#17! The question posed by a reader was just too good not to include the series.
What’s the current take on a deep-sea origin of life? I just finished reading Genesis by Robert Hazen where he discusses some of the hypothesis’ pros and cons and how there is something of a divide between the “ventists” and the “Millerites” and was wondering if deep-sea scientists naturally fell into the “ventist” camp.
First some background, in Origin of Life Circles you can either be a Ventist or Millerite. Millerites are disciples of Stanley Miller, who created an early earth analog in the laboratory that produced organic molecules from water, methane, ammonia, hydrogen, and shot of electricity. Miller and Urey’s experiments in 1952, although quite distant from demonstrating how life evolved, pointed to the possibility that the conditions on the young earth’s surface could produce the basic building blocks of life. They operate under the Oparin-Haldane hypothesis or the organic soup (or primordial ooze) hypothesis. The problem is that the early atmosphere would have to be reducing for these reactions to work. Recent evidence suggests this may not be the case. As well, some argue that CO2 and/or CO would reduce organic material by chemosynthesis. So if the earth as a whole was not reducing, then you would need particular evironments to be.
Fast forward to the 1970’s and the discovery of hydrothermal vents, a reducing envrionment, which spawns a new line of thinking. The interface of cold and hot waters allow for unique reactions to occur. Moreover, the extreme pressure, protection from UV radiation, abundant geothermal energy, and both methane and sulfide provide the necessary conditions to serve as a cradle of life in the deep depths of the ocean.
But to be a ventist is blasphemy, guilty of desertion of the very principles of Miller and Urey!
Of this group is Robert Hazen publisher of 19 books, concert trumpist, professor, cyrstallographer, etc. Hazen claims, “Miller and his scientific cohort had staked their claim to a surface origin of life, and they seemed determined to systematically head off dissenting opinions.” The Millerites attack the theory that life could have begun at ocean vents, saying high temperatures would have destroyed amino acids. Van Dover in her book on vents, points to both empirical and laboratory evidence indicating this is not the case. Van Dover also present an excellent figure of phylogentic tree of Bacteria, Eucarya, and Archaea, that point to the hyperthermophilic nature of the basal taxa.
Add to this a recent study from Geology that types of clay mineral can convert simple carbon molecules to complex ones in conditions similar to the hot and wet environment of hydrothermal vents. The group simulated a vent in the laboratory by immersing various types of clay in pressurized water at 300 °C for several weeks and looking at the fate of methanol, a compound formed readily formed at vents. Having helped such delicate molecules to form, the clays can also protect them from getting broken down in the piping hot water issuing from the vents.” Not to mention the ultimate buffering from meterorite impacts that occurred on the early earth.
On the other hand. Miller, himself, called the vent hypothesis “a real loser.” “This whole hype on hydrothermal systems and everything is just bogus,” says Jeff Bada, professor of marine chemistry at Scripps and the most prominent protégé of Miller. “I think he oversells this.” Bada questions an experiment that Hazen and his colleagues conducted in which they managed, in mimicking deep-sea pressures and temperatures, to create an important biomolecule called pyruvate: “I have some strong questions about whether that experiment is even valid. We haven’t been able to repeat it.” Hazen says, “Ultimately the truth comes out.”
Quotes via Achenbach’s article in the Washington Post