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Chapter 10

ANTHROP 3FA3 Chapter Notes - Chapter 10: Menopause, Osteoporosis, Osteon

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Tracy Prowse

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FA Chapter 10: Age Estimation
Principles of age estimation
-age-at-death is part of the biological profile used to narrow the list of potential missing person
-forensic anthropologists are sometimes asked to apply age estimation to living individuals (using radiography) to
determine whether someone has reached the age of majority which may be factor in determining whether
someone is prosecuted as a juvenile or adult
-skeletal age estimation involves correlating biological age (physiological) with chronological age (the length of
time a person has been alive) — traits or processes used change unidirectionally with age, correlated with
chronological age and change concisely across individuals
biological age varies as a function of genetics, nutrition, environmental factors and activity levels
chronological age is measured by tie
the trajectory effect: the discrepancy between biological age and chronological age widens as people get
-age estimation is a transformative process (anthropologist must translate the descriptive skeletal age indicator
into a chronological age); this process introduces error and results in wide age intervals that are accurate but not
precise (i.e. decades for adults)
-sex and ancestry knowledge of the individual is considered and standards of age used that are based on the
population of the skeletal material
Age categories
-childhood: skeleton changes as aa function of growth and development — structures mineralize, increase in size
and model their shape to achieve mature adult form; influenced by genetic and intrinsic factors
-adulthood: skeleton begins to show degenerative changes as the body attempts to maintain homeostasis; influence
by extrinsic factors (biomechanical loading, diet, health status); selective forces/pressure are no longer acting to
control biological maintenance rates and rates of degenerative changes can vary widely
-skeletal age can be considered juvenile (subadult) (those ages during growth and development process including
the embryonic, fetal, infant, child and adolescent periods) and adult (ages occurring during the mature,
degenerative stage of skeletal change)
-skeleton is considered complete when all permanent teeth have erupted and all epiphyses have fused
Juvenile (subadult) age estimation
-relies on predictable process of growth and development of bones and teeth; proceeds at a rapid rate from birth to
first year of life, rapidly declines from infancy through childhood
-teeth: formation, mineralization and eruption of the deciduous and permanent dentition
-bones: ossification, long bone growth and epiphyseal union
-methods applied depend on the age category and the material available for analysis; dental development is more
highly correlated with chronological age then is bone development; dental methods are typically most accurate and
-dental development is under stronger genetic control (canalized), bone development is more susceptible to
environmental influences (physical loading, nutrition, health status)
Dental methods
-dental development begins around 6th fetal week and reaches completion early adulthood
-a neonatal line is formed (at or soon after birth) in deciduous teeth and on the first permanent molar which is evident
as a dark line in histological sections (likely caused by the stress of birth; may be an indicator baby was born alive
vs. stillborn)
-all deciduous teeth and first permanent molar have begun to mineralize; by age 3, all deciduous teeth have erupted
with completion of root formation; permanent anterior teeth and first molars begins to mineralize during the first year
of life, followed by premolars and second molars from age 2-4; third molar crowns form between ages 6-12;
permanent incisors, canines, premolars and first two molars erupt during two major intervals (6-8 and 10-12),
followed by the third molars, which usually don’t erupt until the late teens to early twenties
-enamel is the hardest tissue and most radiopaque
-most commonly used method: assessment of dental development stage
-development of each tooth follows the same sequence, the timing is different for each position; once the
degree of development i assessed, age is estimated by referencing calculated mean ages for achieving that
developmental stage; absolute accuracy: between 6 mo - 1 yr
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