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Forensic Science: Fundamentals & Investigations, Chapter 13 1
Chapter 13 Forensic Anthropology: What We Learn from Bones By the end of this chapter you will be able to:
o Describe how bone is formed o Distinguish between male and female skeletal
remains o Explain how bones contain a record of injuries
and disease
All Rights Reserved South-Western / Cengage Learning © 2012, 2009
Forensic Science: Fundamentals & Investigations, Chapter 13 2
Chapter 13 Forensic Anthropology: What We Learn from Bones By the end of this chapter you will be able to:
o Describe how a person’s approximate age could be determined
o Explain the differences in facial structures among races
o Discuss the role of mitochondrial DNA in bone identification
Forensic Science: Fundamentals & Investigations, Chapter 13 3
Forensic Anthropology
o Anthropology—the scientific study of all aspects of human development and interaction
o Physical anthropology—studies human differences
o Forensic anthropology—studies these identifying characteristics on the remains of an individual
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Historical Development
o 1800s—scientists begin studying skulls, differences in male/female anatomy, bone formation
o 1897—Leutgert murder case: sausage maker’s wife murdered; bone fragments found in his factory
o 1932—the FBI opens the first crime lab o Smithsonian Institution partners with FBI
Forensic Science: Fundamentals & Investigations, Chapter 13 5
Historical Development
o 1939—William Krogman publishes Guide to the Identification of Human Skeletal Material
o Soldiers killed in World War II are identified using anthropologic techniques
o DNA—new tool to analyze skeletons. Focuses on mitochondrial DNA
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Characteristics of Bone
o Bones are alive – capable of growth and repair
o Marrow—creates blood cells o Hormones affect the amount of
calcium in the blood and bones
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Development of Bone
o Osteoblast cells—where bones originate • Eventually become Osteocytes (mature bone cells)
o Ossification—process where osteoblast cells migrate to the center of cartilage production and deposit minerals
• Begins during the first few weeks of pregnancy o Periosteum – protective layer of nerves and blood
vessels. Keeps bones moist and aids in repair o Life cycle—bone is deposited, breaks down, and
replaced throughout our lives
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Forensic Science: Fundamentals & Investigations, Chapter 13 9
Development of Bone
o Osteoclasts—the 2nd type of bone cell • Specialized to dissolve bone • Allows bones to reshape as they grow • Balances calcium levels in blood • Removes cellular wastes and debris from bones • Removes damaged part of bone
o Osteoporosis—a deficiency of calcium in the bones
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How Bones Connect
cartilage—wraps the ends of bones for protection and prevents scraping
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How Bones Connect
ligaments—bands that connect two or more bones together
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How Bones Connect
tendons—connect muscle to bone
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Aging of Bone
o Under 30 years of age • Bone tissue is built faster than it is broken down • bones increase in size
o Over 30 • Bones deteriorate faster than they are built
o Exercise slows deterioration, makes bones more dense
o Bones can become frail and brittle without enough calcium
o People hunch and shrink as their vertebrae collapse
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What Bones Can Tell Us
o Osteobiography—bones contain a record of the physical life
o Analyzing bones reveals clues to gender, age, height, and health
o Examples: • In a right-handed person, right arm bones might
be slightly larger than the bones of the left arm • X-rays may identify prior fractures, pins, artificial
joints
Gender Female
o Smoother (Gracile)
Male
o Thicker, rougher (Robust) o Larger muscles require
stronger attachment of tendons, makes bones appear bumpy
o Skull is more massive
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Gender—Skull
Male Characteristics
Trait
Female Characteristics
More square Shape of eye More rounded
More square Mandible shape from underside
More V-shaped
Thick and larger Upper brow ridge
Thin and smaller
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Gender—Skull
Male Characteristics
Trait
Female Characteristics
Present Occipital protuberance
Absent
Low and sloping Frontal bone Higher and more rounded
Rough and bumpy
Surface of skull
Smooth
Straight Ramus of mandible
Slanting
Rough and bumpy
Nuchal crest Smooth
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Gender—Skull
o Which skull is smoother? o Which frontal bone is lower and sloping? o Which orbits are more circular? o Which jaw is more square, with an angle that is
closer to 90o?
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Forensic Science: Fundamentals & Investigations, Chapter 13 20
Gender—Pelvis
o An easy method to determine gender o The surface of a woman’s pelvis can be scared o The sub pubic angle of the female pelvis is
greater than 90o; the male’s, less
Gender-pelvis
o Female pelvic cavity is oval shaped, male pelvic cavity is heart shaped
o Female sacrum is tilted back, male is tilted forward
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Forensic Science: Fundamentals & Investigations, Chapter 13 22
Gender—Thigh bones
The male femur is thicker and joins the pelvis at a straighter angle than the female femur
Determining Age of the bones
o Certain bones can reveal age o Absence or presence of cartilage o Not all bones mature at the same time o Must use a range of bones for a more
accurate assessment of age
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Surface of Pubic symphysis
o Where the two pubic bones join o Surface of the bones at this joint change over
time o Forensic anthropologists compare casts of bones
from people of known ages
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Forensic Science: Fundamentals & Investigations, Chapter 13 25
Age—Skull o Infants have a soft spot (fontanel) that
slowly ossifies
o By about age 30, the Lamboidal suture at the back of the skull closes (begins at 21, accelerates at 26)
o By about age 32, the Sagittal suture
running across the top of the skull, back to front, closes
o By about age 50, the Coronal suture running side to side over the top of the skull, near the front, closes
o Not very reliable, must be used in conjunction with other parts of the skeleton
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Forensic Science: Fundamentals & Investigations, Chapter 13 27
Age
o At birth—450+ bones in the skeleton
o Adults— 206 bones o Epiphysis line—appears where
cartilage is replaced by bone o When the cartilage is fully replaced,
the line is no longer visible o This information can be used to
approximate a skeleton’s age
Age in children
o Eruption of teeth is most accurate o Presence of wrist bones
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Forensic Science: Fundamentals & Investigations, Chapter 13 29
Age—Epiphysis
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Age— Epiphysis
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Height
o An estimate of height can be made by measuring one of the long bones
o Gender and race is taken into consideration
Forensic Science: Fundamentals & Investigations, Chapter 13 32
How to Distinguish Race
o Shape of the eye sockets o Absence or presence of a nasal spine o Measurements of the nasal index (width of nasal
opening : height of nasal opening) o Prognathism (how far the upper jaw Projects beyond the lower jaw o Width of the face o Angulation of the jaw and face
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Facial Reconstruction
o Facial muscles follow the contour of the skull o A face can be rebuilt from just skeletal remains
• Facial markers are positioned at critical locations • Clay is contoured to follow the height of the markers
o Computer programs perform a similar function o Computer programs also can “age” missing
persons and criminals
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DNA Evidence
o Bone contains little nuclear DNA but it does contain mitochondrial DNA
o Nuclear DNA degenerates before mitochondrial DNA
o Mitochondrial DNA is inherited only from the mother
o Compare results with living relatives on the mother’s side of the family
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Skeletal Trauma Analysis
o Forensic anthropologists determine if damage to bones occurred before or after death
o Differentiate between trauma and environmental/animal damage
o Distinct patterns exist for damage by • Environment – chew marks from animals • Sharp-force trauma – what kind of mark do you think a
knife would leave? • Blunt-force trauma – more cracks radiating from site of
impact, more damage to bones • Gunshot wounds
Gun shot wound
Forensic Science: Fundamentals & Investigations, Chapter 13 36
Sharp force trauma
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o http://anthropology.si.edu/writteninbone/comic/activity/Evidence_of_trauma.htm
o http://anthropology.si.edu/writteninbone/trauma.html
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