Lee makes this analogy: Three million years ago a few anthropoids made the effort to straighten their backs and walk upright. They raised their arms, and used their hands to pick things up, attack others and manufacture tools, consequently developing greater visual and mental powers and greatly advancing knowledge.
李嗣涔打個比喻，三百萬年前，少數幾隻類人猿奮力挺起腰椎，將兩隻前臂稍稍提了起來，再利用這空出來的前臂取物、攻擊、製造工具，不斷鍛鍊牠們的手腦協調，大大開啟了智力。