The Coolidge Effect.

Coolidge effect

From Wikipedia, the free encyclopedia

In biology and psychology, the term Coolidge effect describes a phenomenon – seen in nearly every species in which it has been tested – whereby males show continuously high sexual performance given the introduction of new receptive females. The sex difference that the effect refers to is explained by Bateman's principle.

Origin of the term

The term comes from an old joke, according to which President Calvin Coolidge and his wife allegedly visited a poultry farm. During the tour, Mrs. Coolidge inquired of the farmer how his farm managed to produce so many fertile eggs with such a small number of roosters. The farmer proudly explained that his roosters performed their duty dozens of times each day.

"Perhaps you could point that out to Mr. Coolidge," pointedly replied the First Lady.

The President, overhearing the remark, asked the farmer, "Does each rooster service the same hen each time?"

"No," replied the farmer, "there are many hens for each rooster."

"Perhaps you could point that out to Mrs. Coolidge," replied the President.

Empirical evidence

The original experiments with rats followed this protocol: A male rat would be placed into an enclosed large box with four or five female rats in estrus. He would immediately begin mating with all of the female rats repeatedly until eventually exhausted. Although the females would continue nudging and licking him to continue, he would not respond. However, if a novel female were introduced to the box, he would become alert and find the ability to mate once again with the new female. This phenomenon is not limited to Rattus norvegicus. It is attributed to an increase in dopamine levels and its subsequent effect upon the limbic system.

While the Coolidge effect is usually seen demonstrated by males – that is, males displaying renewed excitement with a novel female – Lester and Gorzalka developed a model to determine whether or not the Coolidge effect also occurs in females. Their experiment, which used hamsters instead of rats, found that it does occur in lesser degrees in females.

(Apparently this too happens in the human male population. I've seen it and experiencing it right now. haha. n_n sourced from wikipedia.org)