With artificial breeding, the rules of the game have been changed, the test of nature has been removed, and the sole criterion for survival is economic value.
也就是能不能通過大自然「物競天擇，適者生存」的考驗；晚近的人工配種則將遊戲規則改變，單憑經濟價值高低；大自然的考驗，人類已替它們排除。