Skeletal Variation and Estimation

Flashcards generated from lecture notes on skeletal variation and osteological estimation techniques.

What are the four most important biological variables estimated osteologically?

Sex, age, stature, and ancestry

What phenomenon does sex attribution rely on?

Sexual dimorphism

What is age estimation based on, especially for juveniles?

Growth and development (ontogeny)

What is stature estimation based on?

Size, like lengths of bones

What is ancestry estimation based on?

Geographically patterned aspects of human variation, mostly cranial

What are the two main approaches to osteological estimation techniques?

Morphoscopic (anthroposcopic) and osteometric

What does the morphoscopic approach involve?

Observation of features (present/absent, degree of expression)

What does the osteometric approach rely on?

Measurements of the skeleton

What tools are commonly used for osteometric measurements?

Calipers and linear distance measurements

Where are standard skeletal measurements published?

Bojstra and Ubeleker volume (1994)

What recent three-dimensional approaches are used in skeletal measurement?

Microscribe, laser surface scanners, photogrammetry, computerized tomography (CT)

What are examples of discrete or category variables in osteological estimation?

Ancestry and sex

What are examples of continuous or scalar variables in osteological estimation?

Age and stature

What is accuracy in estimation?

Closeness of a measurement/estimate to its true value

What are aspects of error that influence accuracy?

Inter- and intra-observer error

What is precision in estimation?

Repeatability of a measurement

What is bias in estimation?

Tendency of a method to over- or underestimate the true value

What is a population in the context of estimation?

Global or total set you are trying to understand

What is a sample in the context of estimation?

Subset of the population that is actually measured

What is a well-known sample used to derive osteological estimation methods?

Hammond-Todd Collection

What phenomenon can affect estimators based on old collections?

Secular trend

Which component of the biological profile can be estimated with the most accuracy?

Sex

What are the typical categories used for sex estimation?

Male, female, or indeterminate

In what area of the skeleton is sexual dimorphism most strongly manifested?

Pelvis

What is being estimated by osteological approaches to sex estimation?

Biological sex, not gender

What features of the pelvis relate to obstetric considerations?

Subpubic angle, sciatic notch, preauricular sulcus, shape of sacrum, pelvic inlet

In females, is the subpubic angle wider or more acute?

Wider

How does the shape of the greater sciatic notch differ in females compared to males?

Wider

Where is the preauricular sulcus located?

Anterior edge of the auricular surface of the ilium

How does the shape of the sacrum differ in females compared to males?

Wider with relatively large alae

What pubic bone features are used for sex estimation?

Ventral arc, subpubic concavity, medial aspect of ischiopubic ramus

Describe the ventral arc in females.

More prominent ridge spaced laterally away from the pubic symphysis.

Describe the shape of the subpubic concavity.

Concave

Is the medial aspect of the ischiopubic ramus typically sharp or broad in females?

Sharp

What does the ischium-pubic index measure?

Ratio of iliopubic ramus length to length from acetabulum to ischial tuberosity

What does the sacral index measure?

Ratio of sacral breadth to sacral height

What two key ways do male and female crania tend to differ morphologically?

Size of muscle insertions and ratio of cranial vault to face size

Do males or females have proportionately larger faces?

males

Compared to females, do males typically have larger or smaller mastoid processes?

Larger

What factor is important to consider when using skull features for sex estimation?

Related to general robusticity

What does metric sex estimation of postcrania generally rely on?

Size

What is crucial when estimating sex based on size?

Awareness of the population being studied

How accurate is sex estimation in juvenile remains compared to adults?

Much lower

What topic is important to consider before proceeding to ancestry estimation?

Human variation and race

What is the scientific consensus on the biological basis for racial groupings in humans?

No biological basis

What are the 3 main reasons for the scientific consensus on race?

Humans have relatively low levels of biological variation, clinal variation, and strong environmental influence.

What is race considered in the United States?

A cultural construct

Why is race still used in forensic anthropology?

It correlates with access to resources, privilege, how one is treated by the state and other individuals within the country

What two components of human skeletal variation is ancestry estimation based on?

Geographically patterned and heritable

Compared to what species are humans much less genetically different?

Chimpanzees

What is the general trend of human skin color by geography?

Decreasing pigmentation away from the Equator

Where does the genetic variation from the rest of the world derive from?

Subset of sub-Saharan African variation

What were traditional groupings such as European, African, and Asian descent based on?

Patterns of immigration and the US Census forms.

What part of the skeleton is commonly used for ancestry estimation?

Cranium

What age range is ancestry estimation generally done on?

Adult material

What is the one area ancestry can be estimated on from a juvenille?

Teeth

Does human genetic variation fall above or below the FST level recognized as recognizing subspecies?

Below the threshold

What skull features are used for morphoscopic ancestry estimation?

Inferior nasal spine, nasal aperture, interorbital breadth, orbit shape, postbregmatic depression, transpalatine suture

What is the scoring system for the inferior nasal spine?

From one to three

What is the inferior nasal aperture score based on?

Based on the degree of development of the inferior nasal aperture

How are morphoscopic ancestry estimation features analyzed?

Decision tree and Bayesian approach

Instead of placing an individual in a race category, what will modern scoring approaches do?

It'll give a probability assessment among different choices

What program is most commonly used for metric based ancestry estimation?

FourDisc

What term is used to describe human variation as a function of secular trend?

Plastic

What are probably the most useful approaches for ancestry estimation these days?

Landmark based morphometrics

How do brains grow so that a 5 year old brain is 90% of it's adult size.

They grow very early

Which is the most accurate area for estimating sex?

Pelvis

Estimating the height of a deceased individual is based on the sizes of different elements, especially which element?

Stature

What are the two components to sexual dimorphism?

Size and shape

Morphoscopic approaches are based on what?

Observation

Precision focuses on which component of a method?

Repeatability

What did the notes compare Cultural construct to?

Money

What cases are typically used for Probability Assessments?

Forensic cases

What is the growth and development of age estimation technically known as?

Ontogeny

What is the general degradation of the system known as?

Senescence

What is the remodeling of age esimation known as?

Attrition

A diameter of something, and is it bigger or smaller than a particular value is known as a what?

Criterion

What is the ratio of two measurements known as?

Index

From where was the Hammond Todd collection based?

The suburbs of St. Louis

Besides Male and Female, what is the last sex category?

Indeterminate

Who originally described the differences of the pubic bones between males and females?

Fenessee

Which point does the measurement of the ileopubic ramus run to?

Ischial tuberosity

Besides the ischium pubic index, which specific element can be measured to estimate sex?

Sacra

The aspects of human biology that vary, tend to vary in a what style?

Clinal

What reason were the notes to justify the use of race in forensic anthropology?

Missing person's descriptions

What approach does the Bayesian decision tree analyze the skull features using?

Bayesian approach