Sweat-slurping ‘aliens’ live on your skin | Science News for Students

Sweat-slurping ‘aliens’ live on your skin

Kids and the elderly seem to host more of these archaea than do teens and adults
Oct 25, 2017 — 6:45 am EST
microbes on skin

Among the microbes found on people’s skin (artist’s illustration) are single-celled organisms called archaea.


Single-celled lifeforms called archaea (Ar-KEE-uh) thrive inside boiling hot springs and frigid Antarctic lakes. As such, these microbes picked up a reputation for preferring extreme environments. New data now show that’s far from true. Researchers are finding them everywhere — even on skin. And the latest study shows that children and the elderly people host more of these unique tagalongs than do teens and adults.

Archaea are about the size and shape of bacteria. In fact, scientists for a long time confused them with bacteria. But in the 1970s, biologists realized these microbes had different types of cell walls. And their genes, which instruct those cells on what to do, also were very different. Scientists decided archaea must constitute a whole new form of life. It was almost like aliens had been discovered here on Earth.

Some of these weird microbes “like [to eat] our sweat,” reports study author Hoi-Ying Holman. She’s a scientist at Lawrence Berkeley National Laboratory in California. There, she uses a powerful microscope to look at cells or tiny life forms. Holman joined an international team of scientists for the new study. Her team hadn’t set out to study skin. They had been trying to stop archaea from hitchhiking on spacecraft bound for Mars.

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Advanced Light Source machine
Hoi-Ying Holman uses this gigantic machine to look for tiny archaea. This is the Advanced Light Source at Lawrence Berkeley National Laboratory in California.
Hoi-Ying Holman

NASA and the European Space Agency had asked their group to search spacecraft for archaeal hitchhikers. These space agencies want to keep their ships clean. Ferrying even microbial Earthlings to another planet might risk harm to any Martian life (should it exist). The agencies knew bacteria weren’t likely to survive a trip through space. But as renowned extremophiles (Ex-TREEM-oh-files), archaea just might.

And archaea were lurking on spacecraft, she found. They turned up in rooms at labs and hospitals that were supposed to be sterile — as in germfree. “The most likely source was human skin,” Holman notes. So her group did a small study. It checked 13 volunteers for the germs. And all hosted archaea on their skin.

For their new study, the researchers examined samples from another 51 people, all in Germany. Again, all had archaea, but amounts varied. Those under age 12 had five to eight times more archaea on their skin than did teens and adults. So did people over age 60. In any age group, people with dry skin hosted more.

Overall, the differences “surprised me,” says Holman. Her team described its findings online June 22 in Scientific Reports.

Tiny teddy bears

Researchers don’t yet know why age matters when it comes to archaea. One possible explanation is that the skin changes during puberty. That’s when many teens get zits. Those changes also may make the skin less inviting for archaea. And the relationship might work the other way, too — having more archaea might help keep skin healthy.

One group of archaea, among the most abundant on Earth, are Thaumarchaeota (Thau-mar-kee-OH-ta). And they seem to enjoy slurping human sweat. As such, these bugs may even reduce body odor.

When Holman’s teenage son heard about this, he joked that maybe he should apply some to his face to prevent acne. “Don’t do anything of the sort!” Holman told him. Biologists simply don’t know enough about the species of these found on skin. Their studies have yet to find any of them that appear dangerous. Still, archaea are so poorly known that it’s certainly possible some might play a role in disease.

Ecologist Rob Dunn, who was not involved in the study, is not too concerned. At North Carolina State University in Raleigh, he studies many species, from ants to microbes. Five years ago, he turned up archaea in human belly buttons. To him, “they're like the teddy bears of the single-celled world.”

The new study is just “the beginning of the story,” Dunn says. He’s excited that researchers are finally taking notice of these microbes. In the past, scientists hadn’t seen archaea on people for a very simple reason: They weren’t looking. They’d go to hot springs or frozen lakes to search for them. As it turns out, they needn’t have looked farther than their own bodies.

Says Dunn, there’s a lesson in all this: “It’s still possible to discover totally new things without leaving the house.”

Yellowstone microbes
Grand Prismatic Spring at Yellowstone National Park in Wyoming owes some of its bright colors to archaea. These tiny microbes are similar in size and shape to bacteria. But they are different enough that scientists consider them a separate form of life.
Clément Bardot/Wikimedia Commons (CC BY-SA 3.0)

Power Words

(more about Power Words)

acne     A skin condition that results in red, inflamed skin, commonly called pimples or zits.

alien     A non-native organism. (in astronomy) Life on or from a distant world.

archaea    (singular: archaeon)  A domain of life that includes single-celled organisms. Although archaea superficially resemble bacteria, they are distinct. Archaea inhabit many harsh environments.

bacteria     ( singular: bacterium ) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals).

bug     The slang term for an insect. Sometimes it’s even used to refer to a germ.

cell     The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

colleague     Someone who works with another; a co-worker or team member.

ecology     A branch of biology that deals with the relations of organisms to one another and to their physical surroundings. A scientist who works in this field is called an ecologist.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).

gene     (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

microbe     Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.

molecule     An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

NASA     Short for the National Aeronautics and Space Administration. Created in 1958, this U.S. agency has become a leader in space research and in stimulating public interest in space exploration. It was through NASA that the United States sent people into orbit and ultimately to the moon. It also has sent research craft to study planets and other celestial objects in our solar system.

planet     A celestial object that orbits a star, is big enough for gravity to have squashed it into a roundish ball and has cleared other objects out of the way in its orbital neighborhood.

puberty     A developmental period in humans and other primates when the body undergoes hormonal changes that will result in the maturation of reproductive organs.

species     A group of similar organisms capable of producing offspring that can survive and reproduce.

unique     Something that is unlike anything else; the only one of its kind.

zits     A colloquial term for the pimples caused by acne.


Journal:​ ​​C. Moissl-Eichinger et al. “Human age and skin physiology shape diversity and abundance of Archaea on skin.” Scientific Reports. Vol. 7, published online June 22, 2017. doi: 10.1038/s41598-017-04197-4.