简介：LizBonninpresentsacontroversialandprovocativeepisodeofHorizon,investigatinghownewscientificresearchisraisinghardquestionsaboutzoos-thefilmexploreshowandwhyzooskeepanimals,andwhethertheyneedtochangetokeepupwithmodernscienceorultimatelybeconsignedtohistory.　　Shouldzoosculltheiranimalstomanagepopulations?LiztravelstoCopenhagenZoo,whokilledagiraffeandfedittothelions,towitnesstheircullingprocessfirsthand.Theythinkitisanaturalpartofzookeepingthatisoftensweptunderthecarpet.Shouldsomeanimalsneverbekeptincaptivity?Inaworldexclusive,LizvisitsSeaWorldinFloridaandasksifcaptivitydroveoneoftheirorcastokillhistrainer.　　Butcouldzoosbetheanswertoconservingendangeredspecies?Lizexaminestheirrecord,fromhelpingbreedpandasforthewildtoeffortstosavetherhinos.Shemeetsoneofthelastsurvivingnorthernwhiterhinosanddiscoversthefutureofthisspeciesnowliesinamultimillion-dollarprogrammetoengineerthemfromstemcells.VeteranconservationscientistDrSarahBexelltellsLizthescienceofcaptivebreedingisgivinghumanityfalsehope.…