for National Geographic News
Hot action between the sheets has given many human lives their start. Now a scientist says chemical comings and goings between sheets of the mineral mica may have gotten all life on Earth going.
The layered, flaky mineral could have provided support, shelter, and an energy source to jump-start formation of the first complex organic molecules, according to the new theory.
"I think that explains a lot of puzzles about the origins of life," said Helen Hansma, a biophysicist at the University of California, Santa Barbara.
Hansma presented her hypothesis last week at the American Society for Cell Biology's annual meeting in Washington, D.C.
"Soup and Sandwich"
Hansma likens the mica sheets and organic material gathering between them to a sandwich, adding another food item to the list of analogies scientists use to explain the origins of life.
A primary analogy is that life began in a soup of chemicals, but according to Hansma, the model lacks a mechanism to bring molecules together to form the more complex structures of life.
"Soup alone is too unorganized," she said.
But the space between mica sheets, she noted, is restricted like the interior of a cell. This confinement, given sufficient time, could have allowed complex life to evolve.
"So I'm coming up with a soup-and-sandwich hypothesis," Hansma said.
"Hopefully there was a pre-biotic soup out there to provide some of the simplest molecules, and then the more complex molecules evolved in the sandwich between the mica sheets."
Energy, she noted, would come as water sloshed through the mica layers or from expansion and contraction as the mineral was exposed to temperature changes throughout the day. (Related: "Volcanoes May Have Sparked Life on Earth, Study Says" [October 7, 2004].)
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