Reviewed: Peter J. Bowler, Darwin Deleted, Imagining a World Without Darwin, University of Chicago Press, 2013, 328 p.
What if Charles Darwin had never voyaged around the world in the 1830s? What if he had never witnessed the earthquake in Concepción, Chile or collected the iconic finches from the Galápagos Islands? What if, in fact, he had been washed overboard early in his trip and remembered only as a capable naturalist-in-the-making and a pleasant, if perpetually seasick, companion to the ship’s captain?
Welcome to the world of Darwin Deleted, the latest monograph from historian Peter J. Bowler. For many people, Darwin’s name is synonymous with evolutionary theory. But for Bowler, who has authored such influential books as The Eclipse of Darwinism and The Non-Darwinian Revolution,  it’s quite clear that evolutionary theory often did not align with the ideas of Darwin. In fact, in the decades following 1859, when Darwin’s On the Origin of Species was first published, evolutionary conceptions flourished, but their content had little to do with Darwin or his core mechanism of evolution, natural selection. And it is this proliferation of non-Darwinian theories of evolution that provides the credible foundation for the counterfactual world that Bowler postulates here. Evolution was certainly “in the air” in Darwin’s time, but natural selection was not—and in Darwin’s absence, other models of evolutionary change would have gained even more scientific and cultural power.
The first six chapters of Darwin Deleted follow the development of evolutionary ideas, from Darwin’s time into the twentieth century, identifying both Darwinian and non-Darwinian strands of evolutionism and placing them in their scientific and social contexts. Bowler draws distinctions between Darwin and his contemporaries, showing how the particular convergence of life experience, education, and social status afforded Darwin a unique view of life and the privilege of focusing intensively and exclusively on its elaboration and validation over many years. Because Darwin Deleted has been published in the centenary year of Alfred Russel Wallace’s death, it’s valuable to have a clear presentation of the current historical consensus on the relationship between Darwin and Wallace in particular. There is little doubt: in the absence of Darwin, Wallace would have had neither the resources nor the inclination to launch a revolutionary theory of individual natural selection—indeed, his ideas about evolutionary change were notably different from Darwin’s, as Bowler articulates here.
Rather, it would not have been until the 1890s that a theory like natural selection would have surfaced, with the work of biometricians W. F. R. Weldon and Karl Pearson. Their statistical view of individual variation within a population became—in our world—one locus of support for Darwinian natural selection. Rather than the Malthusian “struggle for existence,” built into natural selection by Darwin, this counterfactual version would have been more firmly rooted in the newly emerging science of ecology, with its sense of complex interactions between organisms and their environments.
These first chapters, as rich in detail and nuance as they are, are the preamble to the final two chapters, which address the relationship between Darwinian evolutionary theory and society, and provide the motive force behind Bowler’s book. Imagining the relationship between evolutionism and religion in Darwin’s absence allows Bowler to explore this relationship in the real world from a new angle. And imagining eugenics and “Social Darwinism” in this counterfactual world—and seeing just how easily they can be imagined sans Darwin—effectively decentralizes Darwin and Darwinism in the history of these social movements.
Deleting Darwin—in order to exonerate him
Bowler’s stated goal in writing this book is to exonerate both Darwin and natural selection of the social ills that have been blamed on them over the years. Had Darwin disappeared in 1832, the injustices of the eugenics movement and "Social Darwinism" would have been perpetrated anyway, with an altogether different figurehead. Even in our own world, the factual one, the work of contemporaries like Herbert Spencer and Francis Galton provided more fodder for these movements than that of Darwin. More than anything else, Bowler argues, Darwin has provided a rhetorical focal point upon which both adherents and critics of racism and oppression have converged.
Bowler begins with the understanding, widely held by historians of biology, that the theory of natural selection was shaped by the individualistic, free-market economic values that predominated in Darwin’s milieu, the “heyday of Victorian capitalism,” as he writes.  But following the lines of influence in the opposite direction, from science to society, is far more difficult. Rather than cause social phenomena, Bowler argues, Darwinian theory more often provided a source of metaphors and justifications. This distinction is best appreciated in light of the fact that many social ideologies claiming Darwinian support have been mutually incompatible with each other. It is logically incoherent, Bowler says, to blame Darwinism for both an individualistic, free-enterprise model of human struggle and an imperialist model, in which races and nations struggled for existence; yet Darwin has been invoked in both cases. Based upon such examples, Bowler convincingly argues that connections between Darwinism and social ideologies were connections of “rhetoric, not substance.” 
Because we have ample evidence that Darwinism has been applied to widely divergent social ends, it’s easy to imagine that a different sort of evolutionary theory would have fit the bill. And Bowler is certainly an expert on the non-Darwinian models of evolution that thrived both before and after the Origin was published in 1859. In the late 19th-century, scientists who compared embryological development in different animal species, like Ernst Haeckel, conceived of an evolutionary process that resembled embryological development, an unfolding along a predetermined pathway. Even the earlier evolutionary theory of Jean-Baptiste Lamarck, which (like Darwin’s subsequent theory) emphasized adaptation to the environment, saw evolution as progressive, leading to higher, “improved” forms of life. In contrast with these progressive and purposeful models of evolution, Darwin’s model was open-ended and did not hinge on any absolute standard of “improvement.” Because the environment is always changing, adaptation shifts in response; there is no single ideal toward which to strive and no predetermined progression. Bowler argues that in the absence of Darwinian evolution, the ideas of Haeckel and Lamarck would have gained even more traction. With their strong notions of “higher” and “lower,” non-Darwinian models of evolution made for even more powerful social ideologies, providing a basis on which to argue that particular human qualities and, indeed, entire social groups were superior to others.
Evading conflict between evolution and religion
Such progressive and purposeful non-Darwinian models of evolution were also more acceptable to religious thinkers. The notion that evolution led to an ultimate improvement in organic life allowed humans to continue to imagine themselves at a pinnacle, even if it was no longer the pinnacle of creation, but the pinnacle of an evolutionary progression. Darwin’s model of evolutionary change by natural selection, in contrast, was not only open-ended and non-progressive, but also harsh and mechanistic. According to Bowler, in challenging the benevolent view of nature cultivated by Christianity, Darwinism was responsible for the virulent opposition that seems to exist between religion and evolution in western society. Darwin provided a focal point for tensions and anxieties that might have remained more diffuse in his absence. In a world without Darwin, evolution would have continued to embody an upward motion, moving toward a higher organic and moral goal. This sustained belief in a progressive model of evolution, Bowler writes, would have provided an accommodation between evolution and religion.
The relative roles of determinism and contingency in history
While the relationship between Darwinism and social phenomena are overriding concerns of Darwin Deleted, another critical theme concerns the roles of determinism and contingency in history. Do larger forces or patterns predetermine the unfolding of history? Or can a single individual or a random event alter its course? In Bowler’s account, these questions are equally relevant to human history and the evolutionary history of organic life.
In order to consider counterfactual history, a historian must accept the power of contingency: History does not proceed along a predetermined course and it may instead change direction as a result of random events. In our case, a seasick young naturalist is swept off the deck of a ship in 1832 and the emergence of the theory of evolution by natural selection is delayed by several decades. By contrast, an opposition to counterfactual history may rest on some form of historical determinism. In the case of evolutionary theory, one determinist might argue that the social and economic force of industrialization, with its ethos of competition, made the emergence of natural selection, which naturalized the very concept of individual struggle, an inevitable product of Darwin’s era, with or without Darwin the man. A different determinist might instead argue that the theory of natural selection was inevitable because it is an accurate depiction of how organic evolutionary change actually happens in reality.
In discussing these two general positions, Bowler reveals himself to be a moderate, committed strongly to the power of the social environment and the nature of biological reality, and yet also deeply interested in the historical “nodes” at which “history could have been switched onto a different track.”  As a historian of evolutionary biology, my ears pricked up at this language, which conspicuously echoes the terminology of both evolutionary biology and developmental biology. A “node” is a historical point where an evolutionary lineage splits into two separate lineages; for some contingent reason, such as geographical isolation, one species becomes two species. But to speak of “different tracks” simultaneously suggests developmental pathways, those predetermined possibilities that exist in the development of an individual organism, like the embryological sequences generated by Haeckel in the late nineteenth century. And to combine the two—evolution and development—evokes a tension that has defined biology since the time of Darwin; a tension between two views of biological nature, which, like the two views of human history described above, appear to pit contingency against determinism. But in Darwin Deleted, Bowler is not arguing for the predominance of contingency over determinism. Instead, he is arguing for the value of both—in both history and in evolutionary biology.
From evolution and development to evo-devo
The study of embryological development, as I have already said, suggested a progressive model of evolution to many of Darwin’s contemporaries and successors. Darwinian evolution, by contrast, denied such predetermination and emphasized instead the importance of variation within populations and the power of chance in history. Historians of biology agree that this tension resulted in the marginalization of developmental biology in the early twentieth century, as Darwinism and genetics were united and gained ascendancy. But what if, in a counterfactual world, in Darwin’s absence, developmental biology had been allowed to gain and keep its predominance? According to Bowler, Darwin’s disappearance would have created a critical space for developmental biology to flourish and, with the later emergence of selection, be more easily synthesized into modern evolutionary theory. Much like the relationship between evolution and religion, Bowler suggests that the tensions between evolutionary and developmental biology would have been eased in this counterfactual world, and two perspectives that were at odds might instead have reached an accommodation.
In our world, however, the rapprochement between evolutionary and developmental biology began only a few decades ago, with the emergence of evo-devo (evolutionary developmental biology), a field that combines an appreciation for the contingency of natural selection with a comprehension of the constraints placed by ancestral developmental pathways. Gone are the days when the “gene” is a simple, unitary blueprint for a character that may be simply selected for or against in a particular environment. Instead, biologists today see DNA, developmental processes, and the environment interacting in complex ways that are reminiscent of—though far from identical to—the non-Darwinian developmental models of evolution so popular in Darwin’s time.
This real-world accommodation of evolutionary and developmental biology is the subtext that drives Darwin Deleted and, in my opinion, it is also what makes this book an original and important take on the history of biology. Historians of science, Bowler included, worry that counterfactual histories might appear to undermine the validity of science: If science could have taken multiple plausible pathways, depending on contingent events, then how can it claim to produce objective knowledge about reality? In Bowler’s own words, this fear is based on the assumption that “[s]ince there is only one real world to investigate, there can be only one way to uncover its secrets.” To challenge that “one way” appears to imply “that theories are human constructs that have no anchor in the real world.” 
But each theory is a model of the world that, alone, has little hope of capturing the complexity of the real world. Rather than mutually exclusive alternatives, Bowler argues, Darwinian evolutionary theory and developmental biology are both models that capture something important about the nature of biological reality. Thus, far from challenging the ability of science to get at the nature of biological reality, Bowler’s counterfactual history actually affirms it, by demonstrating how the same models of biological reality would emerge under different historical conditions. “Modern evolutionary developmental biology (evo-devo) has encouraged us to recognize not that Darwinism is wrong, but that it might not be telling the whole story,” Bowler writes. “And some of its “new” perspectives bear a striking resemblance to themes that were once popular alternatives to the ones explored by Darwin.”