Man's Genesis is a short 1912 silent American film starring Robert Harron and Mae Marsh. It was directed by D. W. Griffith for the Biograph Company and survives from an era from which many films are now lost. The movie's plot involves a grandfather recounting a story about cavemen fighting over a woman to his squabbling grandchildren. The work was described as being the first "primitive man" film ever made and, at the time, as the "greatest photoplay of its kind ever made". It is credited as being responsible for creating the pre-historic film boom that occurred in the following years. The film was re-issued alongside other Biograph films on July 23, 1915.