Forensic Anthropology
Why Forensic Anthropology
* Forensic pathologists are trained to analyze soft tissue and organs. Their experience with hard tissue (bone) is limited.
* The forensic anthropologist specializes in hard tissue morphology, structure and variability. In those cases in which soft tissue has been degraded by time, temperature, environment or other external forces, the only tissue remaining more or less intact is bone.
* Physical Anthropologists and Archeologists study human remains-and have become part of solving crimes.
What Questions Can Forensic Anthropology Answer?
* What is the race of the individual?
* What is the sex of the individual?
* What is the age of the individual?
* What is the stature of the individual?
* What pathologies did the individual have?
* What traumas did the individual have?
* What individual traits did the individual have?
Identity of Decomposed or Skeletal Remains
* Are the remains human or animal? (butchers remains and skeletal remains of dead pets etc. may be found in unlikely places)
* Are they really bones? (wood, stones)
* Are they human?
* How many bodies?
* How long dead? - recent or ancient (e.g. construction or digging at an old burial site)
* Cause of death?
How does this Work?
* Forensic anthropologists use regression equations to determine sex, age, stature, and race of skeletal remains.
* Regression equations are mathematical equations developed from studies of bones of individuals of known sex, age, race, and stature, and are used to predict such things of even fragmentary skeletal remains."
Sex Estimation
* The sex of an individual is determined, when soft tissue is not present, by a number of skeletal indicators.
* The more indicators used to determine sex, the more accurate the results.
* A forensic anthropologist is analytically limited by the bones present and the condition of the bones.
* In general, the muscles in a man are stronger and more developed than in a woman.
* Bones of men are larger and more robust than bones of women.
* Some bones display specific features which can be used to help determination of the sex of the skeleton. The best indicators are the:
o Skull
o Pelvis
o Head of the Femur
Sex Estimation – Adult
* Usually related to size in adult long bones
* Male bones: usually larger, longer in a single population – be cautious if different populations are involved
* Maximum diameter of head of humerus and head of femur may be used (Bass).
* Much more difficult to estimate sex in children’s skeletons.
Sex Estimation: Skull
* Good area for sex determination
* Generalization: male skull more robust, muscle-marked than female: ABSOLUTE
* DIFFERENCES SELDOM EXIST (Bass)
* Sex estimation: face, mandible, vault
Sex Estimation: Face
1. Supraorbital (Brow) ridges: more prominent in males
2. Superior orbital margin: sharper in females
3. Palate: larger in males
4. Teeth: larger in males (Bass)
5. Mastoid process: more prominent and rugged in males.
6. Orbit (Eye socket): Rounder in females, more rectangular in males
7. Chin: more pronounced in males and larger jaws.
Pelvis
* Women give birth. For this reason, the pelvis of a woman is larger than the pelvis of a man.
* The pelvis of a woman is wide and circular whereas the pelvis of a man is narrow and heart-shaped.
* Two angles, the sub-pubic angle and the sciatic notch, cause the differences in the shape of the pelvis.
* In women, the sub-pubic angle and sciatic notch are wide. In men, the sub-pubic angle and sciatic notch are narrow.
Male Pelvis Subpubic Notch
Female Pelvis Subpubic Notch
Pubis Bone Traits Related to Sex
Subpubic angle (degrees) angle made by the inferior borders of the articulated pubis bone
Pubis body width (mm)
Ventral arc: a roughened projection of bone visible on the anterior surface of the pubis bone
Head of the Femur
* In men, the diameter of the head of the femur is larger than 51 mm.
* In women, the diameter of the head of the femur is less than 45 mm.
Determining Ages of Skeletons
* Bone growth stops at about 20 yrs. of age in humans.
* Adult bone continuously adapts to prevailing stresses by appropriate deposition and resorption.
* Deposition and resorption are under hormonal control - integrated with regulation of blood calcium levels.
Skeletal Age
* Skeletal age is the estimated age at which a person died. Skeletal age can be determined by looking at the following:
o sutures of the skull
o teeth
o ribs
o vertebrae
o growth areas of the long bones: epiphyses
Sutures of the Skull
* When a baby is born, the skull is still growing.
* To accommodate this growth, the different bones of the skull are separate.
* By the age of 7, all the different bones have finished growing and the fontanelles have disappeared.
Skull Sutures
The Teeth
* The teeth are arranged in upper and lower arches. Those of the upper are called maxillary; those of the lower are mandibular.
Dental Tissues.
* Enamel. The protective outer surface of the anatomic crown. It is 96% mineral and is the hardest tissue in the body.
* Dentin. Located in both the crown and root, it makes up the bulk of the tooth beneath the enamel and cementum. It lines the pulp cavity.
* Cementum. This substance covers the surface of the anatomic root.
* Pulp. The central, innermost portion of the tooth. It has formative, sensory, nutritive, and functions during the life of the tooth.
* There are four types of teeth with very different shapes:
* Incisors (2)
* Canines (1)
* Premolars (bicuspids) (2)
* Molars (2-3)
* Individual teeth are quite distinct, even when lost from a jaw.
Dental Formula (from the midline)
* Primary (deciduous) teeth.
* It is said as: incisors, two upper and two lower; canines, one upper and one lower; molars two upper and two lower equals ten per side.
* Permanent teeth.
* It is said as: incisors, two upper and two lower; canines, one upper and one lower; premolars, two upper and two lower; and molars, three upper and three lower.
Teeth
* The first teeth to appear are the incisors, which are followed by canines and molars.
* When chewing food, teeth grind down.
* Comparing different teeth gives an idea of how long the teeth have been used.
* Eventually teeth may be lost, due to caries or attrition.
X-Rays Are Used to Date Skulls
* This is the side view of the dentition of a six year old boy.
* There is still some variation from person to person in the order in which the teeth erupt.
Baby Teeth Permanent Teeth
Dental Disease - Cavities, Abscesses, and Attrition
Ribs
* Because of breathing, the front part of the ribs is constantly moving.
* As a person gets older, the front part of the ribs begin to change and form bony spikes.
Vertebrae
* As a person gets older, bony spikes can also start growing on the vertebrae.
* This starts at approximately 40 years of age.
Growth areas of the long bones
(epiphysis)
* From birth to ą25 years of age, a person grows at a relatively constant rate.
* Growth takes place at the ends of the long bones.
* At a certain age, growth is completed and this can also be seen on the bone.
Epiphyseal Fusion
* The pattern of fusion of bone ends (epiphysis) to bone shaft (metaphysis) in each bone indicates age.
* Charts & tables are used.
* The upper arm stops growing at the shoulder at approximately age 20 and at the elbow at approximately age 14.5.
* The upper leg stops growing at the hip at approximately age 17.5 and at the knee at approximately age 18.
Determining Ages of Skeletons
* Cranial suture fusion is less reliable.
* Pubic symphysis changes slightly with age.
* Arthritic changes and osteoporosis give further clues.
Arthritic changes and osteoporosis give further clues to the ages of skeletons.
Ossification Centers
* Useful only in fetuses and babies.
* May be determined radiologically or by cutting into ossification centers.
* May be confirmed histologically.
* Most important center in medico-legal work is the distal center of the femur.
* This is present at birth and indicates a full term baby.
Age Determination from Skeleton
* Long bone length (femur, tibia, humerus) is proportional to height.
* Tables are used.
* Fairly reliable up to the age of epiphyseal fusion.
* There are sex, race, nutrition and personal variations to consider.
Individual Characteristics
Fractures
Head Injuries
Individual Characteristics
* Bone disease (Paget's disease, tumors)
* Previous injury to bone (fracture callus, prosthesis, metallic fragments).
* Comparison of trabecular pattern of bone.
* Pattern of skull's frontal air sinuses. Outline is unique and comparisons with clinical X-rays are useful.
Forensic Dentistry
* Teeth are commonly used to establish identity of deceased.
* Dental X-rays and dental casts are available often for 10 years after a patient visits the dentist last..
Height
Body Type
Race or Ethnic Group Determination
Minimum Number of Individuals
Dating of Human Skeletal Remains
Age of Human Remains
* Naked eye appearance is unreliable:
* Tags of soft tissue, periosteum, ligaments etc, indicate less than 5 years old.
* Soapy texture of surface indicates age less than a few decades.
* Light, crumbling bones are likely to be a century or more old.
Laboratory Tests Can Help
* Immunological reaction between bone extract and anti human serum ceases within months of death.
* If blood pigments are present bones are usually less than 10 years old.
* Up to 20 amino acids may be identified in bones less than a century old.
* Fluorescence of freshly sawn bone surface under UV light diminishes after 100 years.
* New bones contain 4.0 - 4.5 gms% nitrogen; 2.5 gms% indicates approximately 350 years.
* Radioactive carbon dating indicates which century.
Taphonomy
* Coined from the Greek words taphos, for "burial," and nomos, for "law."
* Forensic Taphonomy : The Postmortem Fate of Human Remains
* Skeletal trauma, decomposition, and dispersal of remains.
* Weathering, a taphonomic process, is very useful in determining the elapsed time since death.
Facial Reconstruction
* Skull can be scanned into a computer and "fleshed" by computer reconstruction to give likely facial appearance in life.
* Unfortunately eye color, hair color and lips are independent of bony structure.
* Pearl was a female who died in her early forties approximately three hundred years ago.
* She was Caucasian, of European ancestry and stood about 5'1".
* Her dental health was extremely poor and she had lost 63 per cent of her teeth prior to death. She had no teeth on either side of her jaw. This was most important as the loss of those teeth would evidence themselves in the final reconstruction as sunken cheeks. Of her remaining teeth, the condition was poor and she had several abscesses.
* During her lifetime, there are indicators that she also suffered from acute infections, rickets, sinusities, an upper respiratory infection, arthritis, and gout. Whew--all this in an era when aspirin didn't exist!
* On the other hand, it was determined that she was very muscular, as the ridges on her long bones were very developed.
Various items (glasses, clothing, hats) may be applied to better accentuate the features of the individual.
This method can be very successful.
Cause of Death
* Anthropologists can distinguish between marks from the result of a weapon attack and those resulting from the gnawing and biting of bones by scavenging animals.
* They can also determine the exact kind of weapon and animal, and they can tell if a wound is old or if it occurred at death.
* They can be called upon to testify as to the type of weapon used (saw vs. knife).
Lizzie Bordon’s Father’s skull: Ax Whacked.
* Two outstanding cases of the use of forensic anthropology to successfully solve unsolved mysteries are the cases of Francisco Pizarro.
Pizarro conquered the Incas.
* Pizarro was hated by the Peruvians because he was a brutal ruler. On June 26, 1541 (at age 66), he was stabbed to death by a crowd of angry subjects and in view of many witnesses (Dickerson 1993).
* His brutal death is not questioned due to the well documentation at the time. It was his remains that were questioned.
* In the 1890's, Peruvian officials decided to put Pizarro's remains on exhibit. "They asked officials at the Cathedral of the Plaza de Aramis in Lima for Pizarro's body and were directed to a mummy, which they put on view." (Dickerson 1993)
* In 1978 workers discovered a secret niche that had been walled over in the cathedral, and on a shelf in the niche was a box with a skull and an inscription that identified it as the head of Pizarro.
* Another box was found containing the bones of several unidentified individuals (Dickerson 1993).
* An investigation of the bones in the second box led to the discovery that the postcranial bones matched the skull in the first box.
* These bones and the skull were then placed together and prepared for study to determine if they had marks consistent with sword or knife wounds.
Forensic Anthropology.ppt
Read more...
Posts
