translation.en: It's their knowledge that spells the difference between survival and death for their whole society in a time of crisis caused by rare events for which only the oldest people alive have had experience.
translation.zh: 他们的知识是其整个社会 在罕见事件引起的危机时 存亡的关键 因为唯一活着的，最年长的老人 才会有经验。