This introductory chapter notes the expansion of interest in the history of popular science and its role in shaping the relationship between science and society. It outlines the elements needed to understand how science is popularized, including the work of both scientists and media figures. The chapter then shows how historians now interpret the rise of evolutionism, noting that Darwin’s theory of natural selection was at first challenged by rival views of how evolution works with very different implications for the ascent of life, not all compatible with the image of the ‘tree of life’. The application of these ideas to human origins and to ideologies based on social evolution is noted for its potential impact on how the theory was perceived. All of these positions need to be taken into account to understand how the topic was displayed to the wider public.

In the late twentieth century, television provided more immediate ways of representing the processes of evolution, while the press increasingly seized on debates arising from their human implications. Progress remained an important theme, although the image of a linear ascent to humanity was usually qualified by recognition of diversity. The air of unity promoted in the synthesis era evaporated as biologists explored new and disturbing implications of the selection mechanism, including sociobiology and the notion of the ‘selfish gene.’ Studies of primates were used to throw light on human behaviour. Along with new challenges to the plausibility of the Darwinian theory, the resulting controversies were played out in a blaze of publicity. Darwinism also had to be modified to take account of growing evidence for discontinuities in the ascent of life, including mass extinctions. Creationists presented these ‘Darwin wars’ as evidence that evolutionism was losing its credibility even within science.

In the 1920s and 1930s the Darwinian selection theory was linked to genetics, providing it with a secure foundation, although wider dissemination of this initiative was limited until the 1940s. Historians note that the ‘evolutionary synthesis’ was a rhetorical device to create an impression of unity, leaving the various disciplines involved still functioning independently. Radio now became an important means of disseminating science news, as in the 1959 celebrations of the centenary of the Origin of Species. The new version of Darwinism eroded the plausibility of eugenics and race theory, although these ideologies remained active in less visible forms. Popular accounts of evolutionism now stressed its open-endedness and played down the old assumption that humanity must be the inevitable outcome of progress. Julian Huxley tried to give the synthesis a moral dimension by linking it to his philosophy of humanism, but creationists saw the new initiative in science as a continuation of Darwinian materialism and renewed their attacks.

This chapter outlines the development of the theory of natural selection and the events surrounding the publication and reviewing of Darwin’s Origin of Species, especially in non-specialist publications. The different responses in Britain and the United States are noted. The role of supporters such as T. H. Huxley in reaching a popular audience is explored, although their reservations about the adequacy of the theory are also taken into account. Conservative efforts to present evolution as the unfolding of a divine plan provided a very different way of understanding the general idea of evolution. Many popular accounts failed to understand the difference between Darwin’s ‘tree of life’ model and older ideas of a linear ascent toward humanity, especially when dealing with the issue of human origins. In this area, popular interest in the gorilla as a potential ancestral form distracted attention from some aspects of Darwin’s model, as shown in more detail in Chapter 3. The early evolutionism of Herbert Spencer is introduced and his relationship to Darwinism explained.

Dan Janzen and Winnie Hallwachs, his wife and colleague, have spent two lifetimes studying ecological interactions between organisms, mostly at Area de Conservacion Guanacaste (ACG) in northwestern Costa Rica. Early in his career, Janzen investigated many basic questions in evolutionary community ecology. One study of plant reproductive success and life history strategies showed that legume species use one of two alternative strategies to reproduce successfully – producing huge numbers of tiny defenseless seeds or small numbers of large, well-defended seeds. A second study explained high biological diversity in rainforests as arising because baby plants survive poorly near their parents (because seed predators consume them there), and only become established a considerable distance away from them. He also emphasizes that current selection pressures may differ from historical pressures, so it is critical to understand ecosystems in the context of their evolutionary history. Both Janzen and Hallwachs have now shifted their focus to inventorying the diversity of Lepidoptera, their parasitoids and host plants at ACG, so that their complex interactions can be understood by researchers and by students who use ACQ as a natural classroom.

More than most researchers, Bernd Heinrich’s research is rooted in his background as a naturalist, and his powers of observation. He knew his study species very well, so he was quick to identify anomalous or surprising phenomena. He was particularly attracted to evolutionary puzzles – traits that on the surface appear to be maladaptive. One example of an evolutionary puzzle discussed in this chapter was an observation of caterpillars tossing parts of leaves down from trees (when they could be eating them). A second example was ravens making a ruckus when they find a large carcass, thereby being forced to share the food bonanza with many other birds they attract to the scene. Both studies show how science is an iterative process, which involves testing and rejecting multiple alternative hypotheses. Heinrich brought his research into the laboratory as well, designing ingenious experiments to explore the mechanisms underlying insect thermoregulation. One theme shaping Heinrich’s research is the connection between the natural environment and how natural selection influences behavioral and physiological patterns.

Threespine sticklebacks, numerous species of disease-causing bacteria, and Darwin’s finches have all shown rapid evolutionary change in response to changing environments. Evolutionary ecologists use a variety of genetic and molecular approaches to study evolutionary change in these and other species. Gene flow, genetic drift, mutation, and natural selection can cause evolutionary change within a population, but natural selection is the only evolutionary process that can lead to adaptation. The benefits and costs of adaptations are environment-dependent and reflect evolutionary tradeoffs, so a trait may be beneficial in one environmental context and costly in a second. Natural selection may lead to speciation when genetic divergence is maintained either by physical barriers to gene flow, or by assortative mating of similar genotypes within a population. Evolutionary ecologists compare morphological, behavioral, and, most commonly, molecular characters in related groups of organisms, and use similarities in these characters to create phylogenetic trees that reflect evolutionary relationships.

Animal behavior is subject to the action of natural selection, favoring individuals that behave in ways that maximize their fitness by promoting individual survival and reproductive success. Cultural evolution plays an important role, with behavioral traits of surprising complexity spreading rapidly through a population. Behavioral ecologists measure the costs and benefits of alternative types of behavior to gain an understanding of basic behavioral processes such as territory defense, foraging, and mating. This cost–benefit approach allows quantitative predictions of behavior tightly tied to fitness, such as how long to guard a mate, or how long to forage at a particular location before moving on. Both physiological factors, such as the need to keep eggs warm, and ecological factors, such as the spatial distribution of resources, can influence the evolution of mating systems. In many species, individuals cooperate with each other in procuring food or defending against predators. Hamilton’s model of indirect selection is one possible explanation for the evolution of behavior favoring relatives, including the astounding degree of cooperation in eusocial animals. But in some species, cooperation is common even among unrelated individuals; in these cases game theory models may help explain the evolution of cooperation.

The theories of Darwin and Wallace were similar, both seeing evolutionary change coming about as a function of a differential reproduction fueled by the pressure to succeed in the struggle for existence.  Darwin and Wallace came to their thinking independently.  The behavior of both men, in what could have been a tense situation, was exemplary.  Wallace sent his paper to Darwin, a postal journey from the Far East to England that took far longer than people expect.  This has led to beliefs that Darwin sat unfairly on the paper, perhaps using it to burnish his own work.  In truth, upon its receipt, Darwin quickly contacted his senior friends Lyell and Herschel, offering to let Wallace have full priority.  Lyell and Hooker arranged for Wallace’s paper and unaltered, pertinent abstracts of Darwin’s earlier writings to be published together in the journal of the Linnaean Society.  Both Darwin and Wallace always felt that matters had been dealt with speedily and honorably.  That said, there were significant differences in the thinking of Darwin and Wallace.  The latter was never comfortable with the metaphor of selection, he always embraced group selection in opposition to Darwin’s determined individual selectionist thinking, and most famously – notoriously – Wallace turned to spiritualism to explain human evolution, spurring Darwin to give an entirely naturalistic explanation is his Descent of Man.

It is widely believed that Darwin’s Galápagos finches inspired his theory of natural selection. Nothing could be further from the truth.  Darwin’s failure to label his Galápagos finch specimens by island, and his lack of useful behavioral observations about the differing diets of these birds, limited his ability to argue that their diverse beaks had evolved by natural selection to fill different ecological niches. For these reasons, these birds are not even mentioned in the Origin of Species. As is well established by historians of science, and as is further supported by Darwin’s own testimony, his revolutionary theory of natural selection was inspired by his reading of Thomas Robert Malthus’s book On Population in September 1838, three years after Darwin’s historic visit to the Galápagos Islands and two years after his return to England on the Beagle.  What Darwin’s Galápagos birds, including the famous finches, helped him to understand is that species often grade insensibly into one another and that varieties, as he later argued in the Origin of Species, are “incipient species.” It was the largely underappreciated existence of this variability among species in nature that allowed Darwin to grasp how natural selection might give rise to new species. Inspired in part by David Lack’s (1947) influential book Darwin’s Finches, the pervasive myth associated with these iconic birds is a classic instance of how important scientific discoveries often become telescoped around a dramatic moment of eureka-like insight, obscuring what typically proves to be a more protracted and conceptually multifaceted processes of scientific innovation.

In 1866 Alfred Russel Wallace, Herbert Spencer, and Thomas Henry Huxley teamed up to urge Darwin to replace ‘natural selection’ with ‘survival of the fittest’ in future editions of the Origin. They felt that the purely ex post facto process suggested by this phrase would undercut the creationist objection that natural selection is haunted by intentional design. However, this is inaccurate. Thinking of natural selection as survival of the fittest leads to confusions between Darwin’s theory and the closely related but different accounts of Wallace, Spencer, and Huxley. Darwin’s own conceptual framework relied on comparing natural selection to the artificial selection of plant and animal breeders to argue for a trans-generational process in which natural selection gradually shape chance variant traits of individuals into adaptations. The notion of survival of the fittest changed that to perceiving natural selection primarily as the executioner of unfit organisms, in the process allowing it to serve as backing for unrestricted capitalism (‘social Darwinism’), racist imperialism, and eugenics.

This is a myth that is ‘good in parts.’ T. H. Huxley certainly emerged as the leading defender of the Origin of Species against critics who believed that organic forms are designed – directly or indirectly – by God. But this does not mean that he accepted natural selection as a complete explanation of how evolution works. The theory suited his naturalistic ideology because it was based solely on observable processes. From the start, though, Huxley cautioned that Darwin needed to show how artificial selection could produce a new species and (more importantly) that he was wrong to rule out the possibility of new characters appearing by abrupt saltations. The latter point is the key to a basic difference between their worldviews. As a morphologist Huxley was not convinced that the fundamental structure of each type could be the accumulated product of a series of small adaptive modifications. He eventually suggested that forces internal to the organism might play a role in directing variation – a position not far removed from that of anti-Darwinians such as Mivart.

Darwin’s theory, in its uniformitarianism, its materialism, and its elimination of all metaphysical explanations and any element of intelligent agency from the world’s biological phenomena has been taken as an important influence in the growth of the idea that all living creatures are automata – more or less “conscious machines.” Darwin himself, in a least four different aspects of his writing, belies this inference from his theories: the metaphorical work done by his dominant idea – natural selection; his anthropomorphism; his views on instinct; and his theory of sexual selection.

Darwin’s Origin of Species [GK26][GK27](1859), despite its almost complete silence about human evolution, was the catalyst for widespread discussion and debate during the 1860s about the history and future of humanity; about slavery and the identity of the human ‘races’; and about competition and struggle in Victorian society. Three popular novels of the early 1860s – George Meredith’s Evan Harrington [GK28](1860), Charles Dickens’s Great Expectations [GK29](1860–61), and Charles Kingsley’s The Water-Babies [GK30](1862–63) – illustrate how quickly Darwin’s ideas were appropriated into fictions dealing with race and social class in the decade of the American Civil War, the Morant Bay Rebellion, and the Second Reform Bill. Although generally associated with literary realism, Darwin’s work may be better aligned with the new narrative form so popular in the 1860s: sensation fiction.

This chapter discusses Darwin’s lifelong interest in unconscious agency and instinct. Darwin typically treats instinct as a rational action that has become habitual and thus heritable; instinct embodies a cognitive process that does not know itself as such. His discussion of instinct is thus connected to other moments in his work where he uses the term ‘unconscious’; his treatment of previous taxonomists of species as unconsciously providing evidence for species transmutation, and his discussion of unconscious selection as an analogy for the effect of aesthetic preference in sexual selection. Darwin’s unconscious anticipates Freud’s as the embodiment of human agency in biological history.

Chapter three engages in the investigation of the meaning and role of natural selection, teleology and chance in evolutionary processes. From Aristotle and Aquinas, through Darwin and the twentieth-century evolutionary synthesis, to the most current philosophy of evolutionary biology, the fate of the notion of goal-directedness is traced and it is defended as indispensable and intrinsically related to chance in processes that affect the fittingness of organisms, which is tested by natural selection.

Darwin and Wallace proposed that natural selection is the process responsible for the evolution of adaptive features. Mutations provide the raw material of evolution. Interacting species influence each other’s evolution through coevolution. Evolution offers insight into many past and current controversies including Proximate (extrinsic) and ultimate (intrinsic) factors influence species’ vulnerability to extinction. Going through a bottleneck results in low genetic diversity and the high risk of becoming extinct due to inbreeding, catastrophes, and fluctuations in birth and death rates and the sex ratio. The theory of island biogeography states that extinction risk is high in small, isolated populations. Understanding evolution has practical implications for managing the evolution of resistance to pesticides, problems from hybridization, and populations at risk of extinction.