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ithasbeenestimatedthatathousandyearsagotherewerelessthan400millionpeopleonearth.today,however,theworld＇spopulationhasamountedto5,000million.whatisworse,itkeepsgrowingatasurprisingspeed.ifthistrendcontinues,theworld＇spopulationwillshootupto7,000millionbytheyear.thisiswhatwecallpopulationexplosion.
therapiddevelopmentofscienceandtechnologyisthemaincauseofpopulationexplosion.wecanseethatthepopulationhasbeengrowingatatremendousspeedsincetheindustrialandagriculturerevolutionin1650,whichraisedthepeople＇sstandardofliving,andtheemergenceofmodernmedicinein1550,whichloweredthepeople＇sdeathrate.
populationexplosionwillresultinalotofsuchproblemsasfoodshortage,housingshortageandunemployment.itistimethatweactedquicklytocarryoutthepolicyofbirthcontrolotherwise,man＇ssurvivalontheearthwillbethreatened.