But much further back in history, when hunters followed the tracks of wild beasts on the savannas, farmers extended their fields deep into the forests, and traders followed ancient trails over mountain passes, humans were explorers too; simply to survive in the everyday struggle with nature, they swallowed their fears and pressed bravely ahead.
然而想像一下，在人類歷史早期，地球上處處是人煙罕至的險地，獵人在草原上追蹤猛獸足跡，農人把耕地一步步推向密林深處，商隊在古道上翻山越嶺......，日常生活步步危機，處處涉險，而人類之所以按捺著恐懼奮勇向前，其目的不外是為了求生存，不得不與天爭，與大自然搶地盤。