Porcine Decomposition Rates as An Estimate for Human Post-mortem Interval in Yavapai County, AZ
Faculty Mentor Name
Hillary Eaton
Format Preference
Poster
Abstract
The rate of decomposition of human remains is variable, mostly depending on the ecosystem where the body is located. Major areas of the United States, such as Arizona's Sonoran Desert, have been sites for decomposition studies to gain a general understanding of how the weather affects the rate of decomposition. Understanding the rate of decomposition in areas experiencing different weather conditions and insect and animal activity would benefit forensic scientists when determining post mortem interval (PMI), of a decedent. Because of Yavapai County's unique elevation and weather patterns, it is unknown what the standard rate of decomposition is in the area. Sus scrofa domesticus, domesticated pigs, that are of a similar weight to female humans were used in this project because they are biologically similar to humans and are therefore commonly used as proxies. This project measured the air temperature, air humidity, soil temperature, soil moisture, soil pH, UVA/UVB rays, and luminous flux per unit area (LUX ) taken once daily from two deceased 1 00 lb. female pigs, one exposed to full sun and one placed in the shade in mid- February. Additional to the observation of physical changes, entomological activity was studied. Results obtained thus far demonstrate that the typical rate of decomposition, estimated from other areas of Arizona, has slowed, due to the colder temperatures, between 28- and 50-°F, Prescott, AZ has been experiencing. It was observed that rain and warmer temperatures from 60-73 °F, increased the rate of decomposition. Physical changes observed over the first 16 days of the project include: rigor mortis, severe bloating in the abdomen, edema surrounding the urethra seen from the abdomen, skin discoloration, liver mortis, coagulated blood and mucus escaping from the nasal cavity .. Insect and animal activity only began after 6 days of decomposition, with Calliphoridae (blow flies) and Formicidae (desert ants) activity and no visible larval activity in the cavities. With the temperatures recorded, it is likely cold weather and slowed decomposition have discouraged further activity up to this point. The sun pig showed bloating one week before the shade pig, yet the shade pig was more putrescent and exhibited higher insect activity. Changes in the weather, entomology, and physical conditions of the pigs will be monitored for a total of 6 weeks, or until skeletonization occurs. This study will provide important data and information on PM I for our unique high-desert ecosystem.
Porcine Decomposition Rates as An Estimate for Human Post-mortem Interval in Yavapai County, AZ
The rate of decomposition of human remains is variable, mostly depending on the ecosystem where the body is located. Major areas of the United States, such as Arizona's Sonoran Desert, have been sites for decomposition studies to gain a general understanding of how the weather affects the rate of decomposition. Understanding the rate of decomposition in areas experiencing different weather conditions and insect and animal activity would benefit forensic scientists when determining post mortem interval (PMI), of a decedent. Because of Yavapai County's unique elevation and weather patterns, it is unknown what the standard rate of decomposition is in the area. Sus scrofa domesticus, domesticated pigs, that are of a similar weight to female humans were used in this project because they are biologically similar to humans and are therefore commonly used as proxies. This project measured the air temperature, air humidity, soil temperature, soil moisture, soil pH, UVA/UVB rays, and luminous flux per unit area (LUX ) taken once daily from two deceased 1 00 lb. female pigs, one exposed to full sun and one placed in the shade in mid- February. Additional to the observation of physical changes, entomological activity was studied. Results obtained thus far demonstrate that the typical rate of decomposition, estimated from other areas of Arizona, has slowed, due to the colder temperatures, between 28- and 50-°F, Prescott, AZ has been experiencing. It was observed that rain and warmer temperatures from 60-73 °F, increased the rate of decomposition. Physical changes observed over the first 16 days of the project include: rigor mortis, severe bloating in the abdomen, edema surrounding the urethra seen from the abdomen, skin discoloration, liver mortis, coagulated blood and mucus escaping from the nasal cavity .. Insect and animal activity only began after 6 days of decomposition, with Calliphoridae (blow flies) and Formicidae (desert ants) activity and no visible larval activity in the cavities. With the temperatures recorded, it is likely cold weather and slowed decomposition have discouraged further activity up to this point. The sun pig showed bloating one week before the shade pig, yet the shade pig was more putrescent and exhibited higher insect activity. Changes in the weather, entomology, and physical conditions of the pigs will be monitored for a total of 6 weeks, or until skeletonization occurs. This study will provide important data and information on PM I for our unique high-desert ecosystem.