I love this book.
"Perhaps an even more effective way of grasping our extreme recentness as a part of this 4.5-billion-year-old picture is to stretch your arms to their fullest extent and imagine that width as the entire history of the Earth. On this scale, according to John McPhee in Basin and Range, the distance from the fingertips of one hand to the wrist of the other is Precambrian. All of complex life is in one hand, "and in a single stroke with a medium-grained nail file you could eradicate human history."
Fortunately, that moment hasn't happened, but chances are good that it will. I don't wish to interject a note of gloom just at this point, but the fact is that there is one other extremely pertinent quality about life on Earth: it goes extinct. Quite regularly. For all the trouble they take to assemble and preserve themselves, species crumple and die remarkable routinely. And the more complex they get, the more quickly they appear to go extinct. Which is perhaps one reason why so much of life isn't terribly ambitious."
-Bill Bryson, 2003: A Short History of Nearly Everything, pp337.
Fortunately, that moment hasn't happened, but chances are good that it will. I don't wish to interject a note of gloom just at this point, but the fact is that there is one other extremely pertinent quality about life on Earth: it goes extinct. Quite regularly. For all the trouble they take to assemble and preserve themselves, species crumple and die remarkable routinely. And the more complex they get, the more quickly they appear to go extinct. Which is perhaps one reason why so much of life isn't terribly ambitious."
-Bill Bryson, 2003: A Short History of Nearly Everything, pp337.