Liz Bonnin presents a controversial and provocative episode of Horizon, investigating how new scientific research is raising hard questions about zoos - the film explores how and why zoos keep animals, and whether they need to change to keep up with modern science or ultimately be consigned to history. 　　Should zoos cull their animals to manage populations? Liz travels to Copenhagen Zoo, who killed a giraffe and fed it to the lions, to witness their culling process first hand. They think it is a natural part of zoo keeping that is often swept under the carpet. Should some animals never be kept in captivity? In a world exclusive, Liz visits SeaWorld in Florida and asks if captivity drove one of their orcas to kill his trainer. 　　But could zoos be the answer to conserving endangered species? Liz examines their record, from helping breed pandas for the wild to efforts to save the rhinos. She meets one of the last surviving northern white rhinos and discovers the future of this species now lies in a multimillion-dollar programme to engineer them from stem cells. Veteran conservation scientist Dr Sarah Bexell tells Liz the science of captive breeding is giving humanity false hope.

Liz Bonnin presents a controversial and provocative episode of Horizon, investigating how new scientific research is raising hard questions about zoos - the film explores how and why zoos keep animals, and whether they need to change to keep up with modern science or ultimately be consigned to history. 　　Should zoos cull their animals to manage populations? Liz travels to Copenhagen Zoo, who killed a giraffe and fed it to the lions, to witness their culling process first hand. They think it is a natural part of zoo keeping that is often swept under the carpet. Should some animals never be kept in captivity? In a world exclusive, Liz visits SeaWorld in Florida and asks if captivity drove one of their orcas to kill his trainer. 　　But could zoos be the answer to conserving endangered species? Liz examines their record, from helping breed pandas for the wild to efforts to save the rhinos. She meets one of the last surviving northern white rhinos and discovers the future of this species now lies in a multimillion-dollar programme to engineer them from stem cells. Veteran conservation scientist Dr Sarah Bexell tells Liz the science of captive breeding is giving humanity false hope.

人类对动物有着一种与生俱来的痴迷。千百年来，我们为了娱乐自己，将动物带离荒野，关进牢笼。动物园让我们有机会近距离接触那些我们通常无法看到的动物。但随着我们对动物行为的复杂性越来越了解，以及我们可以在电视上看到动物的自然生活状态，我们还应该继续把动物关在动物园里吗？莉兹?博宁是一名电视节目主持人，她同时也是伦敦动物学会的博士研究生，最重要的是，她还是一名动物爱好者。而她现在面临的问题是：二十一世纪的动物园到底该不该被关闭？

Dr Alice Roberts asks one of the great questions about our species: are we still evolving? 　　There's no doubt that we're a product of millions of years of evolution. 　　But thanks to modern technology and medicine, did we escape Darwin's law of the survival of the fittest? 　　Alice follows a trail of clues from ancient human bones to studies of remarkable people living in the most inhospitable parts of the planet and the frontiers of genetic research, to discover if we are still evolving - and where we might be heading.

Dr Alice Roberts asks one of the great questions about our species: are we still evolving? 　　There's no doubt that we're a product of millions of years of evolution. 　　But thanks to modern technology and medicine, did we escape Darwin's law of the survival of the fittest? 　　Alice follows a trail of clues from ancient human bones to studies of remarkable people living in the most inhospitable parts of the planet and the frontiers of genetic research, to discover if we are still evolving - and where we might be heading.

Imagine a world where dinosaurs still walk the earth. A world where the Germans won World War II and you are president of the United States. Imagine a world where the laws of physics no longer apply and where infinite copies of you are playing out every storyline of your life. 　　It sounds like a plot stolen straight from Hollywood, but far from it. This is the multiverse. 　　Until very recently the whole idea of the multiverse was dismissed as a fantasy, but now this strangest of ideas is at the cutting edge of science. 　　And for a growing number of scientists, the multiverse is the only way we will ever truly make sense of the world we are in. 　　Horizon asks the question: Do multiple universes exist? And if so, which one are we actually in?

Imagine a world where dinosaurs still walk the earth. A world where the Germans won World War II and you are president of the United States. Imagine a world where the laws of physics no longer apply and where infinite copies of you are playing out every storyline of your life. 　　It sounds like a plot stolen straight from Hollywood, but far from it. This is the multiverse. 　　Until very recently the whole idea of the multiverse was dismissed as a fantasy, but now this strangest of ideas is at the cutting edge of science. 　　And for a growing number of scientists, the multiverse is the only way we will ever truly make sense of the world we are in. 　　Horizon asks the question: Do multiple universes exist? And if so, which one are we actually in?

本部纪录片是BBC地平线系列推出的一档探寻“土星的秘密”为命题的纪录片。土星，这颗人类用肉眼能够看到的最远行星，以其神秘美丽的土星环而被赋予诸多神话色彩。为了能够近距离地研究土星，美国国家航空航天局于1997年10月15日发射了“卡西尼-惠根斯”探测器。这将是关于航天史上最为野心勃勃的一次无人驾驶航天飞船项目，土星之谜即将被揭开。 　　土星拥有为数众多的卫星，而最著名的“土卫六”上有大气一说，更是最受天文学家瞩目的课题，也是本部纪录片的高潮所在。千百年来，人类都在试图揭开生命起源之谜。那么我们就跟随地平线摄制组的脚步，一起踏上这个跨越太阳系的伟大征程。通过探测这个未知的外星世界，来解答生命是如何开始的提问。

本部纪录片是BBC地平线系列推出的一档探寻“土星的秘密”为命题的纪录片。土星，这颗人类用肉眼能够看到的最远行星，以其神秘美丽的土星环而被赋予诸多神话色彩。为了能够近距离地研究土星，美国国家航空航天局于1997年10月15日发射了“卡西尼-惠根斯”探测器。这将是关于航天史上最为野心勃勃的一次无人驾驶航天飞船项目，土星之谜即将被揭开。 　　土星拥有为数众多的卫星，而最著名的“土卫六”上有大气一说，更是最受天文学家瞩目的课题，也是本部纪录片的高潮所在。千百年来，人类都在试图揭开生命起源之谜。那么我们就跟随地平线摄制组的脚步，一起踏上这个跨越太阳系的伟大征程。通过探测这个未知的外星世界，来解答生命是如何开始的提问。

Dr Kevin Fong tackles moral questions surrounding death that face not just the medical profession, but each and every one of us. Throughout the programme, he meets medical professionals who are at the heart of the dilemmas surrounding our attempts to defeat death and live as long as possible, as well as people who are facing up to the question of how to die a better death.