Question

read the passage.
the evolving human skeleton
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:

The passage starts by describing early hunter - gatherer diet and skeletal needs. Then it focuses on the changes in diet with the development of agriculture (cooking and new food sources) and how these led to significant changes in the human skeleton, especially the jaw and other bones. The first option only mentions the early diet and jaw needs, while the second option encompasses the overall change in bones due to agricultural development.

Answer:

As early humans developed agriculture, their bones changed significantly.