11.4: The Genus Homo (Worksheet) — Read

From LibreTexts, under CC BY-NC 4.0, as the source states it; its equations are written in TeX, which the PDF shows typeset. This page at LibreTexts.

Name: ______________________________

Section: _____________________________

Student ID#:__________________________

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?

This page titled 11.4: The Genus Homo (Worksheet) was last modified on Fri, 03 Jul 2026 01:59:53 GMT and is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Rebecca Frank via source content that was edited to the style and standards of the LibreTexts platform.

Contents

Text

Exercise 1: Genus Homo

Exercise 2: Comparing Species of Homo

Exercise 3: The Postcranial Skeleton