Mica minerals include biotite (on the left) and muscovite (on the right.)
Click on image for full size
Lisa Gardiner/Windows to the Universe

Did Life First Develop in a Mica Sandwich at the Bottom of a Primordial Sea?
News story originally written on December 4, 2007

Earth's first life form may have developed between the layers of a chunk of mica sitting like a multilayered sandwich in primordial waters, according to a new hypothesis. The mica hypothesis, which was developed by Helen Hansma of the National Science Foundation (NSF), proposes that the compartments between layers of mica -- a common mineral that cleaves into smooth sheets -- could have provided the shelter and protection needed for molecules to organize into cells.

Hansma will present her mica hypothesis at the annual meeting of the American Society for Cell Biology in Washington, D.C., on December 4, 2007.

Hansma says that her hypothesis is supported by several lines of evidence, including the many chemical and physical similarities between a cell interior and the space between mica sheets. For example, both environments are potassium-rich and negatively-charged. Such similarities suggest that mica "would have provided a very hospitable environment to the earliest biomolecules," says Hansma.

In addition, the confined spaces formed by mica layers would have provided the isolation needed for Darwinian evolution. What's more, the expansion, contraction and movements of the mica sheets caused by temperature changes and ocean currents would have helped rearrange molecules and trigger the formation of bonds between them, as required for life to originate.

Providing further support to the Hansma mica hypothesis is the close proximity between a huge mica formation in Greenland to rock formations where ancient life is believed to have existed.

Other hypotheses about the origins of life include the idea that life originated in a prebiotic "soup" in ancient oceans. However, the so-called "soup" hypothesis can't explain how the earliest biomolecules -- sloshing around, unprotected in liquid -- would have joined, stayed together and organized into the complex structures of life. Another hypothesis known as the "pizza" hypothesis says that the earliest cells developed on mineral surfaces on land. But this hypothesis can't explain how those cells would have obtained the right amount of water to survive.

Hansma's passion for mica dates back to the 1980s, when she began her NSF-funded work developing pioneering techniques in biological atomic force microscopy (AFM), an imaging technique.
"We put our samples on mica, because it is so atomically flat, so flat that we can see even bare DNA molecules as little ridges on the mica surface," said Hansma. "The layered mineral is made of sheets so thin (one nanometer) that there are a million of them in a millimeter-thick sheet of mica."

Hansma came upon her mica hypothesis one day last spring when -- still a mica devotee -- she was splitting some mica under her dissecting microscope. She had collected the specimens in a mica mine in Connecticut. The mica was covered with organic material. "As I was looking at the organic crud on the mica, it occurred to me that this would be a good place for life to originate -- between these sheets that can move up and down in response to water currents which would have provided the mechanical energy for making and breaking bonds," said Hansma.

Hansma summed up her hypothesis of the origin of life by saying, "I picture all the molecules of early life evolving and rearranging among mica sheets in a communal fashion for eons before budding off with cell membranes and spreading out to populate the world."

Text above is courtesy of the National Science Foundation

Last modified December 7, 2007 by Lisa Gardiner.

Shop Windows to the Universe Science Store!

Our online store includes books on science education, ranging from evolution, classroom research, and the need for science and math literacy!

Windows to the Universe Community



You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Mica Minerals

Mica minerals make some rocks sparkle! Look for them in your igneous and metamorphic rocks. Do they make your rocks sparkle? They break into flat plates because they have cleavage. ...more

What Is a Mineral?

Minerals are the building blocks of rocks. There are many different types of minerals. All of them are solid and all are made of atoms of elements. Minerals can grow even though they are not alive. Most...more

What’s That Mineral?

Spotting minerals is fun! There are many different types of minerals. Each has a different name and special traits. You can learn more about minerals by looking closely at them to understand their special...more


Most things around us are made of groups of atoms connected together into packages called molecules. Molecules are made from atoms of one or more elements. Some molecules are made of only one type of...more

What Is a Fossil?

Fossils are evidence of what life was like long ago. The oldest fossils are over three billion years old and the youngest fossils are about 10,000 years old. Scientists that study fossils know that creatures...more

Triggers of Volcanic Eruptions in Oregon's Mount Hood Investigated

Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. Adam Kent, a geologist at Oregon State University, says this...more

Oldest Earth Mantle Reservoir Discovered

The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core. The mantle is made up of many different reservoirs that have different chemical compositions. Scientists...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA