The cannibal boom is a period in the history of exploitation film, lasting roughly from 1977 to 1981, where cannibal films were at the peak of their popularity in Grindhouse theaters and cinema. Though Umberto Lenzi started the cannibal genre with his film Man from Deep River in 1972, it was not until Ruggero Deodato released his film Last Cannibal World in 1977 that the concept of cannibal films began to catch on. Although five cannibal films were made in 1977 and 1978, none were released in 1979 (though Deodato's Cannibal Holocaust was in the works). In February 1980, Deodato released Cannibal Holocaust, which was the start of a chain of seven similar films to be made and released in the same year. The following year, however, in 1981, only two cannibal films were made (one of them was Cannibal Ferox, second in notoriety only to Cannibal Holocaust). Only four other cannibal films were made after 1981 until the fad's conclusion in 1988 with Antonio Climati's Natura Contro.