I Didn’t Know That ...

Q: How many species of microorganisms live on and in the human body, and how many of them are there?

A. According to New Scientist magazine, there are at least 200 species living in humans--80 in the mouth alone. The best source of information is the 1969 book “Life on Man” by biologist Theodor Rosebury, who found that the numbers of actual microorganisms are staggering. He concluded that the number of bacteria excreted by an adult each day ranges from 100 billion to 100 trillion. From that figure, it can be estimated that there are about 10 billion bugs on every square centimeter of bowel. Rosebury also estimated that about 10 million individual bacteria live on the average square centimeter of human skin. While the numbers are huge, the volume isn’t. Rosebury estimated that all the bacteria living on the skin would fit into a medium-sized pea, while all those living inside would fill a 300-milliliter bottle-less than a pint.