An Introduction to the Prehistory of Indiana

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The terms "prehistory" and "archaeology" are employed many times in the pages that follow, and short description of their usage is appropriate.

Prehistory refers to that interval in human existence prior to the invention or introduction of written records. Man and his immediate ancestors have existed for hundreds of thousands of years, yet writing is a relatively recent development with a time span not much in excess of 5,000 years. It was late in the seventeenth century that what was to become Indiana is represented in the literature in any substantial detail. Therefore, prehistory ends and history begins at different times in different world areas.

It is readily apparent that the prehistoric interval is a very long one, indeed, and if we were totally dependent upon written documents for understanding the past, then that understanding would necessarily be confined to a few thousand years for a very limited portion of the world and only a few centuries for most of it. However, an almost innate inquisitiveness has led to the development of additional ways of learning about the human past that transcend the limits imposed by the absence of writing. Probably the most important and fruitful of these methods is archaeology, an ever-increasing body of methods and techniques designed to identify, recover, and interpret the surviving cultural and physical evidence.

Summarizing, "prehistory" has reference to that period in human existence before the invention of writing systems. "Archaeology" is a scientific activity designed to obtain knowledge about human life and culture during that long time interval.

As one might suppose, an absence of contemporary written records, despite the potential of archaeology, imposes some serious limitations on the kinds of information recoverable through excavation. It is uncommon to gain much of an understanding of the details of an individual life or specific events, both of which are hallmarks of historic inquiry. Similarly, it is possible only in special cases to identify ethnic groups or the languages spoken. The details of social organization, political organization, and religious ritual, among other social attributes, may be only dimly perceived, if at all, because the material that survive are often insufficient to document such practices. Readers need only recall their own activities and conjecture what will survive a few centuries for the archaeologist's use and wonder how these fragments might be interpreted should no written records survive. Much of our daily existence involves verbal behavior and actions that are ultimately based upon knowledge, values, experience, and belief, and none of theses survives directly. Although we are literally surrounded by a wealth of material objects and structures, only a few persist a lifetime given the best of conditions.

Despite these limitations, archaeologists are able to reconstruct the broad picture of cultural development and change through time and comprehend some of the conditions that produced

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them. Further, through a study of living societies, both contemporary and those from the recent past, some meaningful inferential insights into life of prehistoric societies can be obtained. The recovered material that assist in this quest may include manufactured objects (artifacts), remnants of plants and animals originally used for food (ecofacts), evidence for architecture, cemeteries, raw material resources, and the spatial distribution of any or all of these. Meticulous excavation in the contexts (sites) where these occur and careful recording of the relationships (horizontal and vertical placement) of the material encountered provide the data whereby an otherwise silent past is permitted to speak.

The ability to place prehistoric material in their proper chronological order and assign at least an approximation of calendar dates is an important consideration for most problems encountered by archaeologists, yet it is implicit in the idea of prehistory that no such contemporary records exist. While some suggestions of relative time placement may be derived by observing the position of material in the ground (e.g., deeper artifacts might be earlier than less deeply buried ones at the same site), or assuming that similar artifacts encountered in different site situations must reflect the same time interval, or concluding that simpler technologies must predate more complex ones, none of these provides a time perspective capable of being expressed in calendrical terms. [See photo of "An orderly archaeological excavation"]

It remained for the development of the carbon-14 dating procedure in 1950 to make available a widely applicable method for resolving some of the chronological problems. Because carbon-14

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provides most of the chronological insights in the text and is often cited in popular publication, a brief comment concerning the method is included so that the reader may more readily understand its significance.

Carbon-14 is an isotope of carbon which is radioactive. Therefore, given a finite quantity of the isotope, the level of radioactivity will decrease over a period of time at a more or less constant rate. It has been determined that in 5, 730 years the level of radioactivity will have diminished by one half. It was an original assumption that this natural decrease was countered by an equal increase occasioned by the constant creation of the isotope in the upper atmosphere; therefore, the levels of carbon 14 maintained an equilibrium in the environment. Further, it was thought that this equilibrium had been maintained at the same level over long periods of time. This latter assumption has been questioned, however.

All plants and animals, by reason of their participation in the life processes, incorporate carbon-14 at the same levels as that existing in the environment. However, upon the death of the entity, the isotope is no longer assimilated and only radioactive decay occurs. Since the carbon-14 levels in living material are known and the rate of decay has been determined, it remains only to measure the difference in the radiocarbon level of the unknown sample to assess when it ceased to participate in the life process. That is, the difference between the two carbon-14 levels is a measure of the time elapsed since the "death" of the specimen.

Materials such as charred wood, bone, and shell can be dated using the radiocarbon method. About 50,000 years is its limit. Because datable materials are commonly recovered from prehistoric sites and the useful time span more than covers the period of human occupancy in the New World, carbon-14 is widely applicable to the solution of chronological problems.

Although the method produces a result that is expressed as the equivalent of a calendar date, in point of fact, this is not the case. The reasons for this are too complex for inclusion in this brief summary, but what is produced is an average "date" and a plus and minus range of years (e.g., 500 + or - 50 B.C.). This means that there is a 67 percent chance that the "true" date falls within the given plus and minus range.

Further, some of the original assumptions have proven to be incorrect. For example, it is now confirmed that past levels of atmospheric carbon-14 have not been constant, though correction tables are now available to adjust for this error during the most recent few thousand years. Also, not all materials incorporate the isotope in the same concentrations. What is produced, then, is a probability statement, not a precise calendrical date.

Despite the foregoing strictures, carbon-14 dating does provide reasonably accurate time estimates, and its application to archaeological problems, beginning in 1950, succeeded in bringing about a revolution in the field. For the first time, prehistorians were able to view their data with greater sense of absolute time than had been possible heretofore.