section_path: Natural sciences/Biology
section_name: Biology
paragraph_text: Biology
  
  Modern commentators have likened medieval accounts of the "struggle for existence" in the animal kingdom to the framework of the theory of evolution.Thus, in his survey of the history of the ideas which led to the theory of natural selection, Conway Zirkle noted that al-Jahiz was one of those who discussed a "struggle for existence", in his Kitāb al-Hayawān (Book of Animals), written in the 9th century. In the 13th century, Nasir al-Din al-Tusi believed that humans were derived from advanced animals, saying, "Such humans live in the Western Sudan and other distant corners of the world. They are close to animals by their habits, deeds and behavior." In 1377, Ibn Khaldun in his Muqaddimah stated, "The animal kingdom was developed, its species multiplied, and in the gradual process of Creation, it ended in man and arising from the world of the monkeys."
  
  In genetics, Al-Zahrawi was the first physician to identify the hereditary nature of haemophilia.