Transcript Forensic Anthropology

Forensic Anthropology
What Questions Can Forensic
Anthropology Answer?
•
•
•
•
•
•
•
Race
Sex
Approximate age
Approximate stature
Pathologies (diseases)
Traumas (injuries)
Other individual traits
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?
• Regression equations used 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:
– Skull
– Pelvis
– 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
Sciatic notch comparison – which is female?
Pubis Bone Traits Related to Sex
Trait
Ventral arc: a
roughened projection
of bone visible on the
anterior surface of the
pubis bone
Pubis body width (mm)
Subpubic angle
(degrees) angle made
by the inferior borders
of the articulated pubis
bone
Female
Male
Present Absent
40
>90
25-30
<90
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.
Other femur features
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:
– sutures of the skull
– teeth
– ribs
– vertebrae
– 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
Fused sutures in adult
The Teeth
• The teeth are
arranged in upper
and lower arches.
Those of the upper
are called maxillary;
those of the lower are
mandibular.
• 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.
– incisors, two upper and two
lower;
– canines, one upper and
one lower;
– molars two upper and two
lower equals ten per side.
• Permanent teeth.
– incisors, two upper and two
lower;
– canines, one upper and
one lower;
– premolars, two upper and
two lower;
– 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
Incisors:
7-12 months Incisors:
6.5 years
Canines:
2 years
Canines:
10.8 years
Premolar 1:
none
Premolar 1: 10.4 years
Premolar 2:
none
Premolar 2: 11 years
Molar 1:
3 years
Molar 1:
6.2 years
Molar 2:
3 years
Molar 2:
12.2 years
Molar 3:
none
Molar 3:
18 years
Baby Teeth
Teeth with 12 year Molars
Teeth with 6 year molars
Teeth with Wisdom 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 ±25 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.
• 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.
Individual Characteristics
Fractures
Head Injuries
Height
• An intact corpse can be measured, but a
disarticulated or incomplete skeleton has to be
pieced together.
• Stature
• 3.26 x (humerus) + 62.10 = stature +/-4.43cm
• 3.42 x (radius) + 81.56 = stature +/-4.30cm
• 3.26 x (ulna) + 78.29 = stature +/-4.42cm
– (there will be 2 calculations for stature, based on the
upper and lower standard of error)
Race or Ethnic Group
Determination
• The skull is the only reliable bone.
– Caucasian (all whites)
– Negroid (all blacks - African, African
Americans and West Indians)
– Mongoloid (Chinese, Japanese, American
Indians)
In Caucasians:
Nasal openings
are narrow.
Face is flatter
In Mongoloids
“Shovel-shaped"
concave upper
incisor teeth.
Cheekbones
(Zygomatic arches):
are wider and more
prominent.
Greater width
between eyes.
In Negroids:
Face projects forward
Nasal opening is wider
Comparison of the extent of ramus inversion in the mandible of an
individual with caucasoid ancestry (top) and one with negroid
ancestry (bottom)
Minimum Number of Individuals
• Used in mass graves- like in Yugoslavia or
Afghanistan and mass disasters.
• Count all the bones and assign left vs.
right.
• Use the highest number of a bone as the
minimum number.
• Also, can assign bones to individual
skeletons and then count them.
Dating of Human Skeletal Remains
• Are they ancient or modern bones? (i.e.
greater or less than 50 years).
• Rate of skeletonization is highly variable.
In the tropics a body can be reduced to a
skeleton in 3 weeks.
• Remarkable preservation of body is seen
in acidic peaty soil
• Thus, environmental conditions have to be
taken into account.
2400 year old bog body from Denmark
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.
The artist utilizes proper
tissue depth data determined
by race, gender, and age.
Artificial eyes are placed in
the skull’s eye sockets,
centered and at the proper
depth.
The tissue markers are glued
directly onto the skull.
Clay will be systematically
applied directly on the skull,
following the skull's contours;
paying strict attention to the
applied tissue markers.
Various measurements are
made, and logged, to
determine nose
thickness/length, mouth
thickness/width, and eye
placement.
Information such as
geographic location of where
the deceased lived, his or
her lifestyle, and the various
information provided to the
artist by the Forensic
Anthropologist and other
professionals, is heavily
relied upon when completing
the reconstruction.
This woman had
missing side teeth and
a small jaw.
Hair is added by
applying clay or a wig.
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).
The Question was, "Who was the
real Pizarro?"
• 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.
Who’s the Mummy?
• Just by using visual observation, researchers
could tell that the skeleton had been stabbed
many times, dying in the same way as Pizarro
was reported to have died.
• The location of the wounds showed that the
victim had been stabbed "about the head and
body and apparently had tried to shield himself
with his arm, a reaction common in stabbing
deaths." (Dickerson 1993)
• On the other hand, the mummy had no such
injuries at all (Dickerson 1993).