Reading comp PrepTest 139 · Section 3 · Question 25

Topic: Science

Paragraph 1

• Paragraph note
  • Stanley Temple hypothesized that decline of Calvaria major was linked to extinction of dodo.
• Views, minor Meta-Structures, points of intersection, and the author's attitude
  • Temple’s viewpoint: Decline of Calvaria major linked to extinction of dodo on Mauritius (second sentence)
    • Evidence: Temple found only 13 Calvaria major trees, all over 300 years old and dying, with fruits that he thought couldn’t germinate (third-fourth sentences)
  • Author’s attitude: “sidelight” (second sentence); “gained considerable currency” (second sentence); “Temple assumed” (fourth sentence)

Paragraph 2

• Paragraph note
  • Temple hypothesized that fruit of Calvaria major depended on dodo to germinate.
• Views, minor Meta-Structures, points of intersection, and the author's attitude
  • Temple’s hypothesis:
    • Based on temporal correlation between what he saw as last natural germination of Calvaria major and extinction of dodo (first sentence)
    • Fruit of Calvaria major developed thick-walled pit in response to dodo’s consumption, so when dodo became extinct, absence of abrasion in dodo’s digestive tract prevented seeds from germinating (second-third sentences)
  • Author’s attitude: “temporal coincidence” (first sentence); “what Temple considered” (first sentence); “led him to posit” (first sentence); “Temple maintained” (fourth sentence)

Paragraph 3

• Paragraph note
  • Temple supported his hypothesis with calculations and a study on turkeys.
• Views, minor Meta-Structures, points of intersection, and the author's attitude
  • Author: no direct proof of Temple’s hypothesis was obtainable (first sentence)
  • Temple’s evidence:
    • Studied other birds to estimate abrasive force of dodo’s gizzard (second sentence)
    • Studied crush resistance of Calvaria major pits (third sentence)
    • Studied turkeys, fed them Calvaria major pits of which many were destroyed but 10 survived and three sprouted when planted (fourth sentence)
  • Author’s attitude: “semblance of rigor” (first sentence); “he concluded” (third sentence); “he saw as vindicating his hypothesis” (fourth sentence)

Paragraph 4

• Paragraph note
  • Author: Many scientists have challenged Temple’s hypothesis.
• Views, minor Meta-Structures, points of intersection, and the author's attitude
  • Temple’s hypothesis accepted by many scientists (first sentence)
  • Many other scientists were skeptical and have challenged Temple’s findings (first sentence)
    • Wendy Strahm, plant ecologist, found hundreds of Calvaria major trees much younger than 300 years old (second sentence)
      • Calvaria major seeds have germinated in absence of dodo (third sentence)
    • Anthony Speke has found that, though a minority of unabraded Calvaria major seeds germinate, it’s a sufficient number to keep the species from going extinct (fourth sentence)
  • Alternative explanations for decline of Calvaria major: disease and damage done by non indigenous animals (fifth sentence)
  • Author’s attitude: “strongly challenged” (first sentence); “foremost expert” (second sentence); “have in fact germinated” (third sentence); “additional counterevidence” (fourth sentence); “probably sufficient” (fourth sentence); “could easily be due to other factors” (fifth sentence)

Main Point: Stanley Temple’s superficially appealing but ultimately poorly-supported hypothesis that the extinction of the dodo is responsible for the population decline of the Calvaria major tree on Mauritius has been strongly challenged by leading scientists who point out that the tree has continued to germinate in the absence of the dodo and that other factors could well be responsible for its increasing scarcity.

Paragraph 1, Sentence 2 (P1 S2) - General statement of Temple’s viewpoint

P2 S2-3 - Temple’s specific hypothesis

P3 S3 - Temple’s study of Calvaria major pits

P3 S3-4 - Temple’s study using turkeys

P4 S1 - Scientists challenged Temple’s viewpoint

P4 S2-3 - Strahm’s counterevidence

P4 S4 - Speke’s counterevidence

P4 S5 - Author’s alternative explanations for Calvaria major’s population decline

Criticizing a Viewpoint: This passage uses a Criticizing a Viewpoint Meta-Structure. The viewpoint that the author introduces is a hypothesis by Stanley Temple that the decline in population of the Calvaria major tree on Mauritius is due to the extinction of the dodo 300 years ago. Temple posited that the dodo’s intestines abraded the pit of the tree’s fruit to such an extent that the fruit couldn’t germinate without this process, and that when the dodo died out, the tree began to decline. The author explains that Temple did a few studies with other birds including turkeys that seemed to demonstrate the plausibility of his theory, and that it gained considerable support within the scientific community because of its novelty and drama. The author then shoots the theory down using counterevidence from two other scientists and advances alternative explanations for the population decline of Calvaria major.

The author’s viewpoint on Temple’s hypothesis starts to become clear in paragraph 2, where they discuss the “temporal coincidence” that gave rise to Temple’s theory (P2 S1). In the third paragraph, the author’s viewpoint becomes even more explicit as they use terms like “semblance of rigor” to describe Temple’s so-called evidence (P3 S1). Finally, in the fourth paragraph, the author comes right out into the open and presents evidence that runs counter to Temple’s theory, making it clear that they do not subscribe to it. The passage winds up with a couple of alternative explanations for the Calvaria major’s population decline, but these explanations are not the focus of the passage. Instead, the focus is on why Temple’s theory is probably wrong, which is what makes this a Criticizing a Viewpoint passage. The alternative explanations the author presents are not well fleshed out at all.

The minor Meta-Structure at play in this passage is Causality. Temple’s theory, which is the centerpiece of the passage, is based on a causal connection between the extinction of the dodo and the decline of Calvaria major. The author attacks this connection with counterevidence and alternative explanations for the tree’s increasing scarcity.

There is a case to be made for classifying this passage as a “Correcting the Record” passage. However, that classification is most often used for passages that correct a misconception or oversight. Here, the author is arguing about the correct interpretation of scientific evidence, which goes beyond misconception or oversight. At the same time, the author doesn’t offer a full alternative explanation for the decline of the Calvaria major population, so this is not a Proposing a Hypothesis or Phenomenon/Explanation passage either. The focus of the passage is on why Temple was wrong, not on why some other explanation is right.