Eastern African Stone Age

The Stone Age record is longer and better documented in eastern Africa. Archaeological and fossil evidence derives particularly from sites within the Rift Valley of the region, often with secure radiometric age estimates. Despite a relatively late start and disproportionate focus on earlier periods and open-air sites within the rift, scientific research into the region’s Stone Age record continues to play a central role in our understanding of human evolution. Putative stone tools and cutmarked bones from two Late Pliocene (3.6–2.58 million years ago or Ma) contexts are exclusive to eastern Africa, as is conclusive evidence for these by 2.5 Ma. The earliest indisputable technological traces appear in the form of simple flakes and core tools as well as surface-modified bones. It is not clear what triggered this invention, or whether there was a more rudimentary precursor to it. Neither is it certain which hominin lineage started this technology, or if it hunted or only scavenged carcasses. Well-provenienced archaeological occurrences predating 2.0 Ma are limited to sites in Ethiopia and Kenya, becoming more common across eastern Africa and beyond only later. By 1.75 Ma, lithic technologies that included heavy-duty and large cutting tools appeared in Ethiopian and Kenyan localities. Several details about this technological tradition are still inadequately understood, although its appearance in eastern Africa roughly coincides with that of Homo erectus/ergaster. By far the longest-lived Stone Age tradition, hominins with such technologies successfully inhabited high-altitude environments as early as 1.5 Ma, and expanded within and beyond Africaeven earlier. Hunting and use of fire probably started in the earlier part of this technological tradition. Small-sized and highly diverse tool forms gradually and variably started to replace heavy-duty and large cutting tools beginning c. 300 thousand years ago (ka). Conventional wisdom associates this technological and behavioral shift with the rise of Homo sapiens, although the oldest undisputed representatives of our species continued to use large cutting tools in eastern Africa after 200 ka. In addition to small retouched tools, often on products from prepared cores, significant innovations such as hafting and ranged weaponry emerged during the length of this technological tradition. Increasingly complex sociocultural behaviors, including mortuary practices, mark the later part of this period in eastern Africa. The consolidation of such skills and behaviors, besides ecological/demographic dynamics, may have enabled the ultimately decisive Out-of-Africa dispersal of our species, from eastern Africa, 50–80 ka. Even smaller and more diverse stone tool forms and other sociocultural innovations evolved in many areas of eastern Africa by 50 ka. Miniaturization and diversification allowed for the adoption of more complex technologies, including intentional blunting and microlithization. Some of these were used as parts of sophisticated composite implements, such as the bow and arrow. Complex behaviors involving personal ornamentation, symbolism, and rituals that resembled the lifeways of ethnographically known hunter-gatherer populations were similarly adopted. These dynamics eventually led to the development of new technological and socioeconomic systems marked by the inception of agriculture and attendant lifeways.