compared to geological time, humans have lived on Earth for the blink of en eye?
If you think of Earth’s history as a single year, the first single-celled life appears around the end of February. Not until September do we see multi-celled life. Dinosaurs appear in early December and die out suddenly on December 26. Humans don’t show up until 11:58 p.m. on New Year’s Eve.
Scientists think that more than 99 percent of all species that have ever lived are extinct today. Earth is now home to about 1.5 million known species and millions not yet discovered. But this biodiversity is threatened by an extinction rate 100 or more times larger than before year 1800. Scientist Edwards O. Wilson warns “we should preserve every scrap of biodiversity as priceless while we learn to use it and come to understand what it means to humanity.”
Source: Science Encyclopedia, by National Geographic