FORENSIC ANTHROPOLOGY NOTES Forensic Anthropology = the examinations of human skeletal remains for law enforcement agencies to determine the identity of unidentified bones. Questions asked: 1. Are the bones human? 2. What are the biological characteristics of the individual? (size, age,sex, and race). 3. How long has the person been dead? 4. What is the cause and manner of death? The human body has 206 bones. In the average male, they weigh 12 lbs; in the average female, 10 lbs. Is it human? Determining the species of a bone is challenging. The front paw bones of a bear are very similar to those of a human hand, and shell fragments from some turtles can be mistaken for skull fragments. Ribs from sheep and deer resemble human ribs. Infant bones are much smaller and easier to confuse with bones of small animals, including the teeth. What can we determine from bones? 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 A. AGE: Teeth and bones- Teeth and bones in children and adolescents follow a predictable growth and maturation pattern. By assessing the stage of this development, a fairly narrow age range can be determined. Later in life, changes occur at much slower rates, thus leading to age assessments across much wider ranges. Best for ages 0-5 since baby teeth are lost and adult teeth erupt in predictable patterns. Babies have 20 teeth; Adults have 32 permanent teeth (appearance of permanent teeth is complete about age 12. Wisdom teeth typically erupt by age 18. (see handout on use of teeth for age determination)
Long bones of the legs and arms: Best for ages 6-25 years. The epiphyseal fusion (fusion of bone ends to bone shaft) is usually complete by age 25. (see handouts on epiphyseal fusion) A B A lines/layers clear on person not out of puberty B no visible lines when a person reaches adulthood Pelvis: The symphysis (thin band of cartilage that attaches your pelvis to your spinal column) has a zigzag shape when you are young but straightens as you age, stopping around 50 years.
Ribs: Areas where ribs join the sternum are smooth and rounded when young, but become pitted and sharp with age. Best used up to 30 years, then ok until age 70. Bone density: Our bones lose calcium as we age, so x-rays can reveal the density and may help with age determination. Signs of wearing and injury are also helpful. (see handout of signs of wearing and antemortem injury). B. GENDER: Sex determination is more difficult in babies and children than adults since changes in skeleton don t appear until puberty. In general the diameters of the heads of the humerus, the radius, and the femur are larger in males. The maximum length of the humerus in an adult female is 305.9mm and 339.0mm in males. The pelvis is the best bone for sex determination. The males is designed only for support and movement, while the female pelvis is adapted for childbirth. Females have a wider subpubic angle; a wider sciatic (greater than 90 degrees); and a broad pelvic inlet. Crests and ridges are more pronounced in males; the chin is more square; the mastoid process is wide and robust; and the forehead slopes more.
RACE: Determining race is extremely difficult, if not impossible, because no single skeletal trait is racially distinct. Also, it is imprecise because so much human variation exists. (Mixed racial ancestry is common). The only three groups to which a given skeleton can be assigned are Caucasoid (European); Negroid (African and West Indian); and Mongoloid (Asian/Native American). Sometimes you can see difference in shapes of eye orbits: Angular=Caucasian, Rectangular=African, and Round=Asian.(see handouts). The nasal index is the ratio of the width to the height of the nose, multiplied by 100. It is.48-.53 for Asian/Native American; <.48 for Causasian; and >.53 for Africa The nasal spine (the ridge below the nose, above the incisors) is another determining factor of race: Asians=somewhat prominent spine; Caucasian=prominent spine; and African=very small spine.
- Nasal silling (sharp ridges at the base of the nasal cavity, on either side of the nasal spine) or nasal guttering (no ridges at all): Asians= rounded ridge; Caucasian=sharp ridge(silling); African= no ridge(guttering). Prognathism (extended lower jaw): Asians=variable; Caucasians=straight; African=progathic. Shape of eye orbits: Asians=rounded; Caucasians=rounded somewhat square; Africans=rectangular or square. White Asian African
STATURE (height at time of death): Remember a complete skeleton is often not available for Forensic Anthropologists, they formulas were made to be able to figure out stature from three long bones: o Length of femur X 2.38 + 61.41cm = height o Length of tibia X 2.52 + 78.62cm = height o Length of fibula X 2.68 + 71.78cm = height What a Forensic Anthropologist Does: Goes to a crime scene to assist in the collection of human bones Cleans up bones so they can be looked at Analyzes skeletal remains to establish the profile of the individual Looks at trauma evident on the bones to establish the pathway of a bullet or number of stab wounds Works with a forensic odontologist to match dental records Testifies in court about the identity of the individual and /or the injuries that might be evident in the skeleton.