Question

our early ancestors were hunter - gatherers who obtained food by hunting and by searching for edible wild plants. they needed strong bones, including large, strong jaws that enabled them to eat tough, uncooked foods. when our ancestors developed agriculture, however, their diet changed. they began growing plants, such as grains and beans, and raising animals for food; they also started cooking their foods, making them softer and easier to chew. consequently, the human skeleton underwent radical changes. over time, the human jaw became smaller and changed shape. other bones also evolved, becoming lighter, especially in the joints, as a result of both dietary changes and a less active lifestyle. what is the main, or central, idea of the passage?
early humans ate uncooked meats and vegetables, so they needed strong jaws for chewing.
as early humans developed agriculture, their bones changed significantly.

Explanation:

To determine the main idea, we analyze each option:

• Option 1 ("Early humans ate uncooked meats and vegetables, so they needed strong jaws for chewing") is incorrect. The passage states that early humans' diet changed with agriculture, and cooking made food softer, leading to jaw changes. This option focuses only on the past diet and jaws, not the overall evolution.
• Option 2 ("As early humans developed agriculture, their bones changed significantly") aligns with the passage. The passage explains that the development of agriculture (diet change, cooking) led to changes in the human jaw and other bones, along with a less active lifestyle. This option captures the central idea of how agricultural development caused skeletal changes.

Answer:

1. As early humans developed agriculture, their bones changed significantly.