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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

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Title: 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


1
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
2
1923
1936
3
  • 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.

4
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

5
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

6
  • 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)

7
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

8
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
9
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.

10
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.

11
  • 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.

12
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)

13
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).

14
  • 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.

15
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.

16
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.

17
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.

18
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.

19
  • 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.

20
  • 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.

21
3. From spontaneous generation to the creation of
artificial life
22
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.

23
  • 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

24
Leduc, La Biologie Synthétique, 1912
Fig 32. - Croissance osmotique de chlorure et
nitrate de manganèse avec capsules terminales
présentant un haut degré d'organisation.
25
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).

26
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)

27
  • 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)

28
  • 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)

29
  • 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

30
  • 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,

31
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.

32
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

33
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?

34
  • THANK YOU!
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