We are all more or less familiar with the size of a bacterium: more or less, by eye, we can say that they are tiny, generally invisible to the human eye (a few micrometers).
What is less known is their life expectancy. How long does a bacterium live?
The average life of a bacterium is about 20 minutes . During this short-lived existence, however, a bacterium is capable of many things.
Even transforming himself, like a genetic engineer applying improvements on himself.
Because bacteria can exchange genes with each other, and they can also pick up DNA from dead neighboring bacteria (called "horizontal gene transfers"). This allows bacteria to have a great capacity to adapt to the environment.
Bacterial DNA also undergoes more mutations (more errors), which allows it to be even more versatile at the genetic level (only the best adapted survive). If we add to this the speed at which they reproduce, we already have the perfect combo: E. coli , for example, can reproduce 72 times in 24 hours .
As Bill Bryson points out in The Human Body , this means that a bacterium can accumulate as many generations as we have achieved in all of human history in just … 3 days !:
In theory, a single parent bacterium could produce a mass of offspring greater than Earth’s weight in less than two days; and enter his progeny would exceed the mass of the observable universe. Obviously, that could never happen, but the truth is that we are already accompanied by amounts that exceed what is imaginable. If we put all the microbes on Earth in one pile and all animal life in another, the pile of microbes would be 25 times larger than that of animals.