Scientist Journeys Into Caves for Clues to Extreme Life

John Roach
for National Geographic News
Apirl 30, 2001

Caving is a highbrow sport. It takes intellectual prowess in the disciplines of geology and hydrology to know how a cave forms, and thus how to identify where hidden passages lie, said Hazel Barton, a microbiologist at the University of Colorado in Boulder, Colorado.

Barton should know. She started caving as a teenager and has become one of the world's foremost cave cartographers. Today, she employs her uncanny ability to seek out caves as part of her work in studying extremophiles—organisms that thrive in environments where human life could not.

"The majority of life on the planet is microbial and living in an environment that is inhospitable to humans," said Barton. "It is quite amazing."

Alternative Survival

Caves are void of sunlight, and therefore lack organisms that need sunlight or the products of photosynthesis for survival. This means caves are an excellent place to go in search of extremophiles. Studying the organisms that are found there can provide insight on how life might survive on other planets.

Extremophiles that thrive in Greenland's ice caves, for example, may be similar to life on Jupiter's moon Europa, which scientists believe to be covered in ice. Similarly, extremophiles living in the underwater caves of the Yucatan in Mexico might have much in common with bacteria that live on Mars, which some reports indicate may have water beneath its surface.

Barton and other scientists speculate that extremophiles from Mars or some other planet could thrive on Earth today. "It is certainly possible that organisms can survive interstellar travel, and Mars and Earth have been seeding each other for 3.9 billion years," said Barton. "That is a lot of spit swapping."

The biological diversity of extremophiles, like the wide array of life forms in the Amazon rain forest, may also hold secrets to the preservation of human life on Earth. Barton's research leads her into caves in search of extremophiles that may serve as antibiotics to treat infections and diseases such as tuberculosis.

"Caves are pretty starved environments," she said. "[Extremophiles] have to use pretty potent weapons to fight off scavengers. If we can harbor those chemicals, then the possibilities are endless."

Caving With Care

True cavers are a tight-knit group that do not readily share information about the whereabouts of holes in the ground. To do so, they say, could lead to human exploitation that results in the extinction of species that may yield cures to devastating diseases, or cause the contamination of freshwater—25 percent of the world's total—that is stored in caves and limestone.

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