Logic and evolution: a theory in flux (Introduction)

by David Turell @, Wednesday, January 17, 2018, 17:54 (307 days ago) @ David Turell

Epigenetic discoveries among others are upsetting current Darwin extended theories. Is a new set of theories needed?:

https://aeon.co/essays/science-in-flux-is-a-revolution-brewing-in-evolutionary-theory?u...

"Some evolutionary biologists, myself included, are calling for a broader characterisation of evolutionary theory, known as the extended evolutionary synthesis (EES). A central issue is whether what happens to organisms during their lifetime – their development – can play important and previously unanticipated roles in evolution. The orthodox view has been that developmental processes are largely irrelevant to evolution, but the EES views them as pivotal...Some people are even starting to wonder if a revolution is on the cards.

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"Take the idea that new features acquired by an organism during its life can be passed on to the next generation. This hypothesis was brought to prominence in the early 1800s by the French biologist Jean-Baptiste Lamarck, who used it to explain how species evolved. However, it has long been regarded as discredited by experiment.

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"Except they do. The way that genes are expressed to produce an organism’s phenotype – the actual characteristics it ends up with – is affected by chemicals that attach to them. Everything from diet to air pollution to parental behaviour can influence the addition or removal of these chemical marks, which switches genes on or off. Usually these so-called ‘epigenetic’ attachments are removed during the production of sperm and eggs cells, but it turns out that some escape the resetting process and are passed on to the next generation, along with the genes. This is known as ‘epigenetic inheritance’, and more and more studies are confirming that it really happens.

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"There are now hundreds of such studies, many published in the most prominent and prestigious journals. Biologists dispute whether epigenetic inheritance is truly Lamarckian or only superficially resembles it, but there is no getting away from the fact that the inheritance of acquired characteristics really does happen.

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"There’s no longer any doubt that epigenetic inheritance pushes us to think about evolution in a different way.

"Epigenetics is only part of the story. Through culture and society, all of us inherit knowledge and skills acquired by our parents. Evolutionary biologists have accepted this for at least a century, but until recently it was considered to be restricted to humans. That’s no longer tenable: creatures across the animal kingdom learn socially about diet, feeding techniques, predator avoidance, communication, migration, and mate and breeding-site choices. Hundreds of experimental studies have demonstrated social learning in mammals, birds, fish and insects.

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"Even Charles Darwin’s theory of evolution through natural selection took approximately 70 years to become widely accepted by the scientific community, and at the turn of the 20th century was viewed with considerable skepticism. Over the following decades, new ideas appeared, they were critically evaluated by the scientific community, and gradually became integrated with pre-existing knowledge. By and large, evolutionary biology was updated without experiencing great periods of ‘crisis’.

"The same holds for the present. Epigenetic inheritance does not disprove genetic inheritance, but shows it to be just one of several mechanisms through which traits are inherited. I know of no biologist who wants to rip up the textbooks, or throw out natural selection.

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"The EES, at least as my collaborators and I frame it, is best viewed as an alternative research programme for evolutionary biology. Inspired by recent findings emerging within evolutionary biology and adjacent fields, the EES starts from the assumption that developmental processes play important roles as causes of novel (and potentially beneficial) phenotypic variation, causes of differences in fitness of those variants, and causes of inheritance. In contrast to how evolution has traditionally been conceived, in the EES the burden of creativity in evolution does not rest on natural selection alone.

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"If evolution is not to be explained solely in terms of changes in gene frequencies; if previously rejected mechanisms such as the inheritance of acquired characteristics turn out to be important after all; and if organisms are acknowledged to bias evolution through development, learning and other forms of plasticity – does all this mean a radically different and profoundly richer account of evolution is emerging? No one knows: but from the perspective of our adapting dog-walker, evolution is looking less like a gentle genetic stroll, and more like a frantic struggle by genes to keep up with strident developmental processes."

Comment: Still not recognizing design. Giant article worth reading.


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