Forensic Anthropology: Population Affinity Estimation Methods and Practice

What does population affinity refer to in forensic anthropology?

Measures of biological similarity between an individual and reference groups derived from populations.

Why is sex estimation important prior to population affinity analyses?

Most methods require estimation of sex to accurately interpret skeletal variation.

What is the concept of race in the context of forensic anthropology?

Race is not a biological reality; most human variation exists within population groups, not between them.

What are morphoscopic traits?

Traits analyzed from the skeleton, usually the skull, that correspond to geographic variations.

What is the purpose of Optimized Summed Scored Attributes (OSSA)?

To systematically study and statistically calculate interpretations of skeletal traits.

What does craniometric estimation involve?

Measuring dimensions of the skull and anatomical landmarks to identify geographic patterns in skull shape and size.

What is Fordisc used for in forensic anthropology?

A statistical program that classifies measurements of unknown skeletons based on their similarity to known individuals.

What types of analyses are used in dental metrics?

Discriminant function analysis of tooth crown measurements.

What are some non-metric traits used in population affinity estimation?

Ramus inversion, gonial flare, chin shape, and mandibular tori.

What are the main postcranial elements used in forensic anthropology?

Tibia, talus, humerus, and femur.

What is a key challenge in postcranial methods compared to cranial methods?

There are fewer methods for postcrania, and variation is less understood.

Why should macromorphoscopic methods not be applied to juvenile remains?

Juvenile remains require temporally appropriate reference samples due to developmental differences.

What is an example of a disease that may vary between populations?

Paget's disease is more common in European groups.

What is the significance of secular change in forensic anthropology?

It refers to the need for using temporally appropriate reference samples in analyses.

What is the relationship between geographic adaptations and postcranial morphology?

There is a weaker correlation between postcranial morphology and geographic adaptations compared to cranial morphology.

What is the primary focus of morphoscopic estimation?

Analyzing character states and traits of the skeleton that are associated with geographic variations.

What statistical approaches are used in craniometric estimation?

Multivariate statistical approaches including Fordisc.

What does the term 'mandibular tori' refer to?

Bony growths on the mandible that can vary in size and presence among populations.

What is the importance of dental metrics in forensic anthropology?

They provide insights into population affinity through analysis of tooth measurements.

What is the main challenge in analyzing postcranial elements?

The historic emphasis on cranial analysis has led to less understanding of postcranial variation.

What does the term 'gonial flare' refer to?

The shape of the angle of the mandible, which can vary significantly among populations.

cline

a gradient (often of phenotypic form) based on the geography and environment

decision tree modeling

a regression-based model that uses sequential rules to determine group membership through a series of nodes; also called classification tree model

folk taxonomy

traditional, often nonscientific, ways of organizing or categorizing the natural world

morphoscopic traits

quasi-continuous morphological features that show varying forms, degrees of expression, or frequencies in presence of absence

optimized sumed scored attributes (OSSA)

a method of population affinity estimation that uses statistical analysis of morphoscopic traits and their character states

platymeric

Flat in the anterior-posterior direction

population

an a priori defined group of individuals that share characteristics.

population affinity

A measure (e.g., distance, probability of membership) of similarity between the individual and reference groups.

positive assortative mating

mating between individuals of like groups

race

in humans, a grouping based on shared physical or social qualities into categories generally viewed as distinct by society

Subspecies

a geographically isolated subdivision of a species.

Population Affinity:CH 9

Population affinity- the measures of biological similarity between an individual and reference

groups derived from populations

The study of morphoscopic traits and skeletal measurements that correspond to

geographically patterned genetic variation. Based on reference samples

Interpreting skeletal variation within the context of social labels

The concept of race in Anthropology:

-race is not a biological reality

-85% of variation occurs within populations, and only a small percentage occurs

between populations

-scientific racism among forensic anthropology: hooten tried to define 3 separate

races, which were used to determine intelligence and morality

-Social categories/folk taxonomies: race, ethnicity, ancestry, nationality, or other

-The term population affinity: more inclusive, and to also differentiate between the

biological profile and genetic ancestry testing done by biologists

Positive assortative mating- mating between individuals of similar groups. Leads to an

identifiable degree of concordance between an individual's social race and their skeletal

biology

Admixed- when two parents are of two different ancestral backgrounds

A cline or clinal distribution- the continuum of a given trait across a geographic location or

environment

Macroscopic/Morphoscopic studies: usually the skull, traits associated with geographic

variations. Uses traits and character states. previously used "trait lists" which left out actual

statistical methods

Character state- the form, degree of expression, or presence/absence of a morphoscopic trait

-OSSA Optimized Summed Scored Attributes

-uses decision tree modeling

● Nasal aperture width

● Anterior nasal spine-either projects or is more absent-most inferior portion of nasal

bone

● Inferior nasal aperture

● Nasal bone structure-could also be called nasal bone contour. Uses a contour gage

● Interorbital breadth- how far apart the orbits are

● Post-bregmatic depression-either absent or present

Fordisc: uses race and geographic location categories: may not take into account origin, such

as the vietnam village that is traditionally cambodian. Also uses discriminate functions and

craniometric estimations

Craniometrics

Fordisc- uses discriminate functions, classifies measurements of unknown individuals based

on the info of known individuals. Evolved from the Forensic Data Bank in UTK

3Skull

Can also use complex multivariate approaches- frequency distributions, k-nearest neighbor,

logistic regression, random forest modeling, or other bayesian approaches- but requires

extensive training in statistics and computer programming

Dental Metrics and Mandible

Tooth crown measurements-Discriminate function analysis, using buccolingual and

mesiodistal measurements for all teeth except the 3rd molars, which differ in equation by

male and female. Defines individual as African, Asian, or European, requires all teeth

-diseases can sometimes be common within populations

Mandible- (hu)MANid uses morphoscopic and metric data to determine sex and population

affinity via mandible length, height, and angle+mandibulometer

Chin shape from superior view- blunt, pointed, square or bilobate

Mandibular tori

Gonial flare

Ramus inversion

Mandibular border form

Postcranial

Population affinity variation below the skull is less understood

Femur is the most extensively studied

Anterior femoral curvature

Intercondylar shelf angle

Subtrochanteric shape

Also tibia, talus, and humerus