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Hub AI
Coolidge effect AI simulator
(@Coolidge effect_simulator)
Hub AI
Coolidge effect AI simulator
(@Coolidge effect_simulator)
Coolidge effect
The Coolidge effect is a biological phenomenon seen in animals, whereby males exhibit renewed sexual interest whenever a new female of reproductive availability is introduced, even after sex with prior but still available sexual partners. To a lesser extent, the effect is also seen among females with regard to their mates.
The Coolidge effect can be attributed to an increase in sexual responsiveness, and a shortening of the sexual refractory period. The evolutionary benefit to this phenomenon is that a male can fertilize multiple females. The male may be reinvigorated repeatedly for successful insemination of multiple females. This type of mating system can be referred to as polygyny, where one male has multiple female mates, but each female mates with only one or a few males. The Coolidge effect has been demonstrated to occur in humans across cultures and in both sexes.
In a 1974 letter, behavioral endocrinologist Frank A. Beach claims to have introduced the term "Coolidge effect" in either 1958 or 1959. He attributed the neologism to an old joke about Calvin Coolidge when he was President of the United States.
The President and Mrs. Coolidge were being shown [separately] around an experimental government farm. When [Mrs. Coolidge] came to the chicken yard she noticed that a rooster was mating very frequently. She asked the attendant how often that happened and was told, "Dozens of times each day." Mrs. Coolidge said, "Tell that to the President when he comes by." Upon being told, the President asked, "Same hen every time?" The reply was, "Oh, no, Mr. President, a different hen every time." President: "Tell that to Mrs. Coolidge."
The joke appears in a 1972 book (Aggression in Man and Animals, by Roger N. Johnson, p. 94).
The original experiments with rats applied the following protocol: A male rat was placed into an enclosed large box with four or five female rats in heat. He immediately began to mate with all the female rats repeatedly until he eventually became exhausted. The females continued nudging and licking him, yet he did not respond. When a novel female was introduced into the box, he became alert and began to mate once again with the new female. This phenomenon is not limited to common rats.
The Coolidge effect is attributed to an increase in dopamine levels and the subsequent effect upon an animal's limbic system. In a study conducted by Fiorino et al., male rats were used to study the role of the mesolimbic dopamine system on their sexual behaviour. In their experiment, microdialysis was used to monitor dopamine efflux from the nucleus accumbens during three stages of sexual behaviour, these included: copulation, sexual satiety, and the reinitiation of sexual behaviour. Behavioural testing for the Coolidge effect consisted of several phases including, copulation with a female, reintroduction to the same female, access to the same female, introduction to a novel female, and copulation with the novel female. During these phases, dopamine and its metabolites were monitored. Results from this study found that overall there was a significant increase in dopamine efflux in response to both the first female and the second female. During copulation with the first female, concentrations of dopamine in these male rats showed a significant increase, however, when the same female was presented again, a significant increase in dopamine was not observed. When a novel female was presented, initially, there was a small increase in the levels of dopamine, however, after continued copulation with the novel female, a significant increase in dopamine levels was observed. From these results, they concluded that an increase in mesolimbic dopamine efflux is associated with the appetitive and consummatory stages of sexual behaviour in male rats. Their data also suggest that stimuli associated with a novel female may increase dopamine transmission in a rat that is sexually satiated, and hence have a role in the reinitiation of sexual behaviour.
Additional studies have also provided further evidence for the role of the nucleus accumbens on sexual behaviour in rats. In a study conducted by Wood et al., male rats were divided into three conditions, and were presented with a cotton ball laden in either saline (control group), estrous vaginal smear of a familiar female (experimental group), and estrous vaginal smear of a novel female (experimental group). In this experiment, the role of the nucleus accumbens was characterized through recording neuronal activity of single cells in this area of the brain. Results from this study showed a greater proportion of neuronal activation when initially presented with a novel estrus stimulus in comparison to familiar estrus stimulus. Subsequent presentations of the novel estrus stimulus did not show an increase in neuronal activity.
Coolidge effect
The Coolidge effect is a biological phenomenon seen in animals, whereby males exhibit renewed sexual interest whenever a new female of reproductive availability is introduced, even after sex with prior but still available sexual partners. To a lesser extent, the effect is also seen among females with regard to their mates.
The Coolidge effect can be attributed to an increase in sexual responsiveness, and a shortening of the sexual refractory period. The evolutionary benefit to this phenomenon is that a male can fertilize multiple females. The male may be reinvigorated repeatedly for successful insemination of multiple females. This type of mating system can be referred to as polygyny, where one male has multiple female mates, but each female mates with only one or a few males. The Coolidge effect has been demonstrated to occur in humans across cultures and in both sexes.
In a 1974 letter, behavioral endocrinologist Frank A. Beach claims to have introduced the term "Coolidge effect" in either 1958 or 1959. He attributed the neologism to an old joke about Calvin Coolidge when he was President of the United States.
The President and Mrs. Coolidge were being shown [separately] around an experimental government farm. When [Mrs. Coolidge] came to the chicken yard she noticed that a rooster was mating very frequently. She asked the attendant how often that happened and was told, "Dozens of times each day." Mrs. Coolidge said, "Tell that to the President when he comes by." Upon being told, the President asked, "Same hen every time?" The reply was, "Oh, no, Mr. President, a different hen every time." President: "Tell that to Mrs. Coolidge."
The joke appears in a 1972 book (Aggression in Man and Animals, by Roger N. Johnson, p. 94).
The original experiments with rats applied the following protocol: A male rat was placed into an enclosed large box with four or five female rats in heat. He immediately began to mate with all the female rats repeatedly until he eventually became exhausted. The females continued nudging and licking him, yet he did not respond. When a novel female was introduced into the box, he became alert and began to mate once again with the new female. This phenomenon is not limited to common rats.
The Coolidge effect is attributed to an increase in dopamine levels and the subsequent effect upon an animal's limbic system. In a study conducted by Fiorino et al., male rats were used to study the role of the mesolimbic dopamine system on their sexual behaviour. In their experiment, microdialysis was used to monitor dopamine efflux from the nucleus accumbens during three stages of sexual behaviour, these included: copulation, sexual satiety, and the reinitiation of sexual behaviour. Behavioural testing for the Coolidge effect consisted of several phases including, copulation with a female, reintroduction to the same female, access to the same female, introduction to a novel female, and copulation with the novel female. During these phases, dopamine and its metabolites were monitored. Results from this study found that overall there was a significant increase in dopamine efflux in response to both the first female and the second female. During copulation with the first female, concentrations of dopamine in these male rats showed a significant increase, however, when the same female was presented again, a significant increase in dopamine was not observed. When a novel female was presented, initially, there was a small increase in the levels of dopamine, however, after continued copulation with the novel female, a significant increase in dopamine levels was observed. From these results, they concluded that an increase in mesolimbic dopamine efflux is associated with the appetitive and consummatory stages of sexual behaviour in male rats. Their data also suggest that stimuli associated with a novel female may increase dopamine transmission in a rat that is sexually satiated, and hence have a role in the reinitiation of sexual behaviour.
Additional studies have also provided further evidence for the role of the nucleus accumbens on sexual behaviour in rats. In a study conducted by Wood et al., male rats were divided into three conditions, and were presented with a cotton ball laden in either saline (control group), estrous vaginal smear of a familiar female (experimental group), and estrous vaginal smear of a novel female (experimental group). In this experiment, the role of the nucleus accumbens was characterized through recording neuronal activity of single cells in this area of the brain. Results from this study showed a greater proportion of neuronal activation when initially presented with a novel estrus stimulus in comparison to familiar estrus stimulus. Subsequent presentations of the novel estrus stimulus did not show an increase in neuronal activity.