translation.en: That's happened before. About 12,000 years ago, there was a massive wave of mammal extinctions in the Americas, and that is thought to have been a virulent disease.
translation.zh: 这事以前也发生过，在大概一万两千年前， 在美洲发生过大规模的哺乳动物灭绝。 据说这就是由一种致命疾病引起的。