section_path: Science and technology/Communication and medicine
section_name: Communication and medicine
paragraph_text: Communication and medicine
  
  The Inca recorded information on assemblages of knotted strings, known as Quipu, although they can no longer be decoded. Originally it was thought that Quipu were used only as mnemonic devices or to record numerical data. Quipus are also believed to record history and literature.
  
  The Inca made many discoveries in medicine. They performed successful skull surgery, by cutting holes in the skull to alleviate fluid buildup and inflammation caused by head wounds. Many skull surgeries performed by Inca surgeons were successful. Survival rates were 80–90%, compared to about 30% before Inca times. According to chronicler Bernabé Cobo, they also had a deep knowledge of herbalism, and the Spanish soldiers trusted the hands of an indigenous surgeon more than one of the barbers who accompanied them.