High School Summer Program / BIOLOGY 101/ Human Evolution SE
Name: Date:
Student Exploration: Human Evolution - Skull Analysis
Vocabulary: bipedal, canine, cranial capacity, cranium, evolve, foramen magnum, hominid,
hominin, index, maxilla, orbit, palate, skull
1. Label one of the skulls below as human and the other as a chimpanzee skull.
Human Chimpanzee
2. What features did you use to identify which skull was human and which was chimpanzee?
The shape of the skull!
Gizmo Warm-up
In 1924, a fossilized skull that looked very similar to a chimp skull was
discovered. But the skull most definitely did not belong to a chimp. The
location of the foramen magnum—a hole in the skull where the spinal
cord exits—indicated that the individual was bipedal, or walked on two
legs. This fossil was some of the earliest evidence of human evolution.
Using the Human Evolution – Skull Analysis Gizmo™, you will discover
some of the ways that skulls can be used to learn about human evolution .
Start by comparing two modern hominids: a human and a chimpanzee.
1. Examine the Front view of the Homo sapiens (modern human) skull. Then, use the
Select skull menu to examine the same view of the Pan troglodytes (chimp) skull.
How do the skulls compare? The structures of the two skulls look the same, but they have a
different overall shape. They’re teeth are also different.
2. Now, examine the Bottom view of the two skulls. How do they compare? The human skull
looks more like an oval shape that is the same width the entire way. While, the
chimpanzee’s width changes and gets skinner as you go down to the teeth!
This study source was downloaded by 100000843827171 from CourseHero.com on 03-29-2022 08:03:38 GMT -05:00
https://www.coursehero.com/file/15011976/HumanEvolutionSE/
, High School Summer Program / BIOLOGY 101/ Human Evolution SE
Activity A: Get the Gizmo ready:
Foramen magnum • Select the Homo sapiens (modern human) skull.
Introduction: Skulls, even from the same species,
can have a wide variety of shapes and sizes. To
compare skulls, scientists use measurements of
certain features to calculate indexes. An index is a
ratio of one measurement to another.
An important index for measuring hominid skulls is
the opisthion index. This index indicates the
position of the foramen magnum in the base of the
cranium. The opisthion index can indicate
whether a hominid species was bipedal or not.
Question: How does the location of the foramen magnum indicate if a
species was bipedal?
1. Measure: Select the Bottom view. To determine the opisthion index for
humans and chimps, follow the steps below and complete the table.
• Turn on Click to Measure Lengths. Measure the distance from
the opisthocranion to the opisthion, as shown at top right. Record
the opisthocranion-opisthion distance in the table below.
• Measure from the opisthocranion to the orale, as shown at bottom
right. Record the opisthocranion-orale distance in the table.
• To calculate the opisthion index, divide your first measurement by
your second measurement. Multiply this number by 100.
Opisthocranion- Opisthocranion-
Species Opisthion index
opisthion distance (cm) orale distance (cm)
Homo sapiens 6.06cm 20.24cm 29.9cm
Pan troglodytes 2.21cm 20.86cm 10.5cm
2. Analyze: The opisthion index is an indicator of where the foramen magnum is situated. The
greater the opisthion index, the closer the foramen magnum is to the center of the cranium.
This position is usually found in species that stand upright. A low value for the opisthion
index occurs when the foramen magnum is situated in the rear of the cranium. This may
indicate that the species walked on its knuckles or on four legs.
Using the index values you calculated, what can you conclude about humans and chimps?
Humans have a closer foramen magnum that is closer to the center of the cranium.
Therefore, humans stand upright. Chimps have the foramen magnum situated in the rear of
the cranium. Therefore, chimps walk on its knuckles/fours.
This study source was downloaded by 100000843827171 from CourseHero.com on 03-29-2022 08:03:38 GMT -05:00
https://www.coursehero.com/file/15011976/HumanEvolutionSE/
Name: Date:
Student Exploration: Human Evolution - Skull Analysis
Vocabulary: bipedal, canine, cranial capacity, cranium, evolve, foramen magnum, hominid,
hominin, index, maxilla, orbit, palate, skull
1. Label one of the skulls below as human and the other as a chimpanzee skull.
Human Chimpanzee
2. What features did you use to identify which skull was human and which was chimpanzee?
The shape of the skull!
Gizmo Warm-up
In 1924, a fossilized skull that looked very similar to a chimp skull was
discovered. But the skull most definitely did not belong to a chimp. The
location of the foramen magnum—a hole in the skull where the spinal
cord exits—indicated that the individual was bipedal, or walked on two
legs. This fossil was some of the earliest evidence of human evolution.
Using the Human Evolution – Skull Analysis Gizmo™, you will discover
some of the ways that skulls can be used to learn about human evolution .
Start by comparing two modern hominids: a human and a chimpanzee.
1. Examine the Front view of the Homo sapiens (modern human) skull. Then, use the
Select skull menu to examine the same view of the Pan troglodytes (chimp) skull.
How do the skulls compare? The structures of the two skulls look the same, but they have a
different overall shape. They’re teeth are also different.
2. Now, examine the Bottom view of the two skulls. How do they compare? The human skull
looks more like an oval shape that is the same width the entire way. While, the
chimpanzee’s width changes and gets skinner as you go down to the teeth!
This study source was downloaded by 100000843827171 from CourseHero.com on 03-29-2022 08:03:38 GMT -05:00
https://www.coursehero.com/file/15011976/HumanEvolutionSE/
, High School Summer Program / BIOLOGY 101/ Human Evolution SE
Activity A: Get the Gizmo ready:
Foramen magnum • Select the Homo sapiens (modern human) skull.
Introduction: Skulls, even from the same species,
can have a wide variety of shapes and sizes. To
compare skulls, scientists use measurements of
certain features to calculate indexes. An index is a
ratio of one measurement to another.
An important index for measuring hominid skulls is
the opisthion index. This index indicates the
position of the foramen magnum in the base of the
cranium. The opisthion index can indicate
whether a hominid species was bipedal or not.
Question: How does the location of the foramen magnum indicate if a
species was bipedal?
1. Measure: Select the Bottom view. To determine the opisthion index for
humans and chimps, follow the steps below and complete the table.
• Turn on Click to Measure Lengths. Measure the distance from
the opisthocranion to the opisthion, as shown at top right. Record
the opisthocranion-opisthion distance in the table below.
• Measure from the opisthocranion to the orale, as shown at bottom
right. Record the opisthocranion-orale distance in the table.
• To calculate the opisthion index, divide your first measurement by
your second measurement. Multiply this number by 100.
Opisthocranion- Opisthocranion-
Species Opisthion index
opisthion distance (cm) orale distance (cm)
Homo sapiens 6.06cm 20.24cm 29.9cm
Pan troglodytes 2.21cm 20.86cm 10.5cm
2. Analyze: The opisthion index is an indicator of where the foramen magnum is situated. The
greater the opisthion index, the closer the foramen magnum is to the center of the cranium.
This position is usually found in species that stand upright. A low value for the opisthion
index occurs when the foramen magnum is situated in the rear of the cranium. This may
indicate that the species walked on its knuckles or on four legs.
Using the index values you calculated, what can you conclude about humans and chimps?
Humans have a closer foramen magnum that is closer to the center of the cranium.
Therefore, humans stand upright. Chimps have the foramen magnum situated in the rear of
the cranium. Therefore, chimps walk on its knuckles/fours.
This study source was downloaded by 100000843827171 from CourseHero.com on 03-29-2022 08:03:38 GMT -05:00
https://www.coursehero.com/file/15011976/HumanEvolutionSE/
