Revisitando a extinção do mundo RNA

Revisiting the Extinction of the RNA World

Anthony C. Forster*

Cite this: Biochemistry 2022, 61, 9, 749–751

Publication Date:April 7, 2022

https://doi.org/10.1021/acs.biochem.2c00121

Copyright © 2022 The Author. Published by American Chemical Society

Abstract

The ribozyme world is thought to have evolved the burdensome complexity of peptide and protein synthesis because the 20 amino acid side chains are catalytically superior. Instead, I propose that the Achilles heel of the RNA world that led to the extinction of riboorganisms was RNA’s polyanionic charges that could not be covalently neutralized stably by phosphotriester formation. These charges prevented development of hydrophobic cores essential for integration into membranes and many enzymatic reactions. In contrast, the phosphotriester modification of DNA is stable. So, the fact that the charge was never removed in DNA evolution gives further credence to proteins coming before DNA.

FREE PDF GRATIS: Biochemistry

Reflexões sobre a historiografia de Darwin: uma figura-chave científica sendo desconstruída.

Reflections on Darwin Historiography

Janet Browne 

Journal of the History of Biology

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Abstract

Much has happened in the Darwin field since the Correspondence began publishing in 1985. This overview of historiography suggests that the richness of the letters generates fresh scholarly questions and that Darwin, paradoxically, is becoming progressively deconstructed as a key figure in the history of science.

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Journal of the History of Biology

Otodus megalodon, um extinto tubarão superpredador transoceânico

The extinct shark Otodus megalodon was a transoceanic superpredator: Inferences from 3D modeling

Jack A. Cooper, John R. Hutchinson, David C. Bernvi, Geremy Cliff, Rory P. Wilson, Matt L. Dicken, Jan Menzel, Stephen Wroe, Jeanette Pirlo, and Catalina Pimiento Authors Info & Affiliations

SCIENCE ADVANCES 17 Aug 2022 Vol 8, Issue 33 DOI: 10.1126/sciadv.abm9424

 

Abstract

Although shark teeth are abundant in the fossil record, their bodies are rarely preserved. Thus, our understanding of the anatomy of the extinct Otodus megalodon remains rudimentary. We used an exceptionally well-preserved fossil to create the first three-dimensional model of the body of this giant shark and used it to infer its movement and feeding ecology. We estimate that an adult O. megalodon could cruise at faster absolute speeds than any shark species today and fully consume prey the size of modern apex predators. A dietary preference for large prey potentially enabled O. megalodon to minimize competition and provided a constant source of energy to fuel prolonged migrations without further feeding. Together, our results suggest that O. megalodon played an important ecological role as a transoceanic superpredator. Hence, its extinction likely had large impacts on global nutrient transfer and trophic food webs.

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Darwin, nós temos um problema: uma breve história das histórias da carochinha em ciência evolucionária - explanação de narrativa implausível

A Brief (Hi)Story of Just-So Stories in Evolutionary Science

Michal Hubálek

First Published August 6, 2020 

https://doi.org/10.1177/0048393120944223

Volume: 51 issue: 5, page(s): 447-468

Article first published online: August 6, 2020; Issue published: September 1, 2021

Michal Hubálek 1

1 University of Hradec Králové, Hradec Králové, Czech Republic

Corresponding Author:

Michal Hubálek, Department of Philosophy and Social Sciences, University of Hradec Králové, Hradec Králové, EU 500 03, Czech Republic. Email: hubalek.michal.42@gmail.com

Abstract

In this essay, I examine the usage of the term “just-so story.” I attempt to show that just-so storytelling can be seen as an epistemic concept that, in various ways, tackles the epistemological and methodological problems relating to evolutionary explanations qua historical/narrative explanations. I identify two main, yet mutually exclusive, strategies of employing the concept of a just-so story: a negative strategy and a positive strategy. Subsequently, I argue that these strategies do not satisfactorily capture the core of the “original” meaning advanced by Stephen Jay Gould and Richard Lewontin at the end of the 1970s. I revisit the foundation(s) of their anti-adaptationist critique in order to reframe it as a critique of distinctive methodological manners and epistemic maxims related to historical inquiry. Last but not least, I suggest that contemporary evolutionary thinkers have two conceptually different options: they can either adhere to the “original” meaning of the term “just-so story” or accept that “just-so story” is a term equivalent to “implausible narrative explanation.”

Keywords just-so story, narrative explanation, adaptationism, Stephen Jay Gould, Richard Lewontin

Subscription or payment needed/Requer assinatura ou pagamento: Philosophy of the Social Sciences 

Darwin, nós temos um problema - o neodarwinismo é um paradigma falido!

The fight for the future of biology

The broken paradigm of Neo-Darwinism

4th August 2022

Denis Noble | World-renowned physiologist and Emeritus Professor of Cardiovascular Physiology at Oxford University. He is the author of Dance to the Tune of Life: Biological Relativity (CUP 2016).

The Neo-Darwinist paradigm maintains that natural selection is the sole driving force in evolution.  This paradigm is not only wrong, but untrue to Darwin’s theory of evolution which made room for  Lamarck’s suggestion that acquired characteristics can also be inherited. The side-lining any research into Lamarckian evolution has stifled the fruitful work of generations of researchers, limiting our understanding of how inheritance really works, argues Denis Noble.

The Neo-Darwinist paradigm of evolutionary biology is almost defined by its view of inheritance. That view is that acquired characteristics cannot be inherited, and that the organism itself has no active role in the evolution of the species. One of its founders, August Weismann, created the break with the ideas of Charles Darwin in 1883, just a year following Darwin’s death in 1882. He did so by inventing the Weismann Barrier, which he claimed protects the germ-line, the future eggs and sperm, from any influences of use-disuse features acquired by the organism during its lifetime. He was therefore going against the Lamarckian idea of inheritance of acquired characteristics that Darwin had accepted and later expanded upon in his writings on heredity. There was no experimental evidence for Weismann’s idea. He even wrote that it was a “necessary” idea, whether or not any experiments supported it.

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