15.5: Taphonomy

What Happened to the Remains After Death?

The majority of the skeletal analysis process revolves around the identity of the deceased individual. However, there is one last, very important question that forensic anthropologists should ask: What happened to the remains after death? Generally speaking, processes that alter the bone after death are referred to as taphonomic changes (refer to Chapter 7 for a discussion regarding taphonomy and the fossil record).

The term taphonomy was originally used to refer to the processes through which organic remains mineralize, also known as fossilization. Within the context of biological anthropology, the term taphonomy is better defined as the study of what happens to human remains after death (Komar and Buikstra 2008). Initial factors affecting a body after death include processes such as decomposition and scavenging by animals. However, taphonomic processes encompass much more than the initial period after death. For example, plant root growth can leach minerals from bone, leaving a distinctive mark. Sunlight can bleach human remains, leaving exposed areas whiter than those that remained buried. Water can wear the surface of the bone until it becomes smooth.

Some taphonomic processes can help a forensic anthropologist estimate the relative amount of time that human remains have been exposed to the elements. For example, root growth through a bone would certainly indicate a body was buried for more than a few days. Forensic anthropologists must be very careful when attempting to estimate time since death based on taphonomic processes because environmental conditions can greatly influence the rate at which taphonomic processes progress. For example, in cold environments, tissue may decay slower than in warm, moist environments.

Forensic anthropologists must contend with taphonomic processes that affect the preservation of bones. For example, high acidity in the soil can break down human bone to the point of crumbling. In addition, when noting trauma, they must be very careful not to confuse postmortem (after death) bone damage with trauma.

Figure 15.21: Table showing taphonomic processes that affect the preservation of bones. A. Rodent gnawing. B. Carnivore damage. C. Burned bone. D. Root etching. E. Weathering. F. Cut marks. Credit: A. Rodent gnawing (Figure 15.26), B. Carnivore damage (Figure 15.27), C. Burned bone (Figure 15.28), D. Root etching (Figure 15.29), E. Weathering (Figure 15.30), and F. Cut marks (Figure 15.30), all original to Explorations: An Open Invitation to Biological Anthropology by Alex Perrone are under a CC BY-NC 4.0 License.

Taphonomic Process	Definition
Rodent Gnawing	When rodents, such as rats and mice, chew on bone, they leave sets of parallel grooves. The shallow grooves are etched by the rodent’s incisors.
Carnivore Damage	Carnivores may leave destructive dental marks on bone. The tooth marks may be visible as pit marks or punctures from the canines, as well as extensive gnawing or chewing of the ends of the bones to retrieve marrow.
Burned Bone	Fire causes observable damage to bone. Temperature and the amount of time bone is heated affect the appearance of the bone. Very high temperatures can crack bone and result in white coloration. Color gradients are visible in between high and lower temperatures, with lower temperatures resulting in black coloration from charring. Cracking can also reveal information about the directionality of the burn.
Root Etching	Plant roots can etch the outer surface of bone, leaving grooves where the roots attached as they leached nutrients. During this process, the plant’s roots secrete acid that breaks down the surface of the bone.
Weathering	Many different environmental conditions affect bone. River transport can smooth the surface of the bone due to water abrasion. Sunlight can bleach the exposed surface of bone. Dry and wet environments or the mixture of both types of environments can cause cracking and exfoliation of the surface. Burial in different types of soil can cause discoloration, and exposure can cause degreasing.
Cut Marks	Humans may alter bone by cutting, scraping, or sawing it directly or in the process of removing tissue. The groove pattern—that is, the depth and width of the cuts—can help identify the tool used in the cutting process.