Forensic Anthropology: Studying Bones

1. Forensic Anthropology:Studying Bones http://people.stu.ca/~mclaugh/skeleton8a.GIF

2. What are 3 questions that would be very important to answer when a set of “bones” (or material that might be bones) is discovered?

3. First Three Questions: • Are the remains actually bone? macroscopic and microscopic study • Are the remains Human? appearance and DNA if available • Are the Remains Ancient or Modern? look for clothing, historic remains, teeth If human, then proceed to identify the remains

4. So Why Study Bones?...

5. Why Study Bones? • They constitute the evidence for the study of fossils. • 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

6. A Caveat • 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

7. -What can we learn from bones (characteristics)? -What are the specific bones that can tell us this?

8. 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

9. What does bone do? What are the functions of bones in the body? • What about Cartilage, Tendons, and Ligaments?

10. Tissues and Functions of the Human Skeletal System • Bone • Movement • Support • Calcium Storage • Red Blood Cell Production • Protection of Internal Organs

11. Tissues and Functions of the Human Skeletal System • Cartilage • In a fetus, skeleton is made of cartilage, later replaced by bone • Covers ends of bones (especially at joints) • Tendons • Connect muscles to bone • Ligaments • Connect one bone to another bone

12. What is bone? • Organic material (collagen= spongy protein) inside of an inorganic matrix (mostly calcium and potassium) • Osteocytes: bone cells

13. How does bone form and grow? • By early twenties, most human bone growth is complete. • Osteoclasts circulate and recycle damaged bone cells…”remodeling” • Most obvious where bone ends (epiphysis) meet the bone shaft (diaphysis) • “growth plate” or “epiphyseal” plate (Can tell age of person) • Growth in periosteum (membrane acting as a bone cover—not at joints)

14. How many bones are in the human body?

15. How many? • About 206- depending on age of person • 176 in a newborn baby - A lot of bones have not turned from cartilage to bone yet

16. What kind? • Long bones (femur, humerus, radius, ulna, tibia and fibula) • Short bones (metacarples and metatarsals—hand bones and foot bones) • Flat bones (cranial bones, hip bones, shoulder blades) • Irregular bones (vertebra, carpals, tarsals, many cranial bones)

17. Parts of the skeleton • Axial skeleton: • skull (cranium), vertebral column, ribs • Appendicular skeleton: • Pectoral girdle (scapula and clavicle- forms shoulder) • Pelvic girdle (innominate or hip bones) • Upper limbs (humerus, radius, ulna, etc) • Lower limbs (femur, tibia, fibula, etc)

18. 1. Determination of Sex • Pelvis is the best bones (differences due to adaptations to childbirth) • females have wider subpubic angle • females have a sciaticnotch > 90° • females have a broad pelvic inlet 1. 2. 3. 2. 2. 3. 3. 1. 1.

19. 1. Determination of Sex • Pelvis best (another view) • females have wider subpubic angle • females have a broad, shovel-like ilium • females have a flexible pubic symphysis 1. 2. 3. 2. 3. 2. 1. 1.

20. 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)

21. Sex Determination - Skull

22. 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

23. Determination of Race • It can be extremely difficult to determine the true race of a skeleton for several reasons: • Forensic anthropologists generally use a three-race model to categorize skeletal traits: Caucasian (European), Asian (Asian/Amerindian), and African (African and West Indian). • Not all individuals have skeletal traits that are completely consistent with their geographic origin. • 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. • the vast majority of the skeletal indicators used to determine race are non-metric (not involving measurements) 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.

24. European, Asian, African From: Beyers, S.N. (2005). Introduction to Forensic Anthropology

25. 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

26. Nasal Silling and Guttering From: Beyers, S.N. (2005). Introduction to Forensic Anthropology

27. Maxillae Note shapes of nasal openings… African European Asian Spatulate (flat backed) incisors Shovel-shaped incisors

28. General Shapes of the Eye Orbits From: Beyers, S.N. (2005). Introduction to Forensic Anthropology

29. Orbital openings: round Nasal spine: Prominent Progathism: straight Determination of Race:European http://upload.wikimedia.org/wikipedia/en/c/cc/Skullcauc.gif

30. Determination of Race:Asian (Asian decent and Native American decent) http://upload.wikimedia.org/wikipedia/en/b/b3/Skullmong.gif

31. Determination of Race:African: (people of African decent and West Indian decent) http://upload.wikimedia.org/wikipedia/en/5/5e/Skullneg.gif

32. 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

33. 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)

34. 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 2. Figure 1.

35. Cartilage is darker on xray than solid bone. Epiphyses aren’t fused yet. No cartilage visible. Epiphyses are fused.

36. Epiphyseal Fusion: A General Guide

37. 2a. Age Determination: Use of Teeth http://images.main.uab.edu/healthsys/ei_0017.gif http://www.forensicdentistryonline.org/Forensic_pages_1/images/Lakars_5yo.jpg

38. 2b. 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

39. 3. Estimation of Stature • Intact Corpse – easy • Dismembered – must be based on long bones of the corpses • Trotter Method – mathematical regression formula based on the Terry collection and hundreds of servicemen from WW II and the Korean War.

40. Ideally all long bones are available for stature determination. • Bones are measured using an osteometric board for accuracy. • The measurements are then put into standard formulae

41. 3. Determination of Stature(cont’d.) • 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

42. 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

43. Clues to Cause of Death • Beveling • Exit side is larger in diameter than entrance for a high velocity projectile (bullet) • Cut Marks, Chop Marks, Scrape Marks • Caused by a tool • Gnaw Marks • Postmortem- caused by animal activity

44. Clues to Cause of Death • Hyoid Bone • Attachment for tongue, mandible, larynx, etc… • U-shaped bone in neck • Fracture suggests strangulation

45. Identification of an Individual • Dental records • Antemortem x-rays (show old fractures, implants, etc) • Frontal Sinuses • DNA (if possible- in teeth and marrow)

46. Time Since Death • Bones are subject to weathering and scatter. • Bodies left on the surface are skeletonized within 8 months. • If buried, it will take between 1 and 2 years to become completely skeletonized and in arid areas bodies may become mummified.

47. Time of Death • Scatter is important to the Forensic Anthropologist in estimating time of death and burial. • The number and types of bones available at the scene indicates the amount of time the body has been in that spot (smaller bones get lost first). • 3 weeks: articulated bones • 5 weeks: some scatter, some articulated • 4 months: disarticulated, within 10’ circle • 7 to 8 months: most bones within 10’ circle and all within 20’ • 1 year: small bones missing, complete disarticulation • 2 to 4 years: some bones broken, scattered 40’, some large bones missing • 12+ years: bone rot

48. “The Body Farm” • Facility instituted at the University of Tennessee by Dr. William Bass • Human decomposition is scientifically studied to help us understand decay process as well as how to determine a better estimate of time since death and cause of death

49. 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.html • 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/