Chapter 8
Understanding the Past
Archaeological and Paleoanthropological Methods
Biocultural Evolution 1
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The next several chapters will explore the work of both paleoanthropologists and archaeologists. Sometimes these areas of
specialty overlapping, sometimes they remain distinct.
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First we need to recognize that paleoanthropology is a sub-specialty of paleontology (the study of old life).
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The focus of paleoanthropologists is the last 7-8 million years (the book says 5 million years) rather than the complete
record of life on earth.
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The reason for this time frame is the interest in protohominins and hominins:
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Protohominins: The earliest members of the hominin lineage. As yet poorly represented in the fossil record, their
structure and behavior are reconstructed largely hypothetically.
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Hominins: Members of the Tribe Hominini, the evolutionary group that includes modern humans and now-extinct
bipedal relatives.
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Archaeologists focus only on the part of hominin history during which there is evidence of culture.
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One note: In Europe they refer to paleoanthropologists as archaeologists.
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This difference is a reflection of the fact that archaeology is a part of the history programs there, while it part of
anthropology in the United States.
Biocultural Evolution
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One of the most distinctive behavioral features of humans is our extraordinary elaboration of and dependence on culture.
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Many other primates and other animals modify their environments. For humans, culture integrates an entire adaptive strategy
involving cognitive, political, social, and economic components. Remember examples from previous chapters
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The line between early hominin tool-making and other animals is not a clear line
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The material culture, the objects humans use and/or alter, is only a small part of the culture complex
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Much of our evidence of early hominins is based on stone tools; this is because of preservation issues
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This means we know little about the earliest stages of hominin cultural evolution before the regular making of stone tools
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Even so, they were quite likely to have made other tools.
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When did tool-making abilities become apparent in humans?
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We know that the earliest hominins very likely did not regularly manufacture stone tools
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They may have carried naturally sharp stones or stone flacks, parts of carcasses, and pieces of wood around in their home
ranges
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We would expect them to behave similarly to chimps (I wonder about the new data on chimps making spears!)
Biocultural Evolution 3
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When did tool-making abilities become apparent in humans? (continued)
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You do not absolutely need the remains of hominins to know they occupied a site. You can use material clues (artifacts).
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Carrying unmodified stones over long distances (manuports) is seen in humans and and other primates. But carrying
modified rocks over a distance is only seen in hominins.
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Even without the organic examples of tools, we know that early hominins began to have a fascination for stones.
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According to the text, the earliest stone artifacts (so far) were found at Gona and Bouri areas of NE Ethiopia at 2.5 mya
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But in 2011, a new report suggests that the date should be earlier. At Dikika, Ethiopia, there are bones with apparent butchery
marks on them dating to 3.4 mya. Not clear if the stones were altered (artifacts) or picked up and used intact (manuports).
Biocultural Evolution 4
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As mentioned previously, stone tools were not likely to be the only tools made by early hominins.
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Our observations of non-human primates are a convincing line of evidence for this hypothesis.
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Another observation to keep in mind is that, as with other cultural practices, there was likely to be diversity in tool
manufacture and tool use.
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Archaeologists, as students of culture, need to know the ways in which cultures change. There are several mechanisms of cultural
variation and change that have a role in determining cultural development
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Invention and innovation represent sources of intentional variation.
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Cultural selection is the process by which new cultural traits are either accepted or rejected.
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Cultural drift is the imperfect transmission of cultural information between generations or over increasing distances.
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Diffusion describes the transmission of cultural objects or behaviors into new regions.
Paleoanthropology 1
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Paleoanthropology is a specialty of paleontology
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The name paleo- (ancient) and -logos (study of) means ‘study of ancient humanity’
A multidisciplinary pursuit seeking to reconstruct every possible bit of information concerning the dating, structure, behavior,
and ecology of our hominin ancestors.
Today one needs the skills of the physical sciences, the biological sciences and of the social sciences to decipher fossil beds.
Below is a summary of common disciplines involved in the search for early hominins.
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Paleoanthropology 2
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Paleoanthropological fieldwork is expensive, long and arduous and multidisciplinary
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Early in the history of archaeology it was closer to pot collecting, but today these multidisciplinary teams attempt to:
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Date the site using geological, paleontological and geophysical data
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Reconstruct the paleoecology (ancient environment).
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Paleontologists will identify the animals
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Using fossil pollens, the palynologist will try to reconstruct the environment
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Taphonomy helps explain the nature of the fossils uncovered
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The study of how bones and other materials came to be buried in the earth and preserved as fossils. Perhaps the most
famous example (at least for those who read mystery novels) is the Body Farm
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A taphonomist studies the processes of sedimentation, the action of streams, preservation properties of bone, and
carnivore disturbance factors.
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Document the archaeological traces of human behavior (artifacts) by labeling and describing them
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Examine the anatomical evidence from hominin remains (this is the work of biological anthropologists)
Archaeology 1
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Goals of archaeology
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Remember from Chapter 1, anthropological archaeology is only one of many branches of archaeology.
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Anthropological archaeology (archaeology) has at least four main goals:
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Reconstruct past human events as they were played out across space and through time.
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Reconstruct past human lifeways.
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Explain how and why the past happened as it did.
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Interpret cognitive and symbolic aspects of past cultures.
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Archaeological research projects
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As with paleoanthropology, archaeological research draws on the skills of many experts.
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The justification for allocation of resources can be for:
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Cultural resource management (CRM) projects intended to meet legal guidelines for conserving historical sites and
monuments
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Public or private agency-sponsored projects designed to answer specific questions
Archaeology 2
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Archaeological research projects (continued)
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Given a research question or heritage management task and a geographically defined region, fieldwork assumes a common
pattern
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Step 1: The archaeological resources of that region are identified and inventoried
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Step 2: Sites selected from the pool of all known sites in the region are subjected to careful examination. Often statistical
techniques help to decide which to select
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Step 3: Then, some sites are partially or completely excavated.
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This the work that most people think of when they talk about archaeology. Even so, most of the work is done in the
laboratory after the fieldwork is done.
Pictures at: Survey work on Rapa Nui and Test pit
Archaeology 3
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Types of sites and how do they locate them?
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Site types include kill sites, campsites, quarries, middens, villages & cities
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The relationships between them are most often observed on sites (locations of past human activities where archaeologists
concentrate their efforts).
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The assumption of archaeology is that the organization and structure of the archaeological record reflects the behavior of
humans in the past.
How are sites located?
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Sometimes it is obvious (think pyramid) Other times it takes more work to find a site
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Low tech version
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Walkover survey: The members of a walking team walk across a landscape, maintaining a straight line with each
other, and their heads down.
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This is usually the work of unpaid volunteers or undergraduate students (they are free labor!).
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They are looking for indications of human habitation such as arrowheads (this is one reason NOT to take up
arrowhead hunting. It destroys the clues archaeologists look for during walkovers).
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They record data such as the terrain, kinds of artifacts, and other data about sites and group together as the site
survey (the process of discovering the location of archaeological sites; sometimes called site reconnaissance)
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Archaeology 4
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Types of sites and how do they locate them? (continued)
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High tech version
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Archaeologists use a wide array of high-tech tools to help identify sites.
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Aerial photography and satellite imagery, along with remote sensing technologies such as ground-penetrating radar, sidescan sonar, proton magnetometers, and subbottom profilers are used.
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What are they looking to see? Example: Aerial reconnaissance indicate many features:
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Earthworks are the banks, ditches or other features seen in relief by shadow marks
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Often effected by lighting and weather
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Water pooling, snow pooling and vegetation also help delineate
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Soilmarks are changes in the subsoil color
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Usually seen after soil upheaval such as seen from farming
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Also noted by damp marks caused by differences in water retention during thaws
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Here is an interesting example: Maya
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Crop-marks are noted vegetation differences caused by differing substrata for growth
Piecing Together the Past 1
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Artifacts, features, and contexts
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Four essential products – artifacts, features, ecofacts, and contexts – result from archaeological research.
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Artifacts are tangible objects; anything that was made or modified by people in the past qualifies as an artifact
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Features are products of human activity that are integral to a site and not portable
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Ecofacts: Natural materials that give environmental information about a site. This includes plant and animal remains
discarded as food waste, and pollen grains in the soils.
Context describes the spatial and temporal associations existing in the archaeological record among and between artifacts
and features
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Primary context is the setting in which the archaeological trace was originally deposited.
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A secondary context is one to which it has been moved.
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Provenience is the 3-D location of an artifact in the dig. The location, and its proximity to other artifacts, tells about
the context of the artifact.
Piecing Together the Past 2
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Artifacts, features, and contexts (continued)
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Archaeologists create types; categories of artifacts that share selected characteristics.
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There major types of types are:
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Morphological types: The common attributes are size, shape and color. Does not assume the functions of the objects
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Functional types: Looks for evidence of use. Examples would be food residue in pots or microwear (marks left from the
use of the tool)on lithic blades.
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Temporal types: Artifacts go through stylistic changes over time. Examples are changes in pottery styles, tool types and
so forth over time.
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In archaeology there is a tension between discussions of form and of function.
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Ethnoarchaeology
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Examines contemporary societies to gain insights into past human behavior.
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Key to these types of study is the ethnographic analogy: Hypotheses that result from the behaviors of present-day peoples
that guide archaeologists in their research of past peoples.
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An ethnoarchaeologist conducts in-depth ethnographic research among a living group.
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Such studies yield detailed information about hunting or gathering, tool-making, discard of debris and residence data
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Piecing Together the Past 3
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Experimental Archaeology
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Research that attempts to replicate ancient technologies and construction procedures to test hypotheses about past activities.
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Examples include making stone and wooden tools and then using them; eye surgery with obsidian tool, and burying artifacts
to trace decomposition
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One unique analysis of debris is that undertaken in Arizona
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The Tucson Garbage Project began in the 1970s under the direction of William Rathje.
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He gathered together his students and they have been digging in trash cans ever since.
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They learned many things:
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People drink more than they admit on surveys
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Middle class households waste more food than other households.
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Most items that have a use are not found in trash cans, but were found to have been recycled in garage sales and by
donations to charities (this was learned by use of surveys.; the advantage of living culture).
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One of the advantages to this research is that it allows for the interviewing of the persons who created the artifacts.
Dating Methods 1
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Perhaps one of the most common questions asked of archaeologists is, ‘How old is it?”
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The answer is that they have a wide variety of dating methods that fall into two major types: relative dating methods and
chronometric dating methods
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Relative dating methods establish the order from oldest to youngest, but not the time that separates them from each other
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Chronometric dating methods also provides relative order, but also the date (this is way these methods are often called
absolute dating methods.
Archaeological Record is a Finite Resource
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There are some key ideas to keep in mind when considering whether to excavate:
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There are only so many ancient sites. There will not be any more sites, only fewer.
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Archaeological excavation is destructive.
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Excavation should be done only to:
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Answer important questions
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Or, collect information from sites that will be destroyed anyway.
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All this means that excavation is only done when necessary.
Dating Methods 1
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Perhaps one of the most common questions asked of archaeologists is, ‘How old is it?”
•
The answer is that they have a wide variety of dating methods that fall into two major types: relative dating methods and
chronometric dating methods
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Relative dating methods establish the order from oldest to youngest, but not the time that separates them from each other
o
Chronometric dating methods also provides relative order, but also the date (this is way these methods are often called
absolute dating methods.
Dating Methods 2
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Relative Dating
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The oldest dating method is stratigraphy (study of sequential layering of deposits)
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It is based on the principle of superpositioning: In a stratigraphic sequence, the lower layers were deposited before the
upper layers.
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A layer is called a stratum is a single layer of soil or rock; sometimes called a level (plural: strata)
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Closely connected to geological stratigraphy is the method called biostratigraphy (also called faunal correlation)
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This relative dating technique is based on regular changes seen in evolving groups of animals as well in the presence or
absence of particular species.
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When a chronometric date of certain fossils are known, these index fossils can be used to estimate the age of the layers in
which they are found in a new location
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This same concept of applying dates from known objects to sites of unknown ages is also used for features and artifacts and
the technique is known as cross-dating.
There are actually a number of other relative dating techniques, but 2 additional ones are: seriation & fluorine analysis (not
discussed in the book).
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Dating Methods 3
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Relative Dating (continued)
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Seriation orders artifacts into a series based on their similar attributes or the frequency of these attributes.
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This is possible because the items of material culture tend to change in patterned ways over time.
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One well known example is: Stone -> Bronze -> Iron Age
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The designs on clay objects (or the shapes of the objects) often change in patterned ways, too.
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If you are curious visit this site for a demonstration of how this process works
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Fluorine analysis measures and compares the amounts of fluorine that bones have absorbed from groundwater during burial.
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Bones in the earth are exposed to the fluorine in the groundwater
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The longer exposed the more seen in the bones
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Used to expose the Piltdown hoax as it showed the skull was much older than the jaw.
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If you are curious visit this site for a demonstration of how this process works
Dating Methods 4
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Chronometric Dating Methods
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The first of the chronometric dates are based on the process of radiometric decay
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This is a measure of the rate at which certain radioactive isotopes disintegrate.
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Radioactive isotopes are unstable and over time will decay to form an isotopic variation of another element
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Confused? This site is great: Radioactive Dating Game
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The rate at which a radioactive isotope decays is called it’s half-life
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The time period in which one-half of the amount of a radioactive isotope is converted chemically (into a daughter
product).
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For example, if the half life of a radioactive material is 100 years:
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1 half-life ((100 years) 50% of the original material remains (½)
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2 half-lives (200 years) 25% of the original material remains (½ of ½)
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3 half-lives (300 years) 12.5% of the original material remains(½ of ½ of ½)
Dating Methods 5
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Chronometric Dating Methods (continued)
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Potassium-argon (K/Ar) is the most important chronometric technique for hominins involves potassium -40 (40K) which as a
half-life of 1.25 billion years.
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The decay of this radioactive material produces argon-40 (40Ar) Based on the accumulation of argon-40 gas as a byproduct of the radiometric decay of potassium-40 in volcanic materials.
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The more common name used in anthropology is K/Ar or the potassium-argon method
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Used to date materials 1-5 mya, especially in East Africa.
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Argon-argon (40Ar/39Ar) is a variant of the potassium-argon method.
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It uses the ratio of argon-40 to argon-38 for dating igneous and metamorphic rocks.
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It uses smaller samples, has less error, and is more precise a method.
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Fission-track dating is one of the most important techniques for cross-checking K/Ar dates
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Uranium-238 (238U) decay occurs regularly by fission.
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This decay leaves traces in certain geological materials and these microscopic tracks can be counted
Dating Methods 6
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Chronometric Dating Methods (continued)
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Radiocarbon Dating
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Perhaps the most famous of the radiometric dating techniques is radiocarbon dating (also called carbon-14 dating)
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Measures the 14C/12C ratio in samples of organic materials
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Used to measure materials ranging from 1-50,000 years old
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Its half-life is 5,730 years
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Like all dates based on radioactive materials, the estimated date is expressed as a range (date +/- error)
Dating Methods 7
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Chronometric Dating Methods (continued)
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A number of other dating methods are discussed in your book:
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Paleomagnetism is a technique based on the constantly shifting nature of the earth’s magnetic pole.
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o
o
o
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Thermoluminescence (TL) measures the accumulated radiation dose since the last heating or sunlight exposure of an object
Electron spin resonance (ESR) is the measurement (counting) of accumulated trapped electrons
Dendrochronology is a dating method based on the study of yearly growth rings in ancient wood
Ancient calendar systems
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Some can be cross-referenced to our own. For example:
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Ancient Egyptian calendar
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Ancient Maya and Aztec calendars
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I suspect that you heard that 2012 was the end the world according to Mayan calendar. Good news. Newly discovered
Mayan artifact suggests the Maya denoted no end of the world in 2012
Olduvai Gorge 1
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Geography
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Olduvai Gorge is located on the eastern branch of the Great Rift Valley, which stretches for 4,000 miles down the east side of
Africa.
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Today the Gorge is part of Tanzania
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It was named by a German geologist (Hans Reck), based on his mispronunciation of the Maasai word for wild sisal (the
plant pictured here).
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The Maasai word was Oldupai.
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There is an attempt by Tanzanians to revert the name back to Oldupai.
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Olduvai is a steep-sided valley resembling a miniature version of the Grand Canyon.
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The ravine is 300 feet deep and over 25 miles long.
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The semi-arid climate is similar to that seen for the last 2 million years.
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FYI: I took these pictures.
Olduvai Gorge 2
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Fossil Finds
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Olduvai has provided hominin data for Lower Paleolithic sites (A unit of archaeological time that begins >2.5 mya with the
earliest identified tools made by hominins and ends around 200,000 B.C.E.)
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Over 40 fossil hominins have been found at the Gorge. Considering the deep age and the paucity of ancient hominin
individuals this is an extremely rich collection.
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One of the most unusual findings was that of Zinj
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At one time this specimen was its own genus (Zinjanthropus boisei)
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Today we think it is part of the group called Paranthropus boisei, but more on this genus in the next chapter)
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Zinj was a very important find at the time.
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More so because it prompted the financiers to back the Leakeys
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Without this find they may not have been able to continue
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Today, Zinj is less discussed, given we now know it is outside of our direct line
Olduvai Gorge 3
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The Leakeys
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The persons more often linked to the Gorge are Louis and Mary Leakey
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Louis Leakey was the person who concentrated on gathering together the monies, made most
of
the public speeches and such.
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Mary Leakey did the majority of the digging and only after her husband past did her role
become more apparent.
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Their son (Richard) and daughter-in-law (Meave) took over
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Today, the 3rd generation of Leakeys is digging (Louise), and so there is a Leakey dynasty of paleoanthropologists.
Olduvai Gorge 4
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What was happening at Olduvai?
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Chopper tools
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Originally it was thought that earliest stone tools are the Oldowan chopper tool tradition
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Some now suggest that it was the flakes and not the pebbles that formed the basis of the tool tradition.
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Manuports were thought to form another part of the Oldowan tool tradition.
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This idea was that stockpiles of raw stone materials were carried to Olduvai for future use (manuports)
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Another piece of this scenario was the idea that these hominins hunted, scavenged, or collected food and raw materials from the
general locality where they habitually lived (home-based forager) campsites. Such sites are called multipurpose localities.
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This is now being challenged. Recent analysis of these manuports and found most of these manuports are likely ‘just rocks’
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Alternative interpretations for “multipurpose localities”
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Non-hominin predator kill locations where hominins scavenged
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Natural accumulations of natural stones
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