How Long Would It Take Bacteria to Eat the Earth?
A trillion bacteria weigh one gram, 500 million bacteria fit in a grain of sand, and other answers from order-of-magnitude thinking.
When I first heard that bacteria in the body outnumber human cells ten-to-one, eight years ago, I thought, “Now that is truly terrifying, to be mostly bacterial, a container for microbial soup.” The thought is morbid, but I can explain its appeal.
The notion that bacterial cells outnumber human ones is intriguing because I, like others, envision bacteria as microscopic, impotent creatures that only exert their influence when causing some terrible disease. The idea that people are “mostly bacterial” removes the impotent adjective from these creatures — bacteria are interesting because they are me. In the titular words of Ed Yong, “I Contain Multitudes”.
Unfortunately, it turns out that the ten-to-one thing is not true. Bacteria and human cells probably inhabit our bodies at a one-to-one ratio. But I still think of bacteria as mighty beings, packed into a small frame.
