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Forensic Anthropology

By @forensicfield

INTRODUCTION

Forensic Anthropology is the study of skeletal and other human remains to identify an individual and to determine the circumstances involved in someone’s death.

Osteology

Osteology (the study of bones) is very important when forensic scientists wish to identify remains at a crime scene. When forensic scientists arrive at a crime scene area, they are often faced with very badly decomposed remains, along with many other types of physical evidence.

Distinguish Human Bone From Animal Bone

  • Forensic investigators must be able to distinguish human bone from animal bone. For example, bird bones are hollow. Because humans are bipedal (walk on two feet), our bones have unique features. Humans have a large calcaneus (heel bone) and a big toe bone, as we pass all our weight to our feet when walking.
  • The human body has 206 bones. The average male skeleton weighs about five (5) kilograms (about 11 pounds), and the average female skeleton weighs about three and one-half (3.5) kilograms (about 7.7 pounds).

FORENSIC TAPHONOMY

  • Forensic Taphonomy is the study of the postmortem changes to human remains.
  • It is mainly focused on environmental effects including decomposition in soil and water and interaction with plants, insects and other animals.

Work of Forensic Anthropologist

Forensic anthropologists work to determine the age, sex, ancestry, stature, and unique features of a skeleton. At times, they rely on living descendants to provide information about the deceased.

  • A forensic anthropologist may provide basic identification information on skeletonized or badly decomposed remains.
  • From a whole bone or part of a bone, the scientist may be able to determine:
  •    An age range
  •    Sex
  •    Race
  •    Approximate height
  •    Cause of death or Disease

Sex

Sex must be assessed first, as it will prescribe the methods used for the estimation of both age and stature. When a biological anthropologist examines  a skeleton. Sex is a biological consequence of chromosomal inheritance.

Determination of Sex

Pelvis
  • Females have wider sub pubic angle than males.
  •  Females have a wider sciatic notch than males.
  •  Females have a broad pelvic inlet than males.
  •  Females have a larger pelvic brim than males.
Gender

Many gender differences are visible when the skull is examined. Males have sloping foreheads, while females have straighter foreheads. Males have extreme supraorbital ridges, while females have slight ridges, with sharp orbital borders. Males have areas of pronounced muscle attachment visible on the cheek bones and large canines. Females have rounded chins, while the chins of males are more square.

Cranium
  • Crests and ridges more pronounced in males (A, B, C).
  • Chin significantly more square in males (E).
  • Jaw (I, E), mastoid process wide and robust in males.
  • Forehead slopes more in males (F).
Ancestry

The estimation of ancestry, or the biological and geographic origins of the individual according to their genetic history is  an integral  part of the biological profile. While most medico-legal agencies ask for a determination of the race of the individual remains in order to search missing persons files, it is not possible to precisely correlate social race and biogeographic ancestry.

Race is difficult to determine from most skeletal remains, especially since pure races are becoming uncommon. An experienced forensic anthropologist can generally place skulls into one of three groups:

Caucasoid  —  European, Middle Eastern, and Indian descent.

Negroid  —  African, Aborigine, and Melanesian descent.

Mongoloid  —  Asian, Native American, and Polynesian descent.

Age

Age may be estimated from calcifications (stages at which the bones are uniting), successive changes in the pelvis, evidence of bone disease such as arthritis, and the way the teeth are worn.

Determination of Age from Bones

Ages 0-5: teeth are best – forensic odontology.

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, can use pubic symphysis.

Ages 40+: periodontal disease, arthritis, breakdown of pelvis, occupational stress, unique clues.

Stature

If the remains contain any complete long bones. Most stature formulae are based on the assumption that a long bone is proportionally related to the overall stature of the individual. Stature estimation can be quite accurate (if not precise) when the individual is compared to a population with established growth curves, known average statures and stature distributions, and one which is contemporary with the individual.

Trauma

The next phase of the analysis is identifying any evidence of ante mortem trauma or pathology on the skeleton that may aid in the identification of the individual and the final phase is identifying any indications of peri-mortem trauma that may indicate how the individual died. With the latter, the anthropologist must be able to distinguish peri-mortem from post-mortem trauma to bone.

Previous trauma / ante-mortem Trauma

  • The forensic anthropologist must assess the skeleton for congenital abnormalities or any signs of disease or trauma that the individual suffered during life.
  • Evidence of a once broken or fractured bone indicates a previous trauma that may lead to a victim’s identity through comparisons with medical records.

A forensic anthropologist is generally concerned  with three types of peri-mortem trauma :

  • Blunt Force,
  • Sharp Force,
  • And Projectile (Gunshot And Fragmentation Injuries).
Height
  • If the skeleton is incomplete, forensic scientists are able to approximate the height of an individual by measuring the length of the foot. The length of a person’s foot is approximately 15 per cent of his or her height.
  • 15/100 = Length of Foot / x (person’s height) Formulas applied to the length of the femur, tibia, or fibula will also approximate the height.
  • The ratio of body parts is slightly different in growing children.
Estimation of Height

The height of a person can be calculated by measuring the length of certain long bones, including the femur, tibia, humerus, and radius. Below are the equations used to determine average measurements for both male and female. (All measurements are in centimeters.)

Male Height, H                            Female Height, H
H = femur ´ 2.23 + 69.08
H = tibia ´ 2.39 + 81.68
H = humerus ´ 2.97 + 73.57
H = radius ´ 3.65 + 80.40
H = femur ´ 2.21 + 61.41
H = tibia ´ 2.53 + 72.57
H = humerus ´ 3.14 + 64.97
H = radius ´ 3.87 + 73.50

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