Their time was devoted solely to grooming, eating and sleeping. Dr Calhoun called these individuals “the beautiful ones”. Other young mice growing into adulthood exhibited an even different type of behavior.The last thousand animals born never learned to develop the social behaviors, they never learned to be aggressive, which is necessary in defense of home sites not engaging in any stressful activity, and only paying attention to themselves, they groomed themselves well so they looked like very fine specimens.The capacity for reproduction terminated.Their behavioral repertoire became largely confined to eating, drinking, sleeping and grooming. They never engaged in sexual approaches toward females, and they never engaged in fighting. Male counterparts to non-reproducing females were named the “beautiful ones”.The last conception took place about day 920.Incidence of pregnancies decline very rapidly with no young surviving.Population increase abruptly ceased on day 560 after colonization.Phase D – extinction period (days 560-1588) Social disorder – a WM would attack a passive WM, who in turn would attack another.Thus, there were always opportunities for females to select an unoccupied space for rearing young if they so chose. Due to the tendency of many animals to choose to crowd together in numbers in excess of 15 per nest site, at the peak population size of 2200 mice, 20% of all nest sites were usually unoccupied. Considering that there were 256 nest retreat sites in the 16 cells, one would not expect shelter to be a limiting factor until the population exceeded 3840.They started independent life without having developed adequate affect bonds. By midway in phase C, essentially all young were prematurely rejected by their mothers.Incidence of conception decline and resorption of fetuses increases and dissolution of maternal behavior is observed.Males exhibit sexual behavior towards other males you have rat homosexuality. Socially withdrawn male 29 makes a pan-sexual approach to male 16 who he recently saw attacked.These individuals would have badly chewed and scarred tails. Certain individuals became targets of repeated attacks. Social disorder became visible – a WM would attack a passive WM, who in turn would attack another WM. Excess males strived for acceptance, were rejected and withdrew. At this time, some unusual behavior became noticeable.This aggression generalized to their own young who were attacked, wounded, and forced to leave home several days before normal weaning. The nursing females become aggressive, essentially taking over the role of the territorial males.The male ability to defend territory declines.Population doubling time is about 145 days.Phase C – stagnation – a period of equilibrium (315-559 days) At the end of this phase there were 3 times as many socially immature mice as there were socially established older ones.As the population increased, most mice associated eating and drinking with the presence of others. Although each living unit was identical in structure and opportunities, more food and water was consumed in certain areas.The births tended to be concentrated in some sets of nest boxes (dominant males), while others (non-dominant males – withdrawn males = WM) had few or none.Social organization established – frequency of litters proportional to social dominance.Population doubling time is about 55 days.Phase B – Rapid population growth – a period of exploitation of resources (105-314 days) On day 104 began to be born the first “new” mouse.After a relative stabilization of the situation mice have created a sort of territorial division and started to build a nest.Initially, the mice had trouble adjusting to the environment and to each other.On the first day to the habitat were allowed in 4 males and 4 females.The only limitation – a space that could accommodate up to 3840 mice. Maximum limited spread of infectious diseases (health care for the mouse).Ĥ. Unlimited access to food, water and materials needed to build a shelter.ģ. Despite repeated attempts the end result was always the same – unlimited access to food and lack of threats caused the extinction of the population.ġ. The experiment was carried out on mice in 1968 and lasted four years. John Calhoun created the mouse equivalent of human civilization development. The exact question that this experiment is trying to answer is “what happens when individuals of a given species can provide everything you need to survive?”. Many of the problems above questions provide us may “experiment Calhoun”, originally called “Mouse Utopia”. What are the objectives of mankind? What instincts rule us? Do you strive for some higher purpose, is just about to spawn and fight for survival? They approached the problem from both the purely scientific, religious or philosophical. The question of the future of humanity is not new.
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