Zhoukoudian is a small village situated about 50 kilometers to the southwest of Beijing. In the 1920s, archaeologists discovered some prehistoric human bones there which changed people's view of China's history. They came from an unknown species of man and were the first evidence of human life in China thousands of years ago. The remains were three teeth! In 1929, a complete skull was also discovered. Eventually, archaeologists found almost 200 items, including six skulls and more than 150 teeth. These discoveries proved the existence of a human species who lived in the area between 700,000 and 200,000 years ago. Four sites where Beijing Man and his relatives lived were discovered on the northern face of Longgushan. They lived in the caves in the area. However, the life span of Beijing Man was short. About 70% of the people probably died before the age of 14. Fewer than 5% lived to the age of 50. Ashes were found alongside the fossils which showed they had used fire for cooking food and also for light, warmth, and protection against wild animals. This is the earliest evidence of the use of fire anywhere in the world. They also made tools of bones and stones. Unfortunately, when Japan invaded China in 1937, excavations   at the Beijing Man Site stopped and most of the fossils disappeared, including a Beijing Man skull. After the People's Republic of China was established in 1949, the work started again. Zhoukoudian was listed as a World Heritage Site in December 1987. It has not only given us important information about prehistoric Asian societies, but also provided amazing evidence about the process of evolution. Today, parts of the caves have been badly affected by rain. Some areas are almost completely covered in weeds, causing serious damage. Pollution from the nearby factories has also led to the problem. This is a very serious matter and the Chinese Academy of Sciences is trying to raise public awareness of protecting it. Beijing Man used fire to do all of the following things EXCEPT   _  .
light in the dark keep warm scare wild animals away make tools