Posted on 02/02/2010 6:40:58 AM PST by decimon
Earth's chemical energy powered early life through 'the most revolutionary idea in biology since Darwin'
For 80 years it has been accepted that early life began in a 'primordial soup' of organic molecules before evolving out of the oceans millions of years later. Today the 'soup' theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth's chemical energy, from hydrothermal vents on the ocean floor, which kick-started early life.
"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won't work at all," said team leader Dr Nick lane from University College London. "We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent – one that is riddled with tiny interconnected compartments or pores."
The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.
"Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life," said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. "But soup has no capacity for producing the energy vital for life."
In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides giving rise to the first true cells.
The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today - a gradient of protons over a membrane. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO2.
"Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation – positive outside and negative inside – as the inorganic vesicles from which they arose" said co-author John Allen, a biochemist at Queen Mary, University of London.
"Thermodynamic constraints mean that chemiosmosis is strictly necessary for carbon and energy metabolism in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells," said Lane. "Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own."
This was a vital transition, as chemiosmosis is the only mechanism by which organisms could escape from the vents. "The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved – and they could not have evolved without it," said Martin.
"Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis", concluded Lane. "It is time to cast off the shackles of fermentation in some primordial soup as 'life without oxygen' – an idea that dates back to a time before anybody in biology had any understanding of how ATP is made."
Served cold ping.
Mm, Mm good grief!
Only Liberal Slimes believe in Primordial Soup
Evolutionary theory is revised nearly as often as Obama’s economic numbers are.
I wish they would stop teaching things they really don’t know.
I have always had very simplistic questions concerning the “primordial soup” theory on the origin of life.
The earth is thought to have been here for billions of years, did life begin in the “primordial soup” just once? Did it happen many times? Did the many occurances happen thousands or millions of years apart?
If life began accidently in the “primordial soup” why cannot scientists who want to believe this make life happen intentionally, on purpose?
My mom used to say, “I don’t care if you crawled out of a scum pond, fell out of the sky, or God blinked His eye and you were here...you still have to clean your room”.
So CO2 is our mother. Uh oh, we need to tell Al Gore he's trying to kill our biological mother! Since CO2 was here before man and it was the original mother of all life we should do all we can to create as much CO2 in honor of the life it has given all of us.
I'm guessing your room more suggested the scum pond theory than the others.
What I find interesting is that most people who choose to believe that life was a chemical ‘accident’, believe in extra-terrestrial life. I guess the universe must be accident prone.
Problem with this is that is still fails to account for a lot of the other deficiencies in the oceanic abiogenesis model that pretty much kill it, scientifically.
They are proposing that the environment was different than the 80 year-old hypothesis, fair enough. But how do they explain the specified information in DNA ?
The odds of creating a 250-protein cell (in theory the smallest number of proteins needed for a single cell) has been estimated at 1:1041,000
How do you account for protein domains and cumulative selection in your calculation?
On purpose: All things remaining the same, I'm betting maybe under 50 - probably not over 100 - years.
Wouldn't that make the theory settled science? Who are these deniers who think they can question settled science?
I have yet to see anything live crawl out of my pots cooking on the stove.
Hydrothermal vents? I thought it all started with Colin Clive!
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.