Planet Bacteria

I was going to write an essay embroidering on a subject that has become almost a cliché, namely that Earth is not the Planet of Man, that a visitor from another star system would probably describe earth as the planet of microbes, or maybe the planet of insects, with some passing reference to some bi-pedal primates that in the very recent past emerged a capacity for verbal and written communication and self-observation, but that are otherwise of as little interest as the three-toed sloth.
But I decided that there is a better way to illustrate the insignificance of Homo Sapiens on the evolutionary scale by simply, as they say on the radio, "doing the numbers".

Life span (time on earth) - Ratio of Homo Sapiens to the Dinosaurs:

Dinosaurs:
160,000,000 years (from 235 million BP to about 75 million BP)

Humans:
50,000 years (from 50,000 BP to the present)

The ratio is: 1:3,200

In other words, you could fit 3,200 complete human cycles, from barely out of Africa to astronauts in space, and do this 3,200 times, to match the time span that dinosaurs roamed the earth.
Put differently, the fact that after merely 1/3,000th of the longevity of dinosaurs we already think about the possibility of our extinction is an indication of just how tenuous our hold on life here on earth actually is.

And if that were not enough, consider that the Dinosaurs themselves were only a moderately successful experiment in evolutionary terms. Compared to an amoeba they literally came and went in the blink of an eye.