SYLLABUS

TOPIC SCHEDULE

GRADES

ASSIGNMENTS

ACTIVITIES

BACK TO LECTURES

RETURN TO A105
 

 A105 Human Origins and Prehistory
A105 Lecture 4

Archaeological Research and Analysis, Taphonomy, and Dating

Paleoanthropology -- The Study of Ancient Humans
*A multidisciplinary field involving diverse areas such as archaeology, geology, physical anthropology, paleoecology, chemistry, etc.
*Paleoanthropological research is concentrated in the Old World (Africa, Europe, Asia).

Archaeology
*A set of scientific methods applied to the study of the human past
*Three objectives: describe the past, analyze and reconstruct ancient lifeways, explain how and why
*Archaeology is mainly concerned with the recovery and analysis of artifacts

Designing a Research Program: Modern Archaeology and Palaeoanthropology
*Define the hypothesis
*Necessary logistics (getting the money, organizing the project...)
*The joy of fieldwork: gathering the data
*The agony of lab analysis: analyzing the data
*Documenting the results

Olduvai Gorge: Background and Context (You won't need to know the specifics of Olduvai for the first exam, but later on we will revisit the site.)
*First discovered in the early twentieth century and mainly worked by Louis and Mary Leakey
*Located on the Serengeti Plain of northern Tanzania
*Geological processes allow the exposure of bone and artifacts
*Record spans 1.85mya to present

Archaeological/Palaeoanthropological Research: Hypothesis Testing
*Background research of the area and familiarity with previous studies are essential
*Identify an issue or problem of interest
*Formulate a specific question that will address the problem
*Design the research as a strategy to test the hypothesis by collecting data

Necessary Logistics
*Identify a study area; means knowing the regional geology
*Gain permission to work in study area
*Design a budget
*Apply for grants ($$$$)
*Purchase necessary supplies/vehicles
*Negotiate with local officials/peoples

The Joys of Fieldwork What are we looking for?
*Depends upon:
     -What hypotheses we are testing
     -Survey or excavation (digging)
*Survey:
     -Visible fauna (bones) and artifacts on surface
*Excavation:
    -Visible fauna (bones) and artifacts
    -Plant matter and pollen
    -Ecofacts and artifacts not visible to the naked eye

Gathering the Data (see text pg. 361)
*Walkover Survey -- teams walk across potential sites, marking all finds.  Often used to identify areas to investigate further.  To choose the areas to be surveyed, archaeologists may use sampling techniques:
         -- Simple Random Sampling -- a set percentage of the grid is examined at random
         -- Systematic Sampling -- units to be sampled selected in a predetermined way (every 10th unit, for instance)
        -- Stratified Random Sampling -- the area is divided into sub-areas and each sub-area is sampled...often used to ensure all parts of the area are sampled.

*Excavation
Artifact Provenience -- its locational information.
Single Component Site -- only one culture, usually only one cultural level. Here, horizontal excavation: expose a large part of the site, see relationships among artifacts.
Multicomponent Sites -- several cultures, several levels.  Here, vertical excavation: allows each level to be sampled.
Sieving and Flotation -- allow tiny artifact fragments and organic debris to be recovered.

Site Formation Processes
*Geology is important here: stratigraphy and geomorphology.
*Taphonomy: The study of how bones and other materials came to be buried in the earth and preserved as fossils.  A branch of geology.  Vital when we want to get information about hominid behavior from our sites: find out how much influence natural processes have had on the site.
*Primary vs. Secondary Context -- have the materials been moved and re-deposited? For this and other site formation questions, we must consider:
      *Range of factors that can produce bone accumulations (carnivore activity, rivers and streams, hominids)
      *Factors influencing whether a bone becomes a fossil (local environment, speed of burial, carnivore activity)
      *Factors influencing which bones get preserved (bones' physical characteristics, carnivore activity, trampling, etc.)
*Most creatures that die are not fossilized
*Of those that are, not all parts will fossilize
*Even if fossilization occurs, there's no guarantee the fossil will be found (we're largely dependent on fossils eroding out of beds).

Analyzing the Data
*Artifact Typology -- can use several different systems:
     --Morphological types based only on form.  Purely descriptive.
     --Functional types based on inferred use of artifact. Should ONLY be used when there is independent (other than form) as to the artifact's function.
     --Temporal types based on changes in artifacts over time.
Mary Leakey’s Lithic Typology -- we will revisit this later.

*Other Methods of Stone Artifact Analysis
Microwear: small chips or polish on stone tools that give anthropologists clues as to what the tools were used for
X-Ray Fluorescence Spectrometry: allows researchers to determine the chemical makeup of the stone and locate its source

*Paleoenvironmental Reconstruction
  --Geology and taphonomy used here too.
  --Also use pollen, fossilized plants, animals, and phytoliths to find out what animals and plants were present, even which were used by hominids/humans.
  --Stable carbon isotopes are produced in plants in proportions depending on the climate.  When animals eat plants, this carbon signature is recorded in their bones, so we can get a general idea of the environment in which they lived.
*Some environmental theories:
  --Turnover Pulse.  Elisabeth Vrba.  Correlated the appearance of new antelope species with three periods of increased dry climate.  Identified same pattern in hominids.
  --Environmental determinism can be a problem -- links simple environment changes directly to major evolutionary events.  Tends to grossly oversimplify.

Dating Prehistory
*Relative Dating: tells us if something is older or younger than something else, but not by how much
*Absolute or Chronometric Dating: estimates the age of a find in terms of calendar years

Relative Dating Techniques
*Stratigraphy: Law of Superposition -- lower layers older than higher layers.  Faulting is a problem here.
*Biostratigraphy/faunal correlation -- uses well-dated animal evolutionary events to date the layers in which animals are found.  Pigs, elephants, and rodents are commonly used.
*Typological Dating (see book).  This is a method that is particularly dangerous in palaeoanthropology, because of the peril of circularity.
*Fluorine Analysis -- the amount of fluorine in a bone is related to its age.  Can be used to tell which bones are of similar ages.

Absolute Dating Techniques
*Potassium-argon (K/Ar) and argon-argon (Ar/Ar) methods.  Has been extremely valuable in palaeoanthropology, particularly at sites older than 1 million years.  Based on radioactive decay of potassium (K)-40 into argon (Ar)-40, with a half-life of 1.3 billion years.  Ar/Ar dating is a more sophisticated form of K/Ar. ONLY dates volcanic rocks!!  Range: from about 100,000 years ago to the age of the earth.
*Fission-track dating.  Very good for checking K/Ar ages.  Relies on the spontaneous-fission decay of uranium (U)-238.  The fraction of fissioned U atoms gives the age of the mineral.
*Paleomagnetism. Based on the reversal of the earth's magnetic poles, which has occurred many times in the past. Any magnetic particles in sediment align themselves with the pole when rocks form; this can be measured to tell if polarity was normal (like today) or reversed (compasses would point south) when the rock was formed.  K/Ar has helped to pinpoint the dates of many major polarity flips.
*Radiocarbon Dating (C-14). Based on the decay of C-14 into a stable nitrogen isotope. All living organisms take in C-14; while they live, any decay is offset by continued intake.  Once dead, the C-14 decays to N-14 at a constant rate, allowing age determinations.  ONLY works on organic materials (formerly alive).  Range: 1,000 to 50,000 years, but errors rise rapidly after about 40,000 years.
*Thermoluminscence. Thermoluminescence (TL) and the related electron spin resonance (ESR) rely on the behavior of electrons exposed to environmental radiation.  This behavior can be measured and dates determined from it.  TL is often used on pottery, clay hearths, even burned flint; ESR is often applied to tooth enamel.
*Dendrochronology.  Dating by counting annual tree-rings.  Of limited use.

Ethnoarcheology
*An ethnoarchaeologist seeks to enhance his/her understanding of ancient life by studying modern-day tribal peoples such as the !Kung San.  He or she observes their behavior and makes inferences about how this behavior would be represented archaeologically.  Should be interpreted with caution, as human behavior changes constantly; also, should not be extended too far in the past -- as we will see, early hominids were very different from people!

Experimental Archeology
Experimental archeologists attempt to reconstruct prehistoric techniques of stone toolmaking, butchering, etc. through experimentation
Experiments in flintknapping are examples of experimental archeology

Documenting the Results
After the data has been analyzed, a comprehensive final report must be compiled
Submission of an article to a respectable journal
Presentations at professional mtgs.
Press-release
All important for continuation of funding

FOR EXAM 1, concentrate on understanding hypothesis testing, taphonomy, and dating.  The in-class activity is a good guide to the sorts of things you should know about taphonomy and dating. Later exams will cover artifact analysis and some of the other material presented here.