Nicholas Toth

In this dramatic reconstruction of the daily lives of the earliest tool-making humans, two leading anthropologists reveal how the first technologies--stone, wood, and bone tools--forever changed the course of human evolution. Drawing on two decades of fieldwork around the world, authors Kathy Schick and Nicholas Toth take readers on an eye-opening journey into humankind's distant past--traveling from the savannahs of East Africa to the plains of northern China and the mountains of New Guinea--offering a behind-the-scenes look at the discovery, excavation, and interpretation of early prehistoric sites. Based on the authors' unique mix of archaeology and practical experiments, ranging from making their own stone tools to theorizing about the origins of human intelligence," Making Silent Stones Speak" brings the latest ideas about human evolution to life.

A Paleoindian campsite has been uncovered in stratified prehistoric deposits in Caverna da Pedra Pintada at Monte Alegre in the Brazilian Amazon. Fifty-six radiocarbon dates on carbonized plant remains and 13 luminescence dates on lithics and sediment indicate a late Pleistocene age contemporary with North American Paleoindians. Paintings, triangular bifacial spear points, and other tools in the cave document a culture distinct from North American cultures. Carbonized tree fruits and wood and faunal remains reveal a broad-spectrum economy of humid tropical forest and riverine foraging. The existence of this and related cultures east of the Andes changes understanding of the migrations and ecological adaptations of early foragers.

Early Stone Age assemblages called “Oldowan” and early “Developed Oldowan” are discussed, based on the results of a long-term study of Plio-Pleistocene sites at Koobi Fora, Kenya and an extensive experimental research program of replicating and using early stone artifact forms. Five major conclusions are drawn from this investigation: (1) many Oldowan core forms (“core-tools”) are probably simple by-products of flake manufacture rather than representations of stylistic norms; (2) flakes and retouched flakes - were essential tools in Oldowan technology, particularly for activities involving cutting; (3) this simple technology does not necessarily reflect the cognitive abilities of the early hominids that manufactured the stone artifacts; (4) there is evidence to show that Oldowan technology can be viewed as a simple curated one, in which raw material was intentionally carried from place to place for future use; (5) early …

Analysis of prehistoric stone artifacts from Lower Pleistocene sites at Koobi Fora, Kenya, and Middle Pleistocene horizons at Ambrona, Spain reveals a preferential, clockwise rotation of stone cores during flaking. Experimental studies of early stone artifact manufacture show that this non-random pattern is consistent with that produced by right-handed toolmakers. This suggests that there was a genetic basis for right-handedness by 1·4 to 1·9 million years ago, and that there may have already been a profound lateralization in the hominid brain with the two hemispheres becoming more specialized for different functions.

Beginning in May 1990, a long-term collaborative investigation between palaeolithic archaeologists and cognitive psychologists has focused upon the stone tool-making and tool-using abilities of a captive bonobo (Pan paniscus). To date, this bonobo (named Kanzi) has acquired the basic skills required to produce usable flakes and fragments by hard-hammer percussion (as well as by his own innovation of throwing), although his skills in flaking stone are not yet as well developed as those exhibited by the earliest known tool-making hominids of the Oldowan industry. This research strategy allows direct comparisons and contrasts to be made between the products of modern human stone tool-makers, prehistoric proto-human tool-makers and non-human primates that have not evolved a flaked stone technology in the wild. This enables us to investigate what possible cognitive and biomechanical conditions of pre …

Archaeological and palaeontological evidence from the Early Stone Age (ESA) documents parallel trends of brain expansion and technological elaboration in human evolution over a period of more than 2 Myr. However, the relationship between these defining trends remains controversial and poorly understood. Here, we present results from a positron emission tomography study of functional brain activation during experimental ESA (Oldowan and Acheulean) toolmaking by expert subjects. Together with a previous study of Oldowan toolmaking by novices, these results document increased demands for effective visuomotor coordination and hierarchical action organization in more advanced toolmaking. This includes an increased activation of ventral premotor and inferior parietal elements of the parietofrontal praxis circuits in both the hemispheres and of the right hemisphere homologue of Broca's area. The …

The functions of the stone artefacts made and used by early hominids has been a matter for speculation. However, recent experimental work has demonstrated that microscopically distinct wear-polishes form on tools of cryptocrystalline silica when used on different materials, and that these microwear polishes survive on ancient implements 1–3. We have now examined 54 artefacts from five early Pleistocene archaeological sites, dated to 1.5 Myr ago, in the Koobi Fora region of Kenya for microwear polishes and other traces of use. Wear traces were found on nine artefacts, variously resembling traces induced experimentally by cutting soft animal tissue and soft plant material and by scraping and sawing wood. These results greatly extend the time range for which microwear polish analysis is applicable and increase the evidence of early hominid adaptation.

Excavation in the Upper Member of the Koobi Fora Formation in Kenya has revealed a cluster of stone artefacts and broken up bones which accumulated 1–5 million years ago on the banks of a water course. The assemblage had been preserved by layers of silt. The stone artefacts consist of flakes and flake fragments plus simple flaked cobbles. It has been possible to conjoin individual pieces linking about 10 per cent of the artefacts and 4 per cent of the identifiable bones in pairs or sets. In some cases it seems likely that the specimens were fractured on the spot. Some of the fracture patterns on the bones suggest breakage with hammers, and apparent cut marks have also been found on some bones. There are signs of the presence of scavenging carnivores as well as of tool‐making hominids, and both could have contributed to the workings of a complex input‐output system. Whether the site was a home‐base …

A long-term collaborative study by palaeolithic archaeologists and cognitive psychologists has continued in its investigations into the stone tool-making and tool-using abilities of a captive bonobo (a 180 pound male, named Kanzi, aged 12 years at the time of experiments reported here). A major focus of this study has been examination of the lithic reduction strategy over time and detailed analysis of the artefacts Kanzi has produced in 2 years of experimentation since our original report. Kanzi has exhibited marked improvement in his stone-working skills, although to date the artefacts he has produced still contrast with early hominid-produced artefacts in a number of attributes. Statistical analysis revealed that Kanzi is clearly preferentially selecting larger, heavier pieces of debitage (flakes and fragments) for use as tools.

We are separated from the early tool-making hominids at Koobi Fora by about 1.5 million years of time (probably more than 75,000 generations). Our understanding of what happened in this remote period is very incomplete: the hominids that were responsible for the Se archaeological occurrences were not fully human, either physically or presumably mentally, and there are no analog creatures in existence today. Comparisons with modern primates, on one hand, and with fully modern human beings on the other, can give us some idea of a range of possible behavioral models for our early Pleistocene ancestors, but as useful as such comparative models or analog S might be, they are Severely limited in what they can tell us about many aspects of the past. In formation regarding the manufacture and use of Stone tools is quite sparse from amongst modern hunters and gatherers and all but unknown amongst non-human primates. An adaptation dependent upon manufactured Stone tools has very nearly passed out of existence in the modern world, and is a lifestyle other primates have not (yet) adopted. Another approach to bettering our understanding of the adaptive patterns of early hominids is to attempt to re-create aspects of their potential lifestyles:" experimental archaeology"(Coles, 1973)

This study introduces to archaeology a new experimental technique for examining the relationship between stone tool-making and brain function. The principal focus of this exploratory study was the development of effective methods for the identification and examination of the regions of the modern human brain recruited during the manufacture of simple (Oldowan or Mode I) stone tools. The functional brain imaging technique employed, Positron Emission Tomography (PET), examines task-related brain activity by assessing changes in regional cerebral blood flow during specific tasks. The single-subject study reported here represents a heuristic, initial exploration of this subject. Results indicate that during stone tool-making there was heavy activation of cortical and subcortical regions of the brain associated with motor and somatosensory processing. Especially interesting was the high degree of activation in areas …

A methodological approach for assessing the nature and palaeographic distribution of early stone artifact assemblages is presented, modeled after an approach originally used for faunal analysis. By combining experimental replicative studies with careful analysis of Palaeolithic archaeological occurrences, it is potentially possible to reconstruct entire technological systems and to assess what stages of lithic reduction may be preferentially represented at high density artifact concentrations that we normally call archaeological “sites”, and what stages of reduction are found in lower density (“off site”) scatters.Based upon the results of this approach, alternative explanations for certain stages of lithic reduction being preferentially represented at a number of Plio-Pleistocene archaeological sites at Koobi Fora, Kenya are considered and evaluated with regard to early hominid organizational patterns. It appears that …

Attempting to infer levels of cognitive and communicative complexity in early hominids from analyzing the prehistoric technological record is akin to trying to reconstruct the social organization and sexual habits of early hominids by analyzing assemblages of fossil bones from palaeontological localities. Making larger-scale, inductive inferences regarding levels of hominid cognition (or social organization) is problematic since our only models for these are drawn from modern human and non-human species, which are themselves the products of thousands or millions of years of evolution along unique trajectories and of a myriad of selective processes. Thus the accuracy of such inferences from the evidence at hand is largely dependent upon one factor: how closely the extinct forms resemble modern analogs which can be carefully analyzed from a comparative perspective. For early hominids that lived in the late Pliocence and early Pleistocene, our modern analogs are not that good. The challenge to palaeoarchaeology is to identify what patterns of material culture in the prehistoric record have implications for intelligence and language (or proto-language). While the evolution of brain functions proceeds along Darwinian lines, with changes in gene frequencies leading to changes in phenotypic traits that can be advantageous, deleterious, or neutral in given environments, the evolution of technology (and much of culture) proceeds along Lamarckian lines, according to which acquired traits are inherited through learning. This means that it is possible for technologies to change literally overnight if innovations that improve a prehistoric hominid's …

The activity of 17 hand muscles was monitored by electromyography (EMG) in three subjects during hard hammer percussion manufacture of Oldowan tools. Two of the subjects were archaeologists experienced in the replication of prehistoric stone tools. Simultaneous videotapes recorded grips associated with the muscle activities. The purpose of the study was to identify the muscles most likely to have been strongly and repeatedly recruited by early hominids during stone tool‐making. This information is fundamental to the identification of skeletal features that may reliably predict tool‐making capabilities in early hominids. The muscles most frequently recruited at high force levels for strong precision pinch grips required to control the hammerstone and core are the intrinsic muscles of the fifth finger and the thumb/index finger regions. A productive search for skeletal evidence of habitual Oldowan tool‐making …