Download 11/5 Age, Sex, and Race determination from Bones Notes

Age, Race, and Sex
Determination from
Bones
Forensic Science 11/5/14
Languid
 lacking energy; weak; showing little interest in anything
 After eating seven Snickers bars on Halloween, I lay
languidly on my couch.
Drill
 Pick up new packet
 Write your answer to this on a separate half-sheet to be
turned in. You do NOT have to write the question. 3-4
sentences is sufficient.
 Imagine you are brother or sister to one of John Wayne
Gacy’s possible victims. You didn’t know what had
happened to your sibling until now.
 How would you feel if a forensic anthropologist were to
present you with a reconstruction of your relative’s face?
Explain why you feel that way.
 HW: pg. 1 #4-11 (Review Questions)
Objectives
 SWBAT
 Identify the bones of the skeleton
 Determine age, gender, and stature of a skeleton
Agenda
 Drill
 Age, Race, and Sex Determination from Bones Notes
 Closure
Age Determination Notes
 ADD THIS AT TOP OF PAGE
 An adult human body contains 206 bones, but a baby
has 450 bones! Why? As you develop, bones fuse
together.
 Skull Suture Marks
 Coronal Suture – closes around age 50
 Lambdoidal Suture
 Closing ~21
 Accelerates closing ~26
 Fully closed ~30
5 y. o. skull
vs.
skull
60 y. o.
Infant vs. Adult Skull
Age Determination
 Long Bones – Femur or Humerus
 Fused by ~20 – before this, cartilage at ends
 Pelvis
 Fused by ~30 – different areas start as separate bones
 More detailed information in Ch. 13 packet
 NOTE: This is NOT Chapter 13 from our textbook—I am
using resources from another textbook, and the scanned
Ch. 13 is on the website.
Age in X-rays
 Child’s Hand
 Adult Hand (~20 y. o.)
Age and Proportions
 Newborn: Head is 1/4 of body
 Adult: Head is about 1/8 of body
Skull and Race Determination
 3 main racial categories (older terms in parentheses):
 Caucasian (Caucasoid)
 African (Negroid)
 Asian (Mongoloid)
 Main characteristics that distinguish race:






Shape of eye sockets
Nasal spine (absence or presence)
Width of nasal opening
Prognathism – projection of upper jaw past lower jaw
Width of face
Angles of jaw and face
Racial Characteristics
Caucasian African
Asian
Rounded,
somewhat
square
Rectangular
Rounded,
somewhat
circular
Nasal Spine Prominent
Very small
Somewhat
Prognathism
Prognathic
Variable
Shape of
Eye Orbits
Straight
SEXUAL DIMORPHISM
 Differences between men and women include all the
features related to reproductive role, notably the
endocrine (hormonal) systems and their physical,
psychological and behavioral effects.
 Hormonally controlled
 Evident in adults, not children
 Sex hormones increase around the time of puberty, leading
to secondary sexual characteristics
 Varies within a population and between populations
SEXUAL DIMORPHISM –
BASIC PRINCIPLES
 The evaluation of sexual dimorphism in skeleton is
generally based on two factors:
 Size difference
 Function related differences.
 Size:
 Males are usually larger
 Function:
 Females have unique pelvic characteristics due to
childbirth
 Robusticity and muscularity are usually more evident in
males (the opposite term is gracile, meaning “slender”)
Sex Determination
 Determination of sex is based on two
methodological approaches:
 Morphological (based on Shape):
 Adult males and females differ in both general size
and shape, and this variation is reflected in the
skeletal anatomy.
 Osteometric (based on bone dimensions):
 Males’ bones are longer or larger than females’.
Sex Characteristics of
Pelvis
Male and Female
Male and Female Pelvis
Male
Heavy and
Thick
Large
Well marked
Deep
Points of
Comparison
General
Structure
Joint Surfaces
Female
Muscle
Attachment
Greater Pelvis
Rather
indistinct
Shallow
Light and
thin
Small
Male and Female Pelvis
Male
Heart shaped
Comparatively
small
The superior
surface of the body
spans nearly half
the width of the
sacrum.
Points of
Female
Comparison
Pelvic Inlet Circular
Pelvic
Outlet
First Piece
of Sacrum
Comparatively
Large
The superior
surface of the
body spans
almost 1/3 the
width of the
sacrum.
Male
and
Female
Pelvis
Male
Points of
Female
Comparison
Long, narrow, Sacrum
with smooth
concavity
Less than 90
degrees
Small and
deep
Short wide,
flat, curving
forward in
lower part
Pubic Arch
Greater than
90 degrees
Sciatic Notch Wide and
shallow
Skull Dimorphisms
Male and Female
Male and Female Skulls
Male
Points of
Comparison
Heavier and
General
more rugged
Architecture
Squared, small Eye Openings
Female
Prominent and Brow Ridges
heavy
Heavier and
Cheekbones
laterally arched
Smooth and flat
Lighter and less
rugged
Rounded, large
Lighter, lack
lateral arching
Male and Female Skulls
Male
Occipital
bump at the
base of the
skull
Letter U
Sloping, less
round
Larger, more
blunt
Points of
Female
Comparison
Occipital
Almost nonCondyle/
existent
Nuchal Ridge
Chin Shape
Letter V
Forehead
Vertical, fuller
Mastoid
Process
Smaller, more
pointed
Closure
 Consider your own skull. Do you have
 a brow ridge?
 an occipital condyle/ nuchal ridge?
 You have a time machine. If you were to travel to the
future and find your own skeleton, would the bones be
robust or gracile?