Lab 10 -Forensics and Variation

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Name: ________________________________________ Section: __________ ANT 3514 – Introduction to Biological Anthropology Lab 10: Forensic Anthropology and Modern Human Variation Learning Objectives:  Estimate the sex, stature, and age of death of an individual based on skeletal remains.  Critically evaluate the notion that there are different biological human races. Purpose: To become familiar with the methods employed by forensic anthropologists to create biological profiles of skeletal remains. Forensic anthropologists apply their knowledge of biological anthropology to modern medicolegal contexts. Working in various settings (e.g . , for Medical Examiners and coroners, war crimes investigations, or the U.S. military), forensic anthropologists help to identify the dead by generating biological profiles of deceased individuals – estimations of their age, sex, ancestry, stature, and identifying characteristics – based on traits visible and/or measurable in the recovered skeletal remains. Forensic anthropologists often ask questions and use tools that are similar to those of other biological anthologists such as paleoanthropologists and bioarchaeologists, so many of the things you will do in this lab will seem familiar. Yet some tasks that might have been relatively easy in previous labs, such as telling males from females in sexually dimorphic apes, becomes more difficult when we study anatomically modern humans. Homo sapiens is a very young species with little genetic variation and a low degree of sexual dimorphism. As humans, we are adept at perceiving even small differences in appearance that can be used to distinguish individuals. Features that would be considered minor variation within many other species play a significant role in how we identify other people in our day-to-day lives, and may often carry sociocultural meanings that are disconnected from the biological roles of these traits. In this week’s lab we will see how difficult it can actually be to detect variation among anatomically modern humans once some of the more superficial characteristics such as skin color are removed. Since all modern humans spread across the globe are members of the same species ( H. sapiens ), most human variation is continuous, with certain physical traits like skin color and nose morphology following geographic gradients called clines . Some combinations of discrete skeletal traits (that can be described as appearing either one way or another) are concordant, meaning they frequently appear together in the same individual. Forensic anthropologists are often concerned with identifying such traits in order to assess the ancestral population with which human remains might be associated. However, most of the traits contributing to human variation are non-concordant, meaning they are not tied to each other and can be inherited independently (think back to Mendel’s Law of Independent Assortment). For instance, while dark hair and dark eyes are often seen in the same individual, not everyone who has dark hair necessarily has dark eyes. 1

STATION 1: Age-at-Death (2 pts.) Aging Subadults : Recall that as a child your first set of teeth was lost and replaced by your adult teeth. This process is tightly controlled by genetics, and thus children can be aged accurately by assessing their stage in the dental eruption sequence. Refer to the dental eruption sequence schematic in the handout to answer the following questions: 1. During what age range (include ±) do the first adult (permanent) teeth erupt? What teeth are these? 2. By what age range (include ±) would all deciduous teeth be fully replaced by adult/ permanent dentition? By what age are all adult teeth fully erupted? Aging Adults : When examining the remains of fully developed adults, forensic anthropologists cannot rely on tooth development to inform their age estimates. Instead, they look at the joints of the skeleton (in particular, the relatively immobile joints of the pelvis) and chart metamorphic and degenerative (i.e . , “wear and tear”) changes to regions such as the pubic symphysis. 3. Use the Suchey-Brooks method to estimate the age of the adult skeletal remains. This method combines descriptions of age-related changes in the pubic symphysis with helpful casts of known-age skeletal materials. Read the descriptions of the six age phases and compare the unknown specimen with the casts in order to answer the following: a. What phase best matches the forensic case individual’s pubic symphysis? *b . Report the age range for this phase: ____________________ STATION 2: Stature (1 pt.) The bones of the leg are particularly relevant for estimating an individual’s height (i.e., stature). Using the osteometric board , determine the maximum length of the femur and enter it into the stature equation below. (.25 pts) 1. Maximum femoral length ( FL ) = ____________ cm Forensic anthropologists use different stature formulae for males and females of different ancestral populations. This femur is from a male of European descent, so use the following formula to calculate his stature: (.25 pts) *2. 2.32 * FL + 65.53 ± 3.94 = _______________________cm Your answer should have an estimated height and an ERROR RANGE (that’s what the ± is for) 2

3. Why do you think it is important for forensic anthropologists to use population-specific stature formulae? (Hint: think about what we have learned about differences in limb propor- tions in populations living in different climates). (.5 pts) STATION 3: Biological Sex (2 pts.) Use Ascadi and Nemeskeri’s (1970) scoring system to assign scores between 1 and 5 to each cranial feature. Use Phenice (1969) scoring system to assign scores between 1 and 5 or presence/absence to each os coxa feature. Indicate whether each trait is indicative of either a male or female and utilize the handout to estimate the sex of the individual based on the average indication of the traits. TRAIT (Use the handouts) Case Individual’s Score (1-5) Indication of Sex (Male/Female/Indeterminate) Nuchal crest Mastoid process Supra-orbital margin Supra-orbital ridge/glabella Greater Sciatic Notch Subpubic Angle (> or < 90 degrees) *Estimated sex: 1. The cranium is only one of several regions of the skeleton that can be utilized for sex esti- mates. In fact, sex estimates based on the pelvis tend to be more accurate. Why is the pelvis more accurate, and the cranium less accurate? 3

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STATION 4: Modern Human Craniofacial and Dental Variation (2.5 pts.) When investigating individuals from disparate parts of the globe, some geographic variation is captured in the craniofacial skeleton. While none of the below traits occur in all members of a geographic population, certain traits occur with higher frequencies in certain populations. Many of which depend on factors such as latitude, temperature, elevation, or ancestry. Examine the materials provided, and explore how modern human cranial and dental variation can correlate with broad geographic ancestral groups. Keep in mind the clinal and non-concordant nature of many human traits as described in the introductory text. Trait African European Asian Orbit Shape (Round vs. Rectangular) Nasal Aperture (Broad vs. Narrow vs. In- termediate) Anterior Nasal Spine (Prominent vs reduced vs. absent/extremely re- duced) Nasal Sill or Gutter (Sharper sill vs. sloping gutter) Nasal Bone Shape (High/“steepled” vs. Medium/“tented” vs. Low/“Quonset hut- shaped”) Incisor Morphology (“Shovel-shaped” vs. “blade-shaped”) Blade-shaped 1. Based on the traits on the table above, what ancestry would you estimate for your forensic case individual? List 2 traits to support your assessment. *Forensic Case Individual : ___________________________ 2. Did any traits overlap between crania? Based on your answer, how reliable do you think these broad geographic/ancestral classifications are? 4

After Lab Activity (2pts.) Visit the website for PBS’ Race, the Power of an Illusion ( http://www.pbs.org/race/000_General/000_00-Home.htm ) and spend some time browsing through the pages. Use the website to help you answer the following questions. Be sure to use quotes and proper citations for any language taken from the site or any other source. 1. Describe a fact you learned while looking through the website. What did this fact teach you about race in a biological context? 2. Read the interview with Stephen Jay Gould in the background readings section of the web- site ( http://www.pbs.org/race/000_About/002_04-background-01-09.htm ) and answer the fol- lowing questions: a. Where does the term “Caucasian” come from? b. What is Gould’s explanation for why there is so little variation within H. sapiens ? c. What is the U.S. racial classification system based upon? 5

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