The Role of Experiments, Preconceived Ideas, and Scientific Authorities in Early Controversies about the Origin of Life and the Creation of Artificial Life in the Laboratory

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The Role of Experiments, Preconceived Ideas, and
Scientific Authorities in Early Controversies
about the Origin of Life and the Creation of
Artificial Life in the Laboratory
Ute Deichmann Jacques Loeb Centre for the
History and Philosophy of the Life Sciences,
Ben-Gurion University of the Negev, Israel
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1923
1936
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• The question of the origin(s) of life has
  occupied scholars and scientists since ancient
  times.
• For centuries, it had been dominated by the
  general belief in the spontaneous generation of
  various forms of life.

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Outline

1. Origin of life through spontaneous generation
   the examples of evolutionary biology and cell
   biology
2. Experiments and preconceived ideas reviewing
   the controversies on Pasteur
3. From spontaneous generation to the creation of
   artificial life

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1.Origin of life through spontaneous generation
the examples of evolutionary biology and cell
biology

• Spontaneous generation
• Doctrine that organisms, such as insects, worms,
  mice, microorganisms, arise from non-living
  sources, e.g. mud, putrifying animal or
  vegetable matter
• Aristotle (384-322 BCE)
• The early Church Fathers (ca. 300-400 CE)
• Doctrine was finally
• abandoned in early 20th century

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• First major blow to this doctrine regarding
  larger anmals by Francesco Redi (1668)
• Flies are only found in the samples exposed to
  the air, not in those protected from the air.
• Conclusion They do not arise spontaneously, but
  only from eggs (observed under the microscope)

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Extensive discussions on the origin of life in
the 19th century

• Concerned with
• the supposed formation of infusoria and
  micro-organisms from particles of organic matter
• cell theory

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Spontaneous generation and theory of evolution
Lamarck Philosophie Zoologique 1802 Nature is
producing species of animals in a progressive
way, beginning with the most imperfect or simple
and ending with the most perfect that is the most
complex one. But the more primitive forms of
life did not disappear. Solution Spontaneous
generation
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Spontaneous generation and theory of evolution

• Oken 1805 proposed his idea of an Urschleim,
  from which primitive forms of life were
  generated. Was later taken up by...
• Haeckel integrated it into his theory of
  Monera. Primitive living beings which
  supposedly consisted only of a small homogeneous
  mass of protoplasm and built the basis of life.
  Protistologists All Monera forms contain
  single or multiple nuclei. Concept was abandoned.
  
• Darwin accepted possibility of spontaneous
  generation through the 1870s. Remained ambivalent
  thereafter, trying to avoid this question.

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Spontaneous generation and cell theory

• Schleiden, Schwann 1838 Theory for the
  generation of cells as structural elements of
  organisms and for their role in the development
  of form.
• Concept of de novo formation of cells by
  crystallizing out from a continuous and formless
  matrix.

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• Schleiden hoped that that natural science may be
  able one day to regard the cell as the necessary
  form of a normal condition of a permeable
  (assimilated organic) substance, just as the
  crystal is a necessary form of the inorganic
  substance. Then would all individual and simple
  cells originating and existing in organisms be
  but a definite organic crystallization.
• Schwann believed that organisms are nothing but
  the form under which substances capable of
  imbibition crystallize.

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Schwanns and Schleidens predilection with the
cells de novo generation and crystallization

• Fitted the ideas of the spontaneous generation of
  micro-organisms and that of neoplasms as new
  formations of tumours
• May be related to their strong adherence to
  Kantian and Friesian philosophy of the unity of
  nature,
• Might have been influenced by the romantic school
  of natural philosophers (e.g. Lorenz Oken),
• Obscured the fundamental significance of cell
  theory (E.B. Wilson,1928)

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An early critic

• Robert Remak
• Rejected Schwanns theory of de novo cell
  formation from the beginning,
• Rejected Virchows et al.s theory of the new
  formation of neoplasms of tumours.
• The origin of cells de novo is no more credible
  than the spontaneous generation of life (1852).

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• 1850 -1900
• The notion of cells from crystallisation was
  replaced by the notion of cells from the division
  of pre-existing cells. (Remak 1852, Virchow 1855
  Omnis cellula e cellula)
• The doctrine of spontaneous generation continued
  to be upheld by many in regard to
  micro-organisms.

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2. Experiments and preconceived ideas reviewing
controversies on Pasteur

• Experiments of Pasteur in 1861 are considered
  crucial by many for the final abandonment of the
  doctrine of spontaneous generation.

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Pasteur "On the organized bodies which exist in
the air Examination of the doctrine of
spontaneous generation" (1861)

• Micro-organisms do not generate in a boiled
  bouillon as long as dust was prevented from
  entering it. Dust carries micro-organisms.
• Micro-organisms, too, do not arise from inanimate
  matter but only from existing ones of the same
  kind.

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Some historians assessments

• Pasteur allowed his research to be guided by his
  preconceived idea and ideological bias against
  spontaneous generation (e.g. Farley 1978, Geison
  1995).
• Background The debate on spontaneous generation
  in 19th century France was related to a larger
  debate about a materialistic and religious way of
  life.
• Spontaneous generation was embraced by
  anti-religious scholars, because it rendered life
  a merely physical process based on chance events.
  
• As a member of the French cultural establishment
  Pasteur resented these materialistic views.

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My comments

• Pasteur had
• not only
• ideological reasons for disliking spontaneous
  generation.
• but also
• scientific reasons for disliking it Wide
  knowledge on fermentation and micro-organisms
  (e.g. their constancy and specificity)
• ? conviction that a spontaneous generation of
  micro-organisms was highly unlikely.

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• Pasteurs experiments were conducted with a
  preconceived idea.
• This did not render his experiments questionable,
  because they were accompanied by wide knowledge,
  logical designing of the experiment and skills.
• His opponents, too, had preconceived ideas, but
  often lacked his other attributes.
• Experiments alone were not able to disprove
  spontaneous generation.
• Increasing knowledge in micro-biology and
  biochemistry together with logical reasoning and
  clear experimentation led to the final abandoning
  of spontaneous generation.

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• The abandonment of the ideas of spontaneous
  generation of life and cells was a pre-requisite
  for scientific research into the artificial
  creation of life in the laboratory.
• The question of the origin of life became related
  to that of the artificial generation of life in
  the laboratory.

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3. From spontaneous generation to the creation of
artificial life
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A. The primacy of form and growth in the
morphological-colloidal-mathematical approach
(early 20th century)

• Around 1900
• Scientists tried to mimic features of life,
  especially growth and form on the basis of
  osmotic growth and the colloidal concept of
  nature.
• 1864 Moritz Traube
• First scientific study of artificial
  semi-permeable membranes and first
  experiment-based physicochemical theory of cell
  growth mimicked the growth of plant forms.

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• French physicist Stéphane Leduc
• Traube made the first artificial cell, ... This
  remarkable research should have been the
  starting-point of synthetic biology. (1911)
• 1912 La Biologie Synthétique

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Leduc, La Biologie Synthétique, 1912
Fig 32. - Croissance osmotique de chlorure et
nitrate de manganèse avec capsules terminales
présentant un haut degré d'organisation.
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Leduc 1912

• Transformation of substances leads to an increase
  of osmotic pressure in the tissues
  transformation of chemical energy into osmotic
  energy.
• No clear boundary between life and physical
  phenomena.
• Virchows toute cellule vient d'une cellule is
  an error of reasoning cells can be created
  differently.
• Leduc promoted an entirely morphological-physical
  concept of life and neglected novel concepts
  (e.g. individuality of chromosomes specificity
  of enzyme reactions).

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B. The specificity of basic structures and
processes in the molecular approach (early 20th
century)

• The notion of the relevance of specific molecules
  for an understanding of basic features of life
  preceded macromolecular chemistry.
• German American physiologist Jacques Loeb
• The living cell synthesizes its own complicated
  specific material from indifferent or
  non-specific simple compounds of the surrounding
  medium, while the crystal simply adds the
  molecules found in its supersaturated solution.
• This synthetic power of transforming small
  building stones into the complicated compounds
  specific for each organism is the secret of
  life or rather one of the secrets of life.
  (Loeb 1916)

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• Loeb rejected claims of the synthesis of life
  through osmosis
• "The fact that the living cell grows after
  taking up food has given rise to curious
  misunderstandings. Traube has shown that drops of
  a liquid surrounded with a semipermeable membrane
  may increase in volume when put into a solution
  of lower osmotic pressure. This has led, and is
  possibly still leading, to the statement that the
  process of growth by a living cell has been
  imitated artificially. Only one feature has been
  imitated, the increase in volume but the
  essential feature of the process in the living
  cell, i.e. the formation of the specific
  constituents of the living cell from non-specific
  products, has of course not been imitated." (Loeb
  1916)

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• Loeb held that the artificial creation of life
  was not only a physical process, but had to
  involve the synthesis of specific molecules, in
  particular self-replicating DNA (nuclear
  material).
• Nobody has thus far succeeded in this, although
  nothing warrants us in taking it for granted that
  this task is beyond the power of science. (Loeb
  1909)

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• Similar contrasting themes (Holton) or basic
  beliefs (Polanyi) were prevalent in subsequent
  stages of research on the origin of life and
  creation of artificial life

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• Predilection for the concept of unity in nature
  
• Descriptive, mathematical, colloidal approaches
• Emphasis on physical concepts of life, e.g.
  growth and form

• Predilection for the distinction between living
  and non-living nature
• Mechanistic experimental approaches
• Emphasis on chemical concepts of specificity of
  structures and molecules

• ----------------------------------
• Crystallization of cells from unspecific fluids
• Synthesis of life by osmotic growth
• Schleiden, Pouchet, Haeckel, Leduc, Thompson

• ------------------------------------
• Cells only from existing cells of the same type
• Synthesis of life by synthesis of specific
  macromolecules
• Remak, Pasteur, Loeb, Wilson,

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The different approaches have not been equally
successful.

• In 2010, around 100 years after Loebs
  prediction, a completely chemically synthesized
  DNA, which was fully functioning, was
  successfully transferred into a bacterial host
  cell by Craig Venter and his team.

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Science. 2010 July 2Creation of a bacterial cell
controlled by a chemically synthesized genome.

• Gibson DG, Glass JI, Lartigue C, Noskov VN,
  Chuang RY, Algire MA, Benders GA, Montague MG, Ma
  L, Moodie MM, Merryman C, Vashee S, Krishnakumar
  R, Assad-Garcia N, Andrews-Pfannkoch C, Denisova
  EA, Young L, Qi ZQ, Segall-Shapiro TH, Calvey CH,
  Parmar PP, Hutchison CA 3rd, Smith HO, Venter JC

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Outlook

• Research in modern synthetic biology can be
  fruitful for solving basic questions on
  evolutionary biology and the origin of life.
• Questions
• When will it be possible to synthesize a whole
  organism?
• Will this be the same life as that which has
  evolved for 3-5 billions of years?

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• THANK YOU!