In Scandinavia Christian Thomsen's Three Age System had emerged from the 19th century as a way of interpreting prehistoric excavation sites and the materials within. He had concluded that different time periods were signified by a shift in the materials that tools were made from. Hence the Stone, Bronze and Iron ages. Although it later proved to be useful only regionally, it was a step towards figuring out a methodology for interpreting archaeological findings. At the turn of the 20th century archaeologists began seeking ways to devise theories that would explain the archaeological record in terms of culture, rather than time period. Thus was born the Culture-History paradigm.

Archaeologists began seeing trends in how various artifacts had been formed within archaeological records from seperate sites. They attributed these shared traits as a diffusion of culture from one group to another. In this way they explained that the specific traits themselves represented culture. They didn't think it was possible that groups could seperately give rise to the same techniques and ideas, therefore they must have come into contact with one another and transfered knowledge. It is thinking such as this that had people believing that the pyramids in Egypt and the pyramids in Mesoamerica were built by the same people, or that Egyptians had somehow found their way into Mesoamerica and influenced the indigenous peoples living there. A major component to this type of archaeology has been a dependency on Classical literature and historical records that explained the major events that caused groups to develop new techniques and ideas in the first place.

Processualism or The New Archaeology
As anthropologists moved toward a more scientific methodology the Culture-History paradigm was seen as no longer sufficient. The scientific method was stressed as an important technique to be used in anthropology, including archaeological research. Archaeologists wanted to introduce if/then statements into the theory behind interpretations and to stress the material systems that they could examine rather than ideological systems that they could only make assumptions about. In an attempt to make archaeology more about process they developed what is alternatively refered to as either New Archeaology or Processual Archaeology. An illustration of the structure of archeology under this paradigm is as follows:
                    /I \
                  /  S   \
                /    M     \

If you move from the base of the pyramid to the peak you find yourself first dealing with the material goods, whether artifacts or ecofacts. After analyzing these material remains you then begin looking for the systemic aspects; the social systems that may have affected the usage, appearance, placement etc. of these goods. Why, for instance, are there more fish bones found in pithouses of a certain size and none found in pithouses that are smaller? Why is there evidence of multiple fire pits in these larger pithouses and little or no evidence of fire pits in the smaller ones? By examining the placement and frequency of all of these things you could deduce that the larger pithouse belonged to higher statused people. Comparing current societies that appear to operate within similar structures could open up the interpretation of the site. This type of archaeology is known as ethnoarchaeology, and was first suggested by Lewis Binford, a prominent archaeologist.

The last thing Processual archaeologists attempt to do is the step at the top of the pyramid, discerning the ideological structure of the culture that inhabited the site. This is because it is hard to determine the ideological systems of cultures when all you have are projectile points and animal remains. Processualism was largely formed and carried out in American archaeology as a means to interpret prehistoric sites excavated. In American archaeology there is little to no written records preceeding the arrival of colonists and explorers, which is why processualism became the primary means of interpreting the prehistoric data in the US. In Europe, where classical societies had long kept written records the Culture History approach was found to be more popular.

After a hundred years or so of prehistory and history being interpreted largely by upper class white males (as those who had time to be scholarly generally were) there appeared divisions within archaeology concerning how the record had been interpreted. Among the various groups that have challenged Processualism are feminist archaeologists and those that stand up for the disenfranchised. Though they each emerged for their own reasons they are collectively placed under a Post-Processualist paradigm. The methods employeed by those under this paradigm would be illustrated like this:
               \            /
                \    M     /
                  \  S   /
                    \I /
Essentially what Post-Processualism is about, is getting at the area that Processualism has previously ignored, the ideological systems. They feel that since the material goods are so easy to analyze, generally, they should be the last in order of importance. The ideological systems would tell a more complete story about the culture group that employeed them and created the site being examined, as such they deserved to be first and not last.

Beyond the order of importance for examining the archaeological record, the Post-Processualists disagree about another processual theory as well. Rather than placing importance squarely on the scientific method they direct their attention largely at addressing issues that have been ignored within the historical record. Because archaeology had long been carried out by upper class white men there was a strong bias towards the upper class, whites and men within the interpretations and attentions provided by archaeologists. Feminists began wondering where women were in archaeology, not only as practitioners but also within interpretations of the record itself. Various forms of feminist theories concerning the engendering of archaeology have been developed or are in a current state of development. Others, those that focused on the disenfranchised, have started addressing wrongs against native Americans, black Americans, asian Americans, etc. that have been caused by those that ignored their presence in archaeological records and local/national histories in the past. Colonial archaeology has also received a new look with more attention being paid to those that emigrated in and out of America and their influence within the society.

Arguably Post-Processualism deals with history rather than pre-history, though there are those that say it can be used for both. Within the current state of archaeology there is a larger portion of Processualists and Post-Processualists than there are Culture-Historians (a paradigm which has largely been abandoned), and there are more Post-Processualists emerging from American universities than there are Processualists.

Roughly summed up from two semesters worth of various archaeology classes taken at the University of Maryland, College Park.