Deadlier Than the Male intrigue when he comes to visit. The title is a reference to the 1911 Rudyard Kipling poem "The Female of the Species," which includes the line, "The female of the species must be deadlier than the male", and also refers to Sapper's earlier Drummond book, "The Female of the Species". The working title of the film was "The Female of the Species". "Deadlier Than the Male", the song featured in the film`s opening credit sequence, was performed by the Walker Brothers. Filmed in Technicolor and Techniscope, portions of the film were shot in Lerici, La Spezia, Liguria, Italy. A sequel,
Social monogamy in mammalian species was significantly lower in monogamous species than in polyandrous ones. However, there still needs to be more empirical evidence in order to further test this hypothesis. Sexual dimorphism relates to the phenotypic differences between a male and a female of the same species, often referring to the species' body size. Monogamous males tend to be smaller compared to females, which results in sexual competition between the male candidates for a larger female. Comparing to monogamous species, polygynous species tend to display more sexual dimorphism, or difference in body size; it is believed that sexual dimorphism could be an evolutionary consequence