Do we need a new theory of evolution?

The classic Modern Synthesis is effectively dead. It was replaced by a more modern version that includes Neutral Theory, Nearly-Neutral Theory, and the importance of random genetic drift. Proponents of the "Extended Evolutionary Synthesis" don't have anything significant to add to our current understanding of evolutionary theory.

The latest kerfuffle in evolution is over a recent article published in The Guardian by Stephen Buranyi, Do we need a new theory of evolution?. The subtitle of the article summarizes the issue ...

A new wave of scientists argues that mainstream evolutionary theory needs an urgent overhaul. Their opponents have dismissed them as misguided careerists – and the conflict may determine the future of biology.

I think Stephen Buranyi did a pretty good job of covering the controversy as long as you ignore the first four paragraphs of his article. He talked to all the right people¹ and he got to the gist of the fundamental problem; namely, the over-emphasis on natural selection as the only significant player in evolution. There's no question that this is a serious problem. Here's a quotation from his article.

Doolittle and his allies, such as the computational biologist Arlin Stoltzfus, are descendants of the scientists who challenged the modern synthesis from the late 60s onwards by emphasising the importance of randomness and mutation. The current superstar of this view, known as neutral evolution, is Michael Lynch, a geneticist at the University of Arizona. Lynch is soft-spoken in conversation, but unusually pugnacious in what scientists call “the literature”. His books rail against scientists who accept the status quo and fail to appreciate the rigorous mathematics that undergirds his work. “For the vast majority of biologists, evolution is nothing more than natural selection,” he wrote in 2007. “This blind acceptance […] has led to a lot of sloppy thinking, and is probably the primary reason why evolution is viewed as a soft science by much of society.” (Lynch is also not a fan of the EES. If it were up to him, biology would be even more reductive than the modern synthesists imagined.)

What Lynch has shown, over the past two decades, is that many of the complex ways DNA is organised in our cells probably happened at random. Natural selection has shaped the living world, he argues, but so too has a sort of formless cosmic drifting that can, from time to time, assemble order from chaos. When I spoke to Lynch, he said he would continue to extend his work to as many fields of biology as possible – looking at cells, organs, even whole organisms – to prove that these random processes were universal.

As with so many of the arguments that divide evolutionary biologists today, this comes down to a matter of emphasis. More conservative biologists do not deny that random processes occur, but believe they’re much less important than Doolittle or Lynch think.

You would be hard-pressed to find many popular science writers who have that insight.

So, what's the problem? Why is Jerry Coyne (and others) so upset by the article that he has to write about it twice on his website and send a letter to The Guardian? [Once again: A misguided article on why the theory of evolution is obsolete] It mostly boils down to those unfortunate first four paragraphs. Here they are.

Strange as it sounds, scientists still do not know the answers to some of the most basic questions about how life on Earth evolved. Take eyes, for instance. Where do they come from, exactly? The usual explanation of how we got these stupendously complex organs rests upon the theory of natural selection.

You may recall the gist from school biology lessons. If a creature with poor eyesight happens to produce offspring with slightly better eyesight, thanks to random mutations, then that tiny bit more vision gives them more chance of survival. The longer they survive, the more chance they have to reproduce and pass on the genes that equipped them with slightly better eyesight. Some of their offspring might, in turn, have better eyesight than their parents, making it likelier that they, too, will reproduce. And so on. Generation by generation, over unfathomably long periods of time, tiny advantages add up. Eventually, after a few hundred million years, you have creatures who can see as well as humans, or cats, or owls.

This is the basic story of evolution, as recounted in countless textbooks and pop-science bestsellers. The problem, according to a growing number of scientists, is that it is absurdly crude and misleading.

For one thing, it starts midway through the story, taking for granted the existence of light-sensitive cells, lenses and irises, without explaining where they came from in the first place. Nor does it adequately explain how such delicate and easily disrupted components meshed together to form a single organ. And it isn’t just eyes that the traditional theory struggles with. “The first eye, the first wing, the first placenta. How they emerge. Explaining these is the foundational motivation of evolutionary biology,” says Armin Moczek, a biologist at Indiana University. “And yet, we still do not have a good answer. This classic idea of gradual change, one happy accident at a time, has so far fallen flat.”

I will not defend those statements. They are extremely misleading and they distract from an otherwise decent attempt to explain the controversies in evolutionary theory.

Jerry Coyne, along with Brian Charlesworth and Deborah Charlesworth, wrote a letter to The Guardian in which they defend the old version of the Modern Synthesis with its emphasis on natural selection and fail to mention, except obliquely, the major advance that took place in the late 1960s with the discovery of Neutral Theory [Our letter about evolution to the Guardian (and other stuff)]. He also posted a letter from Douglas Futuyma that wasn't published by The Guardian. Futuyma's letter is much better because he acknowledges the changes in evolutionary theory that took place. Here's what Futyma says,

Mr. Buranyi describes some past challenges to the ES [evolutionary synthesis = Modern Synthesis]. Traditional evolutionary biologists were, indeed, taken aback by evidence that considerable evolution at the DNA level was due not to natural selection, but to random genetic drift – which had already been developed in theory by the geneticists who led the ES. They were taken aback not because of blind faith in the supremacy of natural selection, but because of abundant evidence that even slight differences in organisms’ features were affected by natural selection. Random evolution at the DNA level is certainly the most thoroughgoing change, or expansion, of evolutionary biology since the ES.

I talked to Futuyma about this at the 2015 Royal Society meeting where I suggested that the development of Neutral Theory was about as close to a paradigm shift as you could get. He agreed, but he still prefers to view this as an extension of the Modern Synthesis rather than overthrowing it. Here's what he wrote in the article that was based on his presentation at the meeting.

Thus, evolutionary theory has undergone enormous expansion since the ES, with the neutral theory of molecular evolution its most radical extension [Evolutionary biology today and the call for an extended synthesis].

As far as I'm concerned, that "radical extension" deserves more attention and that's partly what Stephen Buranyi tried to do in his Guardian article. There are far too many scientists who don't understand or appreciate Neutral Theory and the importance of drift and I fear that Jerry Coyne's anger is somewhat misplaced. There are good things about that article that got overshadowed by the first few paragraphs.

The other issue that upsets Coyne and his allies (and me) is the attention focused on proponents of the Extended Evolutionary Synthesis (EES), many of whom are members of The Third Way of Evolution cult. Some of these scientists and philosophers are kooks who don't really understand evolution. Some of the other EES proponents, such as Massimo Pigiucci, seem to be well-meaning, but misguided. Then there's Evelyn Fox Keller who's in a category of her own. There's also the fact that many of them are supported by the Templeton Foundation, a point that wasn't mentioned in Stephen Buranyi's article. However, I think Buranyi does a pretty good job of explaining the controversy.

In 2015, the Royal Society in London agreed to host New Trends in Evolution, a conference at which some of the article’s authors would speak alongside a distinguished lineup of scientists. The aim was to discuss “new interpretations, new questions, a whole new causal structure for biology”, one of the organisers told me. But when the conference was announced, 23 fellows of the Royal Society, Britain’s oldest and most prestigious scientific organisation, wrote a letter of protest to its then president, the Nobel laureate Sir Paul Nurse. “The fact that the society would hold a meeting that gave the public the idea that this stuff is mainstream is disgraceful,” one of the signatories told me. Nurse was surprised by the reaction. “They thought I was giving it too much credibility,” he told me. But, he said: “There’s no harm in discussing things.”

Traditional evolutionary theorists were invited, but few showed up. Nick Barton, recipient of the 2008 Darwin-Wallace medal, evolutionary biology’s highest honour, told me he “decided not to go because it would add more fuel to the strange enterprise”. The influential biologists Brian and Deborah Charlesworth of the University of Edinburgh told me they didn’t attend because they found the premise “irritating”. The evolutionary theorist Jerry Coyne later wrote that the scientists behind the EES were playing “revolutionaries” to advance their own careers. One 2017 paper even suggested some of the theorists behind the EES were part of an “increasing post-truth tendency” within science. The personal attacks and insinuations against the scientists involved were “shocking” and “ugly”, said one scientist, who is nonetheless sceptical of the EES.

Now Jon Perry has entered the fray. Jon Perry is interested in science education and he runs a website called Stated Clearly that emphasizes genetics, evolution, and chemistry. I've posted about his video on evolution where it's clear that he's a proponent of the old-fashioned view of evolution as (mostly) equivalent to natural selection and seems to be a bit confused about mutations and populations [What Exactly Is Evolution? Stated Clearly Gets It Mostly Right]. His latest video (below) is a critique of The Guardian article because it lends credence to those who fight against the "genetic theory of evolution by natural selection." His criticism focuses on those unfortunate first four paragraphs; he doesn't mention the part about random genetic drift being important in evolutionary theory.

This is part of the problem. I don't like the EES proponents but underlying all of that rhetoric is a much more serious problem with the general perception of modern evolutionary theory. There is way too much emphasis on natural selection and it's obvious that this emphasis has permeated the scientific community. It's why we have a controversy over junk DNA.

Jon Perry objects to criticism of the Modern Synthesis, which he describes as the merger of evolution by natural selection with Mendelian genetics. He then touts the Price equation and the mathematical formalization of evolution by natural selection as one of the great achievements of the Modern Synthesis. This is exactly the version that Stephen Jay Gould criticized when he pronounced the death of the Modern Synthesis [Is the Modern Synthesis effectively dead?] Jerry Coyne likes the way Jon Perry "explains" the Modern Synthesis and that's a problem [New video attacks the Guardian’s claim that evolutionary biology is obsolete]. These are complicated issues and I think Coyne and his allies are making a mistake by attacking The Guardian article so vehemently without mentioning the parts that are correct and informative.

Watch the Jon Perry video to see if it really contributes to educating the general public about the current controversies.

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1. Full disclosure: I was one of those people.