Shrunken head heads of monkeys or sloths. Some even used goatskin. Kate Duncan wrote in 2001 that "It has been estimated that about 80 percent of the tsantsas in private and museum hands are fraudulent," including almost all that are female or which include an entire torso rather than just a head. Thor Heyerdahl recounts in "Kon-Tiki" (1947) the various problems of getting into the Jívaro (Shuar) area in Ecuador to get balsa wood for his expedition raft. Local people would not guide his team into the jungle for fear of being killed and having their heads shrunk. In 1951 and 1952
Thor Heyerdahl also criticised Heyerdahl's theory in his 2009 book "The Wayfinders", which explores the history of Polynesia. Davis says that Heyerdahl "ignored the overwhelming body of linguistic, ethnographic, and ethnobotanical evidence, augmented today by genetic and archaeological data, indicating that he was patently wrong." A 2009 study by Norwegian researcher Erik Thorsby suggested that there was some merit to Heyerdahl's ideas and that, while Polynesia was colonized from Asia, some contact with South America also existed. Some critics suggest, however, that Thorsby's research is inconclusive because his data may have been influenced by recent population contact. However, more recent work indicates