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Anth 300 Forensic Anthropology
Dr. Darlene Applegate
Spring 2008
LAB 7: ESTABLISHING FORENSIC CONTEXT

INTRODUCTION

After human remains have been discovered, the task of investigating those remains begins. If the human remains are skeletonized, decomposed, desiccated, dismembered, burned, or commingled, the expertise of a forensic anthropologist is required. According to Pickering and Bachman (1997), forensic analysis may be conceived as a ten-step process guided by key questions.
The first three questions allow investigators to establish the forensic context of a case. In other words, does the case have medico-legal significance, such that a detailed forensic analysis is warranted? Ideally, this determination will be made by a forensic anthropologist in the field at the site where the remains were discovered. Whether accomplished in the field or in the lab, the process of assessing the forensic significance is an important one. This exercise introduces the basic principles of establishing forensic context.


OBJECTIVES

TERMS

READINGS

IS IT BONE?

The first step of forensic investigation involves confirming whether or not the discovered material is indeed bone. Complete skeletal elements often are easily identified, but skeletal fragments may resemble objects made of non-bone materials. Natural materials and objects that may be confused with bone include tree roots, wood fragments, shell, and rocks, especially light-colored sedimentary rocks. Human-made materials and objects that may be confused with bone include plastic, styrofoam, foam insulation, sponge, plaster, mortar, and even discarded gum. The more weathered the cultural materials and objects, the more likely they are to be confused with bone.

Both macroscopic (with the unaided eye or a low-power magnifying glass) and microscopic examination can be used to identify bone. Three macroscopic variables that may be used to distinguish bone from other materials and objects are surface texture, internal structure, and color/luster.


 Surface Texture
 Color/Luster
 Internal Structure
Bone
 compact, some degree of graininess
 varies from creamy white to yellowish to brownish; dull luster
 porous, spongy texture
Rock
 compact, some degree of graininess various shades of white, gray, tan, brown;
dull luster
 usually not porous, not spongy
Shell
 compact, smooth
 exterior is dark or light in color when fresh but weathers to shades of white and gray; pearly luster
 not porous, not spongy
Wood
 not compact, fibrous
 various shades of brown; dull luster
 complex layering
Pottery
 compact, smooth to slightly grainy
 undecorated pottery varies from white to cream to yellow to red; dull luster if
unglazed and glassy luster if glazed
 may be porous (especially is not glazed), not spongy
Plastic, Styrofoam, Plaster
 non-compact
 various shades of white, gray, tan; dull luster
 not porous, not spongy


IS IT HUMAN?

Once it is established that bone is present, the next step involves determining whether or not the bone is human. This determination is easier to make when complete skeletal elements are present. In contrast, broken and fragmented human bones, human bones from immature individuals, and isolated human teeth are more difficult to separate from non-human specimens, especially by untrained individuals. Forensic anthropologist Dr. William Bass of the University of Tennessee-Knoxville’s Department of Anthropology estimated that 25-30% of the bones brought to him for identification over his career were non-human (Byers 2008).

Similarities between certain human and non-human skeletal elements are well documented. Bear and seal hand/foot bones lacking the claw elements, for instance, are very similar to human hand/foot bones. Deer vertebrae, especially if the spinous processes are broken off, resemble human vertebrae. Turtle shell fragments resemble human cranial fragments in their morphology; turtle shell sutures, however, are more jagged and regular than human cranial sutures. Forensic anthropologist Stanley Rhine (1998) recounted a case in which a medical doctor incorrectly identified a turtle carapace as a human skull cap, indicating that even physicians who are not specifically trained in forensic anthropology or osteology may misidentify non-human bones.

In many respects, human bones resemble the bones of other mammals and animals. Two traits that may be used, however, to distinguish human from non-human bone are architecture and maturity (Byers 2008). Architecture refers to bone shape and morphology. Many differences in the architecture of bones from animal species are due to locomotor differences, especially differences between quadrupeds and bipeds. Maturity refers to degree of growth and development. Small bones of nonhuman species will not be confused with subadult human bones because the latter lack epiphyses.

Differences in Bone Architecture in Bipeds and Quadrupeds.

 Biped
 Quadruped
Skull
  • foramen magnum centered on inferior view
  • enclosed bony eye socket
  • flattened facial area
  • triangular palate
  • chin on mandible
  • mandible is one single bone
  • small canine teeth
  • foramen magnum posterior on interior view
  • open bony eye socket
  • enlongated facial area
  • elongated palate
  • no chin on mandible
  • mandible is two bones fused in chin area
  • large canine teeth
Vertebrae
  • vertebral column is s-shaped
  • vertebrae have short spinous processes
  • vertebral column is c-shaped
  • vertebrae have long spinous processes
Pelvic Girdle
  • sacrum is wide and broad
  • ilium is broad and wide
  • pelvic outlet is wide
  • sacrum narrows in inferior direction
  • ilium is elongated
  • pelvic outlet is narrow
Thorax
  • body of scapula is a right triangular
  • spine of scapula is perpendicular to long axis of body
  • acromion process of scapula is pronounced
  • rib bodies are more curved
  • sternum is broad at body and narrower at gladiolus
  • body of scapula is an isosceles triangle
  • spine of scapula is parallel to long axis of body
  • acromion process is poorly developed
  • rib bodies are less curved
  • body and gladiolus of sternum are equal width
Long Bones
  • smaller processes (e.g., greater trochanter)
  • tibia and fibula unfused
  • diaphyses are smaller in circumference
  • larger processes
  • tibia and fibula may be fused
  • diaphyses are larger in circumference


IS IT MODERN?

Recall that forensic cases typically involve skeletal remains from individuals who have been deceased no more than about 50 years. Such remains are referred to as “modern,” “contemporary,” or “recent.” In contrast, remains from individuals who have been deceased more than 50 years are referred to as “historic” or “prehistoric” depending on their relative age.

As bones are exposed to various weathering agents, they undergo physical changes that involve loss of moisture and loss of collagen, the organic component of bone tissue. Because of their condition, then, recent skeletal remains may be described as “fresh,” whereas non-recent skeletal remains may be described as “dry.”

There are four lines of evidence used to determine the relative age of a human bone: condition of interment, personal belongings, body modifications, and bone condition or state of preservation (Byers 2005). For this lab we will focus on the latter. Bone condition or state of preservation includes seven traits: color, texture, hydration, weight, condition, fragility, and soft tissue (Byers 2005), as summarized below.


 Recent (Fresh)
 Not-Recent (Dry)
Color
 creamy white
 yellowish or brownish
Texture
 smooth
 pitted and grainy
Hydration
 greasy
 dried out
Weight
 heavier
 lighter
Condition
 breaks in spiral fractures
 breaks in perpendicular fractures
Fragility
 tough, resistant
 fragile, friable
Soft Tissue
 may be present
 absent


ASSIGNMENT

Carefully examine the three sets of specimens provided in the lab. For the first set of specimens, distinguish bone from non-bone materials and objects. For the second set of specimens, distinguish human bone from non-human bone. For the third set of specimens, distinguish recent human bone from non-recent human bone.

Your determinations will be based on several lines of evidence. The lab overview, the Byers textook and lab manual, and your bone drawings constitute the primary line of evidence. Second, comparative collections and materials are provided in the lab. Third, reference books on the human skeleton as well as mammalian osteology are provided in the lab.

Record all answers neatly and legibly in pencil on the answer sheet provided by the instructor. Do not provide more information about a particular specimen than is requested. For example, when asked to identify a skeletal specimen as human or non-human, there is no need to identify the particular skeletal element or non-human species.

As always, remember to handle carefully all specimens by keeping them on styrofoam trays or bubble wrap, wearing gloves with real bones, and using two hands when examining or transporting specimens. Do not separate specimens from their labels or bags.


REFERENCES

Byers, Stephen N.
2008 Introduction to Forensic Anthropology: A Textbook (3rd ed.). Allyn and Bacon, Boston.

Byers, Stephen N.
2008 Forensic Anthropology Laboratory Manual (2nd ed.) Allyn and Bacon, Boston.

Pickering, Robert B. and David C. Bachman
1997 The Use of Forensic Anthropology. CRC Press, Boca Raton, FL.

Rhine, Stanley
1998 Bone Voyage. University of New Mexico Press, Albuquerque.

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Page composed by Darlene Applegate, darlene.applegate@wku.edu
Last updated on January 21, 2008
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