Misunderstood Microbes

Misunderstood Microbes

Recent scientific studies have revealed the importance of microbes. Despite common misconceptions, most microbes are more helpful than harmful to humans and the planet.


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Microbes are organisms that cannot be seen with the naked eye. They include bacteria, archaea, protists, viruses, prions, and fungi. They account for most of the diversity of life on Earth. Far more microbes inhabit a single person’s body than there are people on the entire planet. Microbes also dominate in terms of their ability to live and thrive in extreme environments, including clouds, deep-sea volcanoes, springs, ice caps, and animal intestines.

Most animals, including humans, exhibit numerous associations with microbes. Our "human microbiome" includes our skin, hair, mouth, and gut.

Humans typically associate microbes with disease. Most of our human microbiome, however, is neutral or even beneficial. Microbes help digest food, absorb nutrients, and out-compete harmful bacteria in the intestines. They produce vitamins and proteins that human genes cannot produce. They prevent the growth of harmful skin bacteria and further aid the immune system in fighting infections and diseases throughout the human body.

Fast Fact

  • The microbes that inhabit a single person outnumber the human cells ten to one and can weigh approximately three pounds.

Fast Fact

  • In addition to the human microbiome, microbes live in plants, soil, oceans, and the atmosphere. These microbiomes maintain healthy function of these diverse ecosystems, influencing human health, climate change, food security, and other factors.

Fast Fact

  • Escherichia coli is a bacterium that is one of the most well-studied microbes in our human microbiome. E.coli can cause severe intestinal illnesses, but also plays an important role in providing humans with vitamin K.

Fast Fact

  • The air around you may be as distinctive as a fingerprint. The human body emits bacteria into the air, and the resulting microbial cloud may be used to uniquely identify the person.
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Angela M. Cowan, Education Specialist and Curriculum Designer
National Geographic Society
National Geographic Society
Julie Brown, National Geographic Society
Elaine Larson, National Geographic Society
Last Updated

October 19, 2023

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