous stone tools of different ages. In 2003, not far from the stone tools, in the same layer as these, a hominine fossil was found for the first time , the fragment of a skull whose age is given as at least 900,000 years and which, due to its age and its morphological characteristics, was assigned to Homo erectus .

Finds

The first artefacts - mostly hand axes - were picked up in 1919 by the British geologist John Walter Gregory , but the systematic exploration of the Olorgesailie Basin did not begin until 1943 under the direction of Louis Leakey and Mary Leakey . More recently, the determination of the age of the finds has been refined, in particular with the help of the 39 Ar- 40 Ar method, a modification of the potassium-argon method , as there are several layers of volcanic ash in the sequence of the sediments , which in this way particularly can be reliably dated. According to the findings available so far, this region was populated by early relatives of anatomically modern humans ( Homo sapiens ) between 1.2 million and 490,000 years ago .

One of the peculiarities of the finds in the Olorgesailie Basin is - as in Isimila in Tanzania - the extremely high number of stone tools on individual small areas. During an excavation in a 990,000-year-old layer in the immediate vicinity of the bones of a single elephant, 2300 stone tools were found, including numerous sharp chopping tools , which - as evidenced by cutting marks on several bones - were used to cut off meat. The stones from which the tools were made came from 17 different locations.

Another special feature was published in 2018: smaller and technically much more sophisticated stone tools than the older hand axes were dated to the epoch 320,000 to 295,000 years ago with the help of the 39 Ar- 40 Ar method. These molds are similar to the known from Europe, there, however, only after 200,000 years before present occupied Levallois and are typical of the African Middle Stone Age . According to the researchers, it is the earliest evidence of these tool shapes in Africa. The rock comes from deposits that are around 25 to 50 kilometers away from the site. At the same time, evidence of black and reddish paint adherence ( manganese and ocher ) on stones was reported, which was allegedly used for the production of coloring agents. The finds come from an era with enormous climatic and tectonic changes in the environment at that time, according to a publication in the journal Science : Earthquakes reshaped the landscapes, the climate repeatedly alternated between wet and dry, and these ecological conditions may have contributed to this Authors of the study around the US paleoanthropologist Richard Potts to create technological innovations.

The assignment of the fossil skull fragment to Homo erectus is controversial because "according to current standards" it shares too few features with the type specimen of Homo erectus and the type specimen of Homo ergaster .

literature

  • Glynn Llywelyn Isaac and Barbara Isaac : Olorgesailie: Archeological Studies of a Middle Pleistocene Lake Basin in Kenya. University of Chicago Press, 1977, ISBN 978-0226384849
  • R. Bernhart Owen, Veronica M. Muiruri, Tim K. Lowenstein et al .: Progressive aridification in East Africa over the last half million years and implications for human evolution. In: PNAS . Online pre-publication of October 8, 2018, doi: 10.1073 / pnas.1801357115

Web links

Individual evidence

  1. ^ A b Olorgesailie: Life and Times of the Handaxe Makers. On: humanorigins.si.edu , accessed March 12, 2018
  2. ^ Richard Potts et al .: Small Mid-Pleistocene Hominin Associated with East African Acheulean Technology. In: Science . Volume 305, No. 5680, 2004, pp. 75-78, doi: 10.1126 / science.1097661
    First Human Fossil Found at Olorgesailie (Kenya) Field Site. Press release from the National Museum of Natural History dated July 1, 2004
  3. ↑ So much to see at Olorgesailie. On: nation.co.ke of August 29, 2008, accessed March 12, 2018
  4. ^ Alan L. Deino et al .: Chronology of the Acheulean to Middle Stone Age transition in eastern Africa. In: Science. Advance online publication March 15, 2018, doi: 10.1126 / science.aao2216
  5. ↑ Alison S. Brooks et al .: Long-distance stone transport and pigment use in the earliest Middle Stone Age. In: Science. Advance online publication March 15, 2018, doi: 10.1126 / science.aao2646
    Scientists discover evidence of early human innovation, pushing back evolutionary timeline. On: eurekalert.org from March 15, 2018
  6. ^ Richard Potts et al .: Environmental dynamics during the onset of the Middle Stone Age in eastern Africa. In: Science . Online publication March 15, 2018, doi: 10.1126 / science.aao2200
    Advances in human behavior came surprisingly early in Stone Age. On: nature.com from March 15, 2018
  7. ^ Ian Tattersall : Masters of the Planet. The Search for Our Human Origins. Palgrave Macmillan, 2012, p. 129, ISBN 978-0-230-10875-2 .

Coordinates: 1 ° 34 ′ 40.4 "  N , 36 ° 26 ′ 46.4"  E