Hundredth monkey effect

Since it was first popularized, the effect has been discredited in many cases of research. One of the primary factors in the spread of this claim is that many authors quote secondary, tertiary, or post-tertiary sources that have themselves misrepresented the original observations. The "hundredth monkey" effect was popularized in the mid-to-late 1970s by Lyall Watson, who documented the findings of several Japanese primatologists from the 1950s. Between 1952 and 1953, primatologists conducted a behavioral study of a troop of Macaca fuscata (Japanese macaque or snow monkeys) on the island of Kōjima. The researchers would supply these troops with such foods as sweet potatoes and wheat in open areas, often on beaches. An unanticipated byproduct of the study was that the scientists witnessed several innovative evolutionary behavioral changes by the troop, two of which were orchestrated by one young female, and the others by her sibling or contemporaries. The account of only one of these behavioral changes spread into a phenomenon (i.e., the "hundredth monkey effect"), which Watson would then loosely publish as a story. According to Watson, the scientists observed that some of the monkeys learned to wash sweet potatoes.