animals, all other creatures eat raw and unprocessed food.

　　According to the saying, you are what you eat. Now some experts think that it could be our cooking skills that raised Homo sapiens(智人) above the other apes. It is believed that human beings may have been developed by an ape learning to cook.

　　Two million years ago, early humans came from a group of pre-human apes. We began to go through important changes. We managed to get full movement on our two feet and a larger brain. One and a half million years ago, our ancestors had learned to cook food.

　　Burnt bones found on the fossils(化石) have uncovered this change related to cookery. Scientists guess that when our ancestors began their meat it probably doubled the quantity of heat in their bodies.

　　Cooked food is easier to digest(消化), safer to store, and is the most effective way of introducing complex proteins into early humans' diet. This was an important factor for developing Homo sapiens' growing mental power, with modern humans finally appearing 100,000 years ago.

　　Cooking would have opened up a great number of new foods to our hungry ancestors. Poisonous and uneatable roots became suitable for eating when baked. Tough parts of hunted animals became tender food.

　　Over time, our method of heating food was improving itself. From open fires to modern cooking equipment, ways of cooking are improving and the taste of food is more and more delicious.

　　24. What is the main idea of this passage?

　　A. Only humans eat cooked food.

　　B. Cooking helped a lot in humans' evolution.

　　C. Cooked food improved humans' health.

　　D. Without cooking, without evolution.

　　25. It took early humans ______ million years to learn to cook.

　　A. 0.5 B. 1 C. 1.5 D. 2

　　26. According to the passage, we may infer that ______.

A. two million years ago, early humans learned how to cook