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Age, Race, and Sex Determination from Bones
Forensic Science 11/5/14
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Languid lacking energy; weak; showing little interest in anything
After eating seven Snickers bars on Halloween, I lay languidly on my couch.
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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 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)
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Objectives SWBAT Identify the bones of the skeleton
Determine age, gender, and stature of a skeleton
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Agenda Drill Age, Race, and Sex Determination from Bones Notes Closure
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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
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5 y. o. skull vs y. o. skull
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Infant vs. Adult Skull
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Age Determination Long Bones – Femur or Humerus Pelvis
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.
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Age in X-rays Child’s Hand Adult Hand (~20 y. o.)
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Age and Proportions Newborn: Head is 1/4 of body
Adult: Head is about 1/8 of body
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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
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Racial Characteristics
Caucasian African Asian Shape of Eye Orbits Rounded, somewhat square Rectangular Rounded, somewhat circular Nasal Spine Prominent Very small Somewhat Prognathism Straight Prognathic Variable
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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
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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”)
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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’.
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Sex Characteristics of Pelvis
Male and Female
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Male and Female Pelvis Male Points of Comparison Female
Heavy and Thick General Structure Light and thin Large Joint Surfaces Small Well marked Muscle Attachment Rather indistinct Deep Greater Pelvis Shallow
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Male and Female Pelvis Male Points of Comparison Female Heart shaped
Pelvic Inlet Circular Comparatively small Pelvic Outlet Comparatively Large The superior surface of the body spans nearly half the width of the sacrum. First Piece of Sacrum The superior surface of the body spans almost 1/3 the width of the sacrum.
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Male and Female Pelvis Male Points of Comparison Female
Long, narrow, with smooth concavity Sacrum Short wide, flat, curving forward in lower part Less than 90 degrees Pubic Arch Greater than 90 degrees Small and deep Sciatic Notch Wide and shallow
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Skull Dimorphisms Male and Female
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Male and Female Skulls Male Points of Comparison Female
Heavier and more rugged General Architecture Lighter and less rugged Squared, small Eye Openings Rounded, large Prominent and heavy Brow Ridges Smooth and flat Heavier and laterally arched Cheekbones Lighter, lack lateral arching
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Male and Female Skulls Male Points of Comparison Female
Occipital bump at the base of the skull Occipital Condyle/ Nuchal Ridge Almost non-existent Letter U Chin Shape Letter V Sloping, less round Forehead Vertical, fuller Larger, more blunt Mastoid Process Smaller, more pointed
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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?
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