Little Creatures Among Us THE MANY MICROBES IN OUR DAILY LIVES

When you think you're alone, you're actually not. In the ground, the air, your room, and even your body are Strillions and trillions of creatures so tiny you can't see them.

- Marcus Woo

They're microbes, and they're everywhere. You've probably heard people call them germsmicroscopic critters that you have to wash away with soap and water, so they won't make you sick.

Yes, some microbes can cause deadly diseases and infections. But, in general, they have gotten a bad reputation. Most aren't harmful, and some are even good for you. Microbes in the soil can help plants grow. Those on your skin and in your body can help you stay healthy. Scientists have found that if people don't have the right kinds of microbes in their guts-the stomach and digestive systems-there's a greater chance they may have health problems, such as obesity, diabetes, and even certain types of cancer.

A Whole Other

Scale Look at the back of your hand. Millions of microbes are living on just one square inch of skin. Both inside and out, your body has tens of trillions of microbes (a number with 13 zeroes after it). You have about as many microbes as you have human cells in your body. That means half of the cells you're walking around with are microbial. It's like you're only half human.

"If you were asked what are the species that live in your backyard or in your home, you might say there's a cat, three humans, and a couple potted plants," says Anne Madden, a self-styled "microbe wrangler" in Maine. "But most of life exists at a whole other microscopic scale." The ecosystem of microbes that live in a given environment, such as on your skin or in your gut, is called a microbiome. Each microbiome is vast and complex, with hundreds and even thousands of species as different from one another as you and a flower. There are bacteria, fungi (mushrooms are a kind of big fungi), and another group of microbes called archaea.