The earliest recorded psychological experiment, reported about 429 bc in The Histories (Part 1, Book 2, paragraph 2) of the Greek historian Herodotus (?485–425 bc), the world's first history book. According to Herodotus, the Egyptian Pharaoh Psammetichus I (664–610 bc) performed the experiment to determine whether human beings have an innate capacity for speech, and if so, which particular language is innate. He ordered two infants to be brought up in a remote place by a shepherd who was forbidden to speak in their presence. After two years the children began to speak, and the word that they repeated most often was becos, which turned out to be the Phrygian word for bread. Psammetichus concluded that the capacity for speech is innate, and that the natural language of human beings is Phrygian. The experiment is conceptually similar to the Kaspar Hauser experiments by the British ethologist William H. Thorpe (1902–86), published in 1958, in which birds were reared in isolation to determine which aspects of their songs are innate.