The United States of America's Declaration of Independence would be signed in the last half-inch.


Or if we compared geologic time to a woman stretching her arms to a span of six feet, the simple act of filing her nails would wipe away all of recorded human history.


Finally, let's imagine the history of the Earth as your life: from the moment you're born to your first day of high school.


Your first word, first time sitting up, and first time walking would all take place while life on Earth was comprised of single-celled organisms.


In fact, the first multicellular organism wouldn't evolve until you were 12 years old and starting 7th grade, right around the time your science teacher is telling the class how fossils are formed.


The dinosaurs don't appear until three months into 8th grade and are soon wiped out right around spring break.


Three days before 9th grade begins, when you realize summer is over and you need new school supplies, Lucy, the Australopithecine, is walking around Africa.


As you finish breakfast and head outside to catch your bus 44 minutes before school, the Neanderthals are going extinct throughout Europe.


The most recent glacial period ends as your bus drops you off 16 minutes before class.


Columbus sets sail 50 seconds before class as you're still trying to find the right classroom.


The Declaration of Independence is signed 28 seconds later as you look for an empty seat.


And you were born 1.3 seconds before the bell rings.


So, you see, the Earth is extremely, unbelievably old compared to us humans with a fossil record hiding incredible stories to tell us about the past and possibly the future as well.


But in the short time we've been here, we've learned so much and will surely learn more over the next decades and centuries, near moments in geological time.


来自:VOA英语网 文章地址: http://www.tingvoa.com/html/20180416/550724.html