Stanley Miller's classic "primordial soup" experimental setup,
with a simulated ocean, lightning and broth
of hydrogen, methane, ammonia and water.
Posted on 04/08/2005 7:39:14 AM PDT by PatrickHenry
A new University of Colorado at Boulder study indicates Earth in its infancy probably had substantial quantities of hydrogen in its atmosphere, a surprising finding that may alter the way many scientists think about how life began on the planet.
Published in the April 7 issue of Science Express, the online edition of Science Magazine, the study concludes traditional models estimating hydrogen escape from Earth's atmosphere several billions of years ago are flawed. The new study indicates up to 40 percent of the early atmosphere was hydrogen, implying a more favorable climate for the production of pre-biotic organic compounds like amino acids, and ultimately, life.
The paper was authored by doctoral student Feng Tian, Professor Owen Toon and Research Associate Alexander Pavlov of CU-Boulder's Laboratory for Atmospheric and Space Physics with Hans De Sterk of the University of Waterloo. The study was supported by the NASA Institute of Astrobiology and NASA's Exobiology Program.
"I didn't expect this result when we began the study," said Tian, a doctoral student in CU-Boulder's Astrobiology Center at LASP and chief author of the paper. "If Earth's atmosphere was hydrogen-rich as we have shown, organic compounds could easily have been produced."
Scientists believe Earth was formed about 4.6 billion years ago, and geologic evidence indicates life may have begun on Earth roughly a billion years later.
"This study indicates that the carbon dioxide-rich, hydrogen-poor Mars and Venus-like model of Earth's early atmosphere that scientists have been working with for the last 25 years is incorrect," said Toon. In such atmospheres, organic molecules are not produced by photochemical reactions or electrical discharges.
Toon said the premise that early Earth had a CO2-dominated atmosphere long after its formation has caused many scientists to look for clues to the origin of life in hydrothermal vents in the sea, fresh-water hot springs or those delivered to Earth from space via meteorites or dust.
The team concluded that even if the atmospheric CO2 concentrations were large, the hydrogen concentrations would have been larger. "In that case, the production of organic compounds with the help of electrical discharge or photochemical reactions may have been efficient," said Toon.
Amino acids that likely formed from organic materials in the hydrogen-rich environment may have accumulated in the oceans or in bays, lakes and swamps, enhancing potential birthplaces for life, the team reported.
The new study indicates the escape of hydrogen from Earth's early atmosphere was probably two orders of magnitude slower than scientists previously believed, said Tian. The lower escape rate is based in part on the new estimates for past temperatures in the highest reaches of Earth's atmosphere some 5,000 miles in altitude where it meets the space environment.
While previous calculations assumed Earth's temperature at the top of the atmosphere to be well over 1,500 degrees F several billion years ago, the new mathematical models show temperatures would have been twice as cool back then. The new calculations involve supersonic flows of gas escaping from Earth's upper atmosphere as a planetary wind, according to the study.
"There seems to have been a blind assumption for years that atmospheric hydrogen was escaping from Earth three or four billion years ago as efficiently as it is today," said Pavlov. "We show the escape was limited considerably back then by low temperatures in the upper atmosphere and the supply of energy from the sun."
Despite somewhat higher ultraviolet radiation levels from the sun in Earth's infancy, the escape rate of hydrogen would have remained low, Tian said. The escaping hydrogen would have been balanced by hydrogen being vented by Earth's volcanoes several billion years ago, making it a major component of the atmosphere.
In 1953, University of Chicago graduate student Stanley Miller sent an electrical current through a chamber containing methane, ammonia, hydrogen and water, yielding amino acids, considered to be the building blocks of life. "I think this study makes the experiments by Miller and others relevant again," Toon said. "In this new scenario, organics can be produced efficiently in the early atmosphere, leading us back to the organic-rich soup-in-the-ocean concept."
In the new CU-Boulder scenario, it is a hydrogen and CO2-dominated atmosphere that leads to the production of organic molecules, not the methane and ammonia atmosphere used in Miller's experiment, Toon said.
Tian and other team members said the research effort will continue. The duration of the hydrogen-rich atmosphere on early Earth still is unknown, they said.
I just did. Didn't see any gods.
I checked again to be sure. Alls I see is a bunch of a trees, some wildflowers, ferns, a couple bluejays, and a skittish cat. Is the kitty what I'm looking for?
"A tiny speck of zircon crystal that is barely visible to the eye is believed to be the oldest known piece of Earth at about 4.4 billion years old.
Valley found that the planet had cooled to about 100-degrees Centigrade less than 200 million years after it was formed. Before the research, the oldest evidence for liquid water on the planet was from a rock estimated to be much younger - 3.8 billion years old.
Occam's Razor will not lead you to believe that a rose and a robin came from a common ancestor.
It sure looks like you are requiring one. Let me say, that even if a photograph was presented to you, you would still not believe, at least that is my conclusion.
Assertion noted. Meet Sarah Scantlin.
It will if you study biology, particularly molecular biology.
What a silly discussion. Of course a photograph is not sufficient evidence of anything. Photographs can be faked, and in the early centuries of Christianity there were vast profits to be made in the sale of relics. Some were obvious fakes, but even if the Shroud is what it purports to be, it isn't proof of anything miraculous.
You worship a piece of cloth?
Not really :-)
From this perspective we will see that there was not one particular primordial form, but rather a process that generated many of them, because only in this way can cellular organization evolve. The Doctrine of Common Descent (and classical evolutionary thinking in general) rests on the tacit assumption that the dynamic of the evolutionary process remains unchanged as it gives rise to increasingly complex, specific, etc. cellular forms. Yet the forms in essence are the process. Therefore, fundamental changes in their nature can only mean changes in the underlying evolutionary dynamic. The time has come for Biology to go beyond the Doctrine of Common Descent.
First, you didn't answer my question about your implied belief in Cthulhu.
Second, what are you talking about concerning the worship of a piece of cloth?
Yes, I suspect too many to count. And just a few light years away.
Don't bet on it - I've known too many who thought they could break the bank at Las Vegas. Ask any conman, ask any stage magician, educated people are relatively easy to fool.
True, some seem to believe that their bleeding edge expertise on a narrow slice of reality somehow immunizes them from foolishness elsewhere.
No, of course not. I also never said it did.
It's the evidence in favor of evolution that convinces me of their common descent.
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