A study has found that monogamy leads to husbands, but not wives, becoming less sexually satisfied. In doing so, it has also resolved a 90-year-old dispute between Calvin Coolidge, the US president, and his first lady. The study, taken from a survey of 1,500 married men and women, was inspired by the so-called Coolidge Effect, named after an apparent exchange in the 1920s when the Coolidges were touring a chicken farm. Mrs Coolidge noticed that the rooster was mating frequently, and asked how often that happened. “Dozens of times each day,” an attendant replied.
Mrs Coolidge said: “Tell that to the president when he comes by.” Informed of the observation, her husband asked: “Same hen every time?”
“Oh no, Mr President, a different hen every time,” the attendant replied. He said: “Tell that to Mrs Coolidge.”
Evidence for this effect in humans, however, has been mixed. Chien Liu, a researcher at Wagner College in New York, set out to investigate. His study, in the journal Evolutionary Behavioural Science, asked couples how physically pleasurable their relationship was. Then Professor Liu looked to see how that related to marital duration.“As a reproductive strategy, men could have evolved to be more sexually promiscuous,” he said. “Women, because of the limit of number of children they have, have a different strategy: find a good man and keep him.”
That is what his data showed. If a man starts off his marriage saying his sex life is “extremely pleasurable”, the next year there is a 3 per cent chance of him revising that downwards to “very pleasurable” or below. That rough drop-off rate continues throughout his marriage. “Monogamous marriage has an inherent defect,” Professor Liu said. “Men are programmed to be less satisfied with one sexual partner.”