Or if we compared geologic time to a woman stretching her arms to a span of six feet, 如果我们将地质年代同一个女士伸展的双臂长度——大约6英尺的范围作比较，

　　the simple act of filing her nails would wipe away all of recorded human history. 一个简单的修理指甲便会抹去整个人类历史。

　　Finally, let's imagine the history of the Earth as your life: 最后，让我们把地球历史想象成你的一生：

　　from the moment you're born to your first day of high school. 从你出生的时刻到你进入高中的第一天。

　　Your first word, first time sitting up, and first time walking would all take place 你的第一句话，第一次起立，第一次行走

　　while life on Earth was comprised of single-celled organisms. 统统发生在地球生物界是由单细胞生物构成的时候。

　　In fact, the first multicellular organism wouldn't evolve until you were 12 years old and starting 7th grade, 事实上，第一个多细胞生物直到你12岁的时候才出现，也就是你开始7年级的时候，

　　right around the time your science teacher is telling the class how fossils are formed. 这刚好是你的科学老师在课堂上告诉你化石是怎么形成的时候。

　　The dinosaurs don't appear until three months into 8th grade and are soon wiped out right around spring break. 恐龙是你在8年级上了三个月的时候才出现的，但很快，在你春假的时候它又消失了。

　　Three days before 9th grade begins, when you realize summer is over and you need new school supplies, 9年级开始的三天前，当你发现夏天已经结束，你又需要新学习用具的时候，

　　Lucy, the Australopithecine, is walking around Africa. 南方猿人露西正在非洲散步。

　　As you finish breakfast and head outside to catch your bus 44 minutes before school, 当你吃完早餐出门追赶公交车、还有44分钟就要上课的时候，

　　the Neanderthals are going extinct throughout Europe. 尼安德特人将从整个欧洲消失。

　　The most recent glacial period ends as your bus drops you off 16 minutes before class. 最近的一次冰河时期结束于你从公交车上下来，上课前的16分钟。

　　Columbus sets sail 50 seconds before class as you're still trying to find the right classroom. 哥伦布起航于你上课的50秒前，寻找正确教室的时候。

　　The Declaration of Independence is signed 28 seconds later as you look for an empty seat. 独立宣言签署于28秒钟后，这时你正在寻找空座位。

　　And you were born 1.3 seconds before the bell rings. 然后你出生于上课铃响1.3秒之前。

　　So, you see, the Earth is extremely, unbelievably old compared to us humans 所以你看，地球跟我们人类比起来真的是极不可思议的高龄，

　　with a fossil record hiding incredible stories to tell us about the past and possibly the future as well. 化石记录隐藏了太多过去的惊人故事，还可能包括将来的。

　　But in the short time we've been here, 但在我们存在的短时间内，我们了解了如此之多，

　　we've learned so much and will surely learn more over the next decades and centuries, 当然在未来的几十年到几个世纪我们一定会了解更多，

　　near moments in geological time. 这仅相当于地质年代中的片刻。