More recently, doubts have been raised about the validity of Griaule and Dieterlen's work. In a 1991 article in "Current Anthropology", anthropologist Wouter van Beek concluded after his research among the Dogon that, "Though they do speak about "Sigu Tolo" is what Griaule claimed the Dogon called Sirius they disagree completely with each other as to which star is meant; for some it is an invisible star that should rise to announce the sigu , for another it is Venus that, through a different position, appears as "Sigu Tolo". All agree, however, that they learned about the star from Griaule."