Wednesday, January 17, 2018

What's up with the extended evolutionary synthesis (ESS) in biology?

Despite the excitement of all the new data, it’s unlikely to trigger an evolution revolution for the simple reason that science doesn’t work that way – at least, not evolutionary science. Kuhnian paradigm shifts, like Popper’s critical experiments, are closer to myths than reality. Look back at the history of evolutionary biology, and you will see nothing that resembles a revolution. 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. The debate in evolutionary biology concerns whether we want to extend our understanding of the causes of evolution, and whether that changes how we think about the process as a whole. In this respect, what is going on is ‘normal science’.

Why, then, are traditionally minded evolutionary biologists complaining about the misguided evolutionary radicals that lobby for paradigm shift? Why are journalists writing articles about scientists calling for a ‘revolution’ in evolutionary biology? If nobody actually wants a revolution, and scientific revolutions rarely happen anyway, what’s all the fuss about? The answer to these questions provides a fascinating insight into the sociology of evolutionary biology.

Revolution in evolution is a misattribution – a myth propagated by an unlikely alliance of conservative-minded evolutionists, creationists and the press. I don’t doubt that there are a small number of genuine, revolutionarily minded evolutionary radicals out there, but the vast majority of researchers working towards an extended evolutionary synthesis are simply ordinary, hardworking evolutionary biologists.

We all know that sensationalism sells newspapers, and articles that portend a major upheaval make for better copy. Creationists and advocates of ‘intelligent design’ also feed this impression, with propaganda that exaggerates differences of opinion among evolutionists and gives a false impression that the field of evolutionary biology is in turmoil. What’s more surprising is how commonly conservative-minded biologists play the ‘We’re under attack!’ card against their fellow evolutionists. Portraying intellectual opponents as extremist, and telling people that they are being attacked, are age-old rhetorical tricks to win debate or allegiance.
If the extended evolutionary synthesis is not a call for revolution in evolution, then what is it, and why do we need it? To answer these questions, we need to recognise what Kuhn got right – namely, that every scientific field possesses shared ways of thinking, or ‘conceptual frameworks’. Evolutionary biology is no different, and our shared values and assumptions influence what data is collected, how that data is interpreted, and what factors are built into explanations for how evolution works.

That is why pluralism in science is healthy. Lakatos stressed that alternative conceptual frameworks – what he called different ‘research programmes’ – can be valuable to the extent that they encourage new hypotheses to be generated and tested, or lead to novel insights. That is the primary function of the EES: to nurture, or even open up, new lines of enquiry, and new productive ways of thinking.
And so:
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. This alternative way of thinking is being used to generate fresh hypotheses and establish new research agendas. It’s early days, but there are already signs that this research is starting to yield dividends.

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.

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