Repensando o (im)possível em evolução

domingo, setembro 23, 2012

Progress in Biophysics and Molecular Biology (2013)

March 18-21, 2012, Oxford Workshop on “Conceptual Foundations of Systems Biology”

Rethinking the (Im)Possible in Evolution

James A. Shapiro

Gordon Center for Integrative Science W123B

University of Chicago,

Introduction: The philosophical background

Science inevitably operates in ignorance of future developments. Results and concepts that seem inconceivable in one period become conventional wisdom in later decades and centuries. The history of science is replete with examples (Kuhn 1962). Moreover, it is often the case that we cannot perceive the blinders we impose on ourselves out of philosophical commitments rather than empirical necessities.

Evolutionary thinking began in the 18th Century, at the same time as other fields in biology were transforming into more professional and rigorous disciplines (Stott 2012). In the second half of the 19th Century, the Darwinian ideas of gradual change and natural selection as a creative force engaged in a fierce battle with religious ideas of divine creation over the explanation of biological diversity. In order to combat the teleological arguments of William Paley for a divine watchmaker (Paley 1802 (republished 2006)), the evolutionists rigorously excluded all notions of goal-oriented activity from their theories. In keeping with 19th Century mathematical thermodynamics, they insisted upon randomness at the microscopic level as the basis for macroscopic effects.

As evolutionary thinking integrated Mendelian genetics into the neo-Darwinian Modern Synthesis (Huxley 1942), it adopted the mechanistic thinking that prevailed following the intense Mechanism-Vitalism debate of the early 20th Century. The vitalists, like Hans Driesch, argued that there must be something special about living organisms that informed their activities (Driesch 1908). The mechanicists, led by Driesch’s fellow student, Wilhelm Roux, insisted that only demonstrable physical or chemical entities could be invoked to account for biological phenomena (Roux 1895). Since the vitalists could not explain the nature of their hypothetical special life force, the mechanists prevailed for the rest of the 20th Century.

The issues in the Mechanism-Vitalism debate survive to the present day. In the 1950s, molecular biology and the identification of DNA as “the secret of life” were seen as the final triumph of the mechanists’ physico-chemical view of living organisms. It became possible to describe the cell and multicellular organisms in precise molecular terms. However, the rest of the 20th Century and the beginning of the 21st Century provided a finely ironic turn to the philosophical debate.

As molecular biology advanced, it began to uncover ever more complex and sophisticated multi-molecular networks that carry out sensory, communication, regulatory and decision-making activities within and between cells (Gerhart and Kirschner 1997; Alberts, Johnson et al. 2002). At the same time, the 20th Century development of cybernetics, computers and electronic information-processing systems began to provide real-world examples for capacities the vitalists saw at work in living organisms. The information revolution had come to biology.

This contribution to the workshop attempts to outline how the biological information revolution and its underlying molecular observations impact our thinking about evolution. The intentionally ambivalent title is there for the following reason. Showing how previously excluded (i.e., impossible) notions have been supported by empirical observations inevitably allows us to consider previously excluded concepts as feasible (i.e., possible) hypotheses.




Já cansei de mencionar aqui neste blog que a Biologia do final do século 20 e começo do século 21 é uma ciência de informação. A tarefa, nada fácil para a Nomenklatura científica, é explicar a origem da informação biológica. Até onde sabemos, os cientistas são profundamente ignorantes sobre esta questão!

Algum cientista tupiniquim se habilita??? Francisco Salzano, Sergio Danilo Junho Pena et al (a turma que escreveu a carta ao presidente da Academia Brasileira de Ciências), ou a estudantada da Sociedade Brasileira de Genética deixa de lado os Manifestos e faz ciência normal em busca de uma explicação estritamente naturalista em termos físico-químicos??? Ou a físico-química não explica a origem da informação genética???