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Item CA043004: Recognize a valid argument that supports the claim that chimpanzees and gorillas have a more recent common ancestry than chimpanzees and orangutans because their average genetic similarity is greater.

Scientists studying evolution compared the DNA of several primate species. They looked for genetic similarities.

The scientists summarized their data in the following table:

Pair of Species Compared

Average Genetic Similarity

Chimpanzee and Gorilla

98%

Chimpanzee and Orangutan

97%

Gorilla and Orangutan

97%

 

When the scientists published their findings, they wrote:

"We studied the DNA of several ape species by sequencing their DNA. Genetic similarities can be used to measure how closely related two species are. Gorillas and chimpanzees have 98% genetic similarity and gorillas and orangutans have 97% genetic similarity. Gorillas and chimpanzees have a more recent common ancestor than do gorillas and orangutans."

Which of the following describes a valid argument that the scientists are making?

  1. Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

    Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

    Reasoning: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

  2. Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

    Evidence: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

    Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

  3. Claim: Gorillas and chimpanzees have more genetic similarity than gorillas and orangutans.

    Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

    Reasoning: Genetic similarities can be used to measure how closely related two species are.

  4. Claim: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

    Evidence: Genetic similarity is a measure of how similar the DNA from two organisms is.

    Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

Pre-Test

Distribution of responses (prior to studying evolution in high school)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 572
6–8
n = 18
9–12
n = 502
Male
n = 245
Female
n = 283
English
n = 511
Other
n = 18
A.

Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

Reasoning: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

48% 33% 48% 50% 44% 47% 67%
B.

Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

Evidence: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

14% 22% 13% 13% 15% 14% 6%
C.

Claim: Gorillas and chimpanzees have more genetic similarity than gorillas and orangutans.

Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

Reasoning: Genetic similarities can be used to measure how closely related two species are.

28% 39% 29% 24% 32% 29% 17%
D.

Claim: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

Evidence: Genetic similarity is a measure of how similar the DNA from two organisms is.

Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

10% 6% 10% 12% 9% 10% 11%

Post-Test (Control)

Distribution of responses (following typical high school instruction on evolution)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 274
6–8
n = 14
9–12
n = 230
Male
n = 119
Female
n = 130
English
n = 237
Other
n = 9
A.

Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

Reasoning: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

55% 29% 57% 54% 58% 57% 44%
B.

Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

Evidence: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

14% 7% 14% 15% 12% 13% 22%
C.

Claim: Gorillas and chimpanzees have more genetic similarity than gorillas and orangutans.

Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

Reasoning: Genetic similarities can be used to measure how closely related two species are.

24% 36% 23% 24% 25% 24% 22%
D.

Claim: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

Evidence: Genetic similarity is a measure of how similar the DNA from two organisms is.

Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

7% 29% 5% 7% 6% 6% 11%

Post-Test (Treatment)

Distribution of responses (following completion of an evolution curriculum module)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 278
6–8
n = 4
9–12
n = 248
Male
n = 130
Female
n = 131
English
n = 251
Other
n = 5
A.

Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

Reasoning: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

61% 25% 60% 58% 64% 60% 80%
B.

Claim: Gorillas and chimpanzees have a more recent common ancestor than gorillas and orangutans.

Evidence: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

11% 0% 10% 14% 8% 10% 20%
C.

Claim: Gorillas and chimpanzees have more genetic similarity than gorillas and orangutans.

Evidence: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

Reasoning: Genetic similarities can be used to measure how closely related two species are.

22% 50% 23% 22% 23% 24% 0%
D.

Claim: When comparing multiple species the species with the greater genetic similarity have a more recent common ancestor.

Evidence: Genetic similarity is a measure of how similar the DNA from two organisms is.

Reasoning: The genetic similarity between gorillas and chimpanzees was 98% and the genetic similarity between gorillas and orangutans is 97%.

6% 25% 6% 7% 5% 6% 0%