Forensic Science: Fundamentals & Investigations, Chapter 13 1

Chapter 13 Forensic Anthropology: What We Learn from Bones Historical Development Historical Development

1. In the 1800s, scientists began studying skulls. This laid the framework for today’s knowledge.

2. In 1932 the FBI opened the first crime lab.

3. The Smithsonian Institution became its working partner in the identification of human remains.

4. Soldiers killed in World War II were identified using anthropologic techniques.

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Skeletal System • Made of 206 bones as well as joints and connective tissue.

80 bones

126 bones

http://www.youtube.com/watch?v=e54m6XOpRgU

Functions of Bones

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1. Support & shape

2. Protect internal organs

3. Anchors for muscle attachment

4. Make blood cells

5. Store minerals

http://www.youtube.com/watch?v=REftXTSgR8k

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Development of Bone

Bones originate from cells called osteoblasts.

Osteoblasts migrate to the center of cartilage production and deposit minerals.

Throughout life, bones are being broken down, deposited, and replaced.

Osteoclasts, the 2nd type of bone cell, among other tasks, remove cellular wastes.

Forensic Science: Fundamentals & Investigations, Chapter 13 5

How Bones Connect

Bones are held together by: a. cartilage—wraps the ends of bones and keeps

them from scraping one another. b. ligaments—bands that connect two or more

bones together. c. tendons—connect muscle to bone.

Until about 30 years of age, bones increase in size.

Deterioration after 30 can be slowed with exercise.

Forensic Science: Fundamentals & Investigations, Chapter 13 6

What Bones Can Tell Us What Bones Can Tell Us

Osteobiography tells much about a person through the study of the skeleton.

The bones of a right-handed person, for example, would be slightly larger than the bones of the left arm.

Forensic scientists realize that bones contain a record of the physical life.

Analyzing bones can reveal clues to such things as gender, age, height, and health.

http://www.youtube.com/watch?v=BIxJYag9ltU

Male Female

In the illustration you can see women have: •A pointier chin. •A narrower, rounder jaw. •A rounder cranium. •A less sloping forehead. •Which jaw is more square, with an angle that is closer to 90o? male

Gender

Forensic Science: Fundamentals & Investigations, Chapter 13 8

One of the easiest methods of determining the gender of a skeleton is by examining the pelvis.

The surface of a woman’s pelvis can be scared.

The sub pubic angle of the female pelvis is greater than 90o; the male’s, less.

FemaleMale

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Male Female

Hips•The male's pelvis is higher and narrower than a female's.

•A woman's hips are wider than her shoulders — with men it is the other way around.

•Less obvious is the difference in the iliac crest (the two top ridges of the pelvis). It is more pronounced in women.

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Ribcage and shoulders•Women have a smaller ribcage.

•Their collarbones are also shorter, so they don't have the broad, square shoulders men have.

Male Female

Forensic Science: Fundamentals & Investigations, Chapter 13 11

Age

By about age 30, the suture at the back of the skull will have closed.

By about age 32, the suture running across the top of the skull, back to front, will have closed.

By about age 50, the suture running side to side over the top of the skull, near the front, will have closed.

Lamboidal

Sagittal

Coronal

AGE AND TEETHThe number and type of teeth can estimate age

Wisdom teeth erupt at approx 18

Forensic Science: Fundamentals & Investigations, Chapter 13

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Forensic Science: Fundamentals & Investigations, Chapter 13 13

Age

During life, many of the 450 bones a person has at birth grow together, finally forming 206 bones.

As the cartilage between them is replaced, an epiphysis line is visible.

When the cartilage is fully replaced, the line is no longer visible.

This information can be used to approximate a skeleton’s age.

http://www.youtube.com/watch?v=6f90506PvS8&feature=related

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Bone Development:

Anatomy of an Adult Long Bone:

Ex: femur, humerus

Age

http://www.youtube.com/watch?v=FUjlLIMbCiQ&feature=related

http://www.youtube.com/watch?v=X6E5Rz9tOKE&feature=related

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Height

Just as age can be estimated by looking at the bones of the arm and leg, so also can an estimate of height be made.

Often, the approximate height of a person can be calculated from one of the long bones even if just one of those is found.

Gender and race will need to be taken into consideration in making the estimate.

Calculate Height Using Formulas in book (13-19 and 20)

1. Caucasian male femur of 50.6 cm African-American female femur of 49.5 cm A Caucasian person, sex unknown, tibia of

34.2 cm Caucasian female, humerus of 33.4 cm African-American male, humerus of 41.1 cm Person of unknown sex or ethnic group,

humerus of 31.6 cmForensic Science: Fundamentals & Investigations, Chapter 13 18

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Facial Reconstruction

A face is formed by the skull with the muscles and tissues on top of the skull.

Theoretically, nonetheless, a face can be rebuilt from just skeletal remains.

Facial markers are positioned at critical locations on a skull, and clay is contoured to follow the height of the markers.

Today, computer programs perform a similar function. These computer programs also can age missing

persons and criminals. http://www.youtube.com/watch?v=h_HaJT7OVIQ&feature=related

http://www.youtube.com/watch?v=syK_EYJczyE

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DNA Evidence

Bone contains little nuclear DNA. But it does contain mitochondrial DNA. This has DNA that is inherited only from the

mother. Long after nuclear DNA has been lost through

tissue degeneration, mitochondrial DNA can be obtained from bone.

Results can be compared with living relatives on the mother’s side of the family to identify skeletal remains.

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Skeletal Trauma Analysis Skeletal Trauma Analysis

Forensic anthropologists often determine if damage to bones occurred before or after death.

Definite distinctions exist between patterns on bones made by weapons and the patterns created by the environment after death.

Sharp-force trauma, blunt-force trauma, gunshot wounds, and knife wounds all have distinctive patterns.

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Sharp force trauma

Gun shot wounds

http://www.youtube.com/watch?v=xbIftlX58Lo&feature=related

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. . . . . . . . . . Summary. . . . . . . . . . Summary . . . . . . . . . . . . . . . .

Bones are live and carry on all life functions. The condition of bones can tell investigators

about a person’s health and nutrition during life.

Male and female skeletons differ in many ways.

The age of a person at death can be estimated by analysis of a number of bones.

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. . . . . . . . . . . . . . . . . Summary. . . . . . . . . . . . . . . . . Summary

A person’s height can be estimated by the length of long bones.

Facial reconstruction is possible to some extent.

Mitochondrial DNA can be extracted to help identify skeletal remains.

Skeletal trauma analysis examines bones for evidence of damage.