Question

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?
as early humans developed agriculture, their bones changed significantly.
early humans ate uncooked meats and vegetables, so they needed strong jaws for chewing.

Explanation:

The passage first describes early humans as hunter - gatherers with strong bones for eating tough foods. Then it shows how the development of agriculture led to diet changes like cooking and growing softer foods. As a result, the human skeleton, especially the jaw and other bones, evolved due to these diet and lifestyle changes. The main focus is on the bone changes with the development of agriculture.

Answer:

As early humans developed agriculture, their bones changed significantly.