Presentation on theme: "Chapter 5 Field Methods in Archaeology and Paleoanthropology."— Presentation transcript:
Chapter 5 Field Methods in Archaeology and Paleoanthropology
Chapter Preview How Are the Physical and Cultural Remains of Past Humans Investigated? Are Human Physical and Cultural Remains Always Found Together? How Are Archaeological or Fossil Remains Dated?
Prehistory and History The term prehistory is used to refer to the period of time before the appearance of written records. This does not deny the existence of history, merely of written history.
Paleoanthropology The study of the physical remains of our ancestors and other ancient primates. Paleoanthropologists do more than find and catalogue old bones. Paleoanthropologists recover, describe, and organize these remains to see what they can tell us about human biological and cultural evolution.
Recovering Cultural And Biological Remains The only way to thoroughly investigate our past is to excavate (dig) sites where biological and cultural remains are found.
Recovering Cultural And Biological Remains The fundamental premise of excavation is that all digging is destructive, even that done by experts. The archaeologists primary responsibility, therefore, is to record a site for posterity as it is dug because there are no second chances. - Brian Fagan, archaeologist What kinds of information can we get from recording a site? ANSWER – Material Culture and Skeletal Remains/Fossils
Material Culture The term material culture refers to the durable aspects of culture such as tools, structures, and art.
Types of Material Culture Artifacts = objects which have been modified by hominids (stone tools, ceramics, wood tools, etc.) Manuports = natural objects that were carried by hominids but not modified Ecofacts = natural objects found in association with hominids (e.g. plant remains, animal remains) Features = large, non-portable modified objects found at hominid sites (e.g. hearths, buildings, large statues, rock art, etc.)
Types of Material Culture: For Class Discussion Is this example of one of the Nazca Lines in Peru a feature, artifact, ecofact or manuport?
Types of Material Culture: For Class Discussion Are these examples of Maya sculpture features, artifacts, ecofacts or manuports?
Types of Material Culture: For Class Discussion Look over this list of material objects and decide if they are artifacts, manuports, ecofacts, or features: 1. A lucky rabbits foot 2. Bones of a dairy cow 3. A stepped-pyramid 4. A stone tool 5. A hearth or ring of stones
The Nature of Fossils The term fossil refers to any mineralized trace or impression of an organism that has been preserved in earths crust from past geological time.
The Nature of Fossils It is also important to understand the kinds of factors that led to the placement of the fossil within the ground as well as affected its preservation TAPHONOMY = the study of what happens to bones and other material remains once they have been discarded or the animal has died, and before they are excavated.
Taphonomy Cultural Transforms – burial, mortuary ritual, plowing, looting Natural Transforms – erosion, weathering, scavenging, natural disasters, animal action in the soil, climatic conditions
Natural and Cultural Burial of the Dead Entirely preserved fossil skeletons dating before the cultural practice of burial about 100,000 years ago are quite rare. The human fossil record from before this period consists primarily of fragmentary remains.
Natural and Cultural Burial of the Dead The fossil record for many fossil primates is even poorer, because organic materials decay rapidly in the tropical forests where they lived. By contrast, the fossils of our pre-human ancestors are generally better preserved because of the arid savanna in which they were located.
Searching For Artifacts And Fossils Places containing archaeological remains of previous human activity are known as sites.
Searching For Artifacts And Fossils There are many kinds of sites, and sometimes it is difficult to define their boundaries, for remains may be strewn over large areas. Sites are even found underwater.
Site Identification The first task for the archaeologist is actually finding sites to investigate. Usually archaeologists survey a region in order to plot the sites available for excavation. A survey can be made from the ground, but more territory can be covered using aerial photography. Innovations such as geographic information systems (GIS), remote sensing, and ground penetrating radar (GPR) often complement these exploration methods.
Site Identification What archaeologists look for: (1) soil marks or stains that show up on the surface of recently plowed fields. These may reveal an archaeological site. (2) middens or refuse or garbage disposal areas in an archaeological site. May appear to be large mounds.
Excavation Since excavations are destructive, archaeologists must carefully record the location of material remains in three- dimensional space.
Excavation To begin, the land is cleared, and the places to be excavated are plotted as a grid system – a system for recording data in three dimensions from an archaeological excavation. Usually divides a site into squares (1m x 1m). Grids are established using a datum point or reference point for a grid system.
Excavation Trowels are used to scrape the soil, and screens are used to sift all the loose soils so that even the smallest artifacts, such as flint chips or beads, are recovered. Some archaeologists use flotation – a technique used to recover very tiny objects by immersion of soil samples in water to separate heavy from light particles.
Excavation If a site is stratified (i.e. contains layers of cultural and biological remains), each layer or strata is excavated separately. Archaeologists can also use stratigraphy to relatively date the remains by means of strata. Objects in lower strata are older than objects in higher strata.
Example of Stratigraphy
Stratigraphy Exercise Which material remain is older?
Excavation of Fossils Both skill and caution are required to remove a fossil from its burial place without damage. Paleoanthropologists use a combination of tools and materials to do this: pickaxes, dental tools, enamel coating, burlap for bandages, and sculpting plaster.
State of Preservation Artifacts made of inorganic materials such as stones are preserved better than artifacts made of perishable materials (unless there are favorable climatic conditions).
State of Preservation Sometimes the impressions of organic objects (such as post holes) can provide clues about the objects themselves.
Sorting Out the Evidence Excavation records include a scale map of all the features, the stratification of each excavated square, a description of the exact location and depth of every artifact or bone unearthed, and photographs and scale drawings of the objects.
Sorting Out the Evidence In the lab, artifacts that have been recovered from an excavation must be cleaned and catalogued before they are ready for analysis. From the shapes of the artifacts as well as from the traces of manufacture and wear, archaeologists can usually determine their function.
Sorting Out the Evidence Other kinds of information gathered from fossils: (1) Endocasts - Casts of the inside of a skull which can help determine the size and shape of the brain. (2) Coprolites - Preserved fecal material providing evidence of the diet and health of past organisms.
Sorting Out the Evidence Other kinds of information gathered from fossils: (3) Small fragments of DNA can be amplified or copied repeatedly using polymerase chain reaction (PCR) technology to provide a sufficient amount of material to perform these analyses.
Bioarchaeology and Forensics The term bioarchaeology refers to the archaeological study of human remains emphasizing the preservation of cultural and social processes in the skeleton. Examples include: forensic anthropology, human osteology, and paleopathology.
Human Osteology (1) determine the sex, age (at death), and ancestral population of a skeleton from morphological features (2) determine wear patterns on the bones and teeth from repeated activities (3) comparison with other skeletons to determine species affiliation
Paleopathology - Iron deficiency causes anemia = porous bones - Vitamin D deficiency causes legs to grow bent. - Malnutrition or under-nutrition is inferred from skeletal measurements. - Certain infections leave specific traces in the skeleton. - Various cancers are identifiable in the skeleton.
Paleopathology - Trauma in skeletons is clearly evident in bone fractures, especially when they have not healed successfully. - The individual workload leaves traces in the skeleton. - Growth-disrupting and growth-retarding stresses during childhood will leave transverse lines of dense bone visible in radiographs of long bones of the body.
Case Studies in Paleopathology Tibias from a year old Roman Soldier, 3 rd -4 th Century, AD
Case Studies in Paleopathology Spear injury to right tibia Osteoporosis on both tibias
Case Studies in Paleopathology Patellas of a 40 year old Moche potter ( AD)
Case Studies in Paleopathology Both show wear from extended periods of kneeling
Case Studies in Paleopathology Female Skull, 500 AD
Case Studies in Paleopathology Blunt force trauma to left side of the face
Case Studies in Paleopathology Male Skull, Belize, Postclassic Period (1300 AD)
Case Studies in Paleopathology Possible anemia or syphilitic infection
Case Studies in Paleopathology Yde Girl – a bog body from the Netherlands (1 st Century AD)
Case Studies in Paleopathology Hair has been cut off Evidence of strangulation or hanging
Case Studies in Paleopathology Skulls with evidence for cranial re-shaping
Bioarchaeology and Ethics As scientists, anthropologists know the importance of the information that can be gleaned from studies of human skeletons, but as scholars subject to ethical principles, they are bound to respect the feelings of those who give skeletons a deep cultural and spiritual significance.
Dating the Past Two types of dating: (1) relative dating - designating an event, object, or fossil as being older or younger than another. (2) absolute or chronometric dating – provides dates for recovered material based on solar years, centuries, or other units of absolute time.
Relative Dating Techniques Seriation = a technique for relative dating by putting groups of objects into a sequence in relation to one another. Stratigraphy = a technique for relative dating based on organizing remains by means of strata. Objects in lower strata are older than objects in higher strata.
Relative Dating Techniques Palynology = a method of relative dating based on changes in fossil pollen over time.
Absolute Dating Techniques Radiocarbon dating = a technique of dating based on measuring the amount of radioactive carbon (14C ) left in organic materials found in archaeological sites. Dendrochronology = a method of dating based on the number of rings of growth found in a tree trunk.
Absolute Dating Techniques Potassium-argon dating = a method of absolute dating based on measuring the amount of radioactive potassium left in a layer of volcanic rock.
Absolute Dating Techniques Electron spin resonance = measures the number of trapped electrons in bone Thermo-luminescence = measures the amount of light emitted from a specimen when heated to high temperatures.
Chance and the Study of the Past The archaeological and fossil records are imperfect, partial, and non-representative. Chance circumstances of preservation and discovery have determined what has survived the ravages of time to be excavated by archaeologists.