Does evolutionary theory need a rethink?
Kevin Laland, Tobias Uller, Marc Feldman, Kim Sterelny, Gerd B. Müller, Armin Moczek, Eva Jablonka, John Odling-Smee, Gregory A. Wray, Hopi E. Hoekstra, Douglas J. Futuyma, Richard E. Lenski, Trudy F. C. Mackay, Dolph Schluter& Joan E. Strassmann
08 October 2014
Researchers are divided over what processes should be considered fundamental.
Subject terms: Evolution Developmental biology Philosophy
YES, URGENTLY — Kevin Laland and colleagues
NO, ALL IS WELL — Gregory A. Wray, Hopi E. Hoekstra and colleagues
Does evolutionary theory need a rethink? Yes, urgently
Without an extended evolutionary framework, the theory neglects key processes, say Kevin Laland and colleagues.
Charles Darwin conceived of evolution by natural selection without knowing that genes exist. Now mainstream evolutionary theory has come to focus almost exclusively on genetic inheritance and processes that change gene frequencies.
Yet new data pouring out of adjacent fields are starting to undermine this narrow stance. An alternative vision of evolution is beginning to crystallize, in which the processes by which organisms grow and develop are recognized as causes of evolution.
Some of us first met to discuss these advances six years ago. In the time since, as members of an interdisciplinary team, we have worked intensively to develop a broader framework, termed the extended evolutionary synthesis1 (EES), and to flesh out its structure, assumptions and predictions. In essence, this synthesis maintains that important drivers of evolution, ones that cannot be reduced to genes, must be woven into the very fabric of evolutionary theory.
We believe that the EES will shed new light on how evolution works. We hold that organisms are constructed in development, not simply ‘programmed’ to develop by genes. Living things do not evolve to fit into pre-existing environments, but co-construct and coevolve with their environments, in the process changing the structure of ecosystems.
The number of biologists calling for change in how evolution is conceptualized is growing rapidly. Strong support comes from allied disciplines, particularly developmental biology, but also genomics, epigenetics, ecology and social science1, 2. We contend that evolutionary biology needs revision if it is to benefit fully from these other disciplines. The data supporting our position gets stronger every day.
Yet the mere mention of the EES often evokes an emotional, even hostile, reaction among evolutionary biologists. Too often, vital discussions descend into acrimony, with accusations of muddle or misrepresentation. Perhaps haunted by the spectre of intelligent design, evolutionary biologists wish to show a united front to those hostile to science. Some might fear that they will receive less funding and recognition if outsiders — such as physiologists or developmental biologists — flood into their field.
However, another factor is more important: many conventional evolutionary biologists study the processes that we claim are neglected, but they comprehend them very differently (see ‘No, all is well’). This is no storm in an academic tearoom, it is a struggle for the very soul of the discipline.
Here we articulate the logic of the EES in the hope of taking some heat out of this debate and encouraging open discussion of the fundamental causes of evolutionary change (see Supplementary Information).
Core values
The core of current evolutionary theory was forged in the 1930s and 1940s. It combined natural selection, genetics and other fields into a consensus about how evolution occurs. This ‘modern synthesis’ allowed the evolutionary process to be described mathematically as frequencies of genetic variants in a population change over time — as, for instance, in the spread of genetic resistance to the myxoma virus in rabbits.
In the decades since, evolutionary biology has incorporated developments consistent with the tenets of the modern synthesis. One such is ‘neutral theory’, which emphasizes random events in evolution. However, standard evolutionary theory (SET) largely retains the same assumptions as the original modern synthesis, which continues to channel how people think about evolution.
The story that SET tells is simple: new variation arises through random genetic mutation; inheritance occurs through DNA; and natural selection is the sole cause of adaptation, the process by which organisms become well-suited to their environments. In this view, the complexity of biological development — the changes that occur as an organism grows and ages — are of secondary, even minor, importance.
In our view, this ‘gene-centric’ focus fails to capture the full gamut of processes that direct evolution. Missing pieces include how physical development influences the generation of variation (developmental bias); how the environment directly shapes organisms’ traits (plasticity); how organisms modify environments (niche construction); and how organisms transmit more than genes across generations (extra-genetic inheritance). For SET, these phenomena are just outcomes of evolution. For the EES, they are also causes.
Valuable insight into the causes of adaptation and the appearance of new traits comes from the field of evolutionary developmental biology (‘evo-devo’). Some of its experimental findings are proving tricky to assimilate into SET. Particularly thorny is the observation that much variation is not random because developmental processes generate certain forms more readily than others3. For example, among one group of centipedes, each of the more than 1,000 species has an odd number of leg-bearing segments, because of the mechanisms of segment development3.
In our view, this concept — developmental bias — helps to explain how organisms adapt to their environments and diversify into many different species. For example, cichlid fishes in Lake Malawi are more closely related to other cichlids in Lake Malawi than to those in Lake Tanganyika, but species in both lakes have strikingly similar body shapes4. In each case, some fish have large fleshy lips, others protruding foreheads, and still others short, robust lower jaws.
SET explains such parallels as convergent evolution: similar environmental conditions select for random genetic variation with equivalent results. This account requires extraordinary coincidence to explain the multiple parallel forms that evolved independently in each lake. A more succinct hypothesis is that developmental bias and natural selection work together4, 5. Rather than selection being free to traverse across any physical possibility, it is guided along specific routes opened up by the processes of development5, 6.
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FREE PDF GRATIS: Nature
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RAZÕES PARA SUPRIMIR AS CRÍTICAS FEITAS POR CIENTISTAS E BIÓLOGOS EVOLUCIONISTAS:
The number of biologists calling for change in how evolution is conceptualized is growing rapidly. Strong support comes from allied disciplines, particularly developmental biology, but also genomics, epigenetics, ecology and social science. We contend that evolutionary biology needs revision if it is to benefit fully from these other disciplines. The data supporting our position gets stronger every day.
Yet the mere mention of the EES often evokes an emotional, even hostile, reaction among evolutionary biologists. Too often, vital discussions descend into acrimony, with accusations of muddle or misrepresentation. Perhaps haunted by the spectre of intelligent design, evolutionary biologists wish to show a united front to those hostile to science. Some might fear that they will receive less funding and recognition if outsiders -- such as physiologists or developmental biologists -- flood into their field.
(Kevin Laland, Tobias Uller, Marc Feldman, Kim Sterelny, Gerd B. Müller, Armin Moczek, Eva Jablonka, and John Odling-Smee, "Does evolutionary theory need a rethink? Yes, urgently," Nature, Vol. 514:161-164 (October 9, 2014) (Ênfase deste blogger)
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NOTA DESTE BLOGGER:
Stephen Jay Gould, um evolucionista honesto, afirmou em 1980, em artigo com revisão por pares, junto com Niles Eldredge, que a atual teoria geral da evolução, a Síntese Evolutiva Moderna, era "uma teoria científica morta que teimava posar de ortodoxa somente nos livros didáticos" e que uma nova teoria da evolução se fazia necessária.
A História da Ciência já registrou a postura científica correta de Gould - o neodarwinismo era um referencial morto que não podia ser ressuscitado no contexto de justificação teórica. Este blogger bate nessa tecla desde 1998, e levou ao conhecimento de muitos editores e jornalista científicos de que uma iminente e eminente mudança paradigmática estava para ocorrer em biologia evolucionária. Somente foi levado a sério por Maurício Tuffani, quando trabalhou na editoria de ciência do jornal Folha de São Paulo e na revista Galileu.
Só agora a Nature abre o debate, tarde, mas ainda em tempo de reivindicar este blogger que foi chamado pela Nomenklatura científica e pela Galera dos meninos e meninas de Darwin de não saber o que é ciência e de nem fazer ciência, de medieval, obscurantista y otras cositas mais.
Fui, nem sei por que, rindo da cara de muitos biólogos evolucionistas, professores em universidades públicas de renome que, na ocasião de minhas denúncias disseram que eu estava numa canoa furada ao embarcar na canoa da teoria do Design Inteligente. Respondi: aposto todas as minhas fichas na TDI, pois o pangaré de Darwin não pode ganhar mais a corrida de explicar a origem e evolução das espécies.
Este blogger aprendeu na universidade que a ciência abomina o vazio teórico-epistemológico. Pergunta causticante: Sob qual referencial teórico está sendo feita a biologia evolutiva? Abracadabra? Búzios? Cartas de Tarô? Entranhas de galinha? Leitura das nuvens?
Darwin morreu!!! Viva Darwin!!!
