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Life on Mars? Not When All the Evidence Is Considered!
Hubert P. Yockey
1507 Balmoral Drive Bel Air MD 21014-5638
HPYockey@aol.com
David S. McKay et al. (1) call for martian and earthly biomarkers suitable
for identifying biogenic activity on Mars, as indicated by the SNC meteorite
ALH84001 from Mars. In order to do this one must go to the first principles
of biogenic activity. The standard model for the origin of life, as given by
Christopher P. McKay (2) in his NASA Urey Prize Lecture: Planetary Evolution
and the Origin of Life, begins with the abiotic production of organic
molecules. Abiotic chemical evolution is then thought to occur, forming a
prebiotic soup in the early ocean, resulting in more complex structures
leading to life itself and the onset of biological evolution. The initial
stock of organic molecules could have been either produced in situ on Earth
or carried here from another source. The standard model for the origin of
life affirms that life is a naturally emergent property of matter in
Earth-like environments and would develop rapidly on any similar body. This
conjecture, coupled with theories for planet formation, results in the
prediction that life should have originated on Mars in its early warm and wet
period from 4.0 to 3.0 billion years ago.
According to the standard model, one can look for the earliest evidence of
life on Earth, and coincidentally of the conjecture that life originated on
Mars, in the kerogen found in sedimentary rocks at Isua in Greenland. As
Schidlowski (3) pointed out, the conversion of carbon dioxide to living
matter by biochemical pathways results in a conspicuous fractionation of the
light isotope 12C. 13C is retained in the aqueous medium in which the
inorganic reactions occur, primarily in dissolved bicarbonate. Consequently
on Earth, substances generated by organisms capable of photosynthesis exhibit
a d13Corg between -20 and -40x with respect to the atmosphere.
According to the standard model, one may take the isotopic character as the
martian biomarker by which one can judge the validity of the claim of McKay
et al. (1) of having found evidence of past fossil life on Mars in the
ALH84001 meteorite. Romanek et al. (4) report that the 13C of the martian
atmosphere is x + 41.3 x b and compatible with the atmosphere of Mars being
the source of carbon in the carbonate of ALH84001. This is consistent with
the formation of the inorganic carbonates in the Isua sedimentary rocks by
well-known principles of physical chemistry. Schidlowski (3), in his Figure
4, shows that sedimentary inorganic carbonate and organic carbon in the
kerogen are divided clearly into two groups by their isotopic composition.
Accordingly, the carbonates in ALH84001 do not reflect biogenic activity. In
addition, McKay et al. (1) do not report kerogens or their graphitic
derivatives in ALH84001. Furthermore, ALH84001 is an igneous orthopyroxenite,
not a sedimentary rock.
The standard model of the origin of life predicts that the aromatic
hydrocarbons found in ALH84001 may have been generated by spark discharges in
the martian atmosphere as part of the generation of a primeval soup or they
may have been carried to Mars from some external source. They do not show a
propensity for the selection of 12C.
McKay et al. (1) rely on the morphology of the carbonate globules in their
interpretation of biogenic origin, rather than on their isotopic composition.
Speculations on the morphology of models of living organisms have a long and
dismal history.
Oparin (5) referred to much of the literature on the origin of life in the
nineteenth and early twentieth centuries, which proposed that life emerged
from a primeval soup in the early ocean from "coacervates" or colloids. As
both he and Engels (6) acknowledged, that was first proposed by Haeckel (7)
in 1866, and was widely discussed by scientists, theologians and the public
in the nineteenth century. [Haeckel is famous for the maxim: Ontogeny
recapitulates phylogeny.] Engels (6) in Dialectics of Nature, had mentioned
the efforts of M. Traube (8) to make models of living organisms in papers
published in 1866 and 1867. The discussion of these efforts was so widespread
among the theater-going public in 1878 (sixteen years before Oparin was born)
that Sir William Schwenck Gilbert (1836-1911) ridiculed it by having
Pooh-Bah, a comic, greedy and conceited character, introduce himself by
declaring that he could trace his ancestry back to a "pre-Adamic
protoplasmal atomic globule"(9).
Jacques Loeb (10), a convinced mechanist, cautioned in 1906, against the
value of building models:
But we see that plants and animals during their growth continually transform
dead into living matter, and that the chemical processes in living matter do
not differ in principle from those in dead matter. There is, therefore, no
reason to predict that abiogenesis is impossible, and I believe that it can
only help science if younger investigators realize that experimental
abiogenesis is the goal of biology. On the other hand, our lectures show
clearly that we can only consider the problem of abiogenesis solved when the
artificially produced substance is capable of development, growth, and
reproduction. It is not sufficient for this purpose (abiogenesis) to make
proteins synthetically, or to produce in gelatin or other colloidal material
round granules which have an external resemblance to living cells. [My
emphasis.]
McKay et al. (1) conclude in their paper: "None of these observations is in
itself conclusive for the existence of past life. Although there are
alternative explanations for each of these phenomena taken individually, when
they are considered collectively, particularly in view of their spatial
association, we conclude that they are evidence for primitive life on early
Mars." This assertion implies an accumulation of evidence to a critical mass
of conclusiveness. However, when all the pertinent phenomena are considered,
the speculation of McKay et al. falls apart: measurements of the carbon
isotopes do not show the required favoring (3) of 12C, thus indicating that
the martian carbonate globules are neither Pooh-Bah's "pre-Adamic
protoplasmal atomic globules" (9) nor evidence of primitive life on early
Mars.
Words 990
References:
1. David S. McKay, et al. Science 273, 924-930 (1996)
2. Christopher P. McKay, Urey Prize Lecture: Planetary Evolution and the
Origin of Life Icarus 91, 93-100 (1991); Wanda L. Davis & Christpher P. McKay
Origins of Life and Evolutioin of the Biosphere 26 61-73 (1996)
3. M. Schidlowski, Nature 333, 313-318 (1988); Manfred Schidlowski, Adv.
Space Res. 12, No. 4 110-110 (1992)
4. C. S. Romanek, et al. Nature 372, 655-657 (1994)
5. Alexandr Ivanovitch Oparin, The Origin of Life on Earth Edinburgh and
London: Oliver and Boyd (1957) Translated from the Russian by Ann Synge.; A.
I. Oparin, The Origin and Initial Developoment of Life NASA Technical
Translation F-488 (Washinton D. C. 1968)
6. Friedrich Engels, Ludwig Feuerbach And The Outcome Of Classical German
Philosophy New York: International Publishers (1941)
Friedrich, Engels, Dialectics of Nature, translated by Clement Dutt, with
preface and notes by J. B. S. Haldane. Moscow: Foreign Languages Publishing
House (1940)
7. Ernst Haeckel, Enstehung der ersten Organismen In: Generelle Morphologie
der Organismen 1: 167-190, Berlin: George Reimer (1866)
Ernst Haeckel, : The Wonders of Life Harper & Brothers, New York and London
(1905)
8. M. Traube, Zbl. med. Wiss. pp 97-113 (1866); Physiol. Lpz. pp87-129
(1867)
9. Sir William. S. Gilbert, The Mikado, Act 1, (First performed May 28, 1878)
10. Jacques Loeb, The Dynamics of Living Matter, London: The Columbia
Unversity Press (1906)
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Brian Harper | "People of that kind are academics, scholars,
Associate Professor | and that is the nastiest kind of man I know."
Applied Mechanics | -- Blaise Pascal
Ohio State University |
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