Biological Anthropology Lab Report

Biological Anthropology Lab Report

LAB 1: ADAPTATION BY NATURAL SELECTION & POPULATION GENETICS
BIOLOGICAL
ANTHROPOLOGY Lab 7: Human Osteology
Introduction to Biological Anthropology Laboratory
Digital Lab Workbook
Lab Objectives
● Learn major anatomical features of the human skull and postcrania.
● Calculate indices for the cranium and postcrania.
● Use anthropometric methods to estimate sex and stature.
● Understand the use of standard error in statistical measures.
Lab Assignment Overview
Assessment
Welcome to Lab 7! You will need a computer and wifi connection to complete this assignment.
You might also need a calculator; you can find a web-based scientific calculator here. This
web-based consists of one major exercise and a set of assessment questions you will answer
on your own time.
During each exercise, you will navigate through a slide deck containing descriptive information,
diagrams, images and video. Read all information in full. Use these tools, what you’ve learned in
lecture, and your textbook to assist you in answering questions in the assessment portion.
Below is a breakdown of the concepts covered in this workbook:
Once you’ve read through each exercise, you will complete a set of assessment questions based on
the review material. You can find these questions at the end of this workbook. You will type and
submit your answers into a google form where your TA will grade them. You are encouraged to
review the assessment questions and prepare your answers before accessing the google form.
EXERCISE 1 Human Skeletal Variation
1. Concept Introduction
2. The Human Skeletal System
3. Osteology & Estimation
1
LAB 7 | EXERCISE 1
Human Skeletal Variation
Concept Introduction
Bones provide a means to study the nature and degree of variation in the
human body. Using clues and information from the skeletal system,
practitioners in skeletal biology, osteology, and forensic anthropology
study variation across an individual’s life span, between populations and
even across evolutionary time.
Bones are highly durable, vary between individuals in appearance (in the
same way our faces and bodies do) and also they remodel several times
throughout a person’s life. Additionally, because bones change in
response to the environmental and biomechanical pressures placed on
them, they provide a helpful model for the study of human anatomical
and physiological variability.
In forensic anthropological contexts, practitioners identify morphological
markers in the skeleton to build a biological profile that includes traits
about an individual including their age at death, sex, ancestry, stature,
occupational details, pathological conditions, or traumatic injuries. This
information is given to law enforcement in medico-legal situations to
identify deceased or missing people. In the Exercise 1 assessment
portion, you will employ osteological techniques to measure and describe
human skeletal variation.
2
An Anatomical Review LAB 7 | EXERCISE 1
The human skeleton is a mechanically
optimized biological system whose
composition and organization reflect the
functional demands placed upon it.
The role of the osteologist is to identify
human bones from those of non-human
material (i.e. animal bones) and to
determine as much additional information
about the bones they are confronted with.
Examine the diagram on the right and the
below 3D model of the human skeleton, see
if you can identify the three regions
specified: Pelvis, Skull, and Long Bones
(Femur, Tibia, Fibula, Humerus, Radius, &
Ulna).
Human Skeletal System
3D
Model
Click Here
3D models are a
helpful tool to
illuminate the spatial relationships
and surface structure of anatomical
components. Explore and rotate a 3D
model of the human skeleton below.
The pelvis, skull, and (4 )long bones are a few of the most helpful parts
of the body used to infer, sex, age, stature, and ancestry information.
Femur
(Long Bone example)
Pelvis
Skull
3
LAB 7 | EXERCISE 1
Osteology & Estimation
Concept Introduction
Stature Estimation Using the Long Bones: The stature, or
individual’s height, can be inferred using measurements of an
individual’s long bones, namely the humerus, femur, and tibia. When
these bones are unavailable, other long bones – the ulna, radius, and
fibula can also provide a range. There are several methodologies
that are used within osteology to determine these estimates.
A single skeleton can provide an abundance of data on an individual’s life from their age, sex, and stature all the way to past
struggles like disease, accidents, and developmental instability. The most basic of inferences are estimations on the
individual’s age, sex, and stature. As a person ages, their skeletal morphology will grow and change; long bones, for example,
grow dramatically from childhood to adolescence as individuals grow taller. There are also subtle differences between the
sexes in the morphology of some parts of the skeleton, notably the skull and pelvis.
Sex Estimation Using the Skull: Sexual dimorphism constitutes
the morphological differences in size and shape between males and
females. The marked appearance of sexually dimorphic traits within the
skull appear at puberty and progress into adulthood. We use skull traits
in combination with other skeletal traits to infer the sex of a skeleton.
Sex Estimation Using the Pelvis: The pelvis is a basin-shaped
bone that sits between the trunk and the lower limbs. It is extremely
useful in the estimation of sex because it offers the most accurate
determinations. Anatomically, the male pelvis is longer, more robust,
and displays more rugged features with marked muscle insertions
whereas the female pelvis shows a wider sciatic notch with an obtuse
angle.
END OF
EXERCISE 1
Take a break, then move to the
assessment.
Preview the assessment questions for Exercise 1 on the next few pages. You will type your
answers to each question into a google form where your TA will grade them. You are
encouraged to prepare your answers in a word document or on paper before submitting. To
access the google form, use the link provided on Blackboard. Be sure you are logged in with
your GW email and password.
Lab 7 Assessment
Exercise 1 Assessment
Section 1: The Cranium
The human skull is composed of three regions: the
neurocranium (cranial vault or braincase),
basicranium (cranial base), and face. Examine this
interactive 3D Human Skull noting the definitions of
each bone. Once you’ve done this, fill in each blank
(below) with the name of the appropriate bone.
Neocranium
Basicranium
Face
View in 3D
Neurocranium
The _________________ are two paired bones that form the upper lateral surfaces of the skull.
The _________________ forms the front of the cerebral cranium. This bone is comprised of the squama frontalis, orbital and
nasal portions and sits supra-orbitally (above the orbital eye ridges).
Face
The _________________ are small paired bones that connect the frontal bone with the upper jaw and temporal bones. These
bones intersect with the temporal bone to form an arch.
The _________________ are paired bones forming the bridge of the nasal cavity.
Basicranium
The _________________ are paired bones that form the basal and lateral walls of the skull. These bones house the structures
of the organ of hearing and vestibular system.
The _________________ bone sits at the rear of the cerebral cranium and features a large hole at its base called the foramen
magnum, through which the cranial cavity communicates with the vertebral canal.
4
Exercise 1 Assessment
Section 2: Stature Estimation using Long Bones
Using the long bones of the arm (humerus, radius, and ulna) and the long bones of the leg (femur, tibia, fibula) we can
estimate an individual’s stature (~height). To do this we measure the total length of each long bone at specific locations on
the bone. Examine each bone below, you’ll find a measurement table you need to estimate stature on the next page.
1
1 2 3
4 5 6
Leg Bones
Long Bones
Humerus
Arm Bones
Radius Ulna Tibia Fibula Femur
5
Exercise 1 Assessment
Question 1: Using the long bone measurements provided in the table above (in red), calculate the three most
common cranial indices.
Brachial index (radius length / humerus length) × 100 = ?
Crural index (tibia length / bicondylar femur length) × 100 = ?
Intermembral index (humerus length+radius length / bicondylar femur length+tibia length)× 100 = ?
Measurement Type Description Measurement (cm)
1 Maximum length of the humerus: Measure from the distal to proximal end. 34.5
2 Maximum length of the radius: Measure from the distal to proximal end. 23.8
3 Maximum length of the ulna: Measure from the distal to proximal end. 25.1
4 Maximum length of the tibia: Measure diagonally from the lateral condyle to the medial
malleolus.
34.5
5 Maximum length of the fibula: Measure from the distal to proximal end. 35.1
6 Bicondylar length of the femur: Set both condyles firmly against the stationary upright. Note
that a condyle is a round protuberance at the end of a bone
that often forms a joint.
34.7
Section 2: Stature Estimation using Long Bones
6
Exercise 1 Assessment
Stature formulae for Females SE
3.08 × Humerus Length + 64.67 4.25
2.75 × Radius Length + 94.51 5.05
3.31 × Ulnar Length + 75.38 4.83
2.28 × Femur Length + 59.76 3.41
2.45 × Tibia Length + 72.65 3.70
2.49 × Fibular Length + 70.90 3.80
Stature estimate for humerus (cm) = ?
Stature estimate for femur (cm) = ?
Question 3: Let’s say the stature estimates you calculated for the humerus differed from those you calculated for
the femur. What would this suggest?
Question 2: Assuming these bones belong to the same
individual and assuming this individual was female, use the
stature formulae in the table to the right to estimate her
stature during life.
Calculate stature for the humerus and femur only. All
formulae are followed by their standard error (SE) in red; this
indicates how much variation is in the estimate. The lower the
SE, the better the estimate. These formulae report results in
centimeters.
Section 2: Stature Estimation using Long Bones
7
Exercise 1 Assessment
Section 3: Qualitative Sex Estimation
In primates, males are usually larger than females. Modern humans also exhibit a degree of sexual dimorphism,
described as differences in shape or size due to sex. In humans, sexually dimorphic traits vary within and between
populations. It is common in our culture to refer to sex and gender interchangeably, but sex here refers to
biological traits and gender refers to the behavioral, cultural, and psychological traits we associate with a sex. The
best skeletal areas for estimating sex are the skull and the pelvis. High quality diagrams and images of skull and
pelvic anatomy are included in the back of this digital workbook. Review each image and come back to answer
the below questions.
Question 1: Why do you think these two areas are the best to use for sex determination?
Question 2: Which skeletal element (skull or pelvis) do you think provides higher accuracy in determining sex?
Question 3: Examine the two 3-dimensional mystery skulls linked below. Based on your review of the images
and qualitative skull traits, decide which skull is female and which is male (multiple choice-matching question).
Question 4: Describe 2 traits you used to determine the sex of the two mystery skulls.
Question 5: Examine the two 3-dimensional mystery pelvi (singular pelvis) below. Based on your review of the
images and qualitative pelvic traits, decide which pelvis is female and which is male (multiple choice-matching
question).
Question 6: Describe 2 traits you used to determine the sex of the two mystery pelvi.
1
View Mystery Skulls
View Mystery Pelvi
8
Exercise 1 Assessment
Section 4: Metric Sex Estimation
Both quantitative and qualitative data can be useful for evaluating scientific phenomena. In Section 3, the
characteristics we used to describe male and female skulls and pelvi are qualitative. If we had measured the
bones and provided numerical values, these data would be quantitative. We could have measured the same sex
traits we described in Station 5 to yield quantitative data.
We will perform a quantitative analysis of one feature on a pelvis – the width of the greater sciatic notch. Recall
from the Section 3 images that the greater sciatic notch is usually wider in modern human females and more
narrow in males. Here we will use actual measurements of this notch to make a sex determination.
In a normal lab setting, you and other members of your lab group would take a set of repeated measurements.
Below, a sample set of measurements has been provided for you in red. Using these measurements, determine
the mean for your sample.
1
Trial 1 Measurement (cm): 8.1
Trial 2 Measurement (cm): 8.3
Trial 3 Measurement (cm): 8.1
Trial 4 Measurement (cm): 8.2
Question 1: Mean = ?
Greater Sciatic
Notch
9
Exercise 1 Assessment
Section 4: Metric Sex Estimation
Because error can occur in measurements, particularly when they are taken by different observers, it is
sometimes helpful to report the standard error of a measurement. Standard error (SE) indicates how much
variation is in the estimate. To calculate the standard error of this set of pelvic measurements, use the following
formula:
Standard Error of the Mean (SEM) = √S²/N
1
Variance = s2 → (SS) / (V) ?
SS = Sum of Squares → (X1 − Z) 2
+ (X2 − Z) 2
+ (X3
− Z) 2
+ (X4 − Z) 2
?
Z = Mean ?
V = degrees of freedom → N − 1 ?
N = the number of observations ?
Xsubscript = The trial number ?
Question 2: What is your SEM _________?
Question 3: A “good” standard error depends on the questions you are asking and the data you use. For our
purposes, your SEM should be less than 10% of your mean measurement (Z) for the greater sciatic notch.
Would your SEM be considered “good” for our experiment?
First, plug in the information you have, then use the SEM formula!
10
Typical Female Typical Male
Smaller and lighter or more gracile skull Larger, heavier or more robust skull
Rounded frontal bone when viewed in profile (forehead) Sloping less rounded forehead in profile (frontal bone)
Smooth supraorbital ridge (brow) Raised/ prominent supraorbital ridge (brow)
Round eye orbits Eye orbits that are more square in shape
Sharp upper eye margins Blunt upper eye margins
Pointed chin Square chin
Sloping (obtuse) angle of the jaw Vertical (acute) angle of the jaw
Chin
Jawline
Upper Eye Margin
Frontal Bone
Eye Orbits
If it seems like the
variation here is slight…
IT IS! The morphological
differences between
males and females within
and across populations
are highly variable and
often minute.
What other differences
can you identify? Check
out additional images on
the following pages.
Skull Traits
11
Typical Female Typical Male
Smaller and lighter or more gracile skull Larger, heavier or more robust skull
Rounded frontal bone when viewed in profile (forehead) Sloping less rounded forehead in profile (frontal bone)
Smooth supraorbital ridge (brow) Raised/ prominent supraorbital ridge (brow)
Round eye orbits Eye orbits that are more square in shape
Sharp upper eye margins Blunt upper eye margins
Pointed chin Square chin
Sloping (obtuse) angle of the jaw Vertical (acute) angle of the jaw
Supraorbital Ridge
Jawline
Mastoid Process
Chin
12
Female
Female Male
13
Female
Female Male
14
Female
Female Male
15
Female
Female Male
16
Female
Female Male
17
Female
Female Male
18
Female
Female Male
19
Female
Female Male
20
Pelvic Inlet
Sacrum
Iliac Blade
Typical Female Typical Male
Wider, shorter sacrum with less curvature Longer more curved sacrum
Larger sub pubic angle Smaller sub pubic angle
Wider, flared iliac blades More narrow, vertically pointed iliac blades
Larger, more oval shaped pelvic inlet Smaller, more heart-shaped pelvic inlet
Triangular shaped obturator foramen Oval shaped obturator foramen
Greater sciatic notch opening is wider in profile Greater sciatic notch opening is more closed in profile
Smaller acetabulum that faces anteriorly Larger acetabulum that faces laterally
Pelvic Traits
21
Sub Pubic Angle
Sacrum
Iliac Blade
Typical Female Typical Male
Wider, shorter sacrum with less curvature Longer more curved sacrum
Larger sub pubic angle Smaller sub pubic angle
Wider, flared iliac blades More narrow, vertically pointed iliac blades
Larger, more oval shaped pelvic inlet Smaller, more heart-shaped pelvic inlet
Triangular shaped obturator foramen Oval shaped obturator foramen
Greater sciatic notch opening is wider in profile Greater sciatic notch opening is more closed in profile
Smaller acetabulum that faces anteriorly Larger acetabulum that faces laterally 22
Greater Sciatic Notch
Typical Female Typical Male
Wider, shorter sacrum with less curvature Longer more curved sacrum
Larger sub pubic angle Smaller sub pubic angle
Wider, flared iliac blades More narrow, vertically pointed iliac blades
Larger, more oval shaped pelvic inlet Smaller, more heart-shaped pelvic inlet
Triangular shaped obturator foramen Oval shaped obturator foramen
Greater sciatic notch opening is wider in profile Greater sciatic notch opening is more closed in profile
Smaller acetabulum that faces anteriorly Larger acetabulum that faces laterally
Acetabulum
23
Female
Female Male
24
Female
Female Male
25
Female
Female Male
26
Female Male
Female
27
Female Male
Female
28
Female Male
Female
29
Female Male
Female
30
Female Male
Female
31
END OF
LAB 7
Submit your assessment questions and
you’re all set!

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