Note:  I do not know the author of this excellent article.  It was found at    http:/
/mywebpages.comcast.net/mkent595/Originoflife.html 

Origin Of Life

(and irreducible complexity)
 

 notes 
  
  
 

  Origin of Life – 1

"Any theory with a probability of being correct that is larger than one part
in 1040,000 must be judged superior to random shuffling.  The theory that life
was assembled by an intelligence has, we believe, a probability vastly higher
than one part in 1040,000 of being the correct explanation to the many curious
facts discussed in the preceeding chapters.  Indeed, such a theory is so obvious
that one wonders why it is not widely accepted as being self-evident.  The reasons
are psychological rather than scientific."

         F. Hoyle and C. Wickramasinghe, Evolution from Space, pg 130.
 
 
 

"… the time available for the origin of life seems to have been short, a few
hundred million years at the most.  Since life originated on the earth, we have
additional evidence that the origin of life has a high probability."

        Carl Sagan, Scientific American, 1975, 232(5), pg 82.
 
 
 

"More than 30 years of experimentation on the origin of life in the fields of
chemical and molecular evolution have led to a better perception of the immensity
of the problem of the origin of life on Earth rather than to its solution. 
At present all discussions on principal theories and experiments in the field end
either in stalement or in a confession of ignorance."

         K. Dose, "The Origin of Life:  More Questions than Answers", Interdisciplinary
Science Review  13, 1988, p348.
 
 
 

"The chance that  higher life forms might have emerged in this way is comparable
with the chance that a tornado sweeping through a junkyard might assemble a
Boeing 747 from the material therein."

        F. Hoyle, ‘Hoyle on Evolution’ Nature  294 105, 1981.
 
 
 

"An honest man, armed with all the knowledge available to us now, could only
state that in some sense, the origin of life appears at the moment to be almost
a miracle, so many are the conditions which would have had to be satisfied to
get it going."

         F. Crick, Life Itself, p 88.
 
 
 

"There is other life in the universe   –   guaranteed."

        Paul Horowitz, quoted in Editorial by Joan Beck, Albq. Journal
 
 
 
 

"One has only to contemplate the magnitude of this task to concede that the
spontaneous generation of a living organism is impossible.  Yet here we are
– as a result, I believe, of spontaneous generation."
 

         George Wald, Scientific American, 191, 1954, pg 45.
 
 
 
 
 
 
 

Goals:
 

1.  How close are scientists to creating life in the laboratory?

2.  Best estimates of the probability (from secular scientists) that life arose
spontaneously on the earth.

3.  Understand the problems

4.  Other naturalistic theories to explain life on earth?

5.  SETI / life on Mars?

 
 
 
 

Outline:

1. What is life?
 

2. Requirements for life to originate spontaneously (soup theory)
 

3. Problems/difficulties
 

4. Mainsteps of progress/theories?

 a)  synthesis of some amino acids in prebiotic simulation experiments
 b)  proteinoid microspheres
 c)  RNA world
 d)  self-replicating molecules/templating

5. Other naturalistic theories

  -panspermia (Crick, Hoyle)
  -clay rather than soup (Cairns-Smith)
  -self-organizaion/complexity theory (Kauffman)
  -subterranean biogenesis

6. Search for Extraterrestrial Life / Life on Mars?

 

7. Video interview with D. Kenyon

 
 
 
 
 
 
 
 

1.  What is life?

Living organisms, in contrast to nonliving matter, are able to:
 

 a. replicate

 b. store and process energy (metabolism)

 c. store and process information
 

 no "primitive" or simple form of life

"We now know not only of the existence of a break between the living and non-living
world, but also that it represents the most dramatic and fundamental of all
the discontinuities of nature.  Between a living cell and the most highly ordered
non-biological system, such as a crystal or snowflake, there is a chasm as vast and absolute
as it is possible to conceive."

        M. Denton, Evolution:  A Theory in Crisis,  pg 250.

"After all what impresses us about a living thing is its in-built ingenuity,
its appearance of having been designed, thought out – of having been put together
with purpose. …. The singular feature is the [enormous] gap between the simplest
conceivable version of organisms as we know them, and components that the Earth
might have reasonably been able to generate…. But the real trouble arises
because too much of the complexity seems to be necessary to the whole way in
which organisms work."

        A. G. Cairns-Smith, "Seven Clues to the Origin of Life"
 
 
 

Mycoplasmas – simplest free living organisms we know – 0.5 million base pairs
–

recent study indicates a lower threshold of 265-350 genes for viability

Irreducible or minimal complexity

 
 

2. Steps in spontaneous origin of life
 

             (soup theory, Oparin-Haldane hypothesis)
 
 

 Origin of Life – 2      Origin of life – 3

 

1. Formation of building blocks (amino acids, nucleotides) from early earth
atmosphere
 

2. Polymerization – Proteins, DNA, RNA, Lipid membranes
 

3. Assembly into protocells
 

4. Development into true functioning cells

 
 
 
 

3.  Problems:
 
 

a)  Formation of building blocks (amino acids, nucleotides) from early earth
atmosphere
 
 

1).  Best estimate of early earth atmosphere not consistent with synthesis of
amino acids or nucleotides (oxidizing vs reducing)

&nbs
p;used in experiments:
 

 H2O, NH3, CH4, H2   (formation of amino acids is favored)

 actual (best estimate from atmospheric physics, geology):
 

 H2O, N2, CO2, (O2?)    (formation of amino acids not favored,
                                         requires energy, O2 destroys organics)

 

2)  Without oxygen, no ozone so UV destroys organics
 

(In Miller-type expt – selective use of energy and quick removal)

 
 

3)  Building blocks of RNA, DNA cannot be synthesized under prebiotic conditions
 

"The evidence that is currently available does not support the availability
of ribose on the prebiotic earth, except perhaps for brief periods of time,
in low concentration as part of a complex mixture, and under conditions unsuitable
for nucleotide synthesis."

    R. Shapiro, Prebiotic Ribose Synthesis,presented at a meeting of the
    International Society for the Study of the Origin of Life
 
 

?To avoid the need for ribose, some authors have preferred to invoke an RNA-like
polymer, with a simpler or more accessible backbone, at the start of life. …
These suggestions still presume that the bases adenine, cytosine, guanine, and
uracil were readily available on early Earth.  I have argued that this presumption
is not supported by the existing knowledge of the basic chemistry of these substances.

 R. Shapiro, Proc. Nat. Acad. Sci. 96, 4396, 1999
 
 
 
 

b)  Polymerization – Proteins, DNA, RNA, Lipid membranes
 

 1) concentration of building blocks
 

 2) polymerization of amino acids requires removal of water
 

 3) energy sources break down as well as polymerize

  (equilibrium favors smaller molecules)
 

 4) competing cross reactions (thousands)
 

 5) chemical chirality

         (proteins – only left handed amino acids,   DNA/RNA – only right handed
nucleotides)
 

 6) origin of information

         (not just any sequence, 3-D structure of proteins essential to function)

"Our task is to find an algorithm, a natural law that leads to the origin of
information.?
    Manfred Eigen, Steps towards Life:  A perspective on Evolution, 1992, pg 12.

"the problem of the origin of life is clearly basically equivalent to the problem
of the origin of biological information."
    Bernd-Olaf Kuppers,  Information and the Origin of Life, 1990, pg 170-172

 7) irreducible complexity of existing DNA/protein systems

enzymes needed for protein synthesis, DNA needed to specify sequence of amino
acids in enzymes

(How could one part function alone?)
 

 "to build a single protein or DNA molecule in a cell, about 60 specific proteins
acting as enzymes are needed."

         Davis and Kenyon, Of Pandas and People, pg 53.

 
 

c)  Assembly into protocells
 

  molecular machines and irreducible complexity  (see previous section)

 

 
 
 

4. Mainsteps of progress/theories?
 
 

a).  Miller-Urey  experiments
 
 

  Origin of life – 4

Initial optimism:
 

The Miller-Urey experiment is now recognized as the single most significant
step in convincing many scientists that life is likely to be abundant in the
cosmos.

         Carl Sagan, quoted in Origins:  A Skeptic’s Guide to the Creation of Life
         on Earth. R. Shapiro
 

The Miller-Urey experiment assures us of what we had suspected for a long time: 
that one can bridge the gap between the inanimate and the animate and that the
appearance of life is essentially an automatic biochemical development that
comes along naturally when physical conditions are right.

Astronomer Harlow Shapley, to a televison audience, as quoted in Evolution after Darwin,
S. Tax, ed, 1960.

 

Recent Criticisms:
 

Miller’s experiment has hardly been improved upon.  Even the simpler molecules
are produced only in small amounts in realistic experiments siumulating possible
primitive earth conditions.  What is worse, these molecules are generally minor
constituents of tars; it remains problematical how they could have been separated
and purified through geochemical processes whose normal effects are to make
organic mixtures more and more of a jumble.
        A. G. Cairns-Smith, Seven Clues to the Origin of Life: A Scientific
       Detective Story,pg 90.
 

In sum, the ease of synthesis of the ‘molecules of life’ has been greatly exaggerated. 
It only applies to a few of the simplest, and in no case is it at all easy to
see how the molecules would have been sufficiently unencumbered by other irrelevent
or interfering molecules to have allowed further organization to higher order
structures of the kinds that would be needed.
        A. G. Cairns-Smith, Seven Clues to the Origin of Life: A Scientific
       Detective Story,pg 44.
 

"Many different forms of energy or radiation lead to organic compounds from
such simple gas mixtures, including representatives of all the important types
of molecules found in cells."  That statement is simply incorrect.
     R. Shapiro,  Origins:  A Skeptic?s Guide to the Creation of Life on Earth,
        pg 108.
 

But the expected rush of new developments has not been forthcoming.  Rather,
doubt has been cast on the basic premises, the reducing atmosphere and the prebiotic
soup.
        R. Shapiro,  Origins:  A Skeptic’s Guide to the Creation of Life on Earth,
        pg 278.
 

b)  Proteinoid Microspheres
 

a)  start with only protein-forming L amino acids
b)  heat in N2 to form chains
c)  dissolve in water and cool to precipitate aggregates
 
 

 Origin of life – 5

Proteinoid microspheres do the following:

 -make some kinds of chemical reactions go a little faster
 -are separated from their surrounding by a membrane

Proteinoid microspheres do not:

 -replicate
 -store and process energy
 -store and process information

Information content = virtually zero    (D. Kenyon)

 
 

"[The proteinoid theory] has attracted a number of vehement critics, ranging
from chemist Stanley Miller … to Creationist Duane Gish.  On perhaps no other
point in origin-of-life theory could we find such harmony between evolutionists
and Creationists as in opposing the relevance of the experiments of Sidney Fox."

        R. Shapiro, Origins:  A Skeptics guide to the Creation of Life on Earth,  Summit
Books,
        New York, pg 192.
 
 

"These microspheres are not living cells.  Their formation, however, suggests
the kinds of processes that could have given rise to self-sustaining protein
entities, separated from their environment and capable of carrying out the chemical
reactions necessary to maintain their physical and chemical integrity."

        Curtis and Barnes, Biology, pg 89.

 
 

c)  RNA World
 

Problem:
 

Proteins needed for replication and transcription of DNA
(catalytic ability)

DNA needed to code for proteins   (coded information)
 

Proposed solution to chicken and egg (irreducible complexity) problem:
 

RNA carries coded information, has some catalytic ability

 

Problems with RNA world:
 

 1.  building blocks could not form on primitive earth

 2.  cross reactions during polymerization

 3.  no plausible self-replication scenario

 4.  origin of genetic information
 

Joyce and Orgel conclude that in the face of these difficulties, one must reject

 "the myth of a self-replicating RNA molecule that arose de novo from a soup
of random polynucleotides."

        G. F. Joyce and L. E. Orgel, "Prospects for understanding the RNA world",
in The
        RNA World, 1993.
 
 
 

d)  Self-replicating molecular systems
 
 

   Origin of life – 6

 

short peptide and nucleic acid chains can be used as templates to produce copies
of the original chain or complementary (base-pairing) chains

autocatalytic and cross-catalytic reactions

not starting from amino acids or nucleotides, but prepolymerized chains

careful, pristine laboratory conditions

very interesting chemistry, but not information-generating
 
 
 
 
 
 

5.   Other naturalistic theories
 

  -panspermia (Crick, Hoyle)

  -clay rather than soup (Cairns-Smith)

  -self-organizaion/complexity theory (Kauffman)

  -subterranean biogenesis

  -enitrely different chemistry that evolved into the chemistry of life that
exists today
 

 
 
 

6.  SETI / Life on Mars?

The discovery of life on another planet – e.g. Mars – can , in the words of
the American physicist Philip Morrision of the Massachusetts Institute of Techmology, "
transform the origin of life from a miracle to a statistic."

         Carl Sagan, Intelligent Life in the Universe, 1977, pg 358.
 
 
 

Naturalism leads logically to strong views on extraterrestrial life
 

a)  Earth cannot be unique
 

b)  Since life arose on Earth, it must be an inevitable product of any planetary
surface which has the correct atmosphere, geology, chemistry
 

c)  The known universe is so vast that there are certain to be millions of planets
similar to the Earth
 

d)  "There is other life in the universe   –   guaranteed."

         Harvard physicist Paul Horowitz, quoted in an editorial by Joan Beck in the
Albq. Journal

 
 

Search for Extra-Terrestrial Intelligence  (SETI)
 
 

a)  Direct Contact:

Importance of Mars
 

 -only chance humanity will ever have of establishing the existence of
  extra-terrestrial life by direct contact

 -Venus too hot, other planets too cold

 -other solar systems too far
 

 Viking mission to Mars (summer of 1976)
 

 Initial euphoria
 

 Results:

 4 experiments designed to detect life  –  all negative

 Conclusion:

combination of UV, dryness of soil, and oxidizing nature of soil chemistry prevent
the formation of living organisms at present time – however, the question of
life on Mars at some time in the distant past remains open.

Meteorite from Mars

Initial euphoria

"If this discovery is confirmed, it would surely be one of the most stunning
insights into our universe that science has even uncovered."
     President Clinton, Time  Aug 19, 1996.

implications "are as far reaching and awe-inspiring as can be imagined."
     President Clinton, U.S. News & World Rep., p 48,
     Aug.19, 1996.

"If the results are verified, it is a turning point in human history, suggesting
that life exists not just on two planets in one paltry solar system but throughout
this magnificent universe."
     C. Sagan,  Time p 60, Aug 19, 1996.

the findings raise the "possibility of a universe burgeoning with life."
     C. Sagan, U.S. News &World Rep  p 45, Aug 19,
     1996.

"This is the biggest thing that has ever happened."
     John Pike, Dir. of Space Policy for Fed. of Amer.
     Sci., Newsweek, p 56, Aug 19, 1996

the simple fact of their [Martian microbes] existence radically improves the
odds that we are not alone in the universe.
     Adam Rogers, Newsweek p 56, Aug 19, 1996.

"The Mars discovery confirms the origin of life is easy, and will occur on planets
where conditions are suitable"
     Frank Drake, Pres. of SETI Inst., Newsweek Aug
     19, 1996.

Conclusive evidence of life on Mars, however minute or unintelligent, will bring
fulfillment of one of humanity’s greatest fantasies.
     U.S. News &World Rep,  p 50, Aug 19, 1996.

For such a discovery would not only prove that life arose on Mars and Earth
independently and, therefore, spontaneously, but it would also strongly suggest
that life – unicellular life, at least – is not something rare and special in
the universe but an ordinary event that occurs wherever there is enough water
and light from a sunlike star.
     Time p 62, Aug 19, 1996.

"it confirms what we’ve always believed – that life arises
wherever the conditions
are right."
     F. Drake, Time  p 64, Aug 19, 1996.
 
 
 

Initial Conclusion:

"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.

 McKay, et al., Science  273, 924, 1996.
 
 
 

Current Status:

S isotope ratio

"When we looked at the ratio of [two sulfur isotopes] there was no evidence
that it was in a ratio for life forms."
      Jim Papike, director of the Institute
      of Meteoritics, U of New Mexico
 

amino acids

 "…the amino acids present in this sample of [the martian meteorite] appear
to be terrestrial in origin and  similar to those of the AllanHillsice…..
"

The amino acid results presented here indicate that major and minor organic
constituents in these martian meteorites  are contaminants.
   Science, 279, 362, 1998.
 

carbon isotopic composition

 The organic material in [the martian meteorite] is predominately terrestrial
contamination.   Our results tend to  support the interpretation of [three earlier
reports] that organic material in these Antactic meteorites is predominately
a contamination effect.
  Science, 279, 366, 1998.
 
 
 
 
 

b)  Indirect Contact:
 

Search for signals in the form of electromagnetic radiation

            (radio waves, microwaves, X-rays, etc)
 
 

How to distinguish signals arising from intelligent versus nonintelligent sources?

look for specified complexity or information in the signal

(What conclusions can be drawn from applying the same principles to DNA?)
 
 
 

Summary:

1.  How close are scientists to creating life in the laboratory?

Scientists have not even begun to scratch the surface of the origin of life
problem.  It appears to be intractable.

2.  Best estimates of the probability that life arose spontaneously on the earth.

 All calculations for the spontaneous origin of life give essentially zero chance,
even in 109 yrs.

3.  Understand the problems

no such thing as a "simple" form of life
monomers cannot be synthesized under prebiotic conditions
origin of chemical chirality
origin of genetic information
proteins/DNA/RNA  –   irreducible complexity

4.  Other naturalistic theories to explain life on earth?

Crick, Hoyle  –  panspermia or life seeded from outer space
(would brilliant scientists propose this if there was any hope at all for spontaneous
generation?)

entirely different chemistry that evolved into the chemistry of life that exists
today?
 
 

5.  SETI / life on Mars?

 naturalism – earth cannot be unique in the universe, therefore life must exist
elsewhere

 
 

"The development of the metabolic system … poses Herculean problems.  So does
the emergence of a selectively permeable membrane without which there can be
no viable cell.  But the major problem is the orign of the genetic code and
of its translational mechanism.  Indeed, it is not so much a problem as a veritable
enigma.

Life appeared on earth:  what, before the event, were the chances that this
would occur?  The present structure of the biosphere certainly does not exclude
the possibility that … its a priori probability was virtually zero."

         Jacques Monod, Chance and Necessity, 1972, 135-136.
 
 

"The difficulties that must be overcome are at present beyond our imagination….The
flow sheet in Figure 2 [showing how nucleic acid coded ribosomal protein synthesis
might obtain] is a scheme of ignorance.  Without fundamentally new insights
in evolutionary processes, perhaps involving new modes of thinking, this ignorance is
likely to persist."

         K. Dose, "The Origin of Life:  More Questions than Answers", Interdisciplinary
Science Review 13,
        1988 pg 348.
 
 

"… we desire the best available scientific status report on the origin of
life.  We shall see that adherents of the best known theory have not responded
to increasing adverse evidence by questioning the validity of their beliefs,
in the best scientific tradition; rather, they have chosen to hold it as a truth
beyond question, thereby enshrining it as mythology."

         R. Shapiro, "Origins:  A Skeptic?s Guide to the Creation of Life On Earth",
1985, pg 32.