1. The following passage is followed by 5 questions. After carefully reading the passage, select the most appropriate answer for each question related to the ACT Reading section.
Feel free to review the passage as many times as needed to make your choices.
The advent of large-scale agriculture approximately 10,000 years ago marked a pivotal transition in human societies. As communities adopted intensive farming of domesticated plants and animals, socioeconomic complexity accelerated rapidly. Sedentary settlements grew into the earliest cities supported by agricultural surplus rather than mobile hunter-gatherer lifeways. However, the ecological impacts and public health consequences of these Neolithic changes have often been underestimated.
Artificial selection for maximized yields in a limited number of crop species reduced genetic diversity in cultivated foodstuffs. Monocropping displaced naturally biodiverse landscapes, concentrating calorie production but leaving agricultural systems vulnerable to pests and pathogens. Widespread use of animal dung as fuel further desiccated soils, while compaction from permanent human and livestock presence degraded soil fertility and disrupted water retention in many regions.
Crowded permanent settlements facilitated transmission of zoonotic diseases from domesticates to humans. Evolving in close proximity, these illnesses exerted new selective pressures on populations now living in less hygienic conditions compared to nomadic foragers. Pandemic pathogens caused higher mortality and morbidity, while deficiencies in micronutrients less available from cultivated diets damaged long-term health. Though sedentism conferred benefits of security and social hierarchy, agricultural development imposed hidden biological costs accruing gradually over generations.
Recently analyzed ancient DNA clarifies how these consequences shaped human evolution. Genome-wide studies find natural selection strengthening immune system genes in agricultural populations compared to hunter-gatherers. Other analyses detect selection for metabolisms adapted to diets emphasizing carbohydrates and proteins over wild plants, even as human stature declined after adoption of farming. Thus Neolithic subsistence innovations not only prompted far-reaching cultural transformations, but also durably impacted human physiology through selective pressures related to living in larger, more densely populated settlements.
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According to the passage, what factor contributed to reduced genetic diversity in early agricultural crops?
