Principles of Prehistoric Archaeology

Objectives and Scope of Prehistoric Archaeology

Prehistoric archaeology is the study of human cultures that predate the advent of writing, reconstructed entirely from material remains artefacts, ecofacts, features, and the contexts in which they are found. Its primary objectives are to reconstruct past human behaviour, subsistence strategies, social organization, cognitive evolution, and cultural change across deep time. It is both a sub-field of archaeology and an essential component of anthropology, linking biological evolution to cultural evolution. Because written records are absent, all inference depends on rigorous methodology field methods, analytical techniques, and theoretical frameworks drawn from the natural and social sciences.

Prehistoric archaeology intersects with several disciplines: archaeobotany (plant remains charcoal, grains, phytoliths, pollen for reconstructing past food economies and environments); archaeozoology (animal remains bone, antler, shell for subsistence and domestication patterns); geomorphology (landform evolution and the landscape contexts of sites); sedimentology (physical and chemical analysis of deposits to identify human activity areas and natural formation processes); geology (the basis for stratigraphic analysis); and physics and chemistry (chronometric dating; residue analysis). The social sciences contribute through analogies from cultural anthropology, human geography, history (especially the Annales school), and ethnoarchaeology.

Typology of Stone Tools

Stone tools are the most durable and abundant material evidence of prehistoric cultures. Their classification by form, manufacturing technique, and raw material is called lithic typology, and forms the basis for cultural chronology in the Palaeolithic. A consistent set of tools made by a particular technique or tradition is called a tool industry.

Oldowan Industry (Mode 1)

The earliest stone tool tradition, named after Olduvai Gorge in Tanzania where it was first identified, and associated primarily with Homo habilis (~2.6-1.5 million years ago). Oldowan tools consist of: cores lumps of stone (often river cobbles) from which flakes have been removed, modifying the original rock; and flakes the small fragments detached from the core. Early researchers assumed cores were the tools and flakes the waste, but subsequent analysis showed the majority of cores were raw material for flake tools. Flakes are extremely sharp and effective for cutting through animal hides and removing meat from bones. Hammerstones used to crack open large bones for marrow and to remove flakes from cores are also part of the Oldowan assemblage. Archaeological sites associated with the Oldowan include butchering sites (mammal bones with cut and percussion marks in association with tools), quarrying sites (where raw material was obtained), and possible home bases (concentrations of tools and food remains at central locations).

Acheulian Industry (Mode 2)

Beginning ~1.76 million years ago and associated primarily with Homo erectus, the Acheulian technique involved flaking the entire stone controlling the shape of the whole core tool rather than just the "business end." Named after the site of Saint-Acheul in France where it was first identified. Characteristic tools are: hand axes bifacially worked (flaked on both opposing sides), symmetrical, teardrop-shaped, edged and pointed, all-purpose tools used for butchering, wood cutting, and digging; and cleavers tools with straight, sharp edges, also bifacially worked. A single hand axe reduction produces as many as fifty usable flakes. The Acheulian industry spread throughout Africa and into Europe; Asian Homo erectus populations characteristically made choppers instead with flakes removed from one or both sides but asymmetrical and not flaked across the whole surface. Hand axes persisted for over a million years.

Mousterian Industry (Mode 3)

The Middle Palaeolithic industry associated with Neanderthals (~300,000-40,000 years ago), named after Le Moustier in France. Characterized by the Levallois technique preparing a core in a specific shape from which a predetermined flake could be struck, giving the tool-maker much greater control over the final form than earlier methods. Mousterian assemblages include scrapers, points, and denticulates, considerably more diversified than Acheulian. Mousterian tools are found throughout Eurasia.

Upper Palaeolithic Industries (Mode 4)

Associated with anatomically modern humans (~50,000-10,000 years ago). Characterized by blade technology long, parallel-sided flakes at least twice as long as they are wide, struck from prepared prismatic cores. Distinct regional industries include Aurignacian, Gravettian, Solutrean (including the finely pressure-flaked leaf-shaped Solutrean points of Europe, experimentally reproduced by Louis Leakey, Donald Crabtree, and François Bordes), and Magdalenian in Europe. The Upper Palaeolithic also features the first unambiguous evidence of symbolic behaviour cave art, personal ornaments, figurines, and musical instruments.

Microlithic Industries (Mode 5)

The Mesolithic (post-Pleistocene hunter-gatherer) and later periods are characterized by microliths tiny, standardized stone tools under 3 cm in length, designed to be hafted in composite tools (arrows, spears, sickles). At sites like Langhnaj in Gujarat (excavated by H.D. Sankalia and Irawati Karve), thousands of microliths have been recovered.

Field Methods in Archaeological Anthropology

Survey

Systematic and intensive survey of all categories and sizes of sites in a given region has replaced the random and selective recording of the antiquarian stage. Survey uses maps, aerial photographs, and satellite images to locate sites before excavation. Environmental archaeology draws on survey data to reconstruct past landscapes.

Excavation

Archaeological excavation proceeds through vertical or horizontal trenches, involving detailed recording of all evidence: site and trench maps, three-dimensional provenience recording of finds, photography, and stratigraphic section drawings. All excavation is destruction of original evidence the site record is therefore preserved only in maps, plans, and photographs. Excavation may be triggered by threatened sites (cultural resource management, rescue excavation) as well as by research design.

Methodological Strategies

Environmental Archaeology:: Study of past human interactions with nature, focusing on the impact of environment on culture and vice versa. Karl Butzer termed archaeology "past human ecology." Evidence includes animal remains (bones, eggshell, insects, molluscs), plant remains (wood, charcoal, pollen, phytoliths), and stratigraphic, chemical, and physical analyses of sediments. Two main branches: geoarchaeology and bioarchaeology.

Settlement Archaeology:: Study of societal relationships as inferred from the spatial distribution of archaeological sites on the landscape. Initiated by Gordon Willey (Harvard) in his study of the Virú Valley, Peru (1940s). Settlement patterns reflect the natural environment, the technology of the builders, and the social institutions of their culture. Settlement archaeology reconstructs geographical, political, military, economic, and religious factors governing settlement location, as well as socioeconomic and demographic aspects of past life. Settlement pattern studies have been conducted at prehistoric and proto-historic sites across India.

Ethnoarchaeology:: The use of analogies drawn from the study of living cultures to reconstruct and interpret archaeological cultures. The term was coined by Jesse Fewkes in 1900. Kramer defined it as "ethnographic fieldwork carried out with the express purpose of enhancing archaeological research by documenting aspects of socio-cultural behaviour likely to leave identifiable residues in the archaeological record." Two types of analogy: Direct Historical Analogy applied when there is temporal continuity between the archaeological and the ethnographic culture, based on historical records or area ethnographic field work, considered to provide the highest probability of being correct; and General Comparative Analogy based on similarities between contemporary cultures and archaeological materials across cultures without geographical restriction. Lewis Binford's study of the Nunamiut Eskimos of Alaska and John Yellen's work on the Bushmen of Africa are landmark examples. India has rich potential for ethnoarchaeology studies of the Chenchus, Yanadis, Irulas (hunter-gatherers), and Dhangars, Bhils, Toda, Badagas, Kurubas (agropastoral) have been used for reconstructing prehistoric life. Indian archaeologists studied carnelian bead manufacture in Khambat, Gujarat, illuminating Harappan bead-making and craft-trade social organization. KK Basa studied the artisan community at Bhimbetka to link contemporary painting practice to prehistoric cave art. Limitations: analogies are suggestive, not conclusive; multiple analogies may fit a single situation; migration and invasion may break historical continuity.

Experimental Archaeology:: Use of analogies from experimental studies of ancient techniques and materials. A history of over 150 years. Precautions: materials similar to those used in the past must be employed; modern technology must not influence the experiments. Experimental stone tool making has been practiced since the early 19th century Leakey, Crabtree, and Bordes made experimental specimens of all major tool types including Solutrean points and North American Clovis and Folsom points. Other experimental studies cover dwelling construction, megalithic tomb construction, food preparation, animal butchering, and agricultural practices.

Ethological Studies:: Use of analogies from primate behavioural research to reconstruct prehistoric hunter-gatherer behaviour. Long-term field studies of chimpanzees, baboons, and other higher primates provide analogies: group living facilitating learning; occupation of core areas with a home base; production of flakes by chimpanzees breaking stone blocks (suggesting origins of stone tool making).

Dating Methods

Dating is an indispensable tool in evolutionary investigation, enabling researchers to assess the time of any relict object fossil, artefact, or geological deposit. There are two fundamental approaches: Relative Dating and Absolute (Chronometric) Dating.

Relative Dating Methods

Relative dating gives information about the age of an object in relation to other objects whether it is older or younger than associated materials without providing a calendar date.

Stratigraphic Dating:: Stratigraphy is the study of the origin, physical characteristics, and spatial relationships of stratified rocks, governed by three principles. The Principle of Superposition (Nicolas Steno) holds that in an undisturbed sequence, upper strata are younger than lower strata. The Principle of Original Horizontality states that sediment layers are deposited horizontally under gravity any tilting or folding is the product of subsequent forces, implying geological dynamism over deep time. The Principle of Lateral Continuity states that sediment layers initially extend laterally in all directions; separated outcrops of similar rock can be assumed originally continuous. Geological stratigraphy was the model for archaeological stratigraphy, and geological period terms (Palaeozoic, Mesozoic) inspired archaeological period terms (Palaeolithic, Mesolithic).

Typological Dating:: Artefacts are classified by attributes shape, design, raw material, fabric into types, and the type sequence of a well-studied region is used to cross-date new finds and sites. Once a typological sequence is established for a region, it provides a relative chronology for new discoveries.

Fluorine Analysis:: Used to compare the relative age of fossilized bones buried in the same deposit. Fluorine is distributed in groundwater as soluble fluorides; when absorbed by buried bones and teeth, fluorine ions become permanently locked in the mineral structure. Bones buried for the same length of time in the same deposit will have approximately the same fluorine content; more ancient bones will have higher fluorine concentration. The rate of fluorine deposition varies by region, so the method can only compare specimens from the same site. This method was used to demonstrate that the Piltdown skull and jaw (claimed to be an ancient hominid) were not contemporaneous the jaw had very low fluorine, proving it was a recent forgery.

Pollen Analysis (Palynology):: Microscopic identification of pollen grains of plant species in soil samples recovered from a site. By identifying which plants were growing in a locality at successive periods and counting the relative number of pollen grains from different species in a stratigraphic sequence, a pollen diagram can be constructed that summarizes shifts in vegetation and thus climate over time. Useful for palaeoenvironmental reconstruction and indirect relative dating.

Absolute (Chronometric) Dating Methods

Absolute dating provides a specific calendrical date (or date range), not merely a relative position in a sequence.

Radiocarbon Dating (C14):: Introduced in 1949 by Willard F. Libby. All living organisms exchange carbon-14 (an unstable isotope of carbon, produced in the atmosphere by cosmic ray bombardment of nitrogen-14) with the atmosphere through feeding and photosynthesis. At death this exchange ceases, and the C14 already incorporated begins to decay at a known rate. The half-life of C14 is 5,730 years. By measuring the proportion of C14 remaining in an organic sample and comparing it to the known decay rate, the time elapsed since death can be calculated. Applicable materials: wood, charcoal, peat, grass, cloth, shell, bone, dung, and other organic materials. Reliable up to approximately 50,000 years BP; beyond this, so little C14 remains that it cannot be measured accurately. A critical calibration problem: atmospheric C14 fluctuates with the strength of the Earth's magnetic field and solar activity. Calibration against known-age tree rings (dendrochronology) resolves this overlapping tree ring sets extend back ~12,594 years, providing a reliable calibration for the most recent 12,594 years. Before that, large ± factors apply.

Potassium-Argon Dating (K-Ar):: Radioactive potassium (K-40) in certain volcanic rocks decays to Argon (Ar-40) with a half-life of 1.3 billion years. Because decay is far slower than C14, K-Ar can date material millions of years old but cannot be used on remains younger than ~400,000 years. To date fossils or cultural remains by this method, the volcanic rock must have been deposited at the same time as the remains a coincidence not frequently found. The method was first applied by Mary Leakey (1959) to date volcanic rock associated with an early hominid skull from the lowest strata of Olduvai Gorge, Tanzania the result of 1.8 million years nearly quadrupled the then-assumed timeframe for human evolution. K-Ar has since been invaluable for dating robust Australopithecines and other early hominids. Argon-Argon (Ar-Ar) dating, a refined version, was used to date the Mojokerto child's skull from Java to ~1.8 million years ago.

Thermoluminescence Dating (TL):: Many minerals emit light when heated before reaching red heat as trapped electrons (from exposure to surrounding radioactive elements) are released. If an object was previously heated to high temperature (as in pottery firing or burning of lithics in a hearth), all previously trapped electrons were released, resetting the "clock." Thereafter, new electrons accumulate from ambient radioactivity. When the object is reheated in the laboratory, the amount of luminescence released is proportional to the number of electrons accumulated since last firing and thus to the time elapsed. Age = total luminescence / annual rate of luminescence acquisition (De/DT). Applicable materials: ancient pottery, brick, tile, terracotta, fired lithics, burned hearth stones. TL was used to date Indus Valley civilization occupations and the Tabun (Israel) Neanderthal remains (~120,000-110,000 years). Optically Stimulated Luminescence (OSL) is a related technique using light rather than heat to release trapped electrons, suitable for unburned surfaces exposed to sunlight before burial applied to walls, foundations, and sand grains.

Electron Spin Resonance (ESR):: Like TL, measures trapped electrons from surrounding radioactive material, but does so by exposing the material to varying magnetic fields and measuring the microwave spectrum absorbed. Because no heating is required, ESR is especially useful for dating organic materials such as tooth enamel and shell, which decompose if heated materials inaccessible to TL.

Paleomagnetic Dating:: When rock forms, it records the prevailing direction and intensity of the Earth's magnetic field (paleomagnetism). The Earth's magnetic field has reversed itself many times periods of "normal" and "reversed" polarity are well documented. By reading the geomagnetic patterns preserved in rocks and matching them to the established global polarity timescale, rocks and the fossils within them can be dated. Strictly speaking this is not absolute dating in the same sense as radiometric methods it provides age estimates within the framework of the polarity timescale. Paleomagnetic dating has been applied to primate fossil finds from the Eocene (~55 million years) through Miocene (~5 million years).

Uranium Series (U-series):: Uses the decay chains of uranium-238, uranium-235, and thorium-232, all of which decay to stable lead isotopes, to provide age estimates for calcium carbonates flowstones precipitated in caves, invertebrate shells, and sometimes teeth. U-series techniques usually date the strata or enclosing material associated with a fossil rather than the fossil itself. Flowstones and teeth at Chinese hominin sites established that Peking Man (Zhoukoudian) dates to approximately 200,000-400,000 years ago.

Fission Track Dating:: Based on the spontaneous fission of uranium-238 in minerals and glass, which leaves microscopic damage tracks in the crystal structure. The density of tracks accumulates over time at a known rate; counting them under a microscope gives the date of formation. Applicable to volcanic glasses and minerals useful for dating sites where other radiometric methods cannot be applied.

The Molecular Clock (Genetic Dating):: DNA in living organisms accumulates mutations over time at approximately constant rates. By measuring the genetic distance between species or populations, the time since their divergence can be estimated. The molecular clock for primate divergences was developed by Morris Goodman and others in the 1960s: Old World monkeys diverged from other primates ~25 million years ago; gibbons ~18 mya; orangutans ~14 mya. The molecular clock is calibrated against fossil-based dates and provides an independent chronological framework for evolutionary relationships.

Cultural Stratigraphy

Cultural stratigraphy applies the principles of geological stratigraphy to the deposits left by human occupation at a site. Each identifiable layer or horizon of human activity constitutes a cultural stratum, distinguished by its artefactual content (tool types, pottery styles, animal bone assemblages), soil character, and spatial extent. The sequence of cultural strata at a site reveals the succession of human occupations and the changes in material culture over time.

The interpretation of cultural stratigraphy is complicated by several formation processes: primary deposits where artefacts lie where they were originally discarded or lost; secondary deposits where artefacts have been moved from their original location by human or natural agencies (water, wind, bioturbation); and mixed deposits where material from different periods has been conflated. Distinguishing these requires understanding both the cultural behaviour that produced the deposit and the natural processes that may have altered it the core concern of geoarchaeology.

Cultural stratigraphy is complemented by chronometric dates and typological analysis to produce what is called a cultural sequence the regional succession of tool industries, subsistence strategies, and cultural traditions through time. The terminology of prehistoric cultural periods (Lower, Middle, Upper Palaeolithic; Mesolithic; Neolithic; Chalcolithic) derives from the initial European research sequence but has been applied globally with regional modifications.