Olduvai Gorge, perhaps the most famous site for evidence of early humans, is again the subject of intense research on a decades-old question bearing on human origins: How, when and where did early humans evolve from using the first and simplest stone tool industry, that of Oldowan, to the second-oldest, and more sophisticated, stone tool technology known as the Acheulean?
While Olduvai has been picked over before, most notably by the pioneering scientists L.S.B. and Mary Leakey, advances in archaeological investigative methods and the application of multidisciplinary approaches have made it possible to take another, more detailed and comprehensive look at both the old and the new among the world-famous exposed beds, the geological earthen layers or deposits that have historically produced some of the great ground-breaking discoveries related to early human evolution. Now, under the organizational umbrella of the Olduvai Geochronology Archaeology Project, an international team of scientists composed of a consortium of researchers and institutions is focusing on reconstructing the picture of the early human transition from the simple "chopper" stone tool technology of the Oldowan industry (see image below), the world's first technology discovered at Olduvai, to the Acheulean, the more sophisticated technology represented most by the well-known bifacial "handaxe" (see image below), some of the first examples of which were found at Saint- Acheul in France, and later at Olduvai. The Oldowan is considered to have been made and used during the Lower Paleolithic, from 2.6 to 1.7 million years ago, whereas the Acheulean emerged about 1.76 million years ago and was used by early humans up to about 300,000 years ago or later.
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A chopping tool from Olduvai Gorge, 1 - 2 million years old. GFDL CC-BY-SA, Wikimedia Commons
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A handaxe from Olduvai Gorge, over 1 million years old. This stone tool is most often associated with Homo erectus, a hominin considered by many scientists to be a possible human (Homo) ancestor. Homo erectus is widely thought to be the first species to venture out of Africa to populate the Middle East/Eurasia. British Museum, Discott, Wikimedia Commons
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To find answers, the team will be reappraising the chronological stratigraphy of Bed II, known to have yielded previous significant finds, and will be re-excavating some of the later beds of the best known fossil and stone tool sites. These beds reveal a record of a very important time period (1.79 - 1.15 million years ago), a record that contains evidence of critical changes in the area's fauna, stone tools and climate, such as the disappearance of Homo habilis, a very early hominin and possible human ancestor, and the emergence of Homo erectus, a later hominin considered to be the earliest human ancestor to exit Africa and spread across Eurasia. Scientists suggest that these same beds may include evidence of the long-sought transition from the more primitive Oldowan stone tools to the appearance of the more advanced Acheulean tools. Recent research at Olduvai has focused primarily on earlier beds, so research on these later beds will likely present new data to consider. Four key previously excavated sites will be investigated through full-scale excavation.
More specifically, the team's objectives are including the following activities:
- Conducting test pits (very limited, targeted excavations) at selective Bed II sites that have been determined to contain possible evidence related to the emergence of Acheulean tools at Olduvai;
- Applying the new landscape sampling approach across Middle and Upper Bed II deposits and conducting random test pits in the various paleo-ecological settings;
- Applying advanced dating methodologies to Bed II volcanic ashes to produce higher-resolution, more accurate dates for Bed II locations;
- Measuring stratigraphic sections at and between key archaeological sites to determine their relative order and paleoecological contexts;
- Determining the correlation of volcanic ash layers between sites to test previous proposed correlations and then establishing the basin-wide stratigraphic framework for Bed II; and finally,
- Reconstructing the paleo-environments at Olduvai during the 1.7-1.3 Ma time period.
For information about how to participate in the research, go to the information page at the Institute for Field Research.
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