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9.2: Tactile Evolution

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  • Page ID
    138541

    • Kristen A. Broehl
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    Tactile Evolution

    Format: In-person

    Australopithecus afarensis fossil hominid (Lucy skeleton) (Hadar Formation, Pliocene, 3.2 Ma; Hadar area, Afar Triangle, northern Ethiopia, eastern Africa) 1
    of Australopithecus afarensis (Lucy)A depiction of the lower skeletal anatomy

    Authors: Katherine E. Brent and Sydney Quinn Chizmeshya

    Time needed: 5-10 minutes per element

    Learning Objectives

    • Visualize and explain morphological changes related to bipedalism
    • Use kinesthetic learning to retain information about skeletal features of bipedalism

    Supplies Needed

    • Element reference sheets (included)
    • Modeling clay

    Readings

    • Yoshida-Levine, Bonnie. 2019. Chapter 9: Early Hominins. Explorations.

    Introduction

    Modern humans are obligate bipeds: we are designed to always walk upright on two legs. Human ancestors, however, were not all obligate bipeds-- many were adapted for arboreal activities as well. In this activity, we will examine which skeletal changes are present in non-obligate and obligate bipeds, and we will use chimpanzees and modern humans as examples. Notably, there are also soft tissue changes that come with a shift to obligate bipedalism. Since the primary source of evidence for biological anthropologists is skeletonized and fossilized remains, we will be focusing on skeletal changes.

    Specifically, students will construct models of non-obligate biped skeletal elements using modeling clay and then ‘evolve’ them into obligate skeletal elements. This activity allows students to develop a tactile sense of the skeletal differences and changes between non-obligate bipeds and obligate bipeds.

    Steps

    • Students may work in groups or individually. Each group or individual receives one ball of clay per skeletal element, the Element Reference Sheet(s), and Student Worksheet.
    • Students use the clay to construct the element as it appears in a non-obligate biped, using the Element Reference Sheet for guidance. For this activity, a chimpanzee will be used, but other non-obligate bipeds may be used instead.
    • After constructing the non-obligate biped element, students make appropriate changes in order to transform the element into one resembling that of an obligate biped. Students may add, remove, or sculpt the clay to make changes but they must not destroy the prior element. In this case, the modern Homo sapiens will be used as a model, although a different obligate biped may be used instead.
    • Students should understand that the model non-obligate biped (i.e. modern chimpanzees) are NOT an ancestor of modern humans. The models are only used to display general characteristics of non-obligate bipeds. The line illustrations are simplified to facilitate easier modeling.

    Review Questions

    • Discuss the challenges you encountered in transforming the non-obligate biped model into an obligate biped model.
    • Which morphological or skeletal changes seemed most significant and why?
    • The proportionately smaller upper limbs, and S instead of C curved spines in obligate bipeds can be difficult to model. How did you address this? Why are these features important for obligate bipeds?

    Adapting for Online Learning

    1 Not adaptable 2 Possible to adapt 3 Easy to adapt

    Students could construct the models at home, using clay, and then photograph and upload into the learning management system’s discussion board. Students could then discuss each other’s models and the challenges they encountered.

    Tips and Suggestions

    After the activity, encourage students to read about regional skeletal anatomical variation between obligate and non-obligate bipeds on p. 329 of Explorations—this will help students to connect the kinesthetic knowledge that they have developed to specific anthropological terminology.

    For Further Exploration

    The Smithsonian National Museum of Natural History’s Human Family Tree:

    https://humanorigins.si.edu/evidence/human-family-tree

    References

    Yoshida-Levine, Bonnie. 2019. “Chapter 9: Early Hominins.” Explorations: An Open Invitation to Biological Anthropology, edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association. http://explorations.americananthro.org/

    Image Attributions

    Australopithecus afarensis fossil hominid (Lucy skeleton) (Hadar Formation, Pliocene, 3.2 Ma; Hadar area, Afar Triangle, northern Ethiopia, eastern Africa) 1 by James St. John is licensed under CC BY 2.0.

    All reference sheet images are drawn by Katherine E. Brent and licensed under CC BY-NC 4.0.

    Tactile Evolution Worksheet

    Name______________________ Date___________

    1. List the skeletal elements that you modeled using clay.

    2. For each element, describe how you transformed it from the non-obligate biped form into the obligate biped form.

    3. For each element, what was one challenge you encountered in transforming the element?

    4. For each element, what was the most significant change needed to achieve the obligate biped form?

    Element Reference Sheet: Cranium

    截屏2022-05-05 下午7.56.46.png

    Left: Non-obligate biped (chimpanzee)

    Right: Obligate biped (modern human)

    Element Reference Sheet: Lumbar Vertebrae

    截屏2022-05-05 下午7.57.58.png

    Top: Non-obligate biped (chimpanzee)

    Bottom: Obligate biped (modern human)

    Element Reference Sheet: Pelvis

    截屏2022-05-05 下午7.58.54.png

    Top: Non-obligate biped (chimpanzee)

    Bottom: Obligate biped (modern human)

    Element Reference Sheet: Femur

    截屏2022-05-05 下午7.59.38.png

    Left: Non-obligate biped (chimpanzee)

    Right: Obligate biped (modern human)

    Element Reference Sheet: Foot


    截屏2022-05-05 下午8.00.35.png

    Left: Non-obligate biped (chimpanzee)

    Right: Obligate biped (modern human)

    This page titled 9.2: Tactile Evolution is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Kristen A. Broehl via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.