New hypothesis for origin of life proposed

Dec 04, 2007
New hypothesis for origin of life proposed
Photo of mica from an abandoned mica mine, with water between some layers, showing edges of mica sheets [e.g., black arrows] and air bubbles in the water [red arrows] and brown bands of organic crud and dirt. Credit: Helen Greenwood Hansma, UC Santa Barbara

Life may have begun in the protected spaces inside of layers of the mineral mica, in ancient oceans, according to a new hypothesis.

The hypothesis was developed by Helen Hansma, a research scientist with the University of California, Santa Barbara and a program director at the National Science Foundation. Hansma will present her findings at a press briefing on Tues., Dec. 4, at the annual meeting of the American Society for Cell Biology in Washington, D.C.

The Hansma mica hypothesis proposes that the narrow confined spaces between the thin layers of mica could have provided exactly the right conditions for the rise of the first biomolecules –– effectively creating cells without membranes. The separation of the layers would have also provided the isolation needed for Darwinian evolution.

“Some think that the first biomolecules were simple proteins, some think they were RNA, or ribonucleic acid,” said Hansma. “Both proteins and RNA could have formed in between the mica sheets.”

RNA plays an important part in translating the genetic code, and is composed of nitrogenous bases, sugar, and phosphates. RNA and many proteins and lipids in our cells have negative charges like mica. RNA’s phosphate groups are spaced one half nanometer apart, just like the negative charges on mica.

Mica layers are held together by potassium. The concentration of potassium inside the mica is very similar to the concentration of potassium in our cells. And the seawater that bathed the mica is rich in sodium, just like our blood.

The heating and cooling of the day to night cycle would have caused the mica sheets to move up and down, and waves would have provided a mechanical energy source as well, according to the new model. Both forms of movement would have caused the forming and breaking of chemical bonds necessary for the earliest biochemistry.

Thus the mica layers could have provided the support, shelter, and an energy source for the development of precellular life, while leaving artifacts in the structure of living things today.

Besides providing a more plausible hypothesis than the prebiotic oceanic “soup” model, Hansma said her new hypothesis also explains more than the so-called “pizza” hypothesis. That model proposes that biomolecules originated on the surfaces of minerals from the Earth’s crust. The “pizza” hypothesis cannot explain how the earliest biomolecules obtained the right amount of water to form stable biopolymers.

A biophysicist, Hansma has worked with mica for decades beginning with her work in biological Atomic Force Microscopy (AFM) in the late 1980s. “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 idea one day last spring when 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.

Source: University of California - Santa Barbara

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BigTone
3.4 / 5 (5) Dec 04, 2007
Cool idea to have a ready made natural incubator for fragile lifeforms to take shape... I just hope this doesn't become an arbitrary "Goldilocks Zone" requirement for life... It would be a shame if scientists created yet another absolutist movement on this front and we have to listen to crap like - we just haven't detected enough mica on this planet for it to have created its own indigenous microbial life forms...
Valentiinro
1 / 5 (3) Dec 04, 2007
Haha yes, good point.
mattytheory
5 / 5 (1) Dec 04, 2007
The scientists in this case are only suggesting a new way for life to have possibly originated here on Earth. They say nothing in the article about extending this theory to other worlds. They were merely comparing the structure of our DNA to the similarities in structure of micah at a molecular level (a scale that both share in common). Additionally, classifying this as a "Goldilocks Zone" would be useless because science has already identified other ways in which life can originate.
SDMike
1 / 5 (2) Dec 04, 2007
So, why aren't scientists looking at mica that is exposed to seawater and wave action for new forms of life? Why, there should thousands of new life forms being produced every day! Mica mines should be just the place to look for signs of life on earth.

Zitface
3 / 5 (2) Dec 04, 2007
This may connect to the recent finding that the double helix structure of DNA reflects a crystalline ancestry.
seanpu
1 / 5 (3) Dec 05, 2007
life never originated on earth. there's no evidence for it. Nor does this article attempt to answer the question, where did the information within the DNA come from. Its impossible for Darwinian evolution to answer that question, so this article is practically useless.

Well done to the author though for finding another way in which cells can be created. Its more likely that some DNA will find its way into the mica and process the environment to make a living cell, but it will not work in reverse.
DarkStar
1 / 5 (2) Dec 06, 2007
I may have anticipated Dr. Hansma's findings. The following essay was written, not entirely tongue-in-cheek, in April of 2006, which was the same time period ("one day last spring") quoted by Hansma for her interesting discovery:

http://www.useles...208.html

Sorry, Helen, but I deserve to share the spotlight with you! Read my (humorous?) reaction here: http://www.useles...008.html

S.Dayton
out7x
2.5 / 5 (2) Dec 06, 2007
The pre-biotic soup was at the bottom of the ocean, along a seafloor volcanic vent. This allows for the mixing of many chemicals, and heat flow.
Ragtime
1 / 5 (3) Dec 06, 2007
In general, the protected, calm zones exhibits the slowest speed of evolution. Try to consider, how slowly the sharks have evolved at the bottom of oceans!

The Aether Wave Theory considers instead, the life has begun due the strong competetion of bubbles, fragmented repetetivelly at the surface foam of ground sea.