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Water Sensitive Microbes

Photo of Atacama desert.

Over the eons, microbes in the Atacama desert evolved highly specialized strategies for optimizing the extraction of scarce humidity from their environment. (Wikimedia Commons)

The Atacama Desert in Northern Chile is the driest desert on Earth. The only life there is microbial, and researchers study it to get an idea of what we might find on Mars.

According to geological evidence, the desert core has been semiarid or arid for 15 million years, and no rain had been recorded there for 500 years. But then, something strange happened. Since 2015 it has rained several times in the Atacama desert.

Scientists thought that the dessert might bloom with life, but it didn’t. Actually, the rain killed most microbial life in the region, causing some species to go extinct.

Over the eons, the Atacama microbes evolved highly specialized strategies for optimizing the extraction of scarce humidity from their environment. They couldn’t cope with the sudden influx of abundant water into their cell membranes, and when the rains came, they swelled and burst.

Before the rain, researchers estimated there were 16 different species of microbes in the soil of the Atacama Desert core.

There are only two to four left able to survive in the transitory sources of water.

All this might have implications for finding life on Mars. More than three and a half billion years ago, geological evidence shows water was abundant on Mars. Then it became dry, with occasional episodes of massive flooding. If Mars is like the Atacama, then those floods might not have helped Martian life to persist. They might have killed it off.

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