How many microbes, bacteria, or germs are in a human body?
Take a guess.
(1) a million?
(2) a hundred million (100,000,000) ?
(3) 1.7 billion (170,000,000,000) ?
For the answer use the DOOR.
If you let a a tricked-up number like “c” fool you, you missed by a mile and aren’t even close. In the human body there are human cells, but along with them are microbe cells that total about
One hundred trillion. (That’s 100,000,000,000,000.)
Consider the following:
There are “hundreds of bacterial species that call me home. In sheer numbers, these microbes [perhaps 10,000 different kinds] and their genes dwarf us. It turns out that we are only 10 percent human: for every human cell that is intrinsic to our body, there are about 10 resident microbes — including commensals (generally harmless freeloaders) and mutualists (favor traders) and, in only a tiny number of cases, pathogens. To the extent that we are bearers of genetic information, more than 99 percent of it is microbial. And it appears increasingly likely that this “second genome,” as it is sometimes called, exerts an influence on our health as great and possibly even greater than the genes we inherit from our parents. But while your inherited genes are more or less fixed, it may be possible to reshape, even cultivate, your second genome.”¹
There are “Enough [bacteria in a human] to fill a big soup can. That’s three to five pounds of bacteria,” says Lita Proctor, the program coordinator of the National Institutes of Health’s Human Microbiome Project, which studies the communities of bacteria living on and in us. The bacteria cells in our body outnumber human cells 10 to 1, she says, but because they are much smaller than human cells, they account for only about 1 to 2 percent of our body mass—though they do make up about half of our body’s waste.”²
Consider thirdly: A lot of what we eat, drink, and otherwise let into our bodies affects us more than we realize. It’s staggering to think of the continuing shift of the microbial populations in the human body, perhaps 10,000 different kinds–something our bodies “automatically” manage and control from day to day without a thought from us about what’s going on…
[All colors and boldface are our addition.]
¹Michael Pollan, The New York Times Magazine (May 19, 2013). This is part of a much larger article. The 100 trillion appears in several other descriptions of human anatomy and physiology. A lot of “other creatures” inhabit the human body. Managing the human “planet” with regards to undocumented micro-immigrants is a serious issue regarding human health. Boldface and coloring are our addition.
² From www.popsci.com. Originally from Popular Science Magazine (Oct. 2011).