Pangênese, genes, epigênese / Pangenesis, genes, epigenesis

Resumo Em 1868, Darwin publica seu livro The variation of animals and plants under domestication, no qual expõe sua teoria da hereditariedade. Nela se encontrava o pressuposto de que o desenvolvimento era fundamental para compreensão do processo evolutivo. No presente trabalho, é feita uma releitura da teoria darwiniana da pangênese, no intuito de rediscutir seu valor histórico. Conclui-se que a teoria da pangênese estava bem adequada a seu tempo e, mais do que isso, é possível encontrar ressonâncias de seu pressuposto em trabalhos das novas áreas biologia evolutiva do desenvolvimento (evo-devo) e epigenética.

Abstract In 1868, Darwin published his book The variation of animals and plants under domestication, which laid out his theory of heredity. This included the assumption that development was essential to understanding the evolutionary process. This present article reassesses the Darwinian theory of pangenesis in order to revisit its historical value. The conclusion is that the theory of pangenesis was well-suited to its time, and additionally, reflections of this assumption can be found in work in new areas known as evolutionary biology of development (evo-devo) and epigenetics.

Darwin o el faloo conflicto entre la teoría de a selección natural y la hipóteesis de la pangénesis / Darwin or the False Conflict Between the Theory of Natural Selection and the Hypotheses Pangenesis

Teniendo como objetivo buscar una compresión más integral de la obra de Darwin, presento una reflexión sobre el desarrollo de sus ideas, resaltando las influencias que la visión mecánica de la naturaleza, el lamarckismo y las teorías recapitulacionistas alemanas, ejercieron sobre él. Se destaca la originalidad de la teoría de la selección natural surgida por comparación con el cruce dirigido y fundamentada en una interpretación de la naturaleza como sistema económico donde se aplica la ley de población de Malthus. Sin embargo, la preocupación de Darwin por el origen de la variación lo llevó a considerar el carácter complejo de este problema y en particular, lo relacionado con la influencia del medio ambiente en la variación evolutiva. En este contexto se destaca la importancia histórica que tiene su fallida presentación de la hipótesis de la pangénesis. Para concluir se muestra que a pesar de que el concepto de evolución por selección natural presupone la existencia de variaciones individuales azarosas, Darwin continuó con su intento obstinado de encontrar las leyes de la variación, las cuales creyó haber explicado mediante esta hipótesis.

In order to provide a more integral view of Darwin’s work, I present the development of his ideas, showing the influence of the mechanical view of nature on one hand, and the Lamarckian recapitulationism on the other. The originality of the theory of evolution by natural selection is highlighted, while showing its connection with the analogy with breeders directed crosses and its theoretical justification inspired in Mathus population theory. However, it is explained how Darwin’s concern with the problem of the origin of evolutionary variations led him to consider the role of the environment in the production of variants. In this context it is explained the historical importance of his ill-fated hypothesis of pangenesis. To conclude, it is shown that though the concept of evolution by natural selection assumes the randomness of individual variations, Darwin nevertheless pursued his stubborn search for the laws of variations that he believed to have accounted for with this hypothesis.

El origen de la especies y su relacióncon el inicio de la actual teoría de la hereniia / The Origin of Species and its Relation with the Birth of Present Genetic Theory

En la primera parte se mostrarán algunos elementos históricos relacionados con la "Philosophie Zoologique" de Jean-Baptiste Lamarck, obra fundamental de la biología moderna merecedora de una mención especial en su aniversario número 200. Esta obra contiene algunos conceptos impor-tantes para "The Origin of species by means of natural selection, or the preservation of favoured races in the struggle for life" el trabajo fundamental de Charles Darwin. Posteriormente se revisará la idea general de la pangénesis y sus diferentes contradicciones en la explicación de la variabilidad necesaria para la acción de la selección natural que culminarían con el nacimiento de la genética. Es importante mostrar la posición particular de los experimentos mendelianos en relación con el paradigma evo-lutivo causado por el origen de las especies.

In the first part I present some historical elements related to the "Philosophie Zoologique" by Jean-Baptiste Lamarck, a fundamental work of modern biology. This work deserves a special mention in its 200th anniversary, since it contains some important concepts for "The Origin of Species by Means of Natural Selection, or the Preservation of favored races in the struggle for life" the principal work of Charles Darwin. Subsequently we review the pangenesis and various contradictions in the explanation of the variability required for the action of natural selection that culminate with the birth of genetics. In this paper is important show the particular position of Mendelian experiments in relation with the evolutionary paradigm caused by the origin of species.