Final answer:
Using dental remains, stone tools, and the evidence of fire usage, scientists deduce that hominids like Lucy expanded their diets. Well-worn molars suggest diverse, tough foods, while charred animal bones and tools suggest hunting and the advent of cooking. These various forms of evidence offer a window into the dietary practices of early hominids.
Step-by-step explanation:
Archaeologists and scientists have used various methods to infer that hominids like Lucy were expanding their diets approximately 3.5 million years ago. One significant method is the study of hominid dental remains. Well-worn molars in early hominid skulls suggest a diet of gritty, tough foods such as nuts, seeds, and fruits with hard peels. Another line of evidence comes from examining stone tools associated with early hominins, which indicate the development of hunting and gathering techniques. Further, the evidence of controlled use of fire by H. erectus and the consequent eating of cooked meat points towards dietary change. Cooking not only softened food, making it easier to eat and enabling the consumption of a wider range of foods, but also required less robust teeth and jaws, thereby possibly creating evolutionary pressures that resulted in smaller teeth and affected brain development due to the increased nutrient availability.
Fossilized remains and the presence of animal bones at hominin sites indicate the types of animals they might have eaten. Additionally, findings such as charred bones suggest early use of fire and the possible advent of cooking. Archaeological evidence from sites like Zhoukoudian, China, includes ancient hearths and charred animal bones that provide clear clues to the dietary practices of H. erectus. These findings collectively build a picture of the changing dietary patterns among early hominids.