Site formation, linking arguments, ethnoarchaeology

Introduction to Archaeology: Class 12

Site formation, linking arguments, and ethnoarchaeology

ã Copyright Bruce Owen 2002

So now we are digging.

We want to know about people, cultures, and societies
but we are digging up layers of dirt and garbage.
how can we get from this limited, strange evidence to answers about our anthropological questions?

By using "middle-range theory" that links observations about evidence to inferences about behavior

artifacts were originally made and used by people. They played a role in a functioning society. They were in systemic context

not the greatest term, but we are stuck with it here
refers to the setting, use, meanings, value, etc. of things as parts of a living society
this is presumably what we want to know about

strata, artifacts, etc. are found in archaeological context

this is the relationships among them at the time of excavation (or surface collection, etc.)
the artifacts and their relationships that we observe are the result both of their original systemic context and subsequent processes of disposal, burial, disturbance, etc. that produced the archaeological record that we can observe today

if we want to correctly infer anything about the systemic context, we have to understand how it has been transformed into the archaeological context

Formation processes: Processes that create the archaeological record

may be cultural (what Thomas focuses on) and/or natural (which Thomas does not pay much attention to)
Depositional processes

discard

casual
in dumps, pits, etc.

intentional burial

for retrieval, as food in storage pits or a cache of coins buried in the back yard
not for retrieval, as in burials of the dead, offerings to the supernatural, etc.

loss
abandonment and decay of buildings, walls, etc.
catastrophic burial (mudslides, volcanic ashfalls, sand dunes, etc.)
note that there are two kinds of deposition being discussed here:

deposition of the artifacts themselves, usually by the behavior of people
deposition of soil around and on top of them, either by people or by natural processes

which is often (but not always) important in that it helps to protect and preserve the cultural evidence
and it helps to separate artifacts deposited at different times

with no soil deposition, artifacts from different times would just end up laying on the same ground surface, mixed together in a way that could never be separated by archaeologists

note that in many circumstances, few or no artifacts enter the archaeological record
and that often, even if they do, no soil is deposited on them, so they are exposed to the sun, weather, etc. and may be poorly preserved or not preserved at all

reclamation processes

people taking items out of the archaeological record and returning them to systemic context for reuse

eventually to go back to archaeological context again!

scavenging lithic (stone) points or flakes for reuse
robbing stone or brick from old structures to make new ones
using old midden to fertilize fields, make mud bricks, etc.
grinding up shell or potsherds from old sites to include in clay for new vessels
and many, many others

reuse processes

similar to reclamation processes, but the artifacts don't ever enter the archaeological record before being transformed into something else
like stone tools being reworked for different uses as they get smaller and smaller through resharpening
metals being melted down and reused when the item gets worn, broken, or no longer current or fashionable

disturbance processes

anything that alters the archaeological context after it has been formed
may be cultural, like people digging through it

sometimes to get artifacts or materials for the reclamation processes described above
sometimes to erect new buildings, dig wells, latrines, garbage pits, burials, etc.

but also many, many natural processes

rodents digging through it
freezing and thawing that causes the soil to crack, heave, and move below the surface: "cryoturbation"
erosion, redeposition as soil slides down a hillside, etc.

an uneasy fit somewhere in the area of formation processes: processes of preservation and decay

different natural conditions have a huge effect on how much, and what kinds, of evidence are preserved

the evidence you find from exactly the same behaviors in a bone-dry desert and in a tropical rainforest will very different

Environments that are particularly good for preservation

very dry environments

deserts (my favorite!)

soils often salty, which helps inhibit biological decay even more

certain caves, even in otherwise wet environments

very wet environments

that is, waterlogged and anaerobic (oxygen has been excluded)

very cold (frozen) environments

Environments that are particularly bad for preservation

tropical rainforests

wet but not constantly (not anaerobic)
soils often acidic, which helps to dissolve even inorganic materials like the mineral portion of bone

One way of conceptualizing these formation processes has been to think of them as ways in which material culture has been transformed from its state in systemic context to its state in archaeological context

the cultural processes involved have been called "c-transforms"
and the natural ones "n-transforms"

So, to understand the archaeological context, it is best to understand

the cultural processes that determined what things got into the record, and how

this is where ethnographic analogies and ethnoarchaeology help to improve our assumptions

the usually natural processes that affect what gets preserved and what decays away

so you can estimate what pieces of the picture might be missing, or what might be overrepresented just because it preserved better than other things

the cultural and natural processes that disturbed the record during and after formation

That is, you always have to be asking

how did this get here?
why is this particular kind of dirt here, and why does it have these kinds of artifacts in it?
what behavior created this archaeological evidence?
what behavior and natural forces have altered it since it left its systemic context?

One way I like to think about these issues is that there are "filters" between what we want to know about people in the past and the evidence that we have with which to address them

these are what an understanding of site formation processes, both cultural and natural, should help us deal with

Filter #1: Only material objects can enter the archaeological record

But many things we would like to know about never existed as material objects

Language (other than writing)
Religious beliefs (if not written or portrayed in art)
Dance, music, mythology
Motivations, goals, desires, plans... people's reasons for doing things

So the archaeological record contains a strange subset of the evidence we need

Filter #2: Of the material objects that could enter the archaeological record, only an incomplete and biased subset actually does enter the record

For us to find archaeological evidence, it had to be left on or in the ground
The ways that things get into the ground are highly selective

most things that get into the ground were worthless

things that have any value generally won't be left laying around until they get buried
for example, the archaeological record is biased against gold jewelry - it contains fewer gold rings than does the material culture that it is drawn from.

We find discarded garbage

worthless or broken things of no further use - the vast majority of all archaeological finds
whole objects or things made of recyclable materials like metals are underrepresented

We find things that were accidentally lost

usually small things that were not valuable enough to search hard for
large or valuable objects are underrepresented because they rarely get lost

We find things that were abandoned

like the remains of houses that have gotten too decrepit to live in
Anything valuable or portable will have been taken away
only things that are worthless or not movable will be left for us to find

We find things that were intentionally buried, either for later recovery or not

Caches of valuables that were never recovered
Burials of the dead
Offerings to the earth, spirits, gods, etc.
These contexts sometimes contain whole or valuable items
but still a very biased sample of the things in use

only very specific kinds of things are likely to be buried in these ways
for example, an analysis of modern US burials would find that men usually wore nice suits and that nobody owned a TV, since they are never included in burials.

We find things that were buried suddenly in catastrophes like volcanic eruptions or mudflows

probably the only cases in which the archaeological record at least started off relatively complete
but these cases are very rare

So the objects that did enter the archaeological record are an incomplete and weirdly biased subset of the objects used in a society

Filter #3: Of the incomplete and biased selection of objects that enter the archaeological record, only an even more biased subset actually survives to be found

Many things just decay away: wood, plant material, cloth, leather, even bone in some circumstances

So items that happen to be made of perishable materials are underrepresented

Even if the objects do get buried, they are often disturbed later, by people digging holes for house foundations or other purposes, or by plowing the site for farming

So evidence in places where people continued to live or work -- precisely the best and most important places, usually -- is underrepresented

Result: the archaeological record is a seriously limited, distorted reflection of the past
Response: the better we understand the formation processes (both cultural and natural) that created the biased record, the better we can compensate for those biases

if we ignore them, our interpretations will often be stupidly incorrect
if we try to deal with them, our interpretations should be a lot better, even if we can't be sure that we have completely overcome the problems with the archaeological record

But this incomplete, biased record does have some good points

first, it exists. It is evidence of the past

it can definitely tell us some things about the past
which would be completely lost to us otherwise
so 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 unintentionally or intentionally 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

Which brings us to "middle-range" research

research that is designed to help us understand the formation processes (cultural and natural, including disturbance, etc.) of the archaeological record

so that we can correctly connect the evidence of the record to past behavior

middle-range research thus helps us to make "bridging arguments" - the claims that justify leaping from the potsherds and rocks to statements about what people did
many bridging arguments are made almost unconsciously, using our "common sense"

but our "common sense" might not be the same as the common sense of people from different cultures, foragers, early farmers, etc.
or it might not even be right for anyone, even in your own culture: if you have never worked on a farm, your "common sense" about remains from farming activities might just be wrong because you don't really understand that way of life
or it might not be right for anyone because your "common sense" about formation processes is not correct

the solution is to check whether these bridging arguments are really valid for modern cases where we can observe the behavior, then check out the remains left behind

one approach to this is ethnoarchaeology

observe some people doing what they normally do (!Kung foragers living in a traditional camp, for example), then record the remains as though they were an archaeological site
Thomas's example: three completely different but seemingly reasonable interpretations of the same archaeological evidence (the relative lack of upper limb bones of animals at three different archaeological sites)

Perkins and Daly (studying foragers): meat was butchered off the upper limbs and the bones discarded at the kill site, but the lower limb bones were left in the skins that were used to haul the meat back to the living site that was excavated
Chaplin (studying farmers): the upper limbs, bone and all, were sent to market, leaving the lower limbs at the farming site that was excavated
White (studying foragers): upper limb bones were crushed to get the marrow, while lower limb bones with less marrow were left intact
the question is, which (if any!) of these might really occur?

one approach is to look for other archaeological evidence
Perkins and Daly's theory might be supported by a lot of cutmarks on the upper ends of the lower limb bones
White's theory should result in lots of fragments of large bones
Chaplin's theory might be borne out by evidence of markets or midden near high-status homes that had an excess of upper limb bones

As Thomas points out, each of these tests of the hypotheses involves some "bridging arguments"

for example, the cutmark argument depends on assumptions about how butchery is done and the marks it leaves on bones
these need to be tested, just as much as the hypotheses about the limb bones themselves

one solution is to read ethnographies or, since ethnographies rarely record the data in sufficient detail, to study living people

this has two purposes

to see if these behaviors actually occur

does anyone carry meat in the way Perkins and Daly describe, or is this a silly idea invented by people who have no experience with the realities of hunting?

to see if the bridging arguments that we will use in testing the hypotheses archaeologically are valid

does cutting off the upper bones to remove the meat while leaving the lower limbs in the skin result in lot marks on the upper ends of the lower limb bones?
does extracting marrow leave identifiable fragments of upper limb bones?

this can also be addressed experimentally, by an archaeologist trying to do it

we will look at that next time

but if we have the chance, observing a real expert do it in his or her traditional manner would be much more likely to parallel the behavior of the past

Binford's work with the Nunamiut Eskimos is an outstanding example
Larry Kuznar's work with pastoralists in southern Peru
Rathje's garbage project

in some ways a good example, even though Thomas's discussion does not make that too obvious
it does show the contrast between archaeological data and survey (or historical) data

next time we will look at the experimental approach to testing bridging arguments