Presentation on theme: "Field Methods in Archaeology and Paleoanthropology"— Presentation transcript:
1Field Methods in Archaeology and Paleoanthropology Chapter 5Field Methods in Archaeology and Paleoanthropology
2Chapter PreviewHow 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?
3Prehistory 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.
4PaleoanthropologyThe 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.
5Recovering Cultural And Biological Remains The only way to thoroughly investigate our past is to excavate (dig) sites where biological and cultural remains are found.
6Recovering Cultural And Biological Remains The fundamental premise of excavation is that all digging is destructive, even that done by experts. The archaeologist’s primary responsibility, therefore, is to record a site for posterity as it is dug because there are no second chances.- Brian Fagan, archaeologistWhat kinds of information can we get from recording a site?ANSWER – Material Culture and Skeletal Remains/Fossils
7Material CultureThe term material culture refers to the durable aspects of culture such as tools, structures, and art.
8Types 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 modifiedEcofacts = 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.)
9Types of Material Culture: For Class Discussion Is this example of one of the Nazca Lines in Peru a feature, artifact, ecofact or manuport?
10Types of Material Culture: For Class Discussion Are these examples of Maya sculpture features, artifacts, ecofacts or manuports?
11Types 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 rabbit’s foot2. Bones of a dairy cow3. A stepped-pyramid4. A stone tool5. A hearth or ring of stones
12The Nature of FossilsThe term fossil refers to any mineralized trace or impression of an organism that has been preserved in earth’s crust from past geological time.
13The Nature of FossilsIt 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 preservationTAPHONOMY = 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.
15Natural 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.
16Natural 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.
17Searching For Artifacts And Fossils Places containing archaeological remains of previous human activity are known as sites.
18Searching 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.
19Site IdentificationThe 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.
20Site 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.
21ExcavationSince excavations are destructive, archaeologists must carefully record the location of material remains in three-dimensional space.
22ExcavationTo 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.
23ExcavationTrowels 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.
24ExcavationIf 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.
26Stratigraphy Exercise Which material remain is older?
27Excavation of FossilsBoth 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.
28State of PreservationArtifacts made of inorganic materials such as stones are preserved better than artifacts made of perishable materials (unless there are favorable climatic conditions).
29State of PreservationSometimes the impressions of organic objects (such as post holes) can provide clues about the objects themselves.
30Sorting 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.
31Sorting 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.
32Sorting 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.
33Sorting 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.
34Bioarchaeology 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.
35Human 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
37Paleopathology - 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.
38Paleopathology- 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.
39Case Studies in Paleopathology Tibias from a year old Roman Soldier, 3rd-4th Century, AD
40Case Studies in Paleopathology Spear injury to right tibiaOsteoporosis on both tibias
41Case Studies in Paleopathology Patellas of a 40 year old Moche potter ( AD)
42Case Studies in Paleopathology Both show wear from extended periods of kneeling
43Case Studies in Paleopathology Female Skull, 500 AD
44Case Studies in Paleopathology Blunt force trauma to left side of the face
45Case Studies in Paleopathology Male Skull, Belize, Postclassic Period (1300 AD)
46Case Studies in Paleopathology Possible anemia or syphilitic infection
47Case Studies in Paleopathology Yde Girl – a bog body from the Netherlands(1st Century AD)
48Case Studies in Paleopathology Hair has been cut offEvidence of strangulation or hanging
49Case Studies in Paleopathology Skulls with evidence for cranial re-shaping
50Bioarchaeology 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.
51Dating 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.
52Relative 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.
53Relative Dating Techniques Palynology = a method of relative dating based on changes in fossil pollen over time.
54Absolute 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.
55Absolute 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.
56Absolute Dating Techniques Electron spin resonance = measures the number of trapped electrons in boneThermo-luminescence = measures the amount of light emitted from a specimen when heated to high temperatures.
57Chance 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.