11.2: The Genus Homo

The Genus Homo Lab

Format: In-person or online

many classic Neanderthal features. La Ferrassie 1 Neanderthal is representative of

Author: Rebecca Frank

Source: “Activity 15.” 2019. Frank, Rebecca, Brian Pierson, Philip Stein. LAVC Anthro 111 Lab Manual. 7th Edition.

Time needed: 60-90 minutes

Learning Objectives

• Compare early Homo species to Au. africanus
• Compare species of Homo

Supplies Needed

• Fossil casts of Au africanus, H. erectus, H. heidelbergensis, H. neanderthalensis, H. sapiens
• Student worksheet (provided)

Readings

• Yoshida-Levine, Bonnie. 2019. Chapter 10. Explorations.
• Paskey, Amanda and AnnMarie Beasley Cisneros. 2019. Chapter 11. Explorations

Introduction

The genus Homo first appears around 2.5 million years ago in East Africa. By this time all but one Australopithecus species has become extinct. Paranthropus survives as a contemporary of Homo for almost 1.5 million years.

We see a number of trends in this genus, perhaps the most important being the enlargement of the brain, increase in stature, and the elaboration of technology including stone tools. However, the genus is quite variable. There are many species within Homo including Homo habilis, Homo rudolfensis, Homo erectus, Homo heidelbergensis, Homo neandertalensis, and Homo floresiensis. Some researchers place the early species within the genus Australopithecus, and some refer to the later species as archaic Homo sapiens. This lab includes three exercises in which students examine and measure hominin cranial and postcranial fossil casts, as well as postcranial ape casts. It is assumed that students have a good working knowledge of anatomy from the textbook, lectures, and/or previous exercises.

Steps

• Before class, the instructor should organize fossil casts for students to analyze, either individually or in groups.
• For Exercise 1, students will need access to fossil crania casts of Australopithecus africanus, Homo habilis, Homo erectus.
• For Exercise 2, students will need access to fossil crania casts of Homo erectus, H. heidelbergensis, H. neanderthalensis, and H. sapiens.
• For Exercise 3, students will need access to pelvis and femur casts of an ape, Au. afarensis, H. erectus, H. neanderthalensis, and H. sapiens.
• Students will analyze casts, complete charts, and answer questions on the worksheet.

Review Questions

1. Identify the major species within the genus Homo.
2. Which features can we use to separate an australopithecine from a Homo erectus skull?
3. Specify major cranial differences between the H. erectus, H. neanderthalensis, and H. sapiens.
4. What are some broad trends that occurred over the course of Homo evolution? Discuss skull shape, facial morphology, and tooth or jaw proportions using specific examples from the different species, noting how they compare to each other.
5. What changes have occurred to the breadth of the pelvic inlet over hominin evolution? What does this suggest about the social behavior and life history of the different hominin species?

Adapting for Online Learning

If this is an in-person lab, rank how adaptable to online learning it would be (mark in bold):

1 Not adaptable 2 Possible to adapt 3 Easy to adapt

Much of the data students will collect on the worksheets is descriptive or could be assessed without actually measuring. For online courses, using photographs and online 3D rotation images, students could compare the skulls and pelvic girdles of the species. Many resources are free to post in online course management systems. Additional options could be available with subscriptions or other licensing agreements.

See for example: https://africanfossils.org/, http://efossils.org/, https://sketchfab.com/, https://3d.si.edu/collections/hominin-fossils

References

Frank, Rebecca. 2019. “Activity 14: The Hominin Fossils: Australopithecines.” In LAVC Anthro 111 Lab Manual, 7th Edition, edited by Frank, Rebecca, Brian Pierson, and Philip Stein.

Paskey, Amanda and AnnMarie Beasley Cisneros. 2019. “Chapter 11: Archaic Homo.” In 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/

Yoshida-Levine, Bonnie. 2019. “Chapter 10: Early Members of the Genus Homo.” In 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

Neanderthal Skeleton Articulated by ©BoneClones is used by permission and available here under a CC BY-NC 4.0 License.

Genus Homo Worksheet

Exercise 1: Genus Homo

We will begin our study of the genus Homo by comparing early species to Au. africanus. For this exercise, you will need skull casts of Au. africanus, H. habilis, and H. erectus. Measure and record the features in the chart, and then answer the questions below.

Feature	Au. africanus	H. habilis	H. erectus
Identify specimen you use
Condylar Index = (Basion to Opisthocranion / Basion to Prosthion) x 100
Location of maximum skull breadth as seen in the posterior view
Relative degree of postorbital constriction as seen in the superior view
Relative degree of prognathism as seen in the lateral view
Facial Index = (Upper Facial Height / Cranial Height) x 100
Relative size of supraorbital torus as seen in the anterior and lateral views

Paleoanthropologists generally agree that Homo erectus belongs in our genus and represents a significant shift towards adaptations important to our own species. However, there is much variation among specimens that are grouped into H. erectus. Your instructor will let you know which of these fossil representatives to use for the exercise today.

Based on your measurements and comparisons in the table above, what are major differences among Au. africanus, H. habilis, and H. erectus? Do you think H. habilis is more like Australopithecus or Homo?

How do these three species reflect the major environmental pressures of the time periods in which they lived, respectively?

List three features that are changing in the genus Homo due to these selective pressures.

List three features found in H. erectus that are derived, compared to Au. africanus.

Exercise 2: Comparing Species of Homo

In this exercise, you will compare four species of Homo. You will again measure and calculate the Condylar Index and Facial Index and examine skeletal features of the face. Which features or indexes are getting larger? Which are getting smaller? What trends do you notice and what do these changes tell us about the selective pressures and adaptations observed in our genus? Measure and record the features in the chart and then answer the questions below.

Feature	Homo erectus	Homo heidelbergensis	Homo neanderthalensis	Homo sapiens
Identify specimen you use
Condylar Index = (Ba to Op / Ba to Pr) x 100
Location of maximum skull breadth posterior
(Facial Height/ Cranial Height) x 100 = Facial Index
Postorbital constriction superior view
Degree of Prognathism, lateral view
Relative size of incisors compared to molars

Identify three major evolutionary trends that occurred in the genus Homo over the last two million years.

Discuss one of these trends and compare the Homo species using your measurements and observations to illustrate this trend. What are the likely reasons behind the changes that occurred in our genus?

Exercise 3: The Postcranial Skeleton

Hominins are defined largely on the basis of erect bipedalism so it is also important to examine the fossil evidence for locomotion. We will focus on the pelvis for this class, but adaptations of the femur and feet are also extremely important. Examine the pelves from an ape, Australopithecus afarensis, Homo erectus, Homo neandertalensis, and Homo sapiens. Measure and record the features in the chart and then answer the questions.

Features	Homo erectus	Homo neanderthalensis	Modern Human
Identify specimen you use
General shape of pelvis
Position of iliac blade relative to spine
Shape and direction of pelvic inlet
Breadth / Height of pelvic inlet x 100 = Pelvic Inlet Index
Size of anterior inferior iliac spine
Ilium Breadth/ Ilium Height) x 100 = Ilium Index

What differences do you see? Which species look most like modern humans? How have bodies and pelves changed over hominin evolutionary history?

Why is the breadth of the pelvic inlet important? What might it tell us about a species’ social behavior or life history?