Taphonomy

Taphonomy, from the Greek, taphos, meaning tomb or grave, and nomy, meaning classification, is a field of paleontology, paleo-anthropology, and bioarcheology that studies human and animal remains in relation to the post-mortem (after death) transformations that occur in burial sites. In a broader sense, taphonomy is the study of the processes that leads to fossilization, as well as the stages of transformation of remains through the action of environmental factors. The knowledge gathered by this field is important to forensic science as a tool for the analysis of human remains at old crime scenes, mass graves, and mass disaster areas.

Osteology (or the study of bones), geochemistry, and entomology (the study of insects) are important aspects of taphonomy, as skeletons and skeletal fragments may yield information on the living conditions, availability of food, presence of infections, wear and tear of specific joints due to repetitive effort, size of muscles, and post-mortem events. Therefore, a scenario of living organism versus environmental characteristics may be inferred from such analysis as well as which forces and agents have acted over the remains after death. When the organism dies and is buried or covered by sedimentary layers of soil, such as clay, sand, volcanic ash, or ice, the taphonomic process of post-mortem transformations begins, which can lead to different types of mummification, decomposition, or skeletonization. If the conditions are right, skeletal fossilization will eventually occur. Bones can also be modified by animal scavenging, or be carried by rivers and scattered on riverbanks far from the original site of death before fossilization occurs.

Taphonomy studies three different stages of post-mortem transformation: necrology, biostratinomy, and diagenesis. Necrology refers to the factors present around the time of death or directly associated with the cause of death. Necrologic studies could include examination of bones or bodies for skull fractures, marks of fangs or claws in bones, signs of malnutrition, abscesses, infections, lesions by blunt instruments, bullets, or incineration, among other clues to the cause and events surrounding death. Biostratinomy identifies the changes that occurred after death such as decomposition and changes due to environmental forces acting in burial sites (tombs, graveyards, mass graves), or in places where remains were left or found, such as river or lake bottoms, sedimentary soils, or woods. Several events from this stage may leave their marks on the remains, such as animal scavenging, enzymatic and bacterial activity, insect activity, and transportation by water or landslides. Eventually, some bone fragments or entire skeletons may be buried under conditions that favor diagenesis, the process of lithification (compaction) of the sediments that envelop the remains, ultimately resulting in fossilized bones. Fossilization may occur in terrestrial (earth) and maritime (water) environments, and give clues to researchers about the environmental, geological, topographical, and climatic changes that occurred on Earth throughout the process of fossilization. The study of submarine layers of fossilized marine animals and crustaceans, for instance, allows the description of radical climate changes that occurred in different geological eras.

Forensic taphonomy focuses on the perimortem (at the time of death) and intermediate postmortem (days to weeks after death) biological and biochemical transformations in order to determine the cause of death, estimate the approximate time of death, and to identify humans remains including the sex, age, race, and, whenever possible, the individual's identity. The understanding of how different environments interfere with the biological and biochemical changes in human remains, affecting the process of decomposition, is crucial for the forensic interpretation of mass graves, mass disasters, war crimes, and cold cases of murder.

SEE ALSO Animal evidence; Anthropology; Body Farm; Death, cause of; Decomposition; Entomology; Exhumation; Geology; Medical examiner; Mummies; Osteology and skeletal radiology; Pathology; Skeletal analysis; War forensics.