ZHENGZHOU — An international team of researchers says they have identified seven bone soft hammers or retouchers as China's earliest known bone tools, dating back 115,000 years.

The bone tools, six made of broken long limb bones from herbivores and one made of antler, were discovered in a Paleolithic site in Xuchang city in Central China's Henan province.

Before the new discovery, China's oldest bone tools, dating back 35,000 years, were found in Guizhou province.

Li Zhanyang, researcher with Henan Provincial Institute of Cultural Heritage and Archaeology, said the bone soft hammers were mainly used to make and modify stone tools.

Chinese archaeologists have long been troubled by the questions such as when ancient Chinese started using bone and whether stone tools made by early humans were present in China.

Li said that the findings proved the revolution and progress of stone tool appeared in China at least 115,000 years ago, and Chinese hominids at that time had a relatively developed brain.

The results were published in the journal PLOS ONE.