Marco: Giant kangaroos—one of several extinct species of large mammals (megafauna)—went extinct in Australia around 46,000 years ago. The deposits...
GMAT Two Part Analysis : (TPA) Questions
Marco: Giant kangaroos—one of several extinct species of large mammals (megafauna)—went extinct in Australia around 46,000 years ago. The deposits and wear patterns on the teeth of these animals from around the time of their extinction indicate that they fed mostly on saltbrush shrubs. Saltbrush thrives in arid climates, so it is not likely that the kangaroos' food supply was adversely affected by the increasing aridity of the climate at the time. Thus, something else would have to account for their extinction, and the best candidate for that cause is predation by humans.
Fatima: That argument alone is not likely to satisfy many researchers in this field. Have you found any other evidence to bolster your conclusion?
Select Marco for the statement that, if true, most justifies Marco's assertions, and select Fatima for the statement that, if true, most justifies Fatima's skepticism about Marco's assertions. Make only two selections, one in each column.
Phase 1: Owning the Dataset
Argument Analysis Table
| Text from Passage | Analysis |
| "Giant kangaroos...went extinct in Australia around 46,000 years ago" |
|
| "deposits and wear patterns...indicate they fed mostly on saltbrush shrubs" |
|
| "Saltbrush thrives in arid climates...not likely food supply was adversely affected" |
|
| "something else would have to account...best candidate...is predation by humans" |
|
| "That argument alone is not likely to satisfy many researchers" |
|
Argument Structure
- Marco's Main Conclusion: Human predation caused giant kangaroo extinction
- Marco's Evidence:
- Kangaroos ate saltbrush
- Saltbrush thrives in arid conditions
- Therefore, climate change didn't affect food supply
- Marco's Assumption: If climate didn't cause it, humans must have
- Fatima's Position: Skeptical - the evidence is insufficient
Phase 2: Question Analysis & Prethinking
Understanding Each Part
- Part 1 (Marco): What statement would justify/support Marco's human predation theory?
- Part 2 (Fatima): What statement would justify her skepticism about Marco's reasoning?
Prethinking for Each Part
For Marco (strengthener):
- Evidence that climate really wasn't the problem
- Evidence linking humans to the extinction timeframe
- Evidence of human hunting capability
For Fatima (justifying skepticism):
- Evidence that humans weren't present at extinction time
- Evidence that kangaroos had other food sources affected by climate
- Evidence of other possible causes Marco hasn't considered
Phase 3: Answer Choice Evaluation
Evaluating Each Choice
Choice 1: "Giant kangaroos became extinct during a period that was less arid than previous periods they endured."
- Simple meaning: The extinction period wasn't even the worst drought they'd survived
- For Marco: STRONG - This eliminates climate as a cause even more definitively
- For Fatima: Weak - Doesn't challenge his human predation theory
Choice 2: "Many researchers believe humans first arrived in Australia around 40,000 years ago."
- Simple meaning: Humans arrived 6,000 years AFTER the kangaroos went extinct
- For Marco: WEAK - This actually contradicts his theory
- For Fatima: VERY STRONG - Perfect justification for skepticism!
Choice 3: "Approximately 60 different species in Australia died out in the wave of extinctions around 46,000 years ago."
- Simple meaning: Mass extinction event affecting many species
- For Marco: Moderate - Could suggest human arrival impact
- For Fatima: Moderate - Suggests complexity beyond his simple explanation
Choice 4: "Fossils of giant kangaroos also show evidence that those animals' diets routinely included plants other than saltbrush."
- Simple meaning: Kangaroos ate more than just saltbrush
- For Marco: Weak - Undermines his food supply argument
- For Fatima: STRONG - Shows his reasoning about food is flawed
Choice 5: "Several types of megafauna larger than the giant kangaroo went extinct around 46,000 years ago."
- Simple meaning: Other large animals also died out then
- For Marco: Weak - Doesn't specifically support human predation
- For Fatima: Weak - Doesn't directly challenge his logic
The Correct Answers
- For Marco: Choice 1 - It provides the strongest support by definitively ruling out climate as a cause
- For Fatima: Choice 2 - It perfectly justifies her skepticism by showing humans couldn't have caused an extinction that happened before they arrived
Common Traps to Highlight
- Choice 3 might seem to support Marco by showing a pattern, but it doesn't specifically point to humans
- Choice 4 might seem neutral, but it actually undermines Marco's core reasoning about food supply
- Don't assume that evidence against one theory (climate) automatically proves another theory (humans)