Many conspiracy theories have drawn inspiration from the writings of ancient astronaut proponent Zecharia Sitchin, who declared that the Anunnaki from Sumerian mythology were actually a race of extraterrestrial beings who came to Earth around 500,000 years ago in order to mine gold. In his 1994 book "Humanity's Extraterrestrial Origins: ET Influences on Humankind's Biological and Cultural Evolution", Arthur Horn proposed that the Anunnaki were a race of blood-drinking, shape-shifting alien reptiles. This theory was adapted and elaborated on by British conspiracy theorist David Icke, who maintains that the Bush family, Margaret Thatcher, Bob Hope, and the British Royal Family, among others, are or were such creatures, or have been under their control. Icke's critics have suggested that 'reptilians' may be seen as an antisemitic code word; a charge he has denied.