科学家对25万年前的地下线索进行了研究，这些线索引发了对于人类的早期亲属以及身为人类的真正意义的疑问。
The dream of sending humans to Mars is closer than ever before. In fact, many scientists think that the first person to set foot on the Red Planet is alive today. But where should the first explorers visit when they get there? Horizon has gathered the world's leading experts on Mars and asked them: where would they go, if they got the chance - and what would they need to surviv...
