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 will grant that the revised question is an open one. It is an assumption of science that a materialistic explanation can be found. Of course this assumption applies to all areas of science, not just abiogenesis. Science would not be possible without this assumption, since if we don't assume that the universe is explainable, there's little point in searching for explanations. If the origin of life actually does require Divine intervention, then science will never come up with the right answer.
Thank you both. It looks as though we need to be cautious in equating the existence of organic material with the existence of current or previous life.
The existence of dog food does not guarantee the existence of a dog.
The existence of dog POOP, on the other hand...
I just want to take this time to thank you guys for being willing to talk in a civil manner on this subject. Some of your colleauges would be less inclined, but it's refreshing to actually *bounce* ideas off of one another without mud getting attached to what comes back.
Keep thinking!
Yesterday Miss Manners answered the question we've all been asking: how does a psychic break really bad news to a customer. Should one hedge around, or bluntly advise them to set one less place for dinner.
That matter has certain properties and any regularity we perceive is simply the result of these particles with their respective properties interacting with each other.
So absent any intermeddling force, a proton behaves like a proton, an electron behaves like an electron, a neutron like a neutron, a muon like a muon, etc.
I see no need that any of these regularities that flow from the inherent properties of matter have to be enforced in any way, like for instance djinns taking care that the planets don't violate Kepler's laws.
Should I post my picture of the naturally occuring water pump?
OK. I'm firmly in the ID camp, but this is simply an incorrect statement. Experiments can be designed in such a way as to remove the "intelligence" factor.
Just to clarify...dirt only came into existence after life.. and death.
It's the result of the breakdown of formerly living things, mostly by currently living things.
theos (the root of theology) is God (derived from the Greek goddess Thea before Zeus and the Olympians overthrew the Titans).
thea (the root of theory) is 'to view' (as in theater).
And what if the "djinns" are what are keeping the photons behaving like photons? These lesser "enforcers of God's Will" could simply be what we now call the Laws of Physics.
Certainly I'm not implying that humanoid things fly about from one space to another, demanding that things do what they should. But the order itself is suspicious of there being a law that they must obey.
I guess my question would be "WHY do atoms behave according to their status?"
In an ideal world, yes. In the messy real world with human ego in play, don't believe it for a minute.
There was an article posted last week saying bacteria had been found living in ocean trenches at 750 degrees. Bacteria at Yellowstone can live at 30 degrees above boiling.
Okay, good catch on your part. Certainly life can exist at somewhat elevated temperatures. However, what I really meant was that you cannot accelerate the process to any desired degree; there will always be an upper temperature limit beyond which any potential life would be destroyed. The production of life from non life is a scientific question, however, because there are ways to falsify any given hypothesis on how this comes about. For example, if we were to show that under conditions that exist on the early earth, that organic molecules could not form, then any abiogenesis hypothesis would be falsified. Proposing that an omnipotent God created life, however, is not falsifiable. Any observation would be consistent with the idea that God created life, since He is omnipotent and could make us see anything he wants us to see. Science, therefore, cannot seriously entertain the idea that God created life, since this idea cannot be meaningfully tested. That's not to say, however, that individual scientists could not believe that God created life. God creating life just cannot be the accepted theory of the scientific community. Think of this as a limitation of science if you like.
LOL!!!
Sure. Maybe I can find pictures of one of the two (or more, by now) naturally occuring natural nuclear reactors (complete with cooling system.)
Well there's always, "Are you John Smith's widow?"
Wait.... Thea is the root meaning "view" and Thea is derived from Theo, meaning God...
And this disputes my statement how?
Good point. That's why there is no dirt (a.k.a. soil) on the moon or on Mars. It's technically called regolith.
Thank you. I have some free time from the lab at work while certain equipment calibrates and stabilizes before I can actually get anything useful done today. This give me a chance to engage in some more detailed than usual discussion since much of this thread relates to what I do for a living.
I await someone to post the obligatory pic of Helen Thomas.
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