Reading Comprehension

PT132 · S1 · P3 · Q17 Dental Caries

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Passage A Because dental caries (decay) is strongly linked to consumption of the sticky, carbohydrate-rich staples of agricultural diets, prehistoric human teeth can provide clues about when a population made the transition from a hunter-gatherer diet to an agricultural one.

Topic

The relationship between dental caries (cavities) and carbohydrate consumption — used as a clue to the transition from hunter-gatherer to agricultural diets.

Framework

Dual Passage. Both passages discuss the caries-agriculture link. Passage A presents the prevailing view (more agriculture = more caries) plus exceptions; Passage B applies that view to a specific archaeological site (Ban Chiang, Thailand) and finds an unexpected result.

Main Point

The prevailing view is that increased agricultural (carbohydrate-rich) diets cause more caries — but Passage B's Ban Chiang study found caries decreasing as agriculture increased, likely because the diet remained varied and shifted toward less cariogenic carbohydrates.

Passage A: The prevailing view, with exceptions

Caries strongly linked to sticky carbohydrates of agricultural diets. Leigh's North American study: meat-eating Sioux had almost no caries; maize-dependent Zuni had 75% caries — and But there are exceptions: nonagricultural populations eating processed acorn flour or wild plants high in cariogenic potential (Hopi pinyon nuts, wild tubers).

Passage B: Ban Chiang's anomaly

Ban Chiang, Thailand, transitioned from hunter-gatherer-cultivator to increasing agriculture over 2,000 years. Research generally says agricultural intensification declines health, including dental health. Caries is uncommon in pre-agricultural populations; tooth-wear (which removes fissures and reduces caries) is also a factor. Ban Chiang's diet included rice and yams from the start. Yet caries was slightly greater in the Early Group than the Late Group — opposite the expected pattern. Tooth-wear didn't explain it. Likely explanations: the late-period diet remained varied (no single food dominated), and there may have been a shift from yams (sweeter, more cariogenic) to rice (less cariogenic).

17.

Passage B most strongly supports which one of the following statements about fiber and grit in a diet?

  1. Correct

    They can either limit or

    Why this is right

    This probably isn't super tempting on a first look. The idea that fiber/grit can promote caries formation is in line with what we researched. A reduction of fiber/grit in a diet increases (i.e. promotes) caries frequency So if the prevalence of fiber/grit in a diet is low, it can promote caries formation. But we can seemingly flip this upside down to get the other part of this answer. If we have a high prevalence of fiber/grit in the diet, then we will wear down tooth crown surfaces, removing fissures that can trap food particles, thereby limiting caries formation.

    Skill tested: Inference · how this choice captures the passage's function is the move to repeat next time.

    79% picked this

  2. They are typically consumed in

    Out of Support Window: agriculture

    There's nothing about "agriculture" connected to what we're told about fiber and grit. This is just attempting a Word Salad where they toss together different concepts that appeared in different parts of the passage. This also goes against common sense. Agriculture gives us starchy-sticky stuff like rice and yams, which are not very fibrous or gritty. Eating nuts and meat (a pre-agricultural diet) would likely involve more fiber and grit.

    2% picked this

  3. They have a negative effect

    Too Strong: no value / negative overall

    We know so little about "fiber and grit", and it's all contained in the second half of B's 2nd paragraph. It doesn't say anything there like "fiber and grit have no nutritional value" or "have a negative effect on overall health". The one thing we learn about fiber and grit is that having them in your diet helps to prevent caries formation.

    0% picked this

  4. They contribute to the formation

    Opposite

    Fiber and grit contribute to tooth wear, and the wearing down of tooth crown surfaces removes fissures.

    17% picked this

  5. They increase the stickiness of

    Unsupported Causal Claim: increase sticky

    This is another Word Salad type of answer, grabbing "sticky" from earlier in the paragraph and "carbohydrate-rich foods" from the 3rd paragraph. Nothing in our very tiny window of supporting text suggests that fiber and grit increase stickiness.

    2% picked this

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