Archaeological Field Projects and Laboratory Analyses
A vital component of investigating the human past is conducting archaeological fieldwork, collecting primary data at ancient prehistoric sites through survey and excavation, and then carrying out extensive laboratory studies of excavated and collected materials. Stone Age Institute researchers are collecting such essential data at a number of early Stone Age localities (Gona, Ethiopia; Ain Hanech, Algeria; Transvaal, South Africa; Nihewan Basin, China) documenting the emergence, development, and spread of tool-making hominids in key areas of the world where this evidence is preserved.
Paleoanthropological Research at Gona, Afar, Ethiopia
Excavation of a hominid site at Gona
Located in the Afar triangle of the African Rift Valley, Gona has yielded the world’s oldest archaeological sites, with very early stone tools dated to between 2.5 and 2.6 million years ago. The archaeological record in the Gona area contains sites spanning a large range of Stone Age prehistory, from different periods of the Oldowan, through early and later Acheulean times, and up to the Middle Stone Age. In addition, the Gona study area has produced a number of early hominid fossils from a range of time periods, including Ardipithecus from about 4.5 million years ago, early Homo at about 1.7 million years ago, and Homo erectus at about 1 million years ago.
The Gona Palaeoanthropological Research project is directed by Stone Age Institute researcher, Dr. Sileshi Semaw, and has incorporated a number other research scientists from the Stone Age Institute and other institutions, including archaeologists, physical anthropologists, geologists, and paleontologists. The ongoing research here is documenting the biological evolution of early humans and the emergence and development of stone tool-making and culture in the ancient human past, topics of critical importance to human origins research.
Paleoanthropological Research at Ain Hanech, Algeria
Excavations at Ain Hanech
Located in the high plateau of northeastern Algeria , the important site of Ain Hanech documents the spread of hominids to northern Africa by at least 1.7 to 1.8 million years ago and represents the earliest known archaeological evidence in this part of Africa . Beginning in 1992 excavations by Stone Age Institute researcher, Dr. Mohamed Sahnouni, have produced a large number of Oldowan artifacts and well-preserved animal fossils sealed in fine-grained silts, providing an excellent record of early hominid occupation of this part of the African continent.
Research and excavations here are ongoing, with investigations at the classic site of Ain Hanech and at an earlier, well-preserved Pliocene paleontological horizon in the study area, Ain Boucherit, dating to about 2.2 million years ago. These sites provide invaluable documentation of the spread of hominids out of eastern Africa soon after the advent of stone tool-making, at a time when we see the first evidence of hominid dispersal into North Africa and Asia.
Transvaal Caves, South Africa
Sterkfontein Cave deposits
Zooarchaeological and taphonomic research has been conducted at two important cave sites in the Transvaal region of South Africa by Stone Age Institute researcher Dr. Travis Pickering. These sites are Swartkrans, dated to 1.8 to 1.0 million years ago, in collaboration with Dr. C.K. Brain of the Transvaal Museum, and Sterkfontein, with deposits dating from 4.0 to 1.5 million years ago, in collaboration with Drs. Ron Clarke and Kathleen Kuman. Important hominid fossils of Australopithecus, Paranthropus, and early Homo have been found at these sites.
Animal bones that have been modified by early tool-using hominids have been found at both Swartkrans and Sterkfontein, increasing our knowledge of early hominid tool-using behavior in this part of the African continent. The study of modification of animal bones from these sites is critical to our understanding of how early hominids procured and processed animal carcasses, and what other non-hominid agencies (carnivores, rodents, etc.) were involved in forming and transforming the bone accumulations found at these sites.
Paleoanthropological Investigations in the Nihewan Basin, China
Excavations in the Nihewan Basin
Archaeological excavations by Stone Age Institute directors, Nicholas Toth and Kathy Schick, and the late J. Desmond Clark from the University of California at Berkeley, have investigated some of the earliest archaeological sites in far eastern Asia. Located in an ancient sedimentary basin about 100 west of Beijing, the Nihewan sites document hominid dispersal to eastern Asia, early stone tool-making, and ancient animal fossils beginning at least 1.3 million years ago.
Research here by a joint Chinese-U.S. team of archaeologists beginning in 1990 represents the first collaborative excavations involving foreigners in China since World War II. These sites have produced Oldowan-like stone technologies associated with fossil animal bones, providing valuable information about early Homo erectus in mainland Asia. A monograph on this research will be published by the Stone Age Institute Press and is currently in preparation.
Experimental Archaeological and Actualistic Studies
Experimental archaeological and actualistic studies attempt to recreate and isolate conditions that were present in prehistoric times in order to gain a better understanding of the human past. Such approaches are central to research programs of the Stone Age Institute in a variety of studies probing aspects of human prehistory. Identifying the relationship between prehistoric behaviors and the archaeological patterns they produce are critical to such studies and extremely valuable in helping us interpret the archaeological record.
These diverse studies include experimental investigations into the making and using of stone tools, experimental studies of stone tool-making and tool-using by apes, observations and experiments in archaeological site formation and burial, the nature of animal bone accumulation and modification by human and nonhuman agents, the development of use-wear patterns on the edges of stone tools indicating how they were used, studies of modern primates, brain imaging studies, biomechanical studies, and ethnoarchaeology (studies of modern humans, their material culture, and the potential archaeological record their behaviors would produce). All of these studies are driven by very real, pressing questions that we are asking about the early Stone Age record.
Experimental Manufacture and Use of Stone Tools
Experimental Oldowan toolmaking
How were early stone tools made, and how could they have been used? Stone Age Institute researchers Nicholas Toth and Kathy Schick have devoted three decades of study to the experimental manufacture and use of stone tools. This is important research, at it takes archaeology out of the armchair and into direct investigation of the role tools have played in human evolution and adaptation. Such experimental studies can show us the possible techniques and strategies employed by prehistoric tool-makers. Importantly, they also reveal the types of tool-making debris associated with different manufacturing activities, so that we can identify these at archaeological sites. This gives us powerful means to interpret prehistoric artifactual materials from excavated sites, allowing us to understand tool-making techniques and abilities among prehistoric humans in the distant past.
Such experiments can give us important insights into early hominid tool-makers. They can provide valuable information about stages of manufacture represented at an archaeological site, levels of skill and expertise in early tool-makers, handedness in early human populations, use of different parts of sites for different activities, possible rules and conventions in making tools (and an early sense of ‘style’ and possibly even aesthetics in early stone tools), and decision-making in choosing raw materials for tools.
Experimental butchery of elephant (above) and wildebeast (below), using stone tools. Animals died of natural causes
Experiments in using stone tools address essential functional and adaptive questions: why did early humans start making tools, and what role did these implements serve in their lives and adaptation? By using experimental stone tools for a range of activities, researchers can directly investigate which tools are best for which activities. They can also look for relationships between the form of an artifact and its function.
Stone Age Institute researchers Travis Pickering, Charles Egeland, Nicholas Toth, and Kathy Schick have engaged in a variety of experimental studies of processing carcasses of animals that had died of natural causes. Such functional experiments can also help to identify other types of evidence that can indicate artifact use, such as edge damage and wear patterns on the edges of stone tools; fracture patterns; cut-marks, chop-marks, and hammerstone percussion and abrasion on animal bones; and organic residues on ancient stone tools. The identification of such prehistoric “smoking barrels” of tool use is a high priority in Stone Age research.
Studies of Stone Tool Behavior in Modern Apes
Kanzi flaking stone
How skilled were early hominid tool-makers, and how do these skills compare to those among our closest living relatives, the apes? Apes, especially chimpanzees in the wild, have a rich tool-using heritage that includes ant and termite fishing sticks, leaf sponges, and stone and wooden hammers and anvils for nut-cracking. Unfortunately, they do not intentionally flake stone in their natural settings. Beginning in 1990, Stone Age Institute researchers Nicholas Toth and Kathy Schick, in collaboration with psychologists Sue Savage-Rumbaugh and Duane Rumbaugh at the Language Research Center in Atlanta, Georgia, have been working with African apes, especially bonobos or “pygmy chimpanzees,” teaching them to make and use flaked stone tools. This research allows us to explore the cognitive and biomechanical skills and constraints of modern apes and helps us to assess levels of skill in early prehistoric human ancestors.
Two bonobos in this study, Kanzi and his half-sister, Panbanisha, have acquired the basic skills to flake cobbles of lava, quartzite, and flint and to produce sharp-edged flakes and fragments to use for cutting activities to obtain food items. This ongoing research allows us to investigate the acquisition of stone tool-making and tool-using skills in primates with a brain and body size comparable to that of the earliest known hominid tool-makers, and the transmission of these skills within a social group. We have then been able to compare the tools made by modern apes to those made by early hominids and modern tool-makers, and compare and contrast the amount of finesse and skill shown by the ancient and modern species.
Ethnoarchaeology among Modern Stone Toolmakers
Papuan Adze Maker, Fall 1999
How can studies of modern traditional stone tool-making humans help us to interpret the prehistoric past? Today there are only a few human groups in the world that still retain robust systems of traditional stone technology, as over the past six millenia metal has gradually replaced stone as the principal material for many tools. Studying these last vestiges of a two-and-a-half million year Stone Age legacy can yield important insights into the intricate system of knowledge of techniques, procedures, and raw materials that supported stone tool technology for so much of human prehistory.
Stone Age Institute researcher Nicholas Toth, with Advisory Board members J. Desmond Clark and Giancarlo Ligabue, initiated a pilot study in 1990 of traditional stone adze-makers in Irian Jaya ( New Guinea). More recently, Stone Age Institute researcher Dietrich Stout conducted a more detailed study of these tool-makers. This research has documented the complexity and intricacy of this tool-making tradition, identified diverse stages of manufacture and patterns of discard on the landscape, investigated the local classification of raw materials and terminology related to stone technology, and assessed the different levels of skill in apprentices and experts.
Archaeological Site Formation
Modern depositional environments like this river (above) provide opportunities for controlled experiments in site formation (below)
How do archaeological sites form, and what do patterns at our sites reveal about prehistoric behavior patterns? How archaeological sites form – what patterns are created by hominid tool-making and tool-using activities, and how do these get buried and preserved to form our archaeological record – has become a major concern for paleoanthropological researchers. It has become apparent that we must understand this process of site formation in order interpret the sites that we excavate.
Research by Stone Age Institute researcher Kathy Schick has actively investigated the dynamics of site formation, helping us identify sites showing good preservation of ancient prehistoric behaviors. This research has included setting out experimental sites along rivers, deltas, and lake margins, and monitoring the changes that occur over the course of time during flooding and burial. Such studies have given us powerful criteria to help us identify the behavioral information contained in early archaeological sites.
Research on Chimpanzees in the Wild
Kevin Hunt with chimpanzee
What can modern chimpanzees reveal to us about early human prehistory and evolution? There is no precise modern analog for our early tool-making ancestors. We have changed remarkably over the past few million years, and modern apes have likewise undergone evolutionary change in that period. Although early tool-making ancestors were not like modern humans or modern apes, they were much closer to the common ape-human ancestor in terms of evolutionary time and also were quite close to our African ape heritage in terms of such features as brain, body size, and aspects of their anatomy.
Modern chimpanzees can yield valuable information in terms of their locomotion, feeding behaviors, ecology, and so on, that can yield important insights into the origins of bipedal walking and tool-use in our prehistoric past. Stone Age Institute researcher Kevin Hunt has engaged in a variety of studies investigating such areas as chimpanzee posture, feeding behaviors, and tool-use, in order to develop models for the early evolution of bipedal, tool-wielding hominids. He has conducted chimpanzee research in Uganda and Tanzania.
Brain Imaging Studies of Stone Toolmaking
Subject entering PET scanner
Activation during novice Oldowan tool-making
What are the cognitive demands of making early stone tools? The manufacture and use of early stone tools represents a major evolutionary advance in the behavior of early hominids. Identifying any shifts in brain and cognitive function that may have been associated with this innovative behavior has long been priority in paleoanthropological research. Modern brain imaging techniques are now making it possible to address these questions directly.
The use of Positron Emission Tomography (PET) to examine patterns of brain activation during stone tool manufacture was pioneered in a pilot study of Oldowan tool-making by Stone Age Institute researchers Dietrich Stout, Nicholas Toth, and Kathy Schick, working with Julie Stout of the IU Psychology Department and Gary Hutchins of IU Radiology. This research was continued in a more systematic, multi-subject study by Dietrich Stout which revealed the unusual visual-spatial and motor demands of Oldowan tool-making and documented the changes in brain activation associated with skill acquisition. These results challenge accepted ideas about the psychological implications of the earliest stone tools and highlight those areas of the brain most likely to display evolutionary adaptations relevant to stone tool-making. More recently, Stout, Toth and Schick have completed a pilot study using PET to examine differences between Oldowan and later Acheulean stone tool-making, a project which will be expanded in the future.
Biomechanical Studies
Biomechanics of Oldowan flaking
How have our bodies changed and adapted to our tool-making in the course of human evolution? The configuration of our bones and muscles determines what motions and actions we can perform well and efficiently, and these have changed in human evolution as the human body has evolved into its modern form. The modern human hand, arm, and shoulder are product of at least 2.5 million years of evolutionary selection for tool behavior. To appreciate these changes, it is important to examine the actual biomechnical patterns involved in efficient stone tool-making.
A pilot study by Stone Age Institute affiliate and kinesiologist, Jesus Dapena, and Nicholas Toth examined the biomechanics of manufacturing Oldowan artifacts. Stone Age Institute graduate researcher, Leslie Harlacker, is currently conducting a comprehensive study comparing the biomechanical patterns of tool-making among human novices to those observed in experienced stone knappers, and also comparing the patterns of humans to tool-making apes, as part of her Ph.D. dissertation research.
Zooarchaeological Investigations
Travis Pickering collecting data from a carcass during a taphonomic field study
A scanning electron microscope image of stone tool cutmarks marks on a one million year old fossil bone.
Nicholas Toth surveying an abandoned hyena den in Jordan
How do animal remains become buried and preserved in the fossil record, and what do fossil animal bones at archaeological sites tell us about early hominid behaviors? Fossil animal bones have a persistent presence at early Stone Age archaeological sites, but it has not always been clear what agencies were responsible for collecting and modifying these remains. Were early hominids hunters or scavengers? Did they collect and process animal remains at archaeological sites, or were other animals, such as hyenas or large cats, the principal agents of accumulation and modification? These are important questions to resolve in order to understand early hominid behavior and adaptation, and they demand a profound understanding of how humans and other agents collect and modify bones.
Stone Age Institute researchers Travis Pickering, Jason Heaton, Charles Egeland, Nicholas Toth, and Kathy Schick have pursued these questions in a multitude of ways, including the analysis of animal bones from prehistoric sites, as well as actualistic and experimental studies of the effects of human and carnivore agents on bone assemblages. Examples of such studies include ethnoarchaeological research, experiments processing animals (that had died of natural causes) with stone tools, analysis of bone accumulations made by modern hyenas, and in-depth analyses of tooth-marks and cut-marks as well as bone fracture patterns.
