Forensic Taphonomy and Ecology of North American Scavengers

By Susan N. Sincerbox and Elizabeth A. DiGangi

Forensic Taphonomy and Ecology of North American Scavengers compiles research on vertebrate scavenging behavior from numerous academic fields, including ecology and forensic anthropology. Scavenging behavior can displace remains from their depositional context, confound postmortem interval estimation, destroy osteological markers, and inflict damage that mimics or disguises perimortem trauma. Consequently, the actions of vertebrate scavengers can significantly impact the medicolegal investigation of human remains. It is therefore critical when interpreting a death scene and its associated evidence that scavenging be recognized and the possible effects of scavenging behavior considered.

This book is an ideal reference for both students and medicolegal professionals, serving as a field manual for the identification of common scavenging species known to modify human remains in North America. In addition, this book presents a framework to guide investigators in optimizing their approach to scavenged cases, promoting more complete recovery of human remains and the accuracy of forensic reconstructions of peri- and postmortem events.

• Examines scavenging behavior through an evolutionary and ecological lens, integrating research from diverse fields
• Includes brief summaries of the taphonomic signatures and ecological contexts of common or well-studied North American scavenging taxa
• Proposes strategies to maximize the recovery of vertebrate-scavenged human remains and improve forensic reconstructions of peri- and postmortem events

• Language: English
• Publisher: Academic Press
• Release date: Nov 15, 2017
• ISBN: 9780128132630

Susan N. Sincerbox

Ms. Sincerbox teaches Introductory Biological Anthropology, in the Forensic Anthropology Program, at Texas State University, San Marcos, Texas. Her research spans forensic anthropology, osteology, human decomposition and ecology. She previously participated in the HHMI Interdisciplinary Research Program and is currently focused on decomposition rate and post-mortem interval estimation.

Book preview

companionship.

Chapter 1

Introduction

Abstract

The introduction to the volume discusses the addition of taphonomy, or the suite of things that happen to a body after death, to forensic anthropological investigations. In so doing, it defines both forensic anthropology and taphonomy, and reviews early research conducted in forensic taphonomy. This chapter discusses the benefits to taking an ecological approach in forensic taphonomy. Additionally, a background of evidentiary standards in forensic science is provided. The Daubert trilogy—namely, Daubert, Kumho, and Joiner court decisions—is discussed in light of efforts to improve evidentiary standards in the United States. The recently formed Organization of Scientific Area Committees (OSACs) are discussed as a response to the National Academy of Science report on measures needed to improve the forensic sciences. Finally, the chapter concludes by discussing how the approaches recommended in this volume aim to contribute to improved investigation outcomes of scavenged death scenes.

Keywords

Forensic anthropology; taphonomy; ecology; evidentiary standards; Daubert trilogy; Organization of Scientific Area Committees (OSACs); error

Outline

Forensic Science Under the Medicolegal Microscope

Forensic Error: Proving Guilt in the Innocent

Putting Science in Forensic Science

Conclusion

Guide To This Volume

References

Anthropology is the study of human beings. Given this broad scope, the field is divided into four major subdisciplines to fully answer the question of what it means to be human: (1) archaeology, (2) biological anthropology, (3) cultural anthropology, and (4) linguistic anthropology. Forensic anthropology is a relatively young subfield within biological anthropology which originated when anthropological knowledge of human skeletal biology began to be applied to medicolegal questions. By the 1970s, around the time that the discipline was formalized via establishment of professional organizations in the United States, such questions were limited to decedent identification and were addressed using osteological markers and measurements. Since the field’s inception, however, the role of the forensic anthropologist has expanded beyond identification to include evidence recovery and documentation, skeletal trauma analysis, and interpretation of postmortem modifications to skeletal material (Dirkmaat et al., 2008).

Thus, contemporary forensic anthropologists are concerned not only with the identification of the decedent, but with reconstruction of postmortem events including deposition of remains and decomposition. Forensic taphonomy emerged as a subfield as forensic anthropologists increasingly recognized the importance of context to analyzing human skeletal remains. Taphonomy means laws of burial and was first developed by paleontologists to help them understand what processes and variables would lead to fossilization, important when attempting to locate possible fossil deposits (Efremov, 1940). Paleoanthropologists began applying taphonomic principles to their own studies to answer questions about early hominid behavioral patterns, such as whether populations were engaged in hunting or scavenging of large prey, evidenced by the types of bone modifications present (i.e., marks left by carnivore scavenging vs marks left by stone tools) (Binford, 1981; Blumenschine, 1986, 1988; Brain, 1983). With the expansion of forensic anthropology’s purview discussed earlier, taphonomy was incorporated to better understand the archaeological context of a burial or surface scatter and the factors that may have impacted the remains since deposition, including decomposition.

Early research in taphonomy attempted to identify sequential patterns in human decomposition that could be used to estimate the postmortem interval, or time since death, through retrospective studies of forensic case reports (Galloway et al., 1989; Megyesi et al., 2005). Researchers quickly learned that decomposition is incredibly complex, with the rate and patterning impacted by both intrinsic variables (i.e., body size, presence of disease or trauma) and environmental variables (i.e., climate, animal scavenging) (Mann et al., 1990). To address these challenges, decomposition research facilities, including the University of Tennessee’s Anthropology Research Facility in Knoxville, Tennessee and the Forensic Anthropology Center at Texas State University in San Marcos, Texas, were created to conduct actualistic studies of human decomposition in outdoor contexts.

Scavenging by vertebrate taxa, or animals, is common when human remains have been deposited outdoors, and can also occur indoors, when pets or pests are present. Significant research has been conducted in an attempt to describe the taphonomic signatures (i.e., marks left behind) of different species, including: vultures (Beck et al., 2015; Reeves, 2009; Spradley et al., 2012), bears (Carson et al., 2000; Murad and Boddy, 1987; Saladié et al., 2013), dogs and coyotes (Colard et al., 2015; Haglund, 1997a, Haglund et al., 1989; Steadman and Worne, 2007; Willey and Snyder, 1989), wild cats (Montalvo et al., 2007; Pickering and Carlson, 2004), rodents (Haglund, 1992; Haglund, 1997b; Klippel and Synstelien, 2007; Tsokos et al., 1999), and other small mammals (King et al., 2016; Synstelien, 2013; Synstelien and Klippel, 2005). Most taphonomy textbooks include chapters summarizing these signatures for major scavenging taxa such as canids and rodents (Haglund and Sorg, 1997, 2001; Pokines and Symes, 2014; Schotsmans et al., 2017). However, for many taxa that are less frequently involved in forensic casework, scavenging behavior and taphonomic effects are often extrapolated from a handful of case reports or incidental observations made in larger scavenging studies.

Additionally, the data produced in forensic scavenging studies are inherently context-specific due to behavioral nuances between populations of the same species across space and time (i.e., differences in vulture (Coragyps atratus and Cathartes aura) scavenging patterns between Central Texas and Southern Illinois (Dabbs and Martin, 2013); differences in the food habits of American puma (Felis concolor) populations in temperate compared to subtropical habitats (Iriarte et al., 1990); and different activity patterns and dietary shifts by coyotes (Canis latrans) in response to the reintroduction of wolves (Canis lupus) into northern Montana (Arjo and Pletscher, 2000)). Intraspecies variation in scavenging patterns has seen scant treatment in the forensic literature, as it has been traditionally assumed that all members of a scavenging species will follow predictable patterns of behavior. The above examples demonstrate that this assumption may not always hold true. For instance, in their forensically-focused study of vulture behavior, Dabbs and Martin (2013) found that differences in behavior were reflected in the taphonomic signature left by the birds on human remains. Therefore, understanding the behavioral variability of scavengers is critical in accurately interpreting and identifying taphonomic signatures.

An ecological approach to vertebrate scavenging behavior would allow inferences to be made about scavenged death scenes in regions where scavenger behavior has yet to be forensically studied. While existing forensic research provides a foundation for case analysis and interpretation, an understanding of specific ecological influences on scavenger behavior is important to shape effective, individualized strategies for recovery and analysis of human remains. The ecological principles presented in this book, coupled with detailed profiles of typical behavior of scavenging organisms, may be drawn upon to provide a theoretical underpinning for decisions made in the course of a death investigation. Sound theoretical bases for investigative decision-making and forensic interpretation contribute to successful casework by bolstering the reliability of forensic analyses and, as will be discussed in the following section, support decisions of admissibility of evidence in a courtroom