In 1955, researcher Frank A. Beach first used the term "Coolidge Effect" in a publication to a describe a biological phenomenon in which males become interested in sex when introduced to new partners, even after refusing sex from familiar (but still receptive) partners. The origin for the moniker comes from an old joke:

"It seems that, during a visit to a large chicken farm, the president fell somewhat behind his wife. As the story goes: "Mrs. Coolidge, observing the vigor with which one particularly promising rooster covered hen after hen, asked the guide to make certain that the President took note of the rooster's behavior. When President Coolidge got to the hen yard, the rooster was pointed out and his exploits recounted by the guide, who added that Mrs. Coolidge had requested that the President be made aware of the rooster's prowess. The President reflected for a moment, and replied, 'Tell Mrs. Coolidge that there is more than one hen.'"

The idea behind the phenomenon is that males - particularly from species that have a promiscuous mating style - should want to spread their genes as far as possible, rather than limiting their interest to a small number of females. Learn about the "Coolidge Effect" and more about sperm allocation in Dr. Carin Bondar's new animal sex YouTube series, Sex Bytes. The first episode was posted today.