James A. Shapiro, Author, 'Evolution: A View from the 21st Century;' Professor of Microbiology, University of Chicago
What Is the Key to a Realistic Theory of Evolution?
Posted: 02/16/2012 5:55 pm
In The Origin of Species by Means of Natural Selection, Charles Darwin proposed to explain how one life form gave rise to another. He subtitled the book, "The Preservation of Favoured Races in the Struggle for Life." He argued that a succession of small improvements in reproductive success would gradually lead to the major changes that distinguish one species from another. This gradualist hypothesis followed the Uniformitarian principle learned from his geology professor, Charles Lyell.
Since 1859, Darwin's followers have focused on optimizing reproductive success, now called "fitness." For them, natural selection increases fitness and, thus, generates new life forms, including their sophisticated and complex adaptations.
Darwin put it this way in Chapter 6: "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find no such case."
There has always been controversy about whether random variation and natural selection for improved fitness can truly explain biological evolution over time. Today we can apply genome sequence data to test Darwin's theory. It answers clearly about gradualism.
Many genome changes at key stages of evolution have been neither small nor gradual. For example, plant breeders are familiar with rapid speciation. When we wish to create new plant species artificially, we do not use selection. We generate hybrids by mating different species. In a fine 1951 (!) Scientific American article on this subject entitled "Cataclysmic Evolution," the distinguished 20th Century evolutionist, G. Ledyard Stebbins, explained how flour wheat evolved, suddenly, by hybridization.
Hybridization frequently leads to a process of "whole genome doubling." Doubling the genome takes one generation and potentially affects all hereditary traits. Note that the production of new species with novel characters by hybridization occurs too rapidly for natural selection to act creatively.
Perhaps the most important evolutionary step of all took place at least one billion years ago, when two or more cells fused to produce the first "eukaryotic" cell having a defined nucleus. This nucleated cell was apparently the progenitor of all "higher" forms of life, including plants and animals. Such cell mergers are known as "symbiogenesis," long championed as an evolutionary force by the recently deceased biologist, Lynn Margulis .
It's remarkable that even though processes like hybridization and symbiogenesis have been well-known for decades, many neo-Darwinists firmly insist on gradualism in evolutionary change. Their position notwithstanding, living organisms have many tools at their disposal for generating sudden change.
As I described in my previous HuffPost blog, "Evolutionary Lessons from Superbugs," bacteria get new DNA information from unrelated organisms. Microbes transform into superbugs in a few minutes by "horizontal DNA transfer." Similar events confer new traits to many microbial and eukaryotic recipients, often multiple characters in a single step.
Was Darwin simply mistaken about the gradual nature of hereditary variation? Such ignorance would be unavoidable before we knew about Mendelian genetics and DNA. Or was there a deeper flaw in the theory that he (and Alfred Russell Wallace) propounded? The answer may well be that it was a basic mistake to think that optimizing fitness is the source of biological diversity.
My recent book, Evolution: A View from the 21st Century, begins: "Innovation, not selection, is the critical issue in evolutionary change." This blog expands on that assertion.
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Read more here/Leia mais aqui: Huff Post Science
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NOTA CAUSTICANTE DESTE BLOGGER:
É este conhecimento e status da falência epistêmica da teoria da evolução de Darwin através da seleção e n mecanismos evolucionários que nossos autores de livros didáticos de Biologia do ensino médio aprovados pelo MEC/SEMTEC/PNLEM, sabem, mas INTENCIONALMENTE não abordam, pois fazendo assim estão desnudando a Darwin.
O nome disso é DESONESTIDADE ACADÊMICA, 171 Epistêmico, e nenhum desses autores me processa por danos morais e materiais por chamá-los de desonestos. E é o que eles são, e eu não posso dizer outra coisa!!!
Alunos do ensino médio no Brasil, uni-vos, encostai vossos professores de Biologia na parede com estas questões. Vós estais sendo engabelados na vossa formação acadêmica por esses autores que, INTENCIONALMENTE, sonegam essas informações sobre o status epistêmico da teoria da evolução no contexto de justificação teórica.
Fui, nem sei por que, com vontade de vomitar em cima desta turma que posa como o supra sumo da ciência!!!
O nome disso é DESONESTIDADE ACADÊMICA, 171 Epistêmico, e nenhum desses autores me processa por danos morais e materiais por chamá-los de desonestos. E é o que eles são, e eu não posso dizer outra coisa!!!
Alunos do ensino médio no Brasil, uni-vos, encostai vossos professores de Biologia na parede com estas questões. Vós estais sendo engabelados na vossa formação acadêmica por esses autores que, INTENCIONALMENTE, sonegam essas informações sobre o status epistêmico da teoria da evolução no contexto de justificação teórica.
Fui, nem sei por que, com vontade de vomitar em cima desta turma que posa como o supra sumo da ciência!!!
