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.
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.
They found that the Twa and the Agta hunter-gatherers regularly climbed trees to gather honey, an important element in their diets.
More specifically, they observed that the climbers "walked" up small trees by applying the soles of their feet directly to the trunk and progressing upward, with arms and legs advancing alternately.
The findings are published in the early online edition of Proceedings of the National Academy of Sciences.
An international research team extracted information from the fossilised teeth of three Australopithecus bahrelghazali individuals -- the first early hominins excavated at two sites in Chad.
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.
Along with being among the earliest possible bipedal primates, it has also been thought to be closely related to the genus Homo (which includes the modern human species Homo sapiens), either as a direct ancestor or indirectly through an unknown earlier ancestor.
A chopping tool from Olduvai Gorge, 1 - 2 million years old.
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? 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.