15.2: Roll-Up, Life-Sized Juvenile Age Estimation
- Page ID
- 138562
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Author: Rebecca J. GilmourFabric skeleton with color coded epiphyses
Learning Objectives
- Observe various patterns in epiphyseal fusion
- Read ossification and fusion charts in order to estimate the most likely age-range of each individual.
- Think critically about how age at death is estimated from juvenile (subadult) skeletons,
- Identify limitations and challenges of estimating MNI in archaeological or forensic contexts.
Supplies Needed
- Fabric/paper skeleton prints with color coded epiphyses (image attached)
- Some individuals can be supplemented with other information (e.g., hand x-rays, plastic skeletal casts, see below)
- Blank fabric/paper skeleton print
- Washable colored markers
- Epiphyseal fusion and dental development charts
- Graph paper
Readings
- Kendell, Ashley et al. 2019. Chapter 15: Bioarchaeology and Forensic Anthropology. Explorations.
- Organ, Jason and Jessica Byram. 2019. Appendix A: Osteology. Explorations.
Introduction
Steps
- Distribute color-coded skeletal illustrations (and supplementary radiographs) to students or small groups of students.
- Have students work in groups to observe each epiphysis and element. In consultation with epiphyseal ossification and fusion charts and dental development diagrams, ask students to record each attribute, the state of fusion, and their age estimation for that specific element, epiphysis, or observation using a table (see example below).
| Epiphysis | State of Fusion | Age Interpretation (years) |
| Proximal humerus (head) | Unfused | <20 |
| Distal radius | Fusing | 14-20 |
| Proximal Ulna | Fused | >12 |
- Next, ask students to visualize the overall age-estimation by plotting each age range for each growth and development observation on graph paper (see figure below).
- Students should label the x-axis with age and plot each age range for each point of fusion/development along the y-axis. Students should be reminded to always report age ranges in osteological assessments, as there is some error associated with these methods (some individuals will fuse earlier or later than others)
- Using the chart they have created, students should look for the region of greatest age overlap. The area of greatest overlap is indicated by dotted lines in the figure above.
- Once students have estimated the age of the individual at one station, they should cycle through stations until they have estimated all the ages of all the stations the instructor created.
- In this stage of the exercise, students will apply what they have learned to create their own growth and development templates (these may be used by the instructor in future iterations of the course and activity).
- Provide students with a completely blank sub-adult poster/canvas. Secretly assign them an age at death for their specific individual. You may choose to put ages on slips of paper and have students draw these at random.
- Students should refer to the charts in White and Folkens (2005) and Scheuer and Black (2000) to color in the epiphyses that would be not ossified yet, unfused, fusing, or fused. They should adhere to the same color scheme as the instructor:
- Have students illustrate and indicate an appropriate pattern of dental development and eruption. Be able to discuss what you would expect to observe on their individual’s dental radiograph.
- Once students have completed their growth and development schematics, have them trade their work with a neighboring group. Time the groups to see who can estimate the age fastest while obtaining the most accurate age estimation. At the instructor’s discretion, the fastest and most accurate group could win a prize.
Conclusion
- At the end of each exercise, have students briefly present their observations.
- Check with the students to talk about the limitations and difficulties they encountered. Be sure to discuss how this stylized activity may differ from actual analysis of archaeological human bone.
- Discuss limitations to age-estimation techniques as they relate to preservation and collection/curation complications. For example, you may ask the class: “What if none (or only some) of the epiphyses were collected during excavation? How would the anthropologist know they were missing (as opposed to not ossified)? Could the anthropologist still estimate the age of the individual?”
Adapting for Online Learning
For Further Exploration
References
Image Attributions
Roll-Up, Life-Sized Juvenile Age Estimation Worksheet
Part 1: Estimate the Age of Pre-Prepared Juveniles
- On each skeleton, a series of epiphyses have been color coded according to their degree of fusion:
- Observe each epiphysis and consult the epiphyseal ossification and fusion charts and dental development diagrams in White and Folkens (2005) and Scheuer and Black (2000). Then create a table to help you record your observations and age ranges. An example table is provided below. Please create yours at the top of a sheet of graph paper.
| Epiphysis | State of Fusion | Age Interpretation (years) |
| Proximal humerus (head) | Unfused | <20 |
| Distal radius | Fusing | 14-20 |
| Proximal Ulna | Fused | >12 |
- Observe the pattern of dental development and eruption for each individual. Consult dental development/eruption charts in White and Folkens (2005). Which pattern of development and eruption does your individual best match? Record the age range in your table (on the graph paper).
- Visualize your age-estimations by plotting the age range for each element’s fusion and the dental development pattern on a chart using the graph paper, similar to that of the figure below. Be sure to label your x-axis with age and plot your age range interpretations for each observation along the y-axis.
- Find the area of the greatest age overlap in your chart. This range is your individual’s best estimated age at death. The area of greatest overlap is indicated by dotted lines in the figure below. Remember to always report age ranges in osteological assessments, as there is some error associated with these methods (some individuals will fuse earlier or later than others). What is your estimated age at death range?
Plotted age-estimations with area of greatest age overlap indicated with a dotted line. See White and Folkens (2005: 373, Fig 19.6) for similar fusion charts.
Part II: Create Your Own Sub-Adult
- On a blank sub-adult poster, use the colored markers to create a fusion pattern consistent with the osteological age range your instructor secretly assigned you.
- Illustrate and indicate an appropriate pattern of dental development and eruption. Be able to discuss what you would expect to observe on your individual’s dental radiograph.
- Trade your sub-adult poster with a neighboring student/group. Test yourselves: see who can estimate the age the fastest, while remaining accurate!
Conclusion: Present your Observations and Discuss
- How old was your individual? Tell your classmates why you estimated the age range as you did.
- What limitations and difficulties did you encounter?
- How might this stylized activity differ from actual analysis of archaeological human bone? Discuss limitations to age-estimation techniques as they relate to preservation and collection/curation complications.
