Using Pig Carcasses As Model Corpses
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RECREATINGDEATH'S ACRE IN THE SCHOOLYARD: Using Pig Carcassesas Model Corpses z ToTeach Concepts of ForensicEntomology & EcologicalSuccession 0- KENNETHG. SCHOENLY NEALH. HASKELL DAVIDK. MILLS CARINEBIEME-NDI KRISTIELARSEN YER LEE i-9 V) Downloaded from http://online.ucpress.edu/abt/article-pdf/68/7/402/53800/4452028.pdf by guest on 28 September 2021 t the "BodyFarm," nature takes its course, In homicides and other cases, time-since-death )-q with corpsesburied in shallowgraves, submerged in (called the postmortem interval or PMI) has special water,concealed beneath slabs of concrete,locked in relevance to crime scene investigators because such trunksof cars.As stand-insfor murdervictims, they knowledge narrows the field of possible suspects or the 0- servethe needsof science- and the causeof justice. passage of other events. Typically,the coroner or medical from W. Bass and J. Jefferson (2003) examiner takes legal chargeof a dead body and relies on the forensic z Death's Acre: Inside the Legendary pathologist to estimate the PMI. However, pathology-basedPMI indicators (e.g., body temperature, Forensic Lab-The Body Farm-Where rigor mortis, livor mortis) appear early, usually within the Dead Do TellTales the first 72 hours (Henssge et al., 2002). On the other Each year hundreds of human bodies and skeletal hand, insect indicators interpreted by a forensic ento- remains are uncovered as the result of accidental discov- mologist have lengthier and more staggered timetables S, ery, archeological excavation, and reports of foul play. that can persist for weeks, months, or even years on The position and location of human remains in rela- a human body before discovery. When dating human tion to other artifacts;the degree and nature of insect remains, forensic entomologists primarily use thermal involvement; and the state of decomposition, preserva- development to backtrackegg laying of adult flies (called tion, and medical condition all provide important clues development-based PMI estimation) and, secondarily, about the cause, manner, and time of death that the arthropod replacement patterns of adults and larvae law requires to be ascertained. Application of scien- (called succession-based PMI estimation). Beyond PMI tific principles and methods from the fields of forensic estimation, forensic entomologists have been consulted pathology, anthropology, and entomology can yield on criminalcases involving child abuse, hospital neglect, significant clues from these scenes. Nowhere have such contrabandtrafficking, and wildlife poaching. clues been more forthcoming than at the University of Tennessee's Anthropology Research Facility or "Body Forensic entomology, now at least 150 years old, Farm,"where, in 1981, Dr. William Bass founded the has been accepted as scientific testimony in court- world's first outdoor laboratory devoted exclusively to rooms in at least 30 U.S. states and in many countries the scientific study of postmortem human decay (Bass around the world. Recent publications on the subject & Jefferson, 2003). include three textbooks (Smith, 1986; Byrd & Castner, 2001; Greenberg & Kunich, 2002), a handbook for law enforcement and crime scene investigators (Catts KENNETHG. SCHOENLY,Ph.D., is Associate Professor of & Haskell, 1990), three autobiographies by some of Biological Sciences at California State University,Stanislaus, its most noted practitioners (Erzinclioglu, 2000; Goff, Turlock,CA 95382; e-mail: [email protected]. 2000; Benecke, 2005), and four books for the lay public NEALH. HASKELL,Ph.D., is Associate Professorof Forensic on forensic science with chapters devoted to forensic Science and Biology at SaintJoseph's College, Rensselaer,IN entomology (Sachs, 2001; Bass &Jefferson,2003; Roach, 47978; e-mail: [email protected] K. MILLS, 2003; Innes, 2005). The National Institute of Justice Ph.D., is Associate Professor of Biological Sciences at the whose mission is to fund new technologies and training Institute for Micromanufacturing at Louisiana Technical programs in forensic science has, since 1994, funded University, Ruston, LA 71272; e-mail: [email protected]. forensic entomology research proposals. Case studies CARINEBIEME-NDI (e-mail: [email protected]), KRISTIE and researchresults in forensic entomology continue to LARSEN(e-mail: [email protected]), and YERLEE (e- draw national and international attention on network mail: [email protected])areformer undergraduatestudents and cable television programs,radio documentaries,and in the Department of Biological Sciences at California State national news magazines. University,Stanislaus, Turlock,CA 95382. 402 THEAMERICAN BIOLOGY TEACHER, VOLUME 68,NO. 7, SEPTEMBER2006 e1.Environmental andbiological variables that are known to influencecarcass decay rates, successional processes, and/or arthropod species composition. VARIABLE(S) [ COMPARISON SUGGESTEDREFERENCE Sunlightand Heat Sun-Exposedvs.Shaded Carcasses Shean,B.S.et al. 1993.J. Forensic Sciences 38:938-949. Season Springvs. Summer Tabor,K.L. et al.2004.J. Medical Entomology 41:785-795 Dwellingsand Shade Indoorsvs. Outdoors Goff,M.L. 1991.J. Forensic Sciences 36:748-753. DielActivity Diurnalvs. Nocturnal Schoenly,K.G. 1983.J. N. Y Entomological Soc.91: 342-347. Concealmentand Burial Surface-Exposedvs.Buried Carcasses VanLaerhoven,S.L.and G.S. Anderson. 1999.1. Forensk Sciences 44:31-41. Clothingand Vertebrate Clothed/Scavengedvs.Clothed/ Komar,D.and 0. Beattie.1998.J. Forensk Siences 43: 792-796. Scavenging UnscavengedCarcasses Fire Burntvs. Unburnt Carcasses Avila,F.W. and M.L. Goff. 1998.J. Forensic Sciences 43: 581 -586. Water Submersedvs.Unsubmersed Carcasses Payne,J.A. and E.W. King.1972.J. Georgia Entomological Society 73:153-162. InsectAccessibility Insect-OpenCages vs. Insect-Proof Cages Payne,J.A. 1965. Ecology 46:592-602. InsectPredators Fire-AntPresence vs. Fire-Ant Absence Wells,J.D.andB.Greenberg. 1994.1. Medical Entomology 31:171-174. Downloaded from http://online.ucpress.edu/abt/article-pdf/68/7/402/53800/4452028.pdf by guest on 28 September 2021 In this article, we describe how to construct a mock beetles (Scarabaeidae), clothes moths (Tineidae), crime scene, acquire a pig carcass, sample its arthropod and perhaps several others. fauna, integrate photographic, climatic and arthropod suc- * In unembalmed carcasses lying on the ground, the cessional data, and estimate the PMI from insect succes- carrion-arthropodcommunity proceeds as a con- sional timetables. (For a complementary classroom activity tinuum of gradual changes, not as a series of neatly on development-basedPMI estimation, see Carloye,2003.) defined decay stages with distinct arthropod faunas The experimental layout we describe below represents in each. the untreated control or background condition (i.e., sur- * characterizephysical face-exposed, unclothed, and unscavenged by vertebrates) Decay stages are often used to in a carcass, however, they against which other treatmentscan be compared (e.g., bur- and chemical changes or disappearanceof ied, burned, submerged, clothed, or vertebratescavenged; rarely delineate the appearance in successional process. see Table 1 for other examples). Exposing pairs of carcasses entire arthropodgroups the to contrasting environmental and biological conditions * Carcass decay rates and carrion-arthropodsucces- invites students to explore factors that affect carcass decay sion are affected by season, temperature,exposure rates, order and timing of arthropod succession, and spe- mode, accessibility to insect and vertebratescaven- cies composition. This activity can be incorporated into a gers, degree of concealment, and countless other high school or college-levelforensic science, entomology, or factors. ecology course to illustrate working principles of forensic * Succession aboveground continues with succession entomology or ecological succession or both. Outputs of belowground as the products of carcass decay this activitycan be stored in electronic (Excel) spreadsheets alter the underlying soil structure and biota while (or tabulated on graph paper) and/or digitized images and introducing nutrients for subsequent and enhanced then discussed in relation to actual cases published in the plant growth. forensic science literature.Some of the outcomes students are likely to experience (i.e., see, smell, touch, and even Carcass Acquisition & Handling hear) are listed here and below: Forensicentomologists view the 50-lb domestic pig (Sus * Blow Ries (Family Calliphoridae),typically the most scrofaLinnaeus) as the most promising "model corpse" for reliableand most abundant PMIindicators for devel- both teaching and research due to its similarityto humans opment-based estimation, can lay up to 300 eggs in internal anatomy, fat distribution, size of chest cavity, at a time, typically 3 times in their lifetime, and are and lack of heavy fur (Catts, 1992; Byrd & Castner,2001). generally(with ants) the first insects to discover and Pigs also share with humans an omnivorous diet, indicat- colonize a human body. ing that they may have a similar gut fauna (Anderson & * The insects that hold promise as succession-based VanLaerhoven,1996). Beforeplanning this activity,contact PMI indicators, whose abundances vary sever- your superintendent or supervisor to determine what regu- al thousand-fold on a carcass, are the blow flies lations exist for registering,obtaining and using vertebrate (Calliphoridae),flesh flies(Sarcophagidae), house and animals (living or dead) for teaching. At the college