Using Experiments and Forensics to Understand Cremated Remains

While we can learn a great deal about individuals from their remains and their grave, when we expand our research we can expand our interpretations. Understanding the burial requires an understanding of the burial location, the cultural location, the meaning behind the type of burial and the rituals leading to the burial. This is especially true when analyzing cremated remains, which reveal less information about the individual but more about their funeral. There is a lot that we can discern from cremated remains regarding the funerary rites itself such as the temperature and construction of the pyre, the treatment of the individual prior to cremation, and the grave goods included in the funeral versus those included in the grave.

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Cremation remains are unique because of the diversity in their physical appearance due to the different methods and treatments they endured during the funeral rites. Bones can vary in their color, their fragmentation, and their from their alteration from original shape and dimensions. In order to understand these variations, bioarchaeologists often turn to modern forensics studies or experimental studies. Unlike the symbolism of grave goods or meanings behind burial rites which change over time and between cultures, the reaction of bones to fire is a constant. Therefore, we can directly use modern studies to assess practices in the past.

First, the color of bone prior to cremation depends on three variables: oxygen availability, duration and temperature. Bone can range in color from black and brown charring, through blue and grey moderate burning, to an oxidized buff or white color. Shipman et al. (1984:313) used animal bones argued that pale yellow and brown meant a temperature less than 285 °C (545 °F), black meant 645 °C (1193 °F), and white or light blue-gray meant 940 °C (1724 °F), with temperatures above in neutral white or gray. By taking sheep bones and cremating them at different temperatures, they were able to correlate temperature to color. While there are variables which change this, temperatures around these roughly correlate to temperature. Walker et al. (2008) note the importance of oxygen, material, and environment in determining the color of cremains. They built a number of funeral pyres and used modern human femurs to test differences. They found that open air pyres lost their color and warped more than the pyres that were placed in holes in the soil. These are important to archaeologists since temperature can aid interpretations of the size of the pyre, the duration, the type of wood, and the energy put into the funeral rite.

Second, temperature, type of bone, and method of cooling can alter the form of the bone. An experimental study done by Correia (1997) found that warping of bone due to heat depended on the type of the bone, whether long, short or irregular, and was also dependent on the location of the bone and amount of protective flesh. Denser bones with more flesh were less likely to warp than the spongier bones with little flesh. This is important for archaeologists because we know there are societies where individuals are defleshed prior to cremation, so the pattern of warping can aid in interpreting whether this was practiced. Another important variable is cooling of the remains. If left in the fire there could be increased coloration, if cooled by water there can be increased warping, and if pulled from the fire to cool it could avoid increased color or warping. An experimental study at University of Cardiff was able to make these interpretations through cremation and cooling of a number of sheep. Noting these practices can tell us more about funeral rites in the past and how the remains were removed from the pyre.

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Finally, modern day forensics study continue to improve methods for assessing demographic information about cremated remains. While these are intended for individual identification, they are also useful to archaeologists in order to construct demographic profiles in the past. Like uncremated remains, cremains can be aged, sexed, and assessed for pathological conditions like disease and trauma. Ubelaker (2009) summarized the newest forensics methods and techniques for identification of pathology and DNA analysis. He notes that studies of the remains from the Branch Davidian incident in Waco, Texas revealed important information about the differentiation of bone cracking due to trauma or warping in the fire. As McKinley (Cox and Mays 2002) notes, identification of age and sex requires reassembling the individual and looking at all possible identification markers. She also notes it is important to remember that females and sub-adults are more likely to warp and fragment due to the smaller size of the bone. However, when done carefully, traditional measurements and macroscopic indicators can be used to identify demographic information.

By continuing to look at modern experimental and forensics studies of  cremation, archaeologists can better interpret the funerary ritual in the past. Information about temperature, material, above versus below ground pyre, fleshed or defleshed, and demographic attributes are all important piece of evidence. Without understanding the entire process of the funerary rite, we cannot make as complete interpretations.

Works Cited

SHIPMAN, P. (1984). Burnt bones and teeth: an experimental study of color, morphology, crystal structure and shrinkage Journal of Archaeological Science, 11 (4), 307-325 DOI: 10.1016/0305-4403(84)90013-X

Ubelaker, D. (2009). The forensic evaluation of burned skeletal remains: A synthesis Forensic Science International, 183 (1-3), 1-5 DOI: 10.1016/j.forsciint.2008.09.019

Walker et al. (2008) Time, Temperature, and Oxygen Availability: An Experimental Study of the Effects of Environmental Conditions on the Color and Organic Content of Cremated Bones. In Analysis of Burned Human Bones.

McKinley (2002) The analysis of cremated remains. In Human Osteology, Mays and Cox, eds.