Not technically classed as 'written evidence', prehistoric people left many kinds of paintings, using paints made of minerals such as lime, clay and charcoal, and brushes made from feathers, animal fur, or twigs on the walls caves. Although many of these paintings are thought to have a spiritual or religious purpose,[35] there have been some, such as a man with antlers (thought to be a medicine man), which have revealed some part of prehistoric medicine. Many cave paintings of human hands have shown missing fingers (none have been shown without thumbs), which suggests that these were cut off for sacrificial or practical purposes, as is the case among the Pygmies and Khoikhoi.[36]