Look in the mirror. You're it. The reason you're alive today is because of those changes in our brains that took place in Africa -- probably somewhere in the region where we're sitting right now, around 60, 70 thousand years ago -- allowing us not only to survive in Africa, but to expand out of Africa.
照照镜子，你就是。今天你能够在这里存活， 是因为那时候在非洲人类脑子里的变化。 恐怕就发生在我们现在坐的地方， 六万或者七万年前。 这些变化让我们不光是在非洲存活，也迁移到了非洲之外。