A classic series of experiments to determine the effects of overpopulation on co

       Aclassic series of experiments to determine the effects of overpopulation oncommunities of rats was conducted by a psychologist，John Calhoun．In each experiment，an equal number of male andfemale adult rats were placed in an enclosure（场地）．The rat populations were allowed to increase．Calhoun knew from experienceapproximately how many rats could live in the enclosures without experiencingstress due to overcrowding．He allowed the population to increase to approximately twice thisnumber Then he fixed the population by removing the children that were notdependent on their mothers．At the end of the experiments，Calhoun was able to conclude that overcrowding causes a breakdown inthe normal social relationships among rats，a kind of social disease．The rats in the experiments did not follow the same patterns ofbehavior as rats would in a community without overcrowding．

       Thefemales in the rat population were the most seriously affected by the highpopulation density（密度）．For example，mothers sometimes deserted their children，and，without their mothers’care，the children died．The experiments showed that inoverpopulated communities，mother rats do not behave normally．Their behavior may be considered diseased andpathological（病理学的）．

       Theleading males in the rat population were the least affected by over population．Each of these strong malesclaimed an area of the enclosure as his own．Therefore，these individuals did not  experience the overcrowding in thesame way as the other rats did．．However leading males did behave pathologically at times．Their antisocial（反社会）behavior consisted ofattacks on weaker male，female，andimmature rats．Thisunusual behavior showed that even though the leading males had enough livingspace，they too wereaffected by the general overcrowding．

       Non-leadingmales in the experimental rat communities also exhibited unusual social behavior．Some withdrew（缩回） completely ,avoidingcontact with other rats．Other non-leading males were too active，chasing other rats and fightingeach other．

       Thebehavior of the rat population has similarity in human behavior．People in densely（密） populated areas exhibitunusual behavior similar to that of the rats in Calhoun’s experiments．In large urban areas，such as New York City，London，and Cairo，there are deserted children．There are cruel，powerful individuals，both men and women．There are also people whowithdraw and people who become too active．Is the major cause of these disorders（混乱）overpopulation?

       Calhoun’sexperiments suggest that it might be．In any case，social scientists and city planners have been influenced by theresults of this series of experiments．

1.Which of thefollowing inferences（推断）can NOT be made from the first paragraph?

       A．Overpopulation causes pathological behavior in ratpopulations．

       B．Calhoun had experimented with rats before．

       C．Calhoun’s experiment is still considered importanttoday

       D．Stress does not occur in rat communities unlessthere is overcrowding．

2.The author impliesthat the behavior of the leading male rats is sometimes similar to that of

       A．people who would like to keep to themselves 

       B．people who abandon their children

       C．too active people

       D．cruel，powerful people

3.The main point ofthis passage is that _______________．

       A．although rats are affected by overcrowding，people are not

       B．overcrowding may be an important cause of socialpathology

       C．the social behavior of rats is seriously affectedby overcrowding

       D．Calhoun's experiments have influenced many people

试题答案

【答案】

1.C

2.D

3.B