ABSTRACT
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.
Subject(s)
Humans , Biology , EpigenomicsABSTRACT
About 1700 years BC, the prophet Zoroaster declared equal right for women and men to choose their “own ways.” There is much evidence that ancient Persians believed in the equal contribution of women and men toward producing a child, and all its hereditary characteristics. Even more surprising are the phrases in Vandidad book, which were gathered by Mobedans in the Mad dynasty about egg extraction (gametes) from animal reproductive organs (gonads) and their storage for future conception. Centuries later, Western philosopher beliefs in regard to reproduction were contrary to Persian knowledge. The Greek philosophers believed that man's water (semen) contains all human characteristics, and the female uterus is only responsible for nurturing and development of fetus. After detection of the ovum (de Graaf 2nd half 17 century) Malpigy proposed the preformation theory (ovist) which means there is a miniature human inside ovum, that grows after Semen has entered the uterus and grow into a well-developed fetus. This hypothesis was later delegated to spermatozoa. These contradictory and inappropriate beliefs were subject to discussions and dispute, until C.E. Wolf demonstrated that the embryo is a product of the fertilization of ovum by spermatozoa. 800 years prior this the sage Ferdowsi “The Great Iranian Poet” explains nicely the equal participation of man and woman in the production of the fetus and transmission of characters. After the renaissance and especially in recent years, tremendous achievements have been made in unraveling biological secrets of reproduction. There was no work o n genetics in Iran until 1936, when a genetic course was added to the biology curriculum in related colleges and universities; Iranian Genetics Society was founded in 1966, initiating a steady movement in this field. Although there was an inevitable gap during the revolution and war in our country, now there is great effort by researchers to eliminate the gap and bring us into the mainstream of world science, and development in biomedical sciences in the third millennium.
Subject(s)
Animals , Breeding/history , Breeding/methods , Breeding/veterinary , Female , Fertilization/genetics , Fertilization/history , Fertilization/methods , Heredity/genetics , Humans , Iran , Male , Persia , Ovum , Reproduction/genetics , Reproduction/history , Reproduction/methods , SemenABSTRACT
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 Darwins 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 Darwins 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.
ABSTRACT
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.