You will note that I am not covering almost anything from Feder, and that I am only partially overlapping with Fagan
I am assuming that you can appreciate the viewpoints of both of them without too much help from me
The goals of archaeology: why are we doing this?
same reasons as history and anthropology
mostly intellectual curiosity, with a promise of a little practical application
to reconstruct and understand the steps that led to the world as it is today
as in history, except that archaeology gives us access to much earlier periods
to understand the general processes of change
as in history, except that archaeology gives us access to much longer spans of time
to document the different ways that people can live and organize their societies
as in cultural anthropology, except that archaeology gives us access to kinds of societies that no longer exist
supposedly to learn lessons from the past that apply to the present
"Those that do not understand history are condemned to repeat it."
You can judge for yourself how realistic this often-stated goal is.
to develop a richer appreciation of the modern world and people by appreciating the depth and quality of the past
this is a personal, emotional, subjective benefit
but a real one that many people feel, even if they don't articulate it
just consider how many people like to go to museums, visit archaeological monuments, watch documentaries on the pyramids, read books about the Maya, etc.
there is something cool and satisfying about it
the main, real reason
archaeology is fun, interesting, and challenging
What do we want to know?
In general, archaeology is the extension of anthropology into the past, using mostly material remains as evidence
To be more specific, archaeologists are basically trying to do three things
1. reconstruct how people lived in the past and how their societies were organized ("reconstructing past lifeways")
these are like "snapshots" of the past; like ethnographies (or documentaries) of present societies
essentially, we want to know how things worked at some single time.
often called a "synchronic" view - having to do with a single moment or period in time
cultural features that archaeologists try to reconstruct include
subsistence: how people get their groceries
ie. foraging, fishing, hunting, farming, herding, looting, etc.
technology: both material objects (like tools), and practices (like agriculture)
ie. stone knives, bows, metal smelting, crop mixes, fertilizing, etc.
economy
often includes subsistence
production of food, craft goods, luxury goods, etc.
storage and exchange:
long-distance trade, taxation, warehousing, markets, etc.
consumption
differences between the wealthy and the poor
social organization: the key to really understanding how a society worked, but tricky to figure out
How personal variables like age, sex, and family (kin) relations affected people
The roles of social groups like lineages, moieties, guilds, etc.
The roles of economic groups, especially classes
Power and politics: social hierarchies, who had power, why, how they used it, how they maintained their privileged positions, how power affected different groups, etc.
ideology, cosmology, religion
2. assemble sequences of these snapshots into a historical description of how things changed over time, known as "culture history". ("compiling culture histories")
the "snapshots" in sequence, close enough that the connections are clear
this is essentially the same as history, but not dependent upon written records
hence often called "prehistory"
often called a "diachronic" view - looking at change over time
3. then explain these processes of change; try to figure out why things changed the way they did ("explaining cultural processes")
This is the hard part (not that the rest is easy!)
In practice, the archaeologist usually has one or more theories or hypotheses in mind.
He or she then gathers evidence to see if it is consistent with the theories; if yes, the theory is supported (but not proved); if not, it is disproved and must be discarded or modified
In this way, the evidence increasingly constrains the interpretations.
That is, we can't just say any old thing about what happened in the past; the theories have to coincide with the evidence.
We advance by inventing new stories and explanations that seem to fit the evidence, while progressively discarding ideas that turn out to conflict with the evidence.
We discard the definitely incorrect ideas and keep the rest; hopefully this gets us closer to the truth.
What evidence do we have with which to address these issues?
What we don't have:
We can't actually observe the people or ask them what they are doing, like cultural anthropologists do. The people are all long gone.
We usually don't have any written records, or only very limited ones.
We often don't even have representational art, and when we do, it is generally of only a very limited range of things, like kings, battles, gods, and so on.
What we do have:
All the garbage and debris that people have left behind that hasn't been destroyed.
That is, the archaeological record: All the material remains of human activities, collected and uncollected, that exist today.
Why is there anything left?
people throw away garbage, and it piles up. Just think of an country dump or an empty lot.
people move out of houses, they decay and collapse, or get knocked down to have a new one built on the site.
people intentionally bury their dead, sometimes with goods (like caskets, fancy clothing, objects that belonged to them, etc.)
natural disasters bury things, like the recent mudslide near Rio Nido, the eruption of Vesuvius that buried Pompeii in ash, etc.
and many other reasons.
Junk accumulates. Not always, not everything, but some does.
Why is this junk often buried?
sometimes people bury it intentionally
burials of the dead
putting trash in a pit
hiding a cache of coins in a hole
Leveling an abandoned building or empty lot and building on top of the debris
sometimes it buries itself
as an abandoned adobe house weathers in the rain, the walls melt and the mud covers the floor and bases of the walls -- and anything that was still laying around after the place was abandoned
as abandoned stone walls collapse, the rubble of the upper parts buries the floors and lower parts of the walls
sometimes nature buries stuff
a dump at the bottom of a hill may get covered by dirt washing downhill when it rains
sand may blow in and cover a site.
plants, earthworms, and rodents actually create soil and move it bit by bit, gradually covering things and moving them downwards below the surface.
a lot of garbage does not get buried.
if no soil forms or is brought in, or if the wind is actually blowing the soil away from that place, the junk stays on the surface.
unfortunately, many things tend to break down if they are exposed to the sun, rain, and elements. So stuff that does not get buried tends to decay away, while things that are buried generally last longer.
Given that it is garbage, what can it tell us about the past?
We have a problem here: there is a fundamental gap between what we want to know and the evidence available from which to figure it out
We want to know about, say, the processes that led people to develop agriculture or congregate in cities, but the only evidence we have is broken pottery, dried kitchen garbage, house foundations, broken statuary, and the like.
some parts of the picture will be reasonably easy to reconstruct
the food garbage should reflect what people ate
the housewares they used and broke should reflect the general level of technology, household activities, etc.
differences in the garbage found near different houses can suggest differences in wealth, ethnicity, etc.
debris from manufacturing things like ceramic pots, stone tools, jewelry, etc. can suggest things about technology, division of labor, maybe trade for exotic materials, etc.
but other aspects of culture may be a little harder
like religious beliefs
political organization
social structure, etc.
we hope that we can be clever enough to figure things out about how people lived and what they did from these remains
but there is no guarantee that we can
or that we can necessarily get it right.
In the end, we are out on a very long limb
some things we can be pretty sure of
others we could probably know if someone got the funding and spent the time to do further research
others we can make educated guesses on
and others we just have to admit can probably never be recovered.
like language, dance, music, philosophy, mythology, specific religious beliefs...
Specifically, there are three "filters" between the answers to our questions and the evidence we have to address them.
Filter #1
: Many things we would like to know about were not material objects, so they never entered the archaeological record at all in any direct or obvious way.
Language (other than writing)
Religious beliefs (if not written or portrayed in "art")
Dance, music, mythology
Motivations, goals, desires, plans...
Filter #2
: The things that do enter the archaeological record are an incomplete, biased selection of the material objects in a society.
For us to find archaeological evidence, it had to be left on or in the ground. Things that were eaten, burned, reused, melted down, etc. never even entered the record.
Things have to get into the ground
That mostly happens to things that that are no longer valued; people don't generally just leave a valued item laying around until it gets buried.
Discard. Usually garbage or broken things of no further use.
Loss. Accidental, usually small, less valued things.
Abandonment. A form of discard in which people leave a non-portable artifact like a house. Portable things generally won't be left in it unless they have little or no value.
Intentional burial, either for later recovery or not. Caches of wealth that were never recovered; burial of the dead; offerings to gods.
Catastrophic destruction: sudden burial by volcanic ash, mudflows, flooding; etc.
All of these processes of getting objects into the archaeological record are very selective.
Except in rare cases like Pompeii, what enters the record is by no means a representative sample of the material goods that were around at that time.
In general, we find broken pieces, not wholes; garbage, not goods.
worse than that, even the broken pieces don't represent everything that was around
peanuts leave a lot of shells; potatoes leave almost no waste
worn-out wooden items might be burned in the cooking fire
the archaeological record is biased against diamond jewelry - it consistently contains fewer diamond necklaces than does the material culture that it is drawn from.
Filter #3
: What survives in the archaeological record is an incomplete selection of what entered.
Many things just decay away: wood, plant material, cloth, leather, even bone often rot, weather, and disappear
Things are only buried when soil accumulates on a site; this does not necessarily occur. Wind may blow the soil away, or running water may erode the site, mixing the artifacts and exposing them to weathering.
this is why parts of Europe are famous for ancient cave sites; most of the open-air campsites have long since been destroyed by later farming
obviously, our impression of what happened in the past is distorted if we have lots of cave sites, but few or none of the open-air campsites that were also used by the same people.
People may disturb the record by digging for construction, garbage pits, looting, etc.
But sometimes things are preserved. How?
Some artifact types are just durable, and are preserved in most environments
stone tools
stone architecture, or other massive constructions
pieces of pottery vessels used for cooking, storage, and serving
sometimes bone
patterns of different-colored soils caused by digging and filling in pits or trenches, piling up dirt for defensive barriers or burial mounds, etc.
In most of our cases, that is all we have.
what is lost?
cloth, wood, leather, basketry, paper, almost anything made from plants or animals
Some unusual environments preserve more evidence
Very dry environments (Egypt, Mesopotamia, Peruvian coast) preserve things by preventing bacteria, mold, etc. from growing.
Very wet environments that permanently exclude air (underwater sites, bogs) preserve things
Very cold sites (Siberia, Alaska, the "Ice man" in Switzerland)
Sometimes we just get lucky with odd circumstances
basketry or textiles preserved as impressions on pottery
seeds preserved as voids in pottery
textiles, feathers, leaves, etc. preserved in corrosion on copper artifacts, or next to copper artifacts
seeds, textiles, or other organic materials that get burned to just the right degree and are preserved as charcoal "fossils" of the original object (carbonized)
But this incomplete, biased record does have some good points
first, it is evidence of the past, which we wouldn't know anything about otherwise: it is far better than nothing
second, most of it is free of the biases of historical records
history tends to focus on kings, wars, politics, religion, the wealthy classes
but archaeological evidence is often more balanced in its coverage of kings and commoners, priests and potters alike
historical sources are often intentionally or unintentionally slanted, propagandistic, from a particular point of view
houses and garbage don't lie (at least not intentionally)
example: the difference between what people in Tucson told pollsters about their alcohol consumption and what the Garbage Project determined by actually counting the bottles and cans in their trash
Also, the archaeological record is finite, and it is all we have
whatever is destroyed can never be replaced
the archaeological record is constantly being destroyed by road building, urban sprawl, dam construction, pot-hunters, arrowhead collectors, commercial looters...
it is as if the world had only one library, and people were burning a hundred books from it at random every day
even good archaeological excavation is destructive
when you finish, all that is left is a hole, plus a bunch of artifacts (hopefully labeled) and your notes, drawings, and photographs
no one can ever excavate that same spot again
so archaeologists have a tremendous obligation to do a good job, keep good records, and publish their results
How do we get this evidence?
how do we find sites (places with archaeological remains)?
archaeologists usually find sites by recognizing artifacts on the surface
sometimes mounds of accumulated debris, walls, or foundations are visible
more often, bits of broken pottery or stone tools are scattered on the surface
aside from really obvious sites, sites are typically found by systematically walking across the landscape and recording all artifacts that are laying on the ground; this is called "systematic site survey"
sometimes sites are recognized in photos taken from airplanes, showing patterns in relief, soil color, plant growth, etc.
By asking the local people, who often know where they have encountered artifacts while plowing fields, digging wells, etc., and who may have oral traditions of where events occurred in the distant past
By looking at old maps and documents
By digging small trenches in likely areas, boring holes with augers, etc.
sometimes sites are found accidentally, such as when a bulldozer working on a construction project plows up some artifacts
and many other methods
what do we do when we find sites?
map and study the remains on the surface
sometimes use non-invasive "remote sensing" techniques to learn about what is below the surface
magnetometers, resistivity testing, ground-penetrating radar, etc.
sometimes useful, sometimes not
dig up the evidence
excavations are usually done by natural layers ("strata") in the ground
the idea being that each layer of dirt accumulated in a particular time; layers below accumulated earlier, and layers above accumulated later
digging a site by the natural strata allows the archaeologist to keeps the artifacts from a given time period all together, and not mixing them with earlier or later ones
taking the ground apart in this way, and getting it right, is a major focus of archaeologists in the field, and is much more complicated than it sounds
excavation is very time consuming and expensive, so usually we only excavate a small portion of any site
so we only have samples, not the whole picture
study the artifacts and their distribution in time and space using lab techniques, statistics, replication experiments, etc.
How do we figure out what happened from all this evidence?
in many different ways
you'll see lots of examples as we go through the course
How do we know old things are?
Maybe even more important, how do we know the sequence of things -- what came first, second, and so on?
Two kinds of dating: relative and absolute
Relative puts things in order, older to younger, without specifying dates in years
Absolute gives ages in years.
In theory, this is better than relative dating, because we know both how old things are, and can put them in order
Unfortunately, most "absolute" dating methods give slightly fuzzy dates (radiocarbon dates are usually plus or minus 50 years or more), so sometimes we can get the order more precisely by lower-tech, relative methods.
Relative dating
Stratigraphy (study of strata, or layers of earth)
The layer-cake model, with oldest at the bottom and most recent at the top
Based on the law of superposition: When two strata overlap, the lower stratum must have been deposited first.
So, in general, the artifacts in the lower stratum will have been made, used, and deposited on the ground at an earlier date than the ones in the upper stratum.
There are many complications, of course.
Ceramic (pottery) chronologies
Once you have figured out the order of some sites or layers, by whatever means, you can look at the pottery in each site or layer and establish a sequence of recognizable pottery styles
Then if you find pottery similar to one of these known styles at a different site, you can tell where in the new site falls in the time sequence
just like you could make a sequence of car styles, from horseless carriages, to 50's era boats with fins, to bulbous Ford Tauruses
and then put old photos in chronological order according the cars that appear in them
Why do this with pottery?
Because broken pottery is found almost wherever people live, since it is useful, cheap, but easy to break
and the fragments are very durable, so we expect to find a lot of them
ceramics can be made and decorated in a virtually infinite variety of ways, so fashions or styles of pottery change a lot
so broken pottery can serve as a convenient time marker
the pottery style in itself is not usually important; it is the fact that a given style was made only for a limited period of time, and that we know the order and dates of these styles.
So we often divide time up into units that correspond to fashions in pottery style.
Then, if you find a site that has, say, Tumilaca style pottery on it, you know that the site was occupied during the Tumilaca period, which you know from radiocarbon dating lasted from about 950 AD to 1200 AD.
Note that the same name gets used in various ways here:
The Tumilaca style of pottery: describes a kind of pottery with certain shapes, colors, and decorations
The Tumilaca period (or phase, or epoch, etc.): describes the period of time during which this pottery was made
The Tumilaca culture (or people): describes a group of people who made and used this pottery; maybe an ethnic group
The Tumilaca site: often, a pottery style is named after a site where it is found.
You can only tell which of these meanings is meant by context, although a good writer will try to make it clear.
based on variable width of tree rings in response to annual differences in climate
pick an old tree, record the widths of rings going inwards from the bark, each ring representing one year
then extend the pattern back into time by matching up overlapping sequences from old, dead trees, logs used in buildings, etc.
then you can date a piece of wood by matching its pattern of ring widths to the master sequence
this is extremely accurate - to the exact year - but very time-consuming to create master sequence
someone must find chunks of old wood that overlap with no gaps from the present back to the period of interest
must create a separate master sequence for each region and type of tree
some areas have no suitable trees
or insufficient seasonal and annual variation in climate
or the work just has not been done yet
and only relatively large chunks of wood can be dated; if you don't have beams or posts at your site, you can't use this method
range of dating:
varies by region; up to 8000 years ago in a few places (like Europe and the American Southwest), but no good master sequences for most of the regions we will study in this class
radiocarbon dating
the main points:
it works. No serious scientist doubts the method
it is not precise, that is, radiocarbon dates give a range, not a specific year
like 500 AD ± 60 years (that is, the date probably falls within a 120 year range centered on 500 AD)
only organic materials can be dated (wood, bone, shell, leather, cloth...), not pottery or stone tools
unfortunately, organic materials are often not preserved
except for carbonized wood (charcoal), which since it may be found even when other organic materials have vanished, is often what gets dated
dates are destructive (the sample is burned in the process) and expensive ($200 to $700 per date), so we never have enough of them
how it works
there are 3 kinds (isotopes) of carbon in the natural environment, 12C, 13C, 14C
they are chemically identical (virtually); they differ only in the number of neutrons in the nucleus
most carbon is 12C; about 1% is 13C; and a minute fraction is 14C, which is radioactive
14
C is unstable, and eventually converts to 14N (it "decays")
14
N is a gas that is the major component of the earth's atmosphere, so it essentially gets lost in the crowd
14
C has a half life of 5730 years
that is, if you have 1 gram of 14C, in 5730 years, one half of it has decayed to 14N
in another 5730 years, half of the remaining half has decayed to 14N... and so on
so why is there any 14C around any more?
14
C is constantly produced in the upper atmosphere when cosmic rays strike 14N (7n, 7p), making 14C (8n, 6p)
the relatively constant rate of production of 14C balances against the constant decay of 14C
resulting in a constant percentage of 14C in the atmosphere
plant and animal tissues contain a lot of carbon
land plants get their carbon from the carbon dioxide in the atmosphere
animals get their carbon from plants that they eat
so living things are comprised of carbon that has the same fraction of 14C as the atmosphere
when a plant or animal dies, the 14C in its tissues keeps decaying away, but it no longer gets fresh 14C from the air or from food
so the 14C in its tissues gradually decays away after death
so if you measure the ratio of 14C to 12C, you can calculate how long the 14C has been decaying, that is, how long it has been since the plant or animal died
complication: the amount of 14C in the atmosphere has not actually been exactly constant
but we can now correct for this by using tree-ring dated samples for comparison
these corrected dates are called "calibrated" dates
I try to give you only calibrated dates in this course
careful: the time since death might or might not be relevant
for example, the "old wood" problem
you want to date the use of a fireplace, so you gather charcoal from it for a date
the 14C date from the charcoal tells you when the branch died, not when the person made the campfire
whoever gathered the wood might have picked up a branch that had already been dead for a hundred years
to date a building, ceramic style, etc. that is not itself organic, you need to find datable organic material buried with it in such a way that you think they are the same age, and then date the organic material
for example, you might date a pottery style by dating the bones of a person who was buried with that style of pot
range of dating: up to 50,000 - 70,000 years ago
in samples older than that, then too little 14C is left for an accurate measurement
because the date depends on a measurement, and measurements are never perfect, an estimated error range is included
± 60 years is typical for a date of 2000 years ago
that is the "one standard deviation" error estimate; it means that there is a 68% chance that the true date falls within the indicated range
100 AD ±60 means there is a 68% chance that the date lies between 40 AD and 160 AD.
that means there is 32% chance (one in three!) that it falls outside the range
doubling the error estimate give you 95% certainty, but makes the date seem even more imprecise
there are also other absolute dating methods that are sometimes used in special circumstances
obsidian hydration
gives a cheap but very rough estimate of how long ago a piece of volcanic glass was fractured
useful for getting a large number of dates in places where they used a lot of obsidian tools
these can then be lumped statistically for more useful results
thermoluminesence (TL)
gives a rough estimate of how long ago a piece of ceramic was fired
still technically a bit dicey
potassium-argon
based on the radioactive decay of an isotope of potassium, which is found in many rocks
usually dates the deposition of lava
for very old sites, typically fossil hominids
paleomagnetism
based on the changing orientation of the earth's magnetic field
which is "frozen in" to clays when they are fired
useless for pots or other things that get moved after firing
but good for dating burned earth below hearths, kilns, etc.
requires the creation of a master sequence for every area where it is used
the difficulty of doing this, and of finding and taking appropriate samples, has kept the method from being widely applied
and others...
Conclusions
we can tell reasonably well how old things are and in what order things happened
for this class, you won't have to worry too much about how these dates are generated
You will, however, want to think carefully about the evidence on which the prehistory we study is based
the past is not just given to us as in a history book
it is figured out from complex, material evidence
archaeologists do make mistakes
and reasonable people do disagree on the interpretation of the evidence
For next time:
two great hoaxes in Feder
the archaeology of the first glimmerings of humanity - the origins of human intelligence, social behavior, and culture