Scientists have discovered sticks made from cattle hearts which they say may have served as make-up tools in ancient China. The sticks date back to the early Bronze Age, about 3,600 years ago.

The red sticks were found in Xiaohe Cemetery (1980–1450BC) in northwest China's Xinjiang province, scientists said in their paper published online in the 28 January edition of the journal Scientific Reports. The sticks were covered with a layer of hematite powders, one of the most widely used red pigments to paint red on human skulls during that era.

Scientists said that use of cattle heart in cosmetics is a discovery of both cultural and religious significance.

"These kind of cosmetic sticks might be used as a primitive form of crayon for make-up and painting. The usage of cattle hearts as cosmetic sticks is the first to our knowledge, which not only reveals the varied uses of cattle in Xiaohe Cemetery but also shows the distinctive religious functions," authors of the study wrote.

The irregular-shaped sticks were recovered from a number of female tombs at the cemetery, which is one of the most important Bronze Age sites in Xinjiang. The sticks were found inside leather bags laid near the waist of the mummies, a pattern scientists said was most notable at Xiaohe Cemetery.

"Most of female mummies were buried with a leather bag, a wooden phallus and wooden combs. These stuffs were usually near the waist of the mummy and the wooden phallus is a symbol of reproduction worship," scientists said. "Red cosmetic sticks were found inside most of the leather bags and were presumably used to paint the [red lines on the forehead] of a mummy."

"Painting or tattooing on a human face could directly exhibit cultural connotations," they added. The researchers said that since the cosmetic sticks were found buried with women, it could imply that the women were painters or they played a special role in religious activities.

Religious significance of the cattle heart sticks cannot be ignored as many of the relics found in Xiaohe Cemetery were painted in red, usually considered as a symbol of the worship for the blood.

"The heart is one of the most important organs in cattle, which is the centre of the blood circulation. Using cattle heart as tools to paint red on human face and objects indicated that painting red was a sacred and significant religious behaviour for Xiaohe people," scientists explained.