A TAPHONOMIC STUDY EXPLORING THE DIFFERENCES IN DECOMPOSITION RATE AND MANNER BETWEEN FROZEN AND NEVER FROZEN DOMESTIC PIGS (Sus scrofa)

Author

Lindsey G. Roberts, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2013

Degree Name

Master of Arts

Department

Anthropology

First Advisor

Dabbs, Gretchen

Abstract

AN ABSTRACT OF THE THESIS OF LINDSEY G. ROBERTS, for the Master of Arts degree in Anthropology, presented May 10, 2013, at Southern Illinois University TITLE: A TAPHONOMIC STUDY EXPLORING THE DIFFERENCES IN DECOMPOSITION RATE AND MANNER BETWEEN FROZEN AND NEVER FROZEN DOMESTIC PIGS (Sus scrofa) MAJOR PROFESSOR: Dr. GRETCHEN R. DABBS This research examined differences in decomposition rate and manner of domestic pig subjects (Sus scrofa) in never frozen and previously frozen research conditions. Never frozen subjects and previously frozen subjects were paired and placed in an identical outdoor research environment at the Complex for Forensic Anthropology Research (CFAR) at Southern Illinois University. Extensive quantitative measurements were collected daily: abdominal circumference, total body score, and temperature. Qualitative observations were also taken daily: photographs of subjects, descriptive decomposition stages, and general visual observations concerning insect activity and subject appearance. Necropsies were performed at varying accumulated degree days between 50 and 300 (Celsius). Statistical comparison (paired samples t-tests) of accumulated degree days to three total body scores (TBS) (early decomposition TBS, 9.5 TBS, and advanced decomposition TBS) indicated the rate of decomposition of previously frozen subjects was significantly different than never frozen subjects at both early decomposition TBS and 9.5 TBS (p=0.003 & p=0.002, respectively). Internally, previously frozen subjects displayed less internal putrefaction, less internal color change, less organ distention, and a more dehydrated appearing heart. Externally, previously frozen subjects exhibited overall gray discoloration, increased desiccation, increased oviposition by insects, and nearly non-existent bloat. Internally, never frozen subjects displayed increased putrefaction, more internal color change, increased organ distention, and pleural bubbling around the lungs. Externally, never frozen subjects exhibited normal color change during decomposition, with purple and green discoloration being much more common in these subjects. Bloat was extensive in never frozen subjects. Due to these differences in rate and manner between never frozen and previously frozen subjects, previously frozen subjects should not be used in taphonomic research, as results may not accurately reflect the normal taphonomic condition. In cases of forensic significance, the possibility of freezing should be investigated if the victim displays external gray discoloration, significant external desiccation, decreased internal putrefaction, lack of bloat, and a dehydrated appearing heart.