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11/14/2014
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Forensic Anthropology:Studying Bones
http://people.stu.ca/~mclaugh/skeleton8a.GIF
Forensic Anthropology
Forensic anthropology is the application of
the science of physical anthropology and
human osteology in a legal setting, most
often in criminal cases where the victim's
remains are in the advanced stages of
decomposition.
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Forensic Anthropology
A forensic anthropologist can assist in the identification of deceased individuals whose remains are decomposed, burned, mutilated, or otherwise unrecognizable.
Skills of a Forensic Scientist
• The analysis of skeletal, badly decomposed, or otherwise unidentified human remains is important in both legal and humanitarian contexts.
• In addition to assisting in locating and recovering human skeletal remains, forensic anthropologists work to assess the following features from a skeleton.– the age, sex, ancestry, stature, and other
unique characteristics.
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The Bones Know
• Bones offer amazing clues to the trained eye. A trained forensic anthropologist, using techniques favored by archeologists, can identify illness, pregnancies, and possible careers of the deceased.
• It is also possible to determine other activities the deceased individual was involved with in life.
The Bones Know
• Craniosacral measurements (skull measurements) have been established for all ages and race groups, which allow forensic anthropologists to establish a better picture of the deceased.
• The skull features unique racial identifiers such as the length of jaw and the distance between eye sockets.
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The Bones Know
• The bones also hold clues to what work the person did.
• Bony ridges form where the muscles attach and have pulled over the years.
• A bony ridge on the wrist may indicate that the decedent used their hands for a living, such as a chef or seamstress.
Forensic Anthropology• It’s the application of physical anthropology
to the legal process.
• Identify skeletal, badly decomposed or
unidentified human remains for legal and
human reasons.
• Started during the 19th century, popular
during 1930s because of WWII and the
Korean War.
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Forensic Anthropologists can often answer many questions:
• Are the remains human?
• Are the remains a single individual or mixed
remains of several individuals?
• When did the death occur?
• What are the gender, age, and race of the
individual?
Forensic Anthropologists can often answer many questions:
• What caused the death?
• What kind of death was it – a homicide, a
suicide, and accident or a natural death, or
is the cause still undetermined?
• Did the individual have any anatomical
peculiarities, signs of disease, or old
injuries?
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Forensic Anthropologists can often answer many questions:
• Can the individual’s height, body weight,
and physique be estimated?
Role of the Forensic Anthropologist:
� Recover Human Remains
� Identify Human Remains
� Determine Time or Cause of Death
Forensic Anthropology
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Locating Human Remains
� Cadaver dogs� Remote sensing
methods
Forensic Anthropology > Recovering Remains
� Find small bones or bone fragments
� Recover clothing and trace materials associated with bones
� Prevent damage of bones� Map the location of bones and
maintain chain of custody
Forensic Anthropology > Recovering Remains
Anthropologists can help:
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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
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)
http://en.wikipedia.org/wiki/Forensic_anthropology
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Determination of Gender
Male vs. Female Pelvis
The best indicators of gender :
• Some bones display specific features which can be used to help determination of the sex of the skeleton. The best indicators are the:– Skull– Pelvis– Head of the Femur
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Sex Estimation – Adult
• Usually related to size in adult long bones
• Male bones: usually larger, longer in a single population – be cautious if different populations are involved
• Maximum diameter of head of humerus and head of femur may be used.
• Much more difficult to estimate sex in children’s skeletons.
Sex Estimation: Skull
• Good area for sex determination
• Generalization: male skull more robust, muscle– marked than female:
• Sex estimation: face, mandible, vault
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Sex Estimation: Face
1. Supraorbital (Brow) ridges: more prominent in males2. Superior orbital margin: sharper in females3. Palate: larger in males4. Teeth: larger in males (Bass)5. Mastoid process: more prominent and rugged in males.6. Orbit (Eye socket): Rounder in females, more
rectangular in males7. Chin: more pronounced in males and larger jaws.8. Sloping forehead in males higher, rounded in females
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Skull differences
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Angle of the Jaw
1. Determination of Sex• Pelvis is the best bons (differences due to
adaptations to childbirth)
1. Females have wider subpubic angle
> 90o in women
< 90o in men
1. 1.
2.
2.3.3.
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• Why does a female’s subpubic angle need to be greater than 90o?
2.
1. Determination of Sex• Pelvis is the best bones (differences due to
adaptations to childbirth)
2. Females have a sciatic notch > 90°
2. 2.
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2.
1. Determination of Sex• Pelvis is the best bones (differences due to
adaptations to childbirth)
3. Females have a broad pelvic inlet
Males have a more narrow pelvic inlet
2. 2.
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Determination of Sex
• The acetabulum - the socket in the pelvis, which is used to secure the head of the femur - is larger in males than in females.
Gender with Skulls
Male vs. Female Skull
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Determining Sex using the skullForensic Anthropology
Male (left) and female (right) skulls
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)
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Sex Determination - Skull
Trait Female Male
Upper Edge of Eye Orbit Sharp Blunt
Shape of Eye Orbit Round Square
Zygomatic ProcessNot 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
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
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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
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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
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General Shapes of the Eye Orbits
From: Beyers, S.N. (2005). Introduction to Forensic Anthropology
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Determination of Race:
Caucasian
http://upload.wikimedia.org/wikipedia/en/c/cc/Skullcauc.gif
Trait
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
Orbital openings:round
Determination of Race:Asian (Asian decent and Native American
decent)
http://upload.wikimedia.org/wikipedia/en/b/b3/Skullmong.gif
Trait
Nasal Index .48-.53
Nasal SpineSomewhat
prominent spine
Nasal Silling/ Guttering
Rounded ridge
Prognathism Variable
Shape of Orbital
Openings
Rounded, somewhat circular
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Determination of Race:African: (everyone of African decent and West Indian decent)
http://upload.wikimedia.org/wikipedia/en/5/5e/Skullneg.gif
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)
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Cartilage is darker on xray than solid bone. Epiphyses aren’t fused yet.
No cartilage visible. Epiphyses are fused.
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
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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.
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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
http://library.med.utah.edu/kw/osteo/forensics/pos_id/boneid_th.html
2. Age Determination: Use of Teeth
http://images.main.uab.edu/healthsys/ei_0017.gifhttp://www.forensicdentistryonline.org/Forensic_pages_1/images/Lakars_5yo.jpg
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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 (5’6”) ± 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)
http://library.med.utah.edu/kw/osteo/forensics/index.html
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Sources:
• A very good website with photos and information on forensic anthropology (including estimating age, stature, sex and race):– http://library.med.utah.edu/kw/osteo/forensics/index.ht
ml• A good site with a range of resources:
– http://www.forensicanthro.com/• Another good primer for determining informtion
from bones:– http://www.nifs.com.au/FactFiles/bones/how.asp?page
=how&title=Forensic%20Anthropology• Great, interactive site:
– http://whyfiles.org/192forensic_anthro/