Forensic Anthropology - Delran High School

Forensic Anthropology - Delran High School

Forensic Anthropology: Studying Bones Why Study Bones? They constitute the evidence for the study of fossil man. They are the basis of racial classification in prehistory. They are the means of biological comparison of prehistoric peoples with the present living descendents. They bear witness to burial patterns and thus give evidence for the culture and world view of the people studied. They form the major source of information on ancient diseases and often give clues as to the causes of death. Their identification often helps solve forensic cases. From: "Human Osteology - A Laboratory and Field Manual" 3rd Edition, 1987

A Caveat Informative features about the age, sex, race and stature of individuals based on bones is based on biological differences between sexes and races (males are generally taller and more robust) as well as differences due to ancestry (certain skeletal features of the skull) However, it is imprecise because so much human variation exists and because racial differences tend to homogenize as populations interbreed Still differences do exist and the more features you survey, the more precise your conclusions will be

What Can We Learn? Determination of Sex Pelvis Skull Determination of Race Skull Approximate Age Growth of long bones Approximate Stature Length of long bones Postmortem or antimortem injuries Postmortem interval (time of death) 1. Determination of Sex Pelvis is the best bones (differences due to adaptations to childbirth) 1. females have wider subpubic angle 2. females have a sciatic notch > 90 3. females have a broad pelvic inlet 2. 3. 3. 1.

1. 2. 1. Determination of Sex Pelvis best (another view) 1. females have wider subpubic angle 2. females have a broad, shovel-like ilium 3. females have a flexible pubic symphysis 2. 3. 1.

2. 1. 1. Determination of Sex: Cranium Crests and ridges more pronounced in males (A, B, C) Chin significantly more square in males (E) Mastoid process wide and robust in males Forehead slopes

more in males (F) 1. Determination of Sex Normally, the long bones alone are not used alone to estimate gender. However, if these bones are the only ones present, there are characteristics that can be used for sex determination. E.g. maximum length of humerus in females is 305.9 mm, while it is 339.0 mm in males Determination of Race It can be extremely difficult to determine the true race of a skeleton for several reasons:

First, forensic anthropologists generally use a three-race model to categorize skeletal traits: Caucasian (European), Asian (Asian/Amerindian), and African (African and West Indian). Although there are certainly some common physical characteristics among these groups, not all individuals have skeletal traits that are completely consistent with their geographic origin. Second, people of mixed racial ancestry are common. Often times, a skeleton exhibits characteristics of more than one racial group and does not fit neatly into the three-race model. Also, the vast majority of the skeletal indicators used to determine race are non-metric traits which can be highly subjective.

Despite these drawbacks, race determination is viewed as a critical part of the overall identification of an individual's remains. White, Asian, African From: Beyers, S.N. (2005). Introduction to Forensic Anthropology Features of the Skull Used in Race Determination Nasal index: The ratio of the width to the height of the nose, multiplied by 100 Nasal Spine Feel the base of the nasal cavity, on either side of the

nasal spine do you feel sharp ridges (nasal silling), rounded ridges, or no ridges at all (nasal guttering)? Prognathism: extended lower jaw Shape of eye orbits (round or squareish Nasal spine Nasal Silling and Guttering From: Beyers, S.N. (2005). Introduction to Forensic Anthropology General Shapes of the Eye

Orbits From: Beyers, S.N. (2005). Introduction to Forensic Anthropology Determination of Race: Caucasian Trait Orbital openings: round Nasal Index: <.48

Nasal Spine: Prominent spine Nasal Silling / Guttering: Sharp ridge (silling) Prognathism: Straight Shape of Orbital

Openings: Rounded, somewhat square Nasal spine: Prominent Progathism: straight Determination of Race: Asian (Asian decent and Native American

decent) Trait Nasal Index Nasal Spine .48-.53 Somewhat prominent spine Nasal Silling/ Guttering Rounded ridge Prognathism

Variable Shape of Orbital Openings Rounded, somewhat circular Determination of Race: African: (everyone of African decent and

West Indian decent) Trait Nasal Index >.53 Nasal Spine Very small spine Nasal Silling/ Guttering No ridge (guttering) Prognathism

Prognathic Shape of Orbital Openings Rectangular or square Determination of Age The long bones are

those that grow primarily by elongation at an epiphysis at one end of the growing bone. The long bones include the femurs, tibias, and fibulas of the legs, the humeri, radii, and ulnas of the arms, and the phalanges of the fingers and toes. As a child grows the epiphyses become calcified (turn to

hard bone) 2. Determination of Age from Bones Ages 0-5: teeth are best forensic odontology Baby teeth are lost and adult teeth erupt in predictable patterns Ages 6-25: epiphyseal fusion fusion of bone ends to bone shaft epiphyseal fusion varies with sex and is typically complete by age 25 Ages 25-40: very hard Ages 40+: basically wear and tear on bones periodontal disease, arthritis, breakdown of pelvis,

etc. Can also use ossification of bones such as those found in the cranium Epiphyseal Fusion: A General Guide Epiphyseal Fusion The figures below are of the Epiphyses of the femur or thigh bone (the ball end of the joint, joined by a layer of cartilage). The lines in the illustrated Image 1 show the lines or layers of cartilage between the bone and the epiphyses. The lines are very clear on the bone when a person, either male or female is not out of

puberty. In Image 2, you see no visible lines. This person is out of puberty. The epiphyses have fully joined when a person reaches adulthood, closing off the ability to grow taller or in the case of the arms, to grow longer. Figure 1. Figure 2. 2. Determination of Age from Bone: Signs of wearing and antemortem injury Occupational stress wears bones at joints

Surgeries or healed wounds aid in identification 2. Age Determination: Use of Teeth 3. Determination of Stature Long bone length (femur, tibia, humerus) is proportional to height There are tables that forensic anthropologists use (but these also depend to some extent on race)

Since this is inexact, there are confidence intervals assigned to each calculation. For example, imagine from a skull and pelvis you determined the individual was an adult Caucasian, the height would be determine by: Humerus length = 30.8 cm Height = 2.89 (MLH) + 78.10 cm = 2.89 (30.8) + 78.10 cm = 167 cm (56) 4.57 cm See your lab handout for more tables 4. Other Information We Can Get From Bones: Evidence of trauma (here

GSW to the head) Evidence of post mortem trauma (here the head of the femur was chewed off by a carnivore) Sources: A very good website with photos and information on forensic anthropology (including estimating age, stature, sex and race): ml

A good site with a range of resources: Another good primer for determining informtion from bones: =how&title=Forensic%20Anthropology Great, interactive site: Skull Humerus Lab: the bones

were interested in Pelvis Femur Tibia Sex Determination - Pelvis Sub-Pubic Angle Pubis Body Width Greater Sciatic Notch Pelvic Cavity Shape

Sex Determination - Skull Trait Female Upper Edge of Eye Orbit Male Sharp Blunt Round Square

Zygomatic Process Not expressed beyond external auditory meatus Expressed beyond external auditory meatus Nuchal Crest (Occipital Bone) Smooth Rough and bumpy

External Occipital Protuberance Generally Absent Generally present Frontal Bone Round, globular Low, slanting Mandible shape Rounded, V-shaped

Square, U-shaped Ramus of mandible Slanting Straight Shape of Eye Orbit Sex Determination - Tibia Proximal End Lateral Condyle Distal End

Ankle Bone Medial Condyle If Youre In Doubt If you dont know what something is that is referenced in the lab: Check to see if there is an accompanying picture referenced, and turn to it in your lab handout Try Googling either the structure (e.g. Wikipedia) or Google image search Ask Artiss Some skeletons have a femur and not a tibia, and some have a tibia and not a femur do

appropriate measurements for whichever you have

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