Purpose of Lab is for you appropriate conclusions based on the analysis of qualitative and quantitative empirical data

/in /by

And explain human biological variation from an evolutionary perspective.

This assignment you become familiar with the following important content knowledge in anthropology:

  • human skeletal anatomy
  • application of osteology in anthropology

You will practice the following skills as you complete this assignment:

  • identify major bones of the adult human skeleton
  • infer appropriate conclusions about skeletal anatomy based on qualitative information
  • explain sex differences in the pelvis from an evolutionary perspective

Tasks

Instructions for Lab 5

Step 1: Complete the Human Skeletal Anatomy Worksheet

Step 2: Complete the Human Skull Anatomy Worksheet

  • Step 3: Use the chart below to estimate the sex of the skulls in the image next to the chart. Please note that you would normally use this chart to help estimate sex by touching the bone (in addition to observing features). For this lab, you will only be observing the development of the features (make observations). You can compare the two skulls to help you decide the score for each trait in each skull. For example, if the mastoid process in the top skull looks smaller than in the bottom skull, then the score for this trait in the top skull should be lower than the score for the bottom skull.
    1. OBSERVE each trait as shown in the chart below and score the trait based on the degree of expression/development in both skulls in the 3D model. See the definitions for scoring (1-5) for each trait. To score the trait, you should view the specimens (the skulls in the 3D model below) and compare them to both the descriptions and figures (drawings in the chart). In the case of bilateral traits (i.e., traits present on the right side and the left side), both the right and left sides should be scored as Cole et al. (2017) have demonstrated that using the left side only significantly favors female classification, while using the right side only favors male classification in individuals that are asymmetric. Scoring is somewhat subjective so don’t be overly concerned about being “right”. Score as best as you can (make your best judgement based on your observations)!
      • Descriptions and Scoring of Traits (adapted from Morphopasse Database, Klales and Cole 2018). Open this document for additional pictures to help you score the traits ( Download Images to help with scoring of skull traits for sex estimation).
        1. nuchal crest (NC)
          • Description: Thick transverse nuchal crest along the squamous portion of the occipital bone, at the external occipital protuberance (EOP), for the attachment of the nuchal and trapezius muscles and the nuchal ligament.
          • Scoring: View the skull in lateral position (left or right side).
            • 1–Looks smooth. EOP is not evident.
            • 2–Slight roughening or traces of the nuchal lines. EOP is not evident
            • 3–Nuchal lines and EOP evident, EOP looks rough and has a lip or edge with slight
            • 4–Nuchal lines are marked. EOP is pronounced with clear posterior projection, but has not yet developed a pronounced hook or inferior projection
            • 5–Nuchal lines and EOP with a rough surface. EOP is very pronounced and can be hooked with a marked posteior/inferior projection. A ledge or ridge to either side of the EEOP may be present.
        2. mastoid process (MP)
          • Description: The mastoid process is a conical prominence of bone located on the temporal bones just posterior to the external auditory meatus (EAM). It serves as an attachment site for various muscles including the sternocleidomastoideus, splenius capitis, digastric posterior belly, and longissimus capitis.
          • Scoring: View the lateral side of cranium (left and right separately). Consider the overall volume of the mastoid process (length and width). More weight should be given to overall volume rather than length or width independently. Consider the size of the mastoid relative to the surrounding structures, such as the EAM and zygomatic process, and overall temporal bone size.
            • 1–Very small with low volume. Short and narrow. Little project of the mastoid below the inferior EAM border.
            • 2–Small. Short and/or narrow. Low volume. Slight projection of the MP below the EAM border
            • 3–Medium volume. Projection of the MP well below the inferior EAM border or longer than it is wide.
            • 4–Large volume. Usually long and wide relative to surrounding structures. Projection of the MP below the inferior EAM border. Much wider pr longer than the length/width of the EAM.
            • 5–Very large. Very long and wide relative to the surrounding structures. Largest volume. Pronounced projection of the MP below the inferior EAM border.
        3. supraorbital margin (SM)
          • Description: The superior border of the orbit, comprising the inferior-lateral portion of the frontal bone.
          • Scoring: The portion just lateral to the supra-orbital foramen or notch should be palpated (touched) by pinching the margin of the bone between forefinger and thumb. The degree which the margin posteriorly recurves (red arrows in file above entitled “Images to help with scoring of skull traits for sex estimation”) into the orbit should also be considered secondary to the thinness/thickness. Since you cannot touch the bone, just use your best judgement as to how thick you think the margin looks.
            • 1–Very sharp and thin.
            • 2–Sharp and thin.
            • 3–Blunted, but thin.
            • 4–Blunted/rounded edge and thick.
            • 5–Blunted/rounded edge that looks very thick.
        4. glabella (G)
          • Description: Glabella refers to the anatomical landmark located along the “most anterior midline point on the frontal bone, usually above the frontonasal suture” or nasion landmark (Buikstra & Ubelaker 1994:72). When viewing this landmark laterally, the overall browridge morphology can also be observed and should be considered. In some cases the left and right browridges may project more anteriorly than the actual glabella landmark. The projection of the entire browridge, when viewed laterally, should be considered and included in scoring. In some cases the landmark glabella may be depressed while the entirety of the supraorbital region is projecting in lateral view. In these cases, score the overall projection of the region when viewed laterally.
          • Scoring: View the lateral side of cranium and locate the most anterior projection of the frontal bone in the region near glabella.
            • 1–Little to no anterior projection at midline or in the supraorbital region. Bone looks smooth and nearly vertical.
            • 2–Slight anterior projection at midline or along the supraorbital region. Bone may be slightly ridged or projecting beyond the landmark nasion.
            • 3–Glabella and/or the browridges project anteriorly past the nasion landmark.
            • 4–Glabella and the browridges project anteriorly past the nasion landmark and are rounded.
            • 5–The region is massive and rounded (loaf-shaped) projection. Marked anterior projection past the nasion landmark.
        5. mental eminence (ME)
          • Description: The mental eminence is also known as the mental protuberance. It is a bony protuberance located along the midline of the mandible at the center of the chin and is the attachment site for the mentalis muscle. Lateral to the protuberance, on either side, are the mental tubercles. Together, the protuberance and tubercles make up the mental trigon. Note that the tubercles can be absent or can project anteriorly or inferiorly. In some cases there may be two tubercles present on one or both sides of the protuberance. When this occurs, score the most lateral tubercles. There is considerable variation in the expression of the shape (i.e., squareness), total area, and the tubercles, and these traits are not necessarily all correlated.
          • Scoring: If no tubercles are encountered, see scores 1-2. If tubercles are observed, see scores 3-5. More weight should be given to the presence or absence of tubercles. Since you cannot hold and touch the bone, please just do your best with observation.
            • 1–Pointed or rounded and smooth with no evidence of a projecting protuberance or tubercles.
            • 2–Slightly delimited or roughened area at the protuberance with no tubercles.
            • 3–Slightly or fully delimited projecting protuberance with anteriorly or inferiorly protruding tubercles that are close to the midline or mandibular symphyses.
            • 4–Inverted T-shape with widely spaced anteriorly or inferiorly protruding tubercles. Mental trigon occupies a good portion of the anterior mandible.
            • 5–Inverted T-shape with very widely spaced anteriorly or inferiorly protruding tubercles. Mental trigon takes up most of the anterior mandible.
    2. ADD the scores across the traits (this is a rough breakdown to help you with your sex estimation):
      • ~5= estimated female
      • ~10= probable female
      • ~15= indeterminate
      • ~20= probable male
      • ~25= estimated male
    3. INFER the estimated biological sex of each skull (top skull and bottom skull) based on your observations and scoring. In your lab write-up for this portion of the lab, please be sure to explain the expression/development of each trait you observed on each skull. Please be clear as to which skull you are referring to in your description and in your biological sex estimation. Please refer to the skulls as Top Skull and Bottom Skull.

Traits used to estimate the sex of a skull

(from Buikstra and Ubelaker 1997, after Acsadi and Nemeskeri 1970)

USE THE SPECIMENS IN THIS 3D MODEL BELOW TO ESTIMATE THE SEX FOR EACH SKULL

Sketchfab

  • Step 4: Examine the female and male os coxae in the 3D models below.
    1. LIST 4 sex differences you observe. Please be sure to say which sex has the trait (it may be easier to list your female and male traits in a table).
    2. Look at the last os coxa. Use your knowledge of sex differences in this bone to ESTIMATE the sex of this sample. Please be sure to name and explain at least three traits you used to help you estimate the sex.
      • Poor example: The notch thing.
      • Better example: The greater sciatic notch helped me conclude this is a probable female.
      • Best example: The greater sciatic notch looks [describe what you observe]. This tends to be the condition in females, which helped me conclude this is a probable female.
    3. Briefly EXPLAIN why there are so many sex differences in the os coxa.

Male

Male Pelvis with Annotations by Durham Archaeology on Sketchfab

Female

Female Pelvis Annotated by Durham Archaeology on Sketchfab

Estimate the sex of the os coxa in the 3D model below

Os Coxa (Pelvis) by Durham Archaeology on Sketchfab

  • Step 5: Use the dental development chart from this week’s reading (Applications of Osteology in Anthropology) to estimate the age at death of this child (from this X-ray image). Please describe the teeth that you observe (name of the tooth, deciduous or permanent) and explain your rationale for your age at death estimate. You only have this child’s X-ray so be sure to look at the tooth eruption on the dental development chart. Don’t be too concerned with being “right”. Use the information you have learned in this week’s lab and infer an age at death estimate based on your observations. Just try your best!

denatal eruption image.jpg

Sketchfab

  • Step 6: Examine the images below. Estimate the individual’s ancestry based on the skeletal traits you observe. Be sure to list/name the traits and explain the expression of the traits that helped you come to your conclusion. For example, do not state “the orbits”. Be specific about what the orbits look like (explain/describe the orbits).

Human skull

Sample A

Human skull

Sample B