Re: Abiogenesis and the primordial soup was Re: NTSE #11

Brian D Harper (
Thu, 13 Mar 1997 13:16:45 -0500

At 07:31 PM 3/12/97 -0400, Pim wrote:
>About the hydrothermal vents. Miller wrote a paper addressing the
>possibilities of life originating at these vents and found that the
>temperature made the likelihood (as far as our understanding of chemistry
>goes at least) was quite small. His suggestion is not that it happened in
>the vents but that the vents were a signficant source/sink for relevant
>Now where are my notes....
>Well from memory Nature...... ... ....
>Okay reference when I can find them again...
>Oh I know.
>Miller and Bada 1988, Submarine hotsprings and the origin of life Nature

Thanks Pim, I had intended to mention this paper since it
is one of my main references in support of the idea that the
deep hydrothermal vents work against the notion that the
earth's early oceans contained a primordial soup. Previously
you asked me to define what I meant by this, I'll save that
for a another post.

Here's a quote from the Miller&Bada paper:

< In summary, we have shown that the proposal for a hydrothermal
< vent origin of life fails each of the three proposed steps in
< the origin of life. Any origin-of-life theory that proposes
< conditions of temperature and time inconsistent with the
< stability of the compounds involved can be dismissed solely
< on this basis, unless some protective mechanism exists, but
< no such mechanisms are known at present. This is not to say
< that the hydrothermal vents were a negligible factor on the
< primitive Earth. They would have had a function in the elemental
< balance of the oceans as they do today. The vents would have
< been important in the destruction rather than in the synthesis
< of organic compounds in the primitive oceans, because the entire
< ocean currently passes through the vents in 10^7 years. In fact,
< this latter process was an important factor in fixing the upper
< limit for the organic compound concentration in the oceans of
< the primitive Earth.
< -- Miller and Bada, 1988.

Two other outspoken critics of the hydrothermal vent scenario
are Gerald Joyce and E.G. Nisbet:

< Is there any hope, then, for the hydrothermal-vent hypothesis
< for the origins of life? The problems of conducting useful
< chemical syntheses in the high-temperature outflow tract seem
< to be insurmountable. Perhaps life originated in low-temperature
< vents, such as those at the Galapagos rift or in the intrusion
< zone surrounding the site of hydrothermal discharge. One would
< then have to postulate an energy source other than contact with
< the underlying hot basalt, which Miller and Bada [1988 --BH]
< show to be incompatible with the synthesis of biological polymers.
< The further one backs away from the hot magma chamber, the more
< the hydrothermal-vent hypothesis begins to sound like other
< theories that do not invoke a direct connection between the
< vents and the origins of life.
< -- Gerald Joyce (1988)

< In the modern Earth, a volume of sea water equivalent to the
< entire oceanic volume passes through the mid-ocean ridge
< hydrothermal systems in about 10^7 years, whereas in the early
< Archaean this circulation time was probably 10^6 years or less.
< Unless the production rate of organic molecules was very high,
< the soup was probably clear and with chemistry not greatly
< different from today. Furthermore, NH_3 and CH_4 would not be
< present in any significant amounts as they would have had
< very short lifetimes in the atmosphere. It therefore seems
< unlikely that life began in the open ocean.
< -- E.G. Nisbet, 1986.

To the scenarios which do not seem to require a primordial soup
in the oceans we need to add Nisbet's preferred scenario, a shallow,
luke-warm subaerial (land) hydrothermal system:

< The most likely site for the inorganic construction of an RNA chain,
< which would have occurred in the Archaean, is in a hydrothermal
< system. Only in such a setting would the necessary basic components
< (CH4, NH3 and phosphates) be freely available. Suitable pH
< (fluctuating around 8) and temperatures around 40 C are
< characteristic of hydrothermal systems on land. Furthermore, altered
< lavas in the zeolite metamorphic facies, which are rich in zeolites,
< clays and heavy metal sulphides, would provide catalytic surfaces,
< pores and molecular sieves in which RNA molecules could be assembled
< and contained. If the RNA could then replicate in such a setting
< with the aid of ribozymes and without proteins, the chance of
< creating life becomes not impossible but merely wildly unlikely.
< -- E.G. Nisbet, 1986

Nisbet is responsible for one of my all time favorite abiogenesis

< thus not only appeared in an improbable solar system
< on an unusual planet in (perhaps) the relatively short time in
< which it was habitable, not only assembled a wildly unlikely
< molecule, but also managed to build itself a home at the same
< time. Having done so, if Lovelock (1979) is correct, it managed
< to reproduce itself and to tailor the environment to its liking.
< The monkey, having invented the typewriter and banged out the
< complete Shakespeare without error, then proceeded to become
< pregnant, to set up a theatre and with descendants as actors,
< to perform the plays in a critically comfortable atmosphere.
< -- E.G. Nisbet (1987), p. 349

Now back to hydrothermal vents. The Miller&Bada paper caused
quite a stir among proponents of the hydrothermal vent scenario.
Miller's objections were answered by Holm (1992) and Shock
(1990 and 1992). Basically, Shock answered by presenting some
theoretical work showing organic synthesis under vent conditions
is possible. He also argued that Miller's experiments didn't
adequately simulate vent conditions. Miller answered Shock
in Bada, Miller and Zhao (1994), but I can't recall now what
his answer was :). Anyway, an interesting debate which will likely

In the references below I've also included (in addition to the
references mentioned specifically above) some others of general
interest. For example, Baross and Hoffman (1985) is one of the
pioneering works on the hydrothermal model. Marshall (1994) and
Fox (1995) are recent reviews of the model. I'm pretty sure
they discuss Miller&Bada, but I can't recall any specifics.


J.L. Bada, S.L. Miller and M. Zhao, 1994, "Amino Acid Stability in
Hydrothermal Vents," _Origin of Life and Evolution of the
Biosphere_, <24>:364-365.[this is an abstracts edition
for the 1993 ISSOL Meeting in Barcelona, Spain]

J.A. Baross and S.E. Hoffman, 1985, "Submarine Hydrothermal Vents and
Associated Gradient Environments as Sites for the Origin and
Evolution of Life," _Origin of Life_, <15>:327-345.

Sydney W. Fox, 1995, "Thermal Synthesis of Amino Acids
and the Origin of Life"_Geochimica et Cosmochimica Acta_
59(6): 1213-1214.

Nils G. Holm, "Why are Hydrothermal Systems Proposed as
Plausible Environments for the Origin of Life?", _Origins
of Life and the Evolution of the Biosphere_, 22:5-14, 1992.

G. Joyce, 1988, "Hydrothermal Vents too Hot?", _Nature_, <334>:564.

K.A. Maher and D.J. Stevenson, 1988, "Impact Frustration of the Origin
of Life," _Nature_, <331>:612-614.

W.L. Marshall, 1994, "Hydrothermal Synthesis of Amino Acids",
_Geochimica et Cosmochimica Acta_, <58>:2099-2106.

S.L. Miller and J.L. Bada, 1988, "Submarine Hot Springs and the Origin
of Life," _Nature_, <334>:609.

S.L. Miller, 1992, "The Prebiotic Synthesis of Organic Compounds as a
Step Toward the Origin of Life," in _Major Events in the History
of Life_, J.W. Schopf, ed., pp. 1-28.

E.G. Nisbet, "RNA and Hot Water Springs", _Nature_, v. 322
p. 206, 17 July 1986.

E.G. Nisbet, _The Young Earth: An Introduction to Archaean geology_,
Allen and Unwin, 1987.

E.G. Nisbet, _Living Earth: A Short History of Life and its Home_,
Harper Collins Academic, 1991.

E.L. Shock, 1990, "Geochemical Constraints on the Origin of Organic
Compounds in Hydrothermal Systems," _Origin of Life and Evolution
of the Biosphere_, <20>:331-367, 1990.

E.L. Shock, 1992, "Hydrothermal Organic Synthesis Experiments," _Origin
of Life and Evolution of the Biosphere_, <22>:135-146.

Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University

"Because there's no primordial soup;
we all know that, right?" -- Leo Buss