Stephen Buranyi stated in an article that the modern theory of evolution was not complete. I wrote a longish critique of the piece on this site but of course such an egregious and misleading article needs a critique in the Guardian itself. The distinguished evolutionary biologists Brian Charlesworth, Deborah Charlesworth, and Doug Futuyma all said the same thing. Brian, Deborah and I wrote a rebuttal to the paper, and Doug did the same. None of the letters that were published yesterday were ours. I have permission to put our letters here to show you what we didn't like about the record. It may give you a better idea of what is new in evolutionary biology. Brian wanted to show the editors what shoddy reportage Buranyi had produced so he sent a cover letter detailing some of the factual errors. We were aware of that from the article. They came from Brian, Deborah, and me. Stephan Buranyi’s recent article (Do we need a new theory of evolution?, Guardian, June 28 2022) discusses whether there are serious problems with the widely accepted view of evolution developed in the 1930s and 40s, often called the Modern Synthesis. This article does not, however, give an unbiased or accurate account, making statements such as “The theory dictated that, ultimately, genes built everything”, and implying that authority figures in the field imposed a “party line”. Negative impressions are reinforced by Buranyi suggesting that “its most over-ambitious claims – that simply by understanding genes and natural selection – we can understand all life on earth” have been dropped or greatly modified. Evolutionary biologists made no such claims. The Modern Synthesis combined evidence about how inheritance works with Darwin’s idea of natural selection. It showed how adaptive features of organisms, such as the eyes, wings and placentas mentioned by Buranyi, can evolve through natural selection acting on mutations, producing changes in the genetic composition of populations that, over time, can transform initially poor functions into complex adaptations. A famous 1994 paper by D.-E. Nilsson and S. Pelger showed how a light-sensitive patch can evolve into a light-focussing eye. Similarly, the evolution of placentas presents no major difficulty, as placenta-like organs have evolved independently in several groups of animals, with examples of intermediate structures. Many discoveries since the Modern Synthesis have been incorporated into evolutionary biology without substantially changing its major tenets . For example, the discovery that DNA is the genetic material led to the understanding that there are components of genomes lacking functional significance, which evolve by accumulating mutations without significant effects on fitness. The basic theory that allowed this advance was developed by R.A. Fisher and Sewall Wright, two founders of the Modern Synthesis. Buranyi mis-characterises their work as “ the lofty perspective of population genetics”. In fact, both Fisher and Wright did experiments, and their collaborations with naturalists founded the field of ecological genetics, which has thoroughly documented natural selection acting in wild populations. This use of theoretical work to interpret empirical observations and experiments continues to enrich our understanding of evolution. Buranyi’s article gives a very misleading picture of contemporary work in evolutionary biology . Brian Charlesworth
Deborah Charlesworth
1F2, 17 West Preston Street, Edinburgh EH8 9PU, UK
A man named Jerry Coyne.
Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA.
That's right.
Brian sent a list of mistakes to Buranyi.
Dear Guardian,
I enclose a letter by Deborah Charlesworth, Jerry Coyne and myself concerning Tuesday’s Long Read article by Stephen Buranyi. All three of us were referred to in the article. We feel that the article gives a misleading account of the field of evolutionary biology, which we try to point out in our letter.
The article also contains several errors of fact, which show that Mr Buranyi has a poor understanding of the subject. Unfortunately, space does not permit us to list these in our letter. These errors could easily have been removed by proper fact-checking. We are dismayed that the Guardian would fail to ensure factual accuracy, given its famous motto.
Here are some examples.
Scientists working in the new field of genetics discovered rules that governed the quirks of heredity. But rather than confirm Darwin’s theory, they complicated it. Reproduction appeared to remix genes – the mysterious units that programme the physical traits we end up seeing – in surprising ways.
Mendelian genetics shows that maternal and paternal genes do not mix, but remain distinct from each other, in contrast to Darwin’s belief in blending of maternal and paternal contributions. This lack of blending is actually critical for variability to be maintained in populations, and hence for the effectiveness of selection. Buranyi has got it backwards.
Thomas Hunt Morgan, showed that by breeding millions of fruit flies – and sometimes spiking their food with the radioactive element radium – he could produce mutated traits, such as new eye colours or additional limbs. These were not the tiny random variations on which Darwin’s theory was built, but sudden, dramatic changes.
The artificial induction of mutations used X-rays not radium and was discovered by H.J. Muller, not Morgan. Muller was the leading expert of his time on mutations, and always emphasised that most mutations have very small or no observable effects on the organism.
… the American livestock breeder Sewall Wright…
Wright was a geneticist, not a livestock breeder (he worked on guinea pigs), and did his most famous work as a professor at the University of Chicago.
While the modern synthesists looked at life as if through a telescope, studying the development of huge populations over immense chunks of time, the molecular biologists looked through a microscope , focusing on individual molecules. And when they looked, they found that natural selection was not the all-powerful force that many had assumed it to be.They found that the molecules in our cells – and thus the sequences of the genes behind them – were mutating at a very high rate.
First, molecular evolution was first studied by comparing protein sequences from quite distantly related species, so large “chunks of time” are indeed involved. Second, the major proponent of the neutral theory of molecular evolution (to which this passage refers) was not a molecular biologist but the theoretical population geneticist Motoo Kimura. Third, this statement confuses the rate of evolution of sequences with mutation rates. It is true that these are the same under the neutral theory, but the rates are not “very high”- about 1 in 100 million per DNA site per generation in humans.
Yours sincerely,
Brian Charlesworth
That's right.
Doug Futuyma wrote a letter to the guardian.
Stephen Buranyi (Guardian, June 28, 2022) has provided a sensationalistic portrayal of a controversy in evolutionary biology, pitting supporters of an “Extended Evolutionary Synthesis” (EES) against the “evolutionary synthesis” (ES) of the 1930s and 1940s. He quotes my assertion that the ES “remains, mutatis mutandis, the core of modern evolutionary biology.” It is that. But in that paper, and at the London meeting of the Royal Society to which Mr. Buranyi refers, I described the history of evolutionary biology in the last 80 years as one of constant expansion, in which new subfields such as evolutionary ecology and evolutionary physiology developed, and which was profoundly changed when molecular biology provided new research tools. Almost all the new knowledge has been compatible with, yet has amplified, the ES.
Mr. Buranyi describes some past challenges to the ES. 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. Mr. Buranyi portrays Eldredge and Gould’s claim of rapid, episodic evolution in fossil lineages as a violation of ES principles, but high and variable evolutionary rates were already known to authors of the ES. Eldredge and Gould departed from the ES by proposing a mechanism of episodic, rapid change that was theoretically implausible and which has not been supported by any evidence since they proposed it in 1972.
In contrast to these past challenges, most of the ideas advocated in the EES are fully compatible with traditional theory of evolution by mutation, natural selection, and genetic drift. “Niche construction” occurs when organisms choose to live in certain environments and may modify them; that this guides their evolution of adaptations (by natural selection) is obvious to anyone who compares the form and lifestyle of swallows and ducks. All organisms have some features that are “plastic,” whereby a single genotype develops different features, such as skin melanin, in different environments. Plasticity has been extensively studied since the 1940s. That it might produce novel changes that become inherited features of a species has been recognized as a possibility since the 1950s, but only recently has there been any evidence that this occurs in nature. How often is not known.
Mr. Buranyi cites the origin of complex, novel features, such as eyes, as a special challenge to the notion that mutation plus natural selection explain evolution. The steps by which eyes can have evolved from very simple precursors have been well described in molluscs and other animals, but the origin of novel features is an important theme in modern research. This question resists a simple, general answer because it requires knowing how gene mutations could give rise to novel variations – and that depends on how the relevant genes direct the development of a feature. Advances in molecular biology have clarified many developmental processes, reinvigorating the field of evolutionary developmental biology, which has illuminated the origin of some novel traits. This simply shows that a generalized theory (mutations and natural selection) needs to be particularized in order to understand the origin of any particular feature. (What are the effects of the mutations? What feature is favored by natural selection?) If we want to understand the evolution of particular proteins or physiological or anatomical traits, we need knowledge of proteins, physiology, or development. But in all cases, the ES theory is still fundamental.
Douglas J. Futuyma
Distinguished Professor Emeritus, Stony Brook University, Stony Brook, New York
That's right.
The Guardian chose to publish three letters.
The first letter will be excerpted and the other two will be reproduced.
Jonathan Bard is listed as an evolutionary biologist, but his letter is rather obscure, and in one place completely opaque.
Stephen Buranyi misses some key points in his article (Do we need a new theory of evolution?, 28 June). Darwin saw novel speciation as resulting from natural selection acting on anatomical variants, but that simple skeleton needed fleshing out. It took a century of research, for example, for us to understand the importance of inheritance in very small populations if novel variants were to become predominant.
The professor is sweating. He is talking about genetic drift. Is inheritance more important in small groups than in large ones?
It took a long time to understand how novel neutral or even maladaptive variant could rise in frequencies in small populations. It took a decade or so and not a century. Brian and I don't know what the part in bold means.
Nicholas Maxwell wrote the second letter.
Those biologists who are critical of current Darwinian orthodoxy and who want to modify the theory in the direction of the “extended Darwinian synthesis” need to take things further. They need to recognise that all living things are purposive. They pursue goals – without necessarily being aware of it – the ultimate goal being survival and reproductive success.
Purposive action can, in a multitude of ways, influence what has survival value – and thus influence the future course of evolution. Purposive action that results in living in a new environment, or pursuing new kinds of food, can change what has survival value for that creature and its offspring, and thus can influence the future course of evolution. Foxes hunting rabbits breed rabbits better able to escape; and rabbits escaping breed foxes better able to catch them.
Above all, when animals make discoveries and learn from one another, cultural evolution becomes possible, and that can have a massive impact on subsequent evolution, as the case of human evolution, and the evolution of language, show.
We need a new, unified version of Darwinian theory that recognises that the purposive actions of living things play a vital role in evolution. This is very definitely not Lamarckism, although too many biologists have denied the Darwinian role of purposive action in evolution for fear that that commits one to Lamarckism. For more about this, see chapter 6 of my 2020 book Our Fundamental Problem: A Revolutionary Approach to Philosophy.
Nicholas Maxwell
Emeritus reader, science and technology studies, University College London
The first paragraph says nothing new but is still confusing since what looks likeposive action is molded by natural selection. We have known for a long time that the appearance of purpose is part of the design that was created by nature. There is nothing new in the second paragraph, it has been known for decades that an animal's evolved behavior can change the course of natural selection. The example of animals doesn't seem to fit that point. Gene-culture coevolution has been going on for a long time. The theory of evolution recognizes that evolvedposive actions can affect future evolution. The evolution of behavior is muddied by the introduction of the element ofposiveness. Lay readers will confuse the appearance of purpose with either God's purpose or an animal's.
The third letter was published by the Guardian.
Surely there’s no problem with having several conflicting theories of evolution? Eventually the fittest will survive.
Pete Bibby
Sheffield
The author said, "So it goes."
Anne.
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