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.
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> If one "assumption/theory/guess/could be " is debunked, they have a meeting and think of another idea until some one kills that idea, too.
It's called "science." That's how it works.
Someone is almost sure to drop in and claim that Louis Pasteur "proved" that life can't be created from non-living material. This is a mis-understanding of the ancient term spontaneous generation. This website: The Slow Death of Spontaneous Generation, explains what Pasteur actually did: he demonstrated that meat spoiled because of airborn microbes, not "spontaneously" by itself.
excellent.....
Wonderful. Let's see someone -- anyone -- replicate the creation of the simplest form of life from inorganic elements in a laboratory.
After 50 years of unsuccessful attempts, these experiments were virtually all discontinued in the late 90's.
Such a lot of nonsense.
50 years do not equate to millenia and much much more time.....how naive
"a surprising finding that may alter the way many scientists think about how life began on the planet"
= Were trolling for grant money.
I don't think the article suggests that DNA spontaneously appeared from electrifying protein precursors. The jury is still out on how DNA came to be.
Ping!
It's called biased guessing. Unless they have a time machine, it's all just speculation.
If "Science" were to spend as much time and money on proving creation like they do trying to disprove it, we'd all be wearing halos by now!
Luckily for good 'ol stubborn man kind, quantum psychics (GASP! Why, that's "science" too!) is finally catching up with religion, and it's about time.
So all it takes is a LOT of time, we can't engineer these things as a stepping stone?
Or how about this:
How long DOES it take for life to form by abiogenesis? Are there STAGES of living as opposed to non-living?
Seems like a fairly instant result if you have the right conditions, even if the living thing is short lived.
I would never have imagined that the top of the atmosphere would ever have been even 750 degrees. The ground temperatures must have been incredible.
Apparently, they discovered some ancient stone-carved leaflets that when translated stated all the rich creatures that bought those new "flowers" were filling the air with all that toxic oxygen and that the end of the world was coming.
Enlighten me. You'll be the the fifth anti-creationist to tell me I don't know what I'm talking about on this forum. Yet if you would tell me what you "know" you'd be the first.
If you claim life came about by "chance" then reducing the chances would increase the results. We are yet to see this fulfilled.
So, if scientists are successful at "creating" life, does that mean that that life came about because of "Intelligent Design"?
No. It would mean that life is such an easy step for organic chemistry that mere humans in a lab could do it. This would suggest (not prove) that -- contrary to the claims of some theolgians -- such matters do not require, much less prove, the activities of a deity.
My point is that traditionally, theologians have marveled at the existence of life, and have frequently declared that its very existence is a miracle. Evolution may have happened naturally, many of them admit, but the initial appearance of life is such an impossible thing that it must be the miraculous act of a deity.
Many science-minded folk have suggested that this kind of argument is a trap, because if life is ever created in the lab (by mere men) then the central miracle which sustains many theological systems will be in jeopardy.
Now, sensing that the "miracle" of life is soon to be created in a mundane lab by mere lab rats -- and not by gods and angels -- we can observe an almost instinctive moving of the goalposts. Now they'll demand an exact replication of the conditions on earth billions of years ago. And they'll then insist on perfect proof that those were indeed the young-earth conditions, etc. Endless objections will be raised. All of this is expected.
Every time an alleged "miracle" is demonstrated to be a natural occurence, those who require miracles will squeeze and spin and dance as much as necessary to still find something they can claim is a miracle -- that is, an event not yet explained or demonstrated.
However, even if the first time the "non-life to life" trick is done, the conditions don't mimic those on the young earth, it will nevertheless be momentous, because the trick will have been done. Without supernatural intervention. All the rest will be in the nature of mere sweeping up.
Miller did, and has done for the past 50 years, his experiments in a highly reduced atmopshere, ie: lots of hydrogen.
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