Questionable Motives

February 4, 2010

Is there a better explanation for origin of life than from a primordial soup?

Filed under: abiogenesis,Biology,Evolution,Science — tildeb @ 2:03 pm

Apparently so. Hot off the presses comes this hypothesis (excerpts from the article at ScienceDaily)

“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 which may have given 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.

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We can now expect at least two criticisms from creationists:

1) Darwin was wrong again and that evolution is just a theory that continues to evolve

2) There is no way we are biologically related to a geochemical gradient: where’s the transitional fossil?

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3 Comments »

  1. The article is a bit misleading about the ‘suddenness’ of this idea: The Black Smoker Hypothesis has been championed by Bill Martin, Eugene Koonin, Nick Lane, and and many others for years. Something about a steady heat source in rich chemical environment, which is really what ‘primordial soup’ has commonly been used to mean. To be more accurate (and less sensationalistic) this article should read that this is “One more tick mark in the hydrothermal vent side of the score card.”

    Comment by tildeb — February 4, 2010 @ 2:07 pm | Reply

  2. Except that it isn’t the famous hot magma driven black smokers at hot-spots and mid-oceanic ridges that at the center of this hypothesis, but their cooler cousins at spots miles away from the ridges. Alkaline hydrothermal vents are created by plate tectonics, but from the cracking of rock allowing water down to the mantle, not magma. Serpentinization of ultramafic minerals releases considerable heat and H2, which would have been crucial in the abiotic creation of nucleotides and a primitive metabolism. The heat would also driven the H2 and other newly created chemicals back to the surface where this alkaline fluid and the C02 rich ocean would have set up a naturally chemiosmotic gradient that would have formed the basis for the chemiosmosis that all life depends on today.

    Comment by MarkR — April 3, 2011 @ 3:23 pm | Reply

    • Hey, MarkR thanks for stopping by.

      I don’t know enough to comment intelligently about the chemical differences between hydrothermal vents driven by magma or mantle. But I do know enough to think that any suggestion that the abiogenesis from a primordial soup powered by UV might be better explained by hydrothermal activity wherever it might have taken place will surely be met with claims by creationists listed as my two points above!

      Comment by tildeb — April 3, 2011 @ 5:40 pm | Reply


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