Forensic Anthropology Notes

Transcription

1 Forensic Anthropology Notes 1

2 Chapter 13 Forensic Anthropology: What We Learn from Bones describe how bone is formed distinguish between male and female skeletal remains explain how bones contain a record of injuries and disease describe how a person s approximate age could be determined discuss the role of mitochondrial DNA in bone identification All Rights Reserved South-Western / Cengage Learning

3 Historical Development In the 1800s, scientists began studying skulls. This laid the framework for today s knowledge. In 1932 the FBI opened the first crime lab. The Smithsonian Institution became its working partner in the identification of human remains. Soldiers killed in World War II were identified using anthropologic techniques.

4 Development of Bone 4 Bones originate from cells called osteoblasts. They migrate to the center of a cartilage bone model and deposit minerals- ossification. Throughout life, bones are being broken down, deposited, and replaced- remodeling. Osteoclasts, the 2nd type of bone cell, among other tasks, remove cellular wastes and break down old bone..

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6 Bone development 6

7 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. 7

8 What role do anthropologists play in solving crimes? Watch the video and then answer the questions. 1. What does a physical anthropologist investigate? 2. What four things do we want to know about a skeleton? 3. What bones are most useful for developing a profile of a person? Explain how they are used.

9 Main Characteristics: Sex - Determined by examining the skull, pelvis, humerus, and femur Age and stature (height/build) Determined by analyzing the development of the teeth, bone growth, cranial suture lines, and the length of specific bones, such as the femur. Which skull would belong to a female? Race Determined by analyzing the skull for characteristics that are common among people of different races. Which pelvis would belong to a female?

10 Is it bone? 10 The first thing the examining anthropologist must determine is whether or not the material is bone. A surprising number of other materials may be mistaken for bone on first glance, especially if they are covered with dirt or other substances. To ensure the material is bone, the anthropologist cleans the object and examines it closely, under magnification if necessary.

11 Is it human? 11 The next thing that a forensic anthropologist might need to determine is whether or not the bone is human. All mammals share a generalized skeletal template. However, the shape of the bones and the way they relate to each other, differ between animals. By examining the size, shape, and structure of a bone, an anthropologist can determine if it is human.

12 Are remains modern or ancient? 12 Anthropologists can often tell the difference between an ancient and modern skeleton by the context of deposition. (modern dental work, clothing, cell phone, etc) On the other hand, skeletal remains found in association with cultural objects consistent with local First Nations burial practices are likely to be those of a person buried according to his or her cultural and social heritage and are therefore not of forensic interest.

13 What Bones Can Tell Us 13 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.

14 Gender The female skull is smoother than the male s The male frontal bone is lower and sloping The male s eye orbits are more circular Males have an occipital protuberance and large mastoid process Male jaw is more square and upright 14

15 Gender 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 scarred. The sub pubic angle of the female pelvis is greater than 90o; the male s, less. 15

16 Gender Male have a narrow iliac crest Male have a sacrum that is tilted forward Female sacrum is tilted back 16

17 Age 17 The suture at the back of the skull (lamboidal suture) begins closing at age 21, and by age 30 will have closed. By about age 32, the suture running across the top of the skull (sagittal suture), 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 (coronal suture), will have closed.

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19 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. 19

20 Age 20 Teeth are the best way to determine age in a child

21 Age for permanent teeth 21

22 Age 22

23 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. 23

24 Race Racial classifications in anthropology based on cranial and skeletal morphology: Caucasoid Mongoloid Negroid 24

25 Skeletal Differences 25 Nasal Bones Shape of dental arch Shape of teeth Form of the chin Shape of skull and brow

26 Facial Reconstruction A face is formed by the skull with the muscles and 26 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. reconstruction video

27 What else can we learn from bones? DNA samples can be collected from bone, teeth, and hair to provide clues to a person s identity. Scientists may also be able to gain clues as to a person s past, recent injuries, or the cause of death based on bone fractures and other signs of trauma. Damage from a hammer Healed Fractures Gunshot Wounds Images:

28 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 bones of Richard III remains. 28

29 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. 29

30 Determining Cause of Death Sharp force trauma: bone cut Blunt force trauma: broken bone

31 Antemortem vs. Postmortem 31 Antemortem before death, should show signs of healing Postmortem after death, does not show signs of healing Perimortem occurred very close to time of death

32 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. 32

33 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. 33