Learning about modern evolutionary theory: the drift-barrier hypothesis

Many evolutionary biologists are engaged in research that focuses on large organisms that are (presumably) adapting to a local environment. These "field biologists" are mostly concerned with rapid evolutionary changes. Those kind of changes are almost always due to natural selection. Many of these biologists are not interested in molecular evolution and not interested in any process other than natural selection.

Unfortunately, this promotes an adaptationist mentality where all of evolution is viewed through the filter of natural selection. This is the view criticized by Stephen Jay Gould and Richard Lewontin back in 1978 when they presented the Spandrels paper at a Royal Society meeting in London (UK).

Gould, S. J. and Lewontin, R.C. (1979) The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. Proc. R. Soc. Lond. B 205:581-598. [doi: 10.1098/rspb.1979.0086

I believe there was a substantive change in our view of evolution back in the late 1960s and early 1970s. That's when the results of evolution at the molecular level were first being published. It lead to the development of Neutral Theory, Nearly-Neutral Theory and a growing appreciation of the importance of random genetic drift. Modern population genetics was able to cope easily with this new view of evolution.

On explaining science to the general public

Many science writers complain about the ability of scientists to explain their work to the general public. The latest example is from Susan Matheson, a science writer with a Masters degree in industrial engineering from Rutgers University (New Jersey, USA). She published the following article in Cell a leading journal in the field of cell biology, biochemistry, and molecular biology.

A Scientist and a Journalist Walk into a Bar…
by Susan Matheson, Cell 167: 1140–1143 (2016)[doi: 10.1016/j.cell.2016.10.051] [ScienceDirect PDF] [link from Susan Matheson]
Who are science journalists, and how can journalists and research scientists work together to improve science communication?

Mathesons begins with an anecdote about a science writer who won a Pulitzer Prize in 2011 for writing about a 4-year-old boy with a rare genetic disease. She concludes,

Edinburgh, Scotland

This is our first visit to Scotland. We rented an apartment in the top floor of this house in the middle of the city. It's a 20 minute walk to the port (Leith) and about the same distance to the old city (Edinburgh).

We'll be staying for two weeks in Scotland.

Our first meal in Scotland was at a pub in "the shore" near the main port.

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Extending evolutionary theory? - Melinda Zeder

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Melinda Zeder's talk on Domestication: a model system for evolutionary biology.

In his book The Variation of Animals and Plants under Domestication Darwin used domestication as a model system to explore his theories about the role of natural selection in evolution. Gregor Mendel used peas to trace the rules of heredity that formed the basis of the science of genetics, and that, when combined with Darwinian evolution, formed the basis of the Modern Synthesis. It seems only appropriate for domestication to serve once again as a model system for assessing how recent insights into the role of multiple shaping processes and forms of inheritance can be incorporated into an extended understanding of evolution. This presentation explores the value of domestication in evaluating core assumptions that differentiate the classical Modern Synthesis and the Extended Evolutionary Synthesis including: 1. reciprocal causation, 2. developmental processes as drivers of evolutionary change, 3. inclusive inheritance, and 4. the tempo and rate of evolutionary change.

Melinda Zeder works at the National Museum of Natural History, Smithsonian Institution (USA). I think I'll ask her what domestication teaches us about the fixation of deleterious alleles by random genetic drift and how that fits into Darwin's ideas and her view of the Modern Synthesis.

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Extending evolutionary theory? - Susan Antón

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Susan Antón's talk on Human evolution, niche construction and plasticity.

Recent humans are biocultural organisms. Our worldwide distribution and status as the lone surviving species of our genus signal a level of evolutionary success often explained by both biological and cultural mechanisms. A bio-behavioural package of traits that co-exist in Homo sapiens, including large brains and bodies, small teeth and jaws, extensive cooperative care, a great deal of developmental plasticity, and an extensive amount of niche construction, are variously implicated in our success or seen as its result.

It is broadly accepted that recent humans are ‘different’, particularly in the extent of our cultural interventions, than our earlier hominin forebears. But whether this is a difference in kind or degree, how far back that difference stretches, and whether those outcomes modifiable over an individual’s lifetime are important to human evolution is open to debate. Regardless of whether we accept exogenetic changes – including developmental niche construction – as consistent with an extension of, or break with the evolutionary synthesis, Homo erectus has often been proposed as the locus at which more ‘human like’ modes of behaviour (and presumably more biocultural evolution) is seated. But the paucity of the fossil record and the tenuously established links between bones and behaviours of interest limit our ability to test these assertions. I review the evolution of Homo and recent attempts to locate the transition to a biocultural organism with new data and by both working back from recent humans through archaeological time and working forward from ancestral genera.

Susan Antón is a professor of anthropology at New York University (New York, NY, USA).

It's interesting to learn about the history of life and the evolution of a particular species. However, that specific history usually doesn't usually have much impact on evolutionary theory. I wonder if some speakers are confused about the relationship between studying the history of life and the big picture of evolutionary theory? I fail to see how this study translates to a deeper understanding of the evolution of mushrooms, maple trees, and microbacteria.

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Extending evolutionary theory? - Andrew Whiten

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Andrew Whiten's talk on A second inheritance system: the extension of biology through culture.

By the mid-twentieth century the behavioural sciences could offer only the sketchy beginnings of a scientific literature documenting evidence for cultural inheritance in animals – the transmission of traditional behaviours via imitation and other processes of learning from others (social learning). By contrast, recent decades have seen a massive growth in the documentation of such cultural phenomena, driven by long-term field studies and complementary laboratory experiments. Here I first offer an overview of the major discoveries in this field, which increasingly suggest that this ‘second inheritance system’, built on the shoulders of the primary genetic inheritance system, occurs widely amongst vertebrates and possibly in insects and other invertebrates too. Its novel characteristics suggest it should have major implications for our understanding of evolutionary biology. Two major questions arising are accordingly addressed. One concerns the extent to which this second system echoes or differs from the principal properties of the primary evolutionary system described in the neo-Darwinian synthesis of the twentieth century and its extensions under discussion at this meeting. A subsidiary issue here is how the answers may differ much according to whether the focus is on the massively cumulative cultural evolution distinctive of our own species, or on the forms of cultural transmission documented for other species. The second major, and related, question concerns the extent to which the new discoveries about animal cultural transmission extend evolutionary theory, either in addition to or through interaction with the primary, genetically based inheritance systems.

Andrew Whiten is an emeritus professor in the School of Psychology and Neuroscience at the University of St. Andrews (Scotland, UK). I'm curious to see his explanation of how cultural evolution in, say, bonobos, informs us about biological evolution.

Here's a possible question ...

The people living in St. Andrews experience a very different culture than the people living in the suburbs of Dallas, Texas. Both groups have been exposed to Donald Trump since he owns a golf club near St. Andrews but they are likely to react differently to Trump. How will these cultural differences affect the biological evolution of the two groups in Texas and Scotland?

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Extending evolutionary theory? - Agustín Fuentes

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Agustín Fuentes' talk on
Human niche, human behaviour, human nature.

Scholars from a diverse range of disciplines disagree on what human nature is, what it could be, or even if there is one. There is no single ‘best’ discourse on, or mode of approach to, human nature. However, in the context of what we know about the evolutionary history, anthropology, and biology of Homo sapiens sapiens it is clear that an evolutionary approach should be among the principal modes of inquiry. At present we are faced with a few different narratives as to exactly what such an evolutionary approach entails. However, one point is clear: we need a robust and dynamic theoretical toolkit in order to develop a richer, and more nuanced, understanding of the cognitively sophisticated genus Homo and the diverse sorts of niches humans constructed and occupied across the Pleistocene, Holocene, and into the Anthropocene. In this talk I review current evolutionary approaches to ‘human nature’ and argue that we benefit from re-framing our investigations via the concept of the human niche and in the context of the Extended Evolutionary Synthesis (EES). In providing an overview of human evolution and the human niche I illustrate the benefits of moving the discourse on human nature(s) to an integrated evolutionary approach incorporating processes of the Extended Evolutionary Synthesis. This is not a replacement of earlier evolutionary approaches but rather an expansion and enhancement, a broadening of our toolkit and the landscape of inquiry. I offer brief examples from human evolutionary histories in support of these assertions.

Agustín Fuentes is a professor of anthropology at the University of Notre Dame in Indiana (USA). This is another talk about the nature of "human nature." Since I'll probably be skipping the previous talk I'll likely stay in some pub until this one is over. Looking forward to a "full English."

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Extending evolutionary theory? - Tim Lewens

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Tim Lewens' talk on Human nature, human culture: the case of cultural evolution.

In recent years, far from arguing that evolutionary approaches to our own species permit us to describe the fundamental character of human nature, a prominent group of cultural evolutionary theorists has instead argued that the very idea of 'human nature' is one we should reject. It makes no sense, they argue, to speak of human nature in opposition to human culture. But the very same sceptical arguments have also led some thinkers – usually from social anthropology – to dismiss the related idea that we can talk of human culture in opposition to human nature.

How, then, are we supposed to understand the cultural evolutionary project itself, which seems to rely on a closely allied distinction between 'organic' and 'cultural' evolution? This talk defends the cultural evolutionary project against the charge that, in refusing to endorse the concept of human nature, it has inadvertently sabotaged itself.

Tim Lewens is a professor in the Department of the History and Philosophy of Science at the University of Cambridge (UK). I'm not the least bit interested in cultural evolution (i.e. history) and I'm certainly not interested in quibbling about the meaning of "human nature." I hope there's a good pub nearby 'cause I'm going to skip this talk.

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Extending evolutionary theory? - Karola Stotz

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Karola Stotz's talk on
Developmental niche construction.

In the last decade niche construction has been heralded as the neglected process in evolution. But niche construction is just one way in which the organism’s interaction with, and construction of the environment, can have potential evolutionary significance. This constructed environment not just selects for, it also produces new variation. Nearly three decades ago, and in parallel with Odling-Smee’s book chapter ‘Niche-constructing phenotypes’, West and King introduced the ‘Ontogenetic Niche’ to give the phenomena of exogenetic inheritance a formal name. Since then a range of fields in the life sciences and medicine has amassed evidence that parents influence their offspring by means other than DNA (parental effects). Diverse scientists use different theoretical constructs for overlapping sets of processes, all of which show one way or another how heritable variation can be environmentally induced and developmentally regulated. Here I propose the concept of ‘developmental niche construction’ as a framework to integrate findings from fields ranging from molecular biology to developmental psychology. It elucidates how a diverse range of mechanisms contributes to the transgenerational transfer of developmental resources. This talk will explore the overall significance of these developments in the life sciences, and particularly how they advance the ongoing integration of development, heredity, ecology, and evolution.

Karola Stotz is a philosopher at Macquarie University in Sydney, Australia.

Organisms interact with, and change, their environment. This is hardly news but it's being promoted as one of the "new trends in evolutionary biology." Why?

I think I'll ask her what's "new" about this?

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Scientists at the Lawrence Berkeley National Laboratory do not understand basic molecular biology

The Lawrence Berkeley National Laboratory employs a number of scientists who work on genes and gene expression. Here's part of a press release published two days ago [For Normal Heart Function, Look Beyond the Genes: Loss of noncoding elements of genome results in heart abnormalities, finds Berkeley Lab study]. It demonstrates that the workers at this National Laboratory don't understand anything about mammalian genomes.

The only other possibility is that the person who wrote the press release doesn't understand molecular biology¹ and the scientists who work there just don't care what their institution publishes.

Researchers have shown that when parts of a genome known as enhancers are missing, the heart works abnormally, a finding that bolsters the importance of DNA segments once considered “junk” because they do not code for specific proteins.

Regular readers of this blog know that ...

1. No knowledgeable scientist ever said that all noncoding DNA was junk.
2. We've known about regulatory sequences for half a century. We've known about enhancers—just another kind of regulatory sequence—for thirty-five years. Nobody ever thought they were junk. Nobody ever thought they were unimportant.

When scientists sequenced the human genome, they discovered that less than 5 percent of our DNA were genes that actually coded for protein sequences. The biological functions of the noncoding portions of the genome were unclear.

Over the past fifteen years, however, there has been a growing appreciation for the importance of these noncoding regions, thanks in large part to the efforts of individual labs and, more recently, large international efforts such as the Encyclopedia of DNA Elements (ENCODE) project.

What became clear from this work is that there are many elements of the genome, including enhancers, that are involved in regulating gene expression, even though they do not encode for proteins directly.

At some point this flagrant misrepresentation of facts must be stopped. It's hurting science.

How can you believe anything in the press release once you read this? Do you think this represents the views of the scientists who published the paper? Is so, shame on them. If not, shame on the Lawrence Berkeley National Laboratory.

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1. I sent her a link to this post.

Extending evolutionary theory? - Patrick Bateson

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Patrick Bateson's talk on Adaptability and evolution.

The capacity of organisms to respond in their own lifetimes to new challenges in their environments probably appeared early in biological evolution. At present few studies have shown how such adaptability could influence the inherited characteristics of an organism’s descendants. Nevertheless such effects on biological evolution are likely to have been important and when they occurred accelerated the pace of evolution. Ways in which this might have happened have been suggested many times since the 1870s. I shall review these proposals and discuss their relevance to modern thought.

I don't get it. A key example of organisms responding to their environment is transcription of the lac operon in E. cloi. How does regulation of the lac operon accelerate evolution?

Part of the confusion here is that Bateson is using "adaptability" in two different senses. I'm curious to see if he makes this distinction clear in his talk.

I don't see anything new or revolutionary here. Apparently his motive isn't to overthrow or extend evolutionary theory but to introduce evolution to nonscientists. Here's what he said in an interview with Suzan Mazur [Sir Patrick Bateson: Zoologists Should Not ‘Hog’ Upcoming Royal Society Evolution Meeting ...

Patrick Bateson: It may be a mistake not to have anybody talking about that specifically at the meeting. But I want to repeat that in organizing the meeting we are focused on a discussion about evolution with our colleagues in the social sciences and the humanities, and we don’t want to blind them with all the details of the sciences.

There’s also a lot of fascinating work going on in population genetics that we’re not going to talk about. Evolutionary biologists will say this is an important part of evolutionary biology, which it is, of course. But it isn’t relevant to this particular meeting.

Suzan Mazur: How will an evolution paradigm shift affect society in general?

Patrick Bateson: I’m not sure we’re going to be talking about a completely new set of ideas, a lot have been around for a while. Frankly, I think some evolutionary biologists have not shed their neo-Darwinist clothing. There are some conservative-minded biologists who still think of the organism as being essentially passive, a view about which I am particularly concerned. However, the overall movement in biology is to integrate different disciplines making it a very lively area at the moment. The molecular biologists are talking to the ethologists, the ecologists to the physiologists, the population geneticists to the paleontologists, and so forth.

I don't know who's going to be at the meeting but I don't see very many molecular biologists or population geneticists among the speakers. It's mostly zoologists and a few philosophers.

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Extending evolutionary theory? - Andy Gardner

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Andy Gardner's talk on Anthropomorphism in evolutionary biology.

A longstanding tension exists in evolutionary biology between behavioural ecology – in which organisms are treated as having adaptive, fitness-maximising agendas; and population genetics – in which such notions are decried as naïve ‘anthropomorphism’ and are widely rejected. I explore the formal and scientific justification for evolutionary anthropomorphism and consider its application to the understanding of adaptive design at the level of genes, individuals and societies.

Andy Gardner is a biologist at the University of St. Andrews in Scotland (UK). Here's a description of his research interests from his website.

I work on Darwinian adaptation. Natural selection explains the appearance of design in the living world, but at what level is this design expected to manifest – gene, individual, society – and what is its function? Social evolution provides a window on this problem, by pitting the interests of genes, individuals and societies against each other. I develop general theory on the topics of inclusive fitness and multilevel selection, and also tailor general theory to the biology of particular species to facilitate empirical testing. I work on a wide range of biological systems, including viruses, bacteria, protozoa, crustaceans, insects, fish and humans.

I'm not sure how this view differs from Gould's writings on hierarchical theory. I'm looking forward to hearing the answer.

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Extending evolutionary theory? - Denis Noble

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Denis Noble's talk on Evolution viewed from medicine and physiology.

Medicine and physiology are multi-level disciplines. So is physics. From physics we learn that ordered properties at high levels co-exist with randomness at lower levels. Molecules in organisms must obey the same principles. Stochasticity at low levels does not therefore exclude order at higher levels. Organisms enlist stochasticity in their development of functional behaviour, through restraints exerted by higher over lower levels. The physics of organisms must therefore interact with their genomes to produce the phenotype1,2. Reverse engineering from physiological models is then required to understand genotype-phenotype relations3. There is no privileged level of causality4, nor privileged level of selection5. Evolution involves interaction between several processes at multiple levels, as Charles Darwin also believed5,6. Without understanding these interactions, gene-centred approaches will continue to produce disappointing results in healthcare7,8, including trans-generational disease risks.

I have heard Denis Noble speak and I've read some of his papers [Physiologists fall for the Third Way; A physiologist thinks about evolution]. Denis Noble is a physiologist who worked on hearts and circulation in complex mammals (humans). He's very annoyed at biochemists and molecular biologists for getting so much attention (and money) over the past few decades. He has constructed in his mind a false image of evolution. He thinks it's entirely adaptationist and gene-centric and that's what he rails against. He doesn't like Richard Dawkins. He's a prominent member of The Third Way.

You can see for yourself by watching a video of a talk he gave a few years ago.


I agree completely with Jerry Coyne's analysis of this talk [Famous physiologist embarrasses himself by claiming that the modern theory of evolution is in tatters]. Jerry says ....

I’m writing this post in a bit of anger, as Noble’s attacks on the modern synthesis are both poorly informed and clearly motivated by his ambition to make physiology a central part of evolutionary biology. Although he’s an FRS and famous, he wants more: he wants his field to be central to evolution. But such misguided hubris is not the way science is supposed to be done. And physiology is already important in evolutionary biology. It’s the reason why we look at the effects of a gene substitution, for example, not as a simple one-gene-produces-one-trait issue, but as a the gene’s overall effect on reproductive output through its effects ramifying through the complexities of development. Noble says that evolutionists are guilty of this “one-gene-one-trait” error, but he’s just wrong: I don’t know a single person in my field who holds this simplistic view.

None of the arguments that Noble makes are new: they’re virtual tropes among those people, like James Shapiro and Lynn Margulis, who embarked, at the end of their careers, on a misguided crusade to topple the modern theory of evolution.

However famous Noble may be in physiology, he’s a blundering tyro when it comes to evolutionary biology. He might try discussing his ideas with other evolutionists and listening to their responses. He obviously hasn’t done that, and yet travels the world trading on his expertise in physiology to show that the edifice of modern evolutionary biology is rotten. And he writes papers to that effect, including the dreadful piece referenced below.

But what’s really rotten is Noble’s knowledge of the field and his claim that virtually every assumption of neo-Darwinian evolution is wrong. In fact, his arguments are so rotten that they stink like old herring.

They’re not even wrong.

I'm not going to ask any questions after this talk. I'll report back on how many people seem to agree with him.

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Extending evolutionary theory? - Eva Jablonka

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Eva Jablonka's talk on
The role of epigenetic inheritance in evolution.

The construction of the ‘Modern Evolutionary Synthesis’ in the mid-twentieth century involved the exclusion of soft inheritance – the inheritance of the effects of developmental modifications – and, by implication, the possibility of any form of ‘Lamarckian’ evolution. However, in later decades, discoveries of molecular mechanisms that can support such inheritance led to a broadening of the notion of biological heredity. After discussing the historical context in which this change occurred, I present an extended notion of inheritance, focusing on epigenetic inheritance and its underlying mechanisms. I examine the evidence for the ubiquity of epigenetic inheritance, present models of population epigenetics, and discuss the involvement of epigenetic inheritance in adaptive evolutionary change and macro-evolution. I argue that considering the many evolutionary consequences of epigenetic inheritance requires an extension of the evolutionary synthesis beyond the current neo-Darwinian model.

Eva Jablonka has been pushing the importance of epigenetics for many years. Here's a video where she explains why epigenetic inheritance needs to be incorporated into evolutionary theory.


I think she's exaggerating the importance of epigenetic inheritance in evolution. I'd like to ask her how she defines "epigenetics" and how much of it is heritable over enough generations to seriously affect the evolution of a population. I'm particularly interested in her claim that epigenetic inheritance affects macro-evolution.

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Extending evolutionary theory? - Paul E. Griffiths

I will be attending the Royal Society Meeting on New trends in evolutionary biology: biological, philosophical and social science perspectives. I'll post each of the abstracts and ask for your help in deciding what question to pose to the speakers. Here's the abstract for Paul Griffiths's talk on Genetic, epigenetic and exogenetic information in development and evolution.

I outline an approach to measuring biological information where ‘information’ is understood in the sense found in Francis Crick’s foundational contributions to molecular biology. Genes contain information in this sense, but so do epigenetic factors, as many biologists have recognised. The term ‘epigenetic’ is ambiguous, and I introduce a distinction between epigenetic and exogenetic inheritance to clarify one aspect of this ambiguity. These three heredity systems play complementary roles in development and evolution.

Paul Griffiths is a philosopher of biology from Australia. He has been interested in genes for many years. I don't know what he's going to say about epigenetics. I suspect he can make a case for information in the sense that a naked DNA sequence differs in information from a methylated DNA sequence. (Restriction/modification is a good example.)

The problem with this kind of hair splitting is that ultimately the extra information (e.g. methylation) is provided by enzymes (methylases) encoded by genes in the genome. Epigenetics, per se, doesn't add any new information. It's just a consequence, or outcome, of the information already in the DNA.

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