前言如果把我们星球的年岁——目前测定为约五十亿年——浓缩为一年,那前8个月里毫无生命迹象。接下来的两个月,见到的只是植物和极原始的动物形式。进入12月很久以后,哺乳动物才露面。在这“年”中,“直立人”的成员,我们的远古先辈,只是在12月31日夜里的 Foreword If the age of our planet - currently measured as about 5 billion years - is condensed into one year, there is no sign of life in the first eight months. The next two months saw only plants and extremely primitive animal forms. Long into December, mammals only appeared. In this “Year”, the “Homo erectus” members, our ancient ancestors, were only on the night of December 31st.