How did life arise on Earth? Are we alone in the universe, a strange fluke, or is there life somewhere out there in the depths of space?
Recent discoveries of unusual microbes surviving in extreme temperatures and other conditions on Earth are changing scientists' ideas about where and how microbial life can survive. They are also leading to new theories about how microscopic life may form.
Until just a few decades ago, scientists didn't think any living thing could survive in places such as volcanic vents, hot springs or other superhot environments. But in the late 1960s, a type of bacterium was discovered thriving in temperatures hotter than 170 degrees Fahrenheit in a hot spring in Yellowstone National Park.
Since then, microbiologists have found microbes living happily in even hotter places, as well as extremely cold, acidic and salty environments--places where we once thought NOTHING could survive. These creatures have become collectively known as "extremophiles" (ex-treem-oh-files) because they thrive in extreme conditions that would kill any other living thing.
Just imagine--microbes can survive in water hotter than boiling! You could not live long at temperatures a little over half that hot. Human beings' upper temperature limit is 122 degrees Fahrenheit.
The upper temperature limit for the most heat-tolerant bacteria is about 194 degrees Fahrenheit. There are bacteria-like creatures called archaea (ar-key-ah) that can live in heat topping 235 degrees. Archaea weren't even known to exist until relatively recently!
Go here for more information on archaea.
Given the unusual places we've found microscopic life on Earth, the question arises as to whether microbes might exist in similar conditions on other planets or moons.
What do you think?
See also the article Life on Mars for other possible hints about life on another planet.
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