Why is the EES contentious?

Evolution by natural selection requires that: (i) variation exists between individuals, (ii) some variants leave more descendants than others, and (iii) offspring resemble their parents. Organisms fulfil these criteria and so they evolve, adapt and diversify, but this description is too general to do much explanatory work. Evolutionary biologists need a way to think about the three principles of evolution by natural selection that is realistic enough to apply to real organisms, but simple enough to guide research.

For about a century, a genetic representation of the three principles has dominated evolutionary theory. The genetic representation does not only describe evolution in terms of genes, it also makes assumptions about the causal relationships between the three criteria for evolution by natural selection. For example, heredity and development are considered separate processes. There is nothing inherently wrong with this, but it is important to realize that the genetic representation is a viewpoint, and not necessarily a true representation of nature.

There may be other descriptions of biological causation that are better suited to answer interesting questions about evolution. The Extended Evolutionary Synthesis (EES) is such an alternative way to think about the nature of development, the construction of heredity, and the causes of evolutionary change and adaptation. The Darwin review entitled The extended evolutionary synthesis: its structure, assumptions and predictions is a first attempt to define the assumptions of the EES, describe the key ideas that lend it coherence, and specify some distinctive predictions.

Conceptual frameworks, and their research programs, can’t be proven right or wrong with a single experiment; they should be evaluated on the basis of the research they inspire. For illustration, no experiment would disprove the gene-centric perspective that adaptive evolution proceeds through differential survival of competing genes, but a research program can support or disprove predictions that follow from this way of thinking. This research program is entitled Putting the extended evolutionary synthesis to the test exactly because it is perfectly possible that the research will show that some of the hypotheses motivated by the EES are well-founded, whereas others may turn out to be of limited importance, or simply wrong.

Many researchers are attracted to the EES concept as a positive opportunity to conduct new exciting research into evolutionary biology. Initially the EES was not yet well-specified, which meant it possessed limited capacity to stimulate novel research, and was difficult to evaluate. Scientific ideas are most useful when assumptions and hypotheses are laid out clearly. Accordingly, a team of experts on various topics (evolutionary genetics, ecology, epigenetics, evolutionary developmental biology, and philosophy of science) came together to try to add substance to the concept. The result was published as Proceedings of the Royal Society B’s Darwin Review of 2015. It demonstrates that the debate surrounding the EES is not about the neglect of phenomena, such as developmental plasticity or epigenetic inheritance, but rather about the implications of these findings for the structure of evolutionary theory. There is a middle ground between revolution and business as usual and this is where the EES research program sits. The objective is to conduct distinctive, novel research with the potential to bring profound change in how evolutionary biology is understood.

All recognized causes of both evolution (e.g. natural selection, genetic drift, mutation, etc) and inheritance (e.g. genes), as well as the vast body of empirical and theoretical findings generated by the field of evolutionary biology, are accepted by the EES. Hence the EES does not entail a rejection of current understanding within the field, and does not require revolution. The EES seeks only to supplement the existing causal framework through recognition of additional causes of evolution (e.g. developmental bias) and inheritance (e.g. epigenetic inheritance), entirely complementary to those long-established within the field. Nevertheless, should these additional processes prove to be important, the conceptual change to evolutionary biology could very well be fundamental.

The benefits of defining an extended evolutionary synthesis are twofold. Firstly, alternative perspectives are useful in that they can motivate research that is unlikely under the dominant view. No single framework can support all interesting avenues for research. The hope is that the EES is sufficiently different from traditional viewpoints to stimulate new questions, generate new answers, and thus bring more insights into the causes of evolution.

Secondly, it is important to recognize that different ways of representing biological processes influence the structure of evolutionary theory and the nature of evolutionary explanation. It is helpful to specify these as it can reduce the risk of disagreement from misunderstanding. For example, one of Mayr’s main goals with his promotion of the distinction between proximate and ultimate causation was to formalize understanding of, and communication around, biological causation. Unfortunately, Mayr did not realise that the distinction need not hold if one rejects the genetic representation of the three principles of evolution by natural selection. The proximate-ultimate distinction therefore eventually became a hindrance to communication because it seemed to rule out the possibility that developmental causes can be evolutionary causes.

The EES has been met with both enthusiasm and skepticism. The majority of responses to the EES research program are extremely supportive, but there are of course those who claim that the EES is not going to do any good. The skepticism is to some extent warranted, as the EES has yet to prove itself a vehicle for productive research within evolutionary biology. That is why this project sets out to put EES predictions to the test with a dedicated research program. The project aims to show that, precisely because it is spelled out in a disciplined way, the EES can stimulate novel questions, devise critical tests, open up new lines of enquiry, and provide insights that are unlikely under traditional perspectives.

Absolutely not. These portrayals are extremely misleading and this project disavows any such claims. The Darwin review (Laland et al., 2015) should make this quite clear:

“[Evolutionary biology is] a highly successful research program” [p1]

“Following the advent of the Modern Synthesis, the field of evolutionary biology has continued to evolve, allowing incorporation of new theoretical and empirical findings” [p2]

“Evolutionary biology has never been more vibrant, and it would be a distortion to characterize it as in a (Kuhnian) state of ‘crisis’ ” [p10]

“the EES requires no ‘revolution’ ” [p10]

There are some other researchers who do criticize the field of evolutionary biology using inflammatory language (e.g. Fodor & Piattelli-Palmarini, 2010). This is strongly discouraged within the project and seen to be unjustified. However, individual scientists have the right to think differently and to express their views in the manner they see fit without vilification.

The EES research program represents a sizeable and growing community of researchers, spanning multiple disciplines. As the Darwin review states:

“the EES is a developing line of contemporary evolutionary thought that exists within the field.” [p3]

The scientists and philosophers running this research program are all highly respected in their fields, with exceptional track records. They publish in top journals, participate in prestigious conferences, and are the recipients of multi-million dollar grants, which could not happen if independent editors, reviewers, and committee members did not feel their ideas are worth taking seriously. EES research involves, and is endorsed by, numerous academics, including members of the National Academy of Sciences, Fellows of the Royal Society, Fellows of the American Association for the Advancement of Science, members of other national academies, a former President of the European Society for Evolutionary Biology, the President of the European Society for Evolutionary Developmental Biology, former lead editors of the Journal of Evolutionary Biology, The American Naturalist, Evolutionary Ecology, Theoretical Population Biology and a winner of the Motoo Kimura Prize for outstanding contribution to population genetics. Many people who are not part of the project endorse it. For instance, Mary Jane West-Eberhard, a member of the National Academy of Sciences and world-renowned evolutionary biologist who pioneered research into the role of plasticity in evolution, wrote of the research program:

“This big project is exciting because many of the studies … go to the heart of how Darwinian adaptive evolution works”
Mary Jane West-Eberhard

This criticism is somewhat ironic, as it was the recognition of commonalities and parallel themes amongst independently emerging fields that stimulated the development of the EES research project. In the Darwin review, after discussing key novel findings of research into evolutionary developmental biology, developmental plasticity, inclusive inheritance and niche construction, it states:

“while the lines of research discussed above arose largely independently, there is considerable coherence across topics. Developmental processes play important evolutionary roles as causes of novel, potentially beneficial, phenotypic variants, the differential fitness of those variants, and/or their inheritance…. Thus, the burden of creativity in evolution (i.e. the generation of adaptation) does not rest on selection alone.” [p4]

The paper then dedicates considerable space to describing two key themes – constructive development and reciprocal causation – that unite the distinctive research streams of the EES into a coherent perspective. For more about these concepts, read the article or view our explanatory slideshows.

While the EES research project is supported by a number of funders, the major source is a $8m grant from the John Templeton Foundation (JTF), which has provoked some criticism. This criticism is multifaceted, but includes the claims that (i) JTF funds research that conflates sciences and religion; (ii) the agenda driving the research is not one that came from the scientists themselves, and (iii) the research proposal is not subject to peer review from independent academics. It is not the place of this project to defend JTF, although it should be noted that JTF has been supporting excellent research into evolutionary biology and other topics for many years, and more and more scientists are taking JTF money without experiencing any pressure to do anything except produce high-quality science.  Suffice to say that in the experience of this and related projects, JTF operates with the same academic rigor as any research council or charity, showing no evidence that it pursues any such agenda. Specifically:

(i) The EES research program involves no research into religion. This research program is comprised solely of research into evolutionary biology, evolutionary ecology, developmental biology, theoretical biology, philosophy of science and history of science. Neither the research proposal for the grant, nor any of the 22 individual research projects, mentions religion, God, or theology. Summaries of the 22 research topics can be found on the Research projects page.

(ii) All EES research projects were devised by the principal investigators as extensions of their own research.  Following consultation with, and suggestions from, the Project Leader and Co-Leader, the principal investigator for each of the 22 research projects developed the plan of research with their collaborators. There has been no interference with the science from the John Templeton Foundation.

(iii) The EES research proposal was subject to expert peer review.  The research proposal Putting the extended evolutionary synthesis to the test was subject to vigorous and extensive peer review, with the JTF deploying procedures largely identical to research councils such as the ERC (European Research Council), RCUK (Research Councils, UK), and NIH (National Institutes of Health, USA). Feedback from the (clearly expert) referees’ reports included the standard scientific suggestions, queries and constructive criticisms regarding experimental/theoretical details, to which the project leaders responded with a revised proposal that was eventually funded.

Scientists are passionate about their work, their achievements, and their legacy. So they should be. Some of the sometimes-heated discussion surrounding the EES can only be understood by recognizing that science is done by humans in social contexts. Casting opponents as extremist, and telling people that they are being attacked, are age-old rhetorical tricks to win debate or allegiance. EES critics sometimes claim that the EES is a radical movement composed of people with hidden motives, while some EES supporters believe that a conservative agenda is at play, and that those who hold the purse strings and the power are desperate to cling on to it and protect their intellectual legacy. Some scientists proclaim loudly that everyone with an unfamiliar perspective is wrong, without actually trying to understand the alternative point of view. A few regularly become involved in acrimonious debates, propagating their views via large followings on social media. Without getting into details, it is telling that none of the critiques of the EES to date have addressed, or even cited, the 2015 Darwin Review, which would be the natural way to determine what the EES is all about.

Exchanges between EES supporters and critics need not escalate into mudslinging battle. Instead, researchers should be allowed simply to get on with their exciting science. Readers are recommended to make up their own minds about the legitimacy or otherwise of EES research. In this post-truth world, it becomes even more important that scientists stand up for rational enquiry, relying on evidence and their own reading of the literature rather than authoritative pronouncements. In fact, studies of evolutionary biology in historical and social contexts, pursued by those without vested interests, such as independent philosophers and historians, are strongly encouraged and their analyses highly valued.