Post-Darwinism: The New Synthesis
A review of Ecological Developmental Biology: Integrating Epigenetics, Medicine, and Evolution,
By Scott F. Gilbert and David Epel (Sunderland, MA: Sinauer 2009).
As a combatant in the evolution wars here in the United States and abroad, I have penned and processed quite a few papers on the interpretation of evolution.1 This means also reviewing the vast literature in evolutionary psychology, particularly its attempts to explain religious behaviors.2 I am convinced that most of what is transmitted and consumed in the way of popular accounts of genetics and evolution by and for philosophers, theologians, and lay readers is pretty much bunk. This is not a question of whether evolution is true. The weight of the evidence for evolution is conclusive. The mythological literalism of the Young Earth Creationist is delusional and Intelligent Design is more of the same confusion.3 That is not what this review is about. The problem is that the popular accounts of how evolution and genetics actually work are so simplistic as to be misleading. These popular accounts then serve as the basis for philosophical and theological interpretations of evolution and genetics, so we, the philosophers and theologians, are getting the current state-of-the-science wrong. The simplistic views of evolution and genetics are also uncritically adopted in the emerging field of evolutionary psychology, where they are applied to understanding human behavior, including religious behavior. I have nothing against evolutionary psychology in principle; it is just that the paradigm being applied is too simplistic. And if it is not true of plants and animals, it certainly will not be true for complex human cultures.
Espalier, 60x48" Oil/Mixed Media. © 2009 Jeanie Tomanek. www.jeanietomanek.com
Ecological Developmental Biology, the new textbook4 by biologists Scott F. Gilbert and David Epel5 is the antidote to these deficits in the public understanding and scholarly interpretation of biology. And while biologists and their students should certainly read this book, I want to make the case in this review for why philosophers, theologians, bioethicists, environmentalists, and evolutionary psychologists should be required to read this book. Anyone who purports to teach and interpret evolution and genetics to the public should read this remarkable book. Indeed, policy-makers and homemakers will find much relevant to public health and safety in these pages.
The book is divided into three parts, involving ten chapters, a philosophical coda, and four appendices. Unlike most biology textbooks, this book actually has a plot and a dramatic denouement. Unique also is that Ecological Developmental Biology includes an insightful history of the evolution of evolution, which as a discipline has itself sometimes been “red in tooth and claw.” An outsider might otherwise have no idea about the interesting scientific and ideological battles waged within the field. Moreover, since the book is intended for a heterogeneous audience across the biological sciences, it carefully explains its vocabulary and contains numerous charts, diagrams, and photographs. This is important since the languages of science are not the languages of philosophy and theology. (It is amazing how many humanists in the academe have not cracked open a science book since high school.)
Part one examines “Environmental Signals and Normal Development,” which will charm the reader with many details of strange and familiar species that change their phenotype based on their environment. In chapter one, we learn how the environment signals an organism to develop different phenotypes. In chapter two, we learn how other organisms, for instance predators or siblings, also affect gene expression in the maturation of organisms. Chapter three explores the central role of symbiosis and co-development in the life of species. In chapter four, we learn of embryonic defense mechanisms.
Why should one care about these disciplinary details? The full story will not be apparent until part three, the coda, and the appendices, but Gilbert and Epel mention early on that genetics has been the dominant paradigm in biology since World War II. There has been a “marked antipathy against the notion of phenotypic plasticity and the inheritance of nonallelic phenotypic variations…” (8) They write:
…the environment is not merely a filter that selects existing variations. Rather, it is a source of variation. The environment contains signals that can enable a developing organism to produce a phenotype that will increase its fitness in that particular environment. This isn’t the view of life usually presented in today’s textbooks or popular presentations of biology (8).
The authors call this dominant view “geneticism.” James Watson, who won the Noble Prize for his part in discovering the Double Helix, writes:
We used to think our fate was in the stars. Now we know in large measure, our fate is in our genes”
Watson here is giving expression to genetic determinism, the myth of the “master molecule.” He has been aided and abetted in promoting these misconceptions by Richard Dawkins and a host of others. We learn that genetic determinism is a fallacy.6 We might just as well talk about environmental determinism. The distinction between nature and nurture is a false dichotomy in biology. It is nature-nurture and nurture-nature all the way down to the level of gene encoding and expression. Gilbert and Epel write:
In standard embryology, the focus has always been on the internal dynamics through which the genes of an individual’s cell nuclei produce the phenotype of the organism. Within the past century, we have discovered that cell-cell communication is the key to this phenomenon. By itself, the genetic information in a cell’s nucleus cannot directly produce the many differentiated cell types in a multicellular organism; cells must interact, reciprocally instructing each other as they differentiate (9).
It is not just cell-to-cell interactions that effect the differentiation of cell types in multicellular organisms, but all kinds of environmental factors as well. There are temperature-dependent pathways, nutritional-dependent pathways, pressure-dependent pathways, predator-induced pathways, maternal-care dependent pathways, and conspecific dependent pathways (the effects of siblings and close relatives). Depending on the kind of species, these environmental determinants can radically change how an individual looks, acts, and whether and when it develops into a male or female adult. Some of these environmentally induced changes in gene expression are heritable, passed on to the next generation, in violation of the “Central Dogma” still found in biology textbooks today. And that’s just the first two chapters of this book. All of this is normal biology and there are plenty of entertaining examples.
Chapter three we learn of developmental symbiosis. Far from being competitive, much of evolution is about cooperation. You need only consider your own body, a multicellular collaboration of trillions of eukaryotic cells coming in some 214 tissue types which began once upon a time as a single, undifferentiated zygote in your mother’s womb. However, it is estimated that 90 percent of the cells in your body, by number not mass, perhaps as many as 100 trillion (1014) are not “yours” at all, but are a rich ecosystem of up to 1000 different microbial species living in your intestines (98).7 These bacteria not only provide a number of nutritional benefits to us, as we do for them by consuming three-square meals per day, they also help regulate gene expression in the development of intestinal cells.
The boundaries of identity in modern biology are up for grabs. Whatever the individual organism may be, it is not contained within the boundaries of epidermis, membranes, or genomes. The individual is always internally and externally composite and interactive. The individual is always an interdependent variable. The organism is a “social construction.”
My favorite example from Gilbert and Epel’s book is the protozoan Myxotricha paradoxa, a symbiont found in the gut of an Australian termite, which helps in digesting cellulose. M. paradoxa, however, is itself a symbiont, containing within its cell membrane the separately replicating genomes of a protist and three species of bacteria (97).8 All of life is Anima paradoxa.
It would be nice to have a simple theory of evolution, as Darwin has provided in his elegant algorithm, but the catechism of random drift, universal struggle, survival, reproduction, and differential selection just doesn’t hack it anymore.9 It is time to embrace complexity, symbiosis, multi-level selection, contextuality, and as we will see, even some aspects of Lamarckianism.10 Along the way we can banish the geneticist dogma of “selfish genes,” because genes do absolutely nothing by themselves. Indeed, it is equally valid and descriptively accurate to talk about “sharing genes.”11
Part two examines ecological developmental biology and diseases and it is here that the regulators, policy-makers, and homemakers should pay close attention, because birth defects, cancer rates, infertility, and intersexuality, as they relate to environmental pollutants take center stage. Chapter six on endocrine disruptors is particularly disturbing and worthy of careful study, because pollutants affect development differently at different stages. Most product safety testing, for instance, does not test the impact of chemicals on fetus development, but as we learn, the presence of trace chemicals in the environment can have dramatic impact on gene expression differentially at different stages in the development of embryos or young adults. This book documents the dramatic rise of testicular cancer, breast cancer, and hypospadias (deformity of the penis), all accompanied by an equally dramatic drop in sperm count (214). Such disorders are not primarily "genetic" in origin, but thought to be caused by endocrine disruptors in the environment altering gene expression, i.e., epigenetic. Compounds found in soy products (estrogenic chemicals), pesticides, herbicides (atrazine), sunscreen (4-MBC), plastics (bisphenol A or BPA), and electronics (polychlorinated biphenyls) are all thought to be involved in endocrine disruption in humans and other species. Note that all of these chemicals affect organisms differentially at different stages of development. Note also that some of these effects have been demonstrated to be transgenerational, i.e., the phenotypic effects are passed on to the next generation. It seems we are threatening our health, our fertility, and our survival with the proliferation of certain chemicals in our environment.
Part two, however, is a side story to the main thesis, which the authors begin in part three – “Toward a Developmental Evolutionary Synthesis.” This section will most interest philosophers and theologians who try to interpret evolution, because it is here that Gilbert and Epel develop the idea that Neo-Darwinism – the combination of Darwinian natural selection with modern genetics also known as the Modern Synthesis – is no longer adequate biology. Chapter eight provides the history and theoretical background. Chapter nine argues that “without the integration of developmental genetics and developmental plasticity into [evolution], evolutionary biology has no complete theory of variation” (323). Here they focus on developmental regulatory genes (e.g., Hox complex). In chapter ten, they propose a “New Synthesis” between environment, development, and evolution.
The book contains four appendices of special interest: two are historical and two are technical. Appendices A and C are the historical pieces, fascinating essays that review the collapse of developmental biology in continental Europe (the indirect results of Stalinism and Nazism) and how developmental biology was written out of the Modern Synthesis in post-war Anglo-American science. These essays are fascinating behind-the-scenes glimpses at how ideologies and history impact the making of science and meaning in the modern world.
Appendices B and D are technical discussions of the molecular level processes by which epigenetic changes occur in the development of an organism (i.e., changes in the DNA that alter the expression of the gene rather than the DNA sequence of the gene) and how these epigenetic changes can then be passed on as inheritable traits (i.e., what Eva Jablonka has called “Neo-Lamarckianism”). It turns out that gene function can be deleted more easily by altering its expression (epigenetics) than by altering its sequence (genetics).
I must confess that a lot of this technical material was very hard for me to follow given that I am not formally trained in biology. Fortunately, I was able to get a memorable tutorial on DNA methylation from my daughter, Maisy Grassie, now a second-year student in veterinary medicine at the University of Pennsylvania. Both the institution and my daughter are wonderful examples of Lamarckian evolutionary processes at work in human culture. That human culture evolves in a Lamarckian pattern throws a wrench in evolutionary psychology, which tries to explain complex cultural formations through the lenses of survival and reproduction.
The real gem in Gilbert and Epel’s book, and the reason I am writing this review, is the coda entitled “Philosophical Concerns Raised by Ecological Developmental Biology.” If nothing else the philosophers and theologians really need to read this section, because it opens up the territory for much more realistic and productive reflections on the interpretation and meaning of evolution and genetics than we are normally exposed to in the popular and scholarly literature. This section is divided up into discussions of ontology, pedagogy, epistemology, and ethics. The longest section is on ontology, proving once again that metaphysics is politics by other means. How we interpret evolution has implications for everything from political economy to childrearing to religion.
The first problem in reconceptualizing ontology in light of the New ynthesis is that the individual has disappeared. “Individuality is illusionary,” write the authors. There is no spatial definition of an organism simply “contained” in an epidermis, a membrane, or a genome. “At the very least,” write the authors, “the prevalence of polyphenisms and reaction norms instructed by environmental agents abolishes any notion of a genetic determinism” (404). Actually I suppose many examples of genetic determinism remain – for instance, cystic fibrosis or Tay-Sachs disease – but these are now the exceptions and not the rule.
The authors favor integrative philosophical traditions, discussing the Buddhist concepts of co-dependent origination and no-self, and focusing especially on the process philosophy of Alfred North Whitehead, along with the phenomenology of Merleau-Ponty. They understand the organism to be “the concrete, fleshy nexus integrating (in time and space) the internal networks of developmental genetic interactions with the external networks of ecological interactions” (409). All processes are context specific and are examples of reciprocal induction. They quote Donna Haraway: “relationships are the smallest possible pattern for analysis” (410).12
Emergence, which has always been “normative in developmental biology,” is now normative in our understanding of evolution as well as in the new ontology. There can no longer be simple reductionistic explanations of complex phenomena:
Entities need to be thought of in terms of several geometries at the same time. They are defined by the braiding of down-top and top-down (as well as lateral and temporal) networks built from patterns of reciprocal causation (410).
Our understanding of competition and cooperation in nature is also due for revision. “[D]evelopmental symbioses are no longer relegated to marginal exceptional cases,” write the authors. “Rather, they are the norm” (404).
How we conceive of nature is a magic mirror for human society.13 The Anglo-American tradition of evolutionary biology finds in nature the ontology of Smith, Locke, Mills, and Hobbes. “Just as the wooden pencil was created from self-interested individuals, so was the tree from which the wood came.”
The tradition of embryology, however, was oriented toward the European continent and found its philosophical underpinnings in the emergent forms of Immanuel Kant and Wolfgang Goethe. Embryology embraced both mechanistic and teleological views of the organism. “Interdependence, harmony, and integration” is “a different perspective on nature than the autonomous, competitive nature of classical evolutionary biology.” Gilbert and Epel are not promoting an either/or choice, rather “in addition to Locke and Hobbes, we have Kant and Goethe” (406).
Group selection theory, an “outlier” in Anglo-American biology, is now central to any adequate evolutionary theory:
Both traditional evolutionary biology and existentialism grow from the soil of Hobbesian competition and individuality. While ecological developmental biology similarly postulates that we are defined, in part, by the “other,” it depicts our identities as becoming with the “other.” (407)
The authors have given us a new dialectics of nature: process and relations, emergence and reduction, self and no-self, individuals and groups, cooperation and competition. If that seems like a muddle, it is because that is what life turns out to be. As Whitehead warned:
The aim of science is to seek the simplest explanations of complex facts. We are apt to fall into the error of thinking that the facts are simple because simplicity is the goal of our quest. The guiding motto in the life of every natural philosopher should be, Seek simplicity and distrust it.14
It is time to jettison the simplicity of the Darwinian algorithm and geneticism. Life is a “social construction” of interdependent variables. This insight provides a much more interesting possibility space for doing constructive and realistic philosophies and theologies of nature than we have been led to believe was the case by the sometimes shrill proponents of ultra-orthodox Darwinism.15
All of this has implications for education and research. In terms of pedagogy, Gilbert and Epel call for the integration of developmental biology into the teaching of evolution, genetics, ecology, and medicine. While I can appreciate the integration of developmental biology in these other disciplines, I would also be interested in how the pedagogy itself, as opposed to the content thereof, might actually be transformed by these insights.
In terms of epistemology and methodology, Gilbert and Epel suggest that we get away from using model systems. They note that six model systems have dominated biological research – the fly Drosophila, the frog Xenopus, the nematode Caenorhabditis, the mammal Mus, the bird Gallus, and the zebrafish Danio – and that each was selected for laboratory studies in part because of the absence of major environmental factors, so of course biologists failed to understand the ubiquitous role of the environment in gene expression and evolution (412). They pose a series of research questions:
What does evolution look like when the proper unit of analysis is not the individual but the relationship (at each different level)? What does evolution look like when selection may be on ‘teams’ of organisms and on the relationships between these teams? What does natural selection mean when the environment is not only an agent that selects adaptive phenotypes but also contains agents that help instruct the formation of adaptive phenotypes (and may undergo changes itself because of it?) Moreover, how do we revise our views about the environment and evolution when germline DNA methylation can effect the transmission of environmentally induced characters from one generation to the next? (414)
Finally, Gilbert and Epel wonder about the ethical and policy implications of the New Synthesis. Policy gets short shrift here, though they address those implications elsewhere in the book. They cite here only one example: 88 percent of breast cancer is thought to be caused by the environment. The so-called “cancer genes” BRCA1 and BRCA2, account for only 5 to 10 percent of breast tumors. They warn that “Our emphasis on the genetic component of this disease appears to be dangerously misplaced” (415).
I wonder whether we might enlarge this policy discussion substantially, including not only public health and safety, but ways that the New Synthesis might help address problems in the “science wars,” as well as the problem of general science literacy. The relational and process ontology explored here is much more conducive to romantic and even comic readings of evolution than the Stoic and existentialist interpretations promoted today.16
The take-home message and the ethical bottom line is that the stories that scientists tell matter! We need new and better stories about nature:
Scientists have a moral imperative to tell accurate stories. Scientific stories must always fall within the limits of the existing data. Evolutionary narratives are the most critical stories in biology, in science, and perhaps in Western civilization, so we had better get them in line with the biological data (415).
This brings me back to my opening observation. Many of the public interpreters of evolution are doing a disservice to the current state of the science and therefore also to our ontologies, our epistemologies, our pedagogies, and our ethics. These oracles of science are then read and debated by philosophers and theologians, replicating the distortions and distorting our interpretations. It is time to give Richard Dawkins a rest and read something new that is, if not revolutionary, at least evolutionary in our understanding of biological complexity and the theory thereof.17
“The image of man affects the nature of man,” observed Rabbi Abraham J. Heschel. “We become what we think of ourselves” (415). We cannot avoid the Naturalistic Fallacy; the only question is how to relate the “Is” and the “Ought.” Let’s be sure we use science to the best of our ability to get the “Is” of nature as accurate as possible, because we will surely morph that “Is” into political economy, social policies, behavioral norms, and child-rearing practices. Gilbert and Epel note that “If we think of ourselves as killer apes, certain behavioral phenotypes are acceptable that would not be socially allowed if we view humans as the current apex of an evolutionary trend towards cooperation” (415).
Gilbert and Epel are not just specialists in the intricacies of biology, but reveal themselves to be sage philosophers: “One has to know what is true in order to do what is good” (416). The truth of our planet, however, is changing rapidly and dramatically, as humans engage in large-scale environmental engineering and prepare to embark upon large-scale genetic engineering of the other species and ourselves. Humans are a Lamarckian wildcard in the Epic of Evolution. Our thoughts about nature not only transform our human nature, they are literally transforming our planet and therefore also the future evolution of all life. We live in the Anthropocene, a new era in evolution in which humans dominate the biosphere with unknown consequences. The authors call for an “ethics of flourishing and well-becoming” adequate for the Anthropocene:
Ecological developmental biology fosters an ethic that can integrate both selfishness and otherness, as one might expect of a discipline where self and other mutually construct each other (417).
So I am bullish on Scott Gilbert and David Epel’s remarkable book, Ecological Developmental Biology (2009). My only problem is that it needs a better marketing strategy in our information-saturated world if it is going to have the impact they envision within and outside the guild. “Eco-evo-devo” won’t get very far. Better to sin more boldly and simply declare “Post-Darwinism” in this the two hundredth anniversary year of Charles Darwin’s birth and the hundred-fiftieth anniversary year of The Origin of Species. It seems to me that Post-Darwinism is a better designation for the New Synthesis and for what comes after Neo-Darwinism, by which I mean no disrespect for Charles Darwin, a remarkable scientist and human being, but surely evolution has evolved and we better, too.
Post-Darwinism does not mean that "Darwin is pass�." On the contrary, his name and ideas are appropriately enshrined in the very title, a title which is also a warning. The elegant simplicity of the Darwinian algorithm is misleading, as is the geneticism of Neo-Darwinism. Life is a “social construction” in innumerable, context specific biochemical, multicelluar, and ecological niches. There is even more grandeur in this new view of life!
1 William J. Grassie, "Re-Reading Economics: In Search of New Economic Metaphors for Biological Evolution," Metanexus Global Spiral 8, no. 2 (2007), http://www.metanexus.net/Magazine/ArticleDetail/tabid/68/id/9932/Default.aspx.; ———, "Toward a Constructive Theology of Evolution," AFT, http://www.grassie.net/articles/2003_theologyofevolution.html.; ———, "Biocultural Evolution in the 21st Century: The Evolutionary Role of Religion," Metanexus Global Spiral, http://www.metanexus.net/Magazine/tabid/68/id/9301/Default.aspx.
2 John Cartwright, Evolution and Human Behavior: Darwinian Perspectives on Human Nature (New York: Palgrave, 2000).; Joseph Bulbulia et al., eds., The Evolution of Religion: Studies, Theories, & Critiques (Santa Margarita, CA: Collins Foundation Press,2008).; Jay R. Feierman, ed. The Biology of Religious Behavior: The Evolutionary Origins of Faith and Religion (Westport, CT: Praeger,2009).
3 William J. Grassie, "Beyond Intelligent Design," http://www.metanexus.net/magazine/tabid/68/id/9284/Default.aspx.
5 Scott F. Gilbert is a Professor of Biology at Swarthmore College. As an undergraduate at Wesleyan he studied biology and religion (1971). He earned his PhD in Biology at Johns Hopkins University along with an MA in the history of science (1976). His textbook on Developmental Biology is now in its eighth edition. David Epel is Professor Emeritus in Marine Sciences, Cell and Developmental Biology at Stanford University. He earned his Ph.D. at the University of California at Berkeley, and was president of the American Society for Cell Biology in 1972. Both Gilbert and Epel have received numerous research and teaching awards, including a pair of Guggenheim Fellowships.
6 This is probably too strong a statement. In most cases, genetic determinism is a fallacy, but in some cases of particular diseases – cystic fibrosis, sickle-cell, Tay-Sachs – we can still talk of genetic determinism in the strong sense. These are rare examples.
7 “If you were to count them, you’d find that microbial cells outnumber your own by a factor of 10. On a cell-by-cell basis, then, you are only 10 percent human. For the rest, you are microbial. (Why don’t you see this when you look in the mirror? Because most of the microbes are bacteria, and bacterial cells are generally much smaller than animal cells. They may make up 90 percent of the cells, but they’re not 90 percent of your bulk.)” Olivia Judson, "Microbes 'R' Us," New York Times /em>, <a target="_bla
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