Question 54·Medium·Central Ideas and Details
Until recently, paleontologists believed that the giant short-faced bear became extinct about 10,000 years ago. A 2023 study, though, analyzed fragments of DNA preserved in sediments from Yukon caves and matched them to the bear’s genome. The genetic material dated to roughly 6,500 years ago, indicating that small populations of the species survived thousands of years longer than previously thought. The researchers argue that this extended survival period suggests climatic shifts, rather than human hunting alone, played a major role in the bear’s eventual disappearance.
Which choice best states the main idea of the text?
For SAT main-idea questions, first restate the passage’s point in your own words in a short phrase or simple sentence, focusing on what changed, what was discovered, or what the author is trying to show. Then eliminate choices that (1) bring in ideas not mentioned, (2) focus on a detail or example instead of the overall point, or (3) exaggerate or twist what the passage actually says. Finally, choose the option that best matches your own summary without adding or leaving out important parts.
Hints
Find the contrast
Look at the first and third sentences. What did paleontologists think before, and what does the new evidence suggest now?
Ask what most of the passage is doing
Is the paragraph mainly about where evidence comes from, who collected it, which method is better, or how our understanding of the bear’s extinction timing has changed?
Separate main point from supporting detail
The last sentence mentions climate and human hunting. Is that the central focus of the paragraph, or is it an idea that depends on a more important finding stated earlier?
Step-by-step Explanation
Restate what scientists used to think
Look at the first sentence: it says paleontologists believed the bear went extinct about 10,000 years ago. This gives the old view or original belief about the extinction time.
Identify what new evidence shows
The passage then introduces a 2023 study that analyzed DNA fragments from Yukon cave sediments and matched them to the bear’s genome. The key result is that this genetic material dates to about 6,500 years ago, which is much more recent than 10,000 years ago. This means the species was still around thousands of years after scientists thought it had disappeared.
Decide what idea is most important overall
Ask: What is the biggest change or main message? Most of the text is about how the new DNA evidence changes the timeline of the bear’s extinction. The final sentence discusses possible causes (climate vs human hunting), but that is used as a consequence of the new, longer survival period, not as the main focus.
Match the main idea to the best answer choice
Now compare the choices to your summary: the passage’s main point is that a recent DNA study shows the giant short-faced bear lived thousands of years longer than previously believed. Choice A) New DNA evidence indicates the giant short-faced bear survived far longer than previously believed. directly and fully matches this idea, so A is correct.