Past Visions of Artificial Futures: One Hundred and Fifty Years under the Spectre of Evolving Machines

The influence of Artificial Intelligence (AI) and Artificial Life (ALife) technologies upon society, and their potential to fundamentally shape the future evolution of humankind, are topics very much at the forefront of current scientific, governmental and public debate. While these might seem like very modern concerns, they have a long history that is often disregarded in contemporary discourse. Insofar as current debates do acknowledge the history of these ideas, they rarely look back further than the origin of the modern digital computer age in the 1940s-50s. In this paper we explore the earlier history of these concepts. We focus in particular on the idea of self-reproducing and evolving machines, and potential implications for our own species. We show that discussion of these topics arose in the 1860s, within a decade of the publication of Darwin's The Origin of Species, and attracted increasing interest from scientists, novelists and the general public in the early 1900s. After introducing the relevant work from this period, we categorise the various visions presented by these authors of the future implications of evolving machines for humanity. We suggest that current debates on the co-evolution of society and technology can be enriched by a proper appreciation of the long history of the ideas involved.


Introduction
"And why should one say that the machine does not live? It breathes . . . It moves . . . And has it not a voice? . . . And yet the mystery of mysteries is to view machines making machines; a spectacle that fills the mind with curious, and even awful, speculation." Coningsby (Disraeli, 1844, p. 154) By the climax of the British Industrial Revolution in the early 1800s, the widespread introduction of increasingly sophisticated manufacturing machines had raised anxiety about the potential long-term consequences of mechanisation. Areas of unease included not just the impact of technology on the labour conditions of working people-a driving concern of the Luddite movement (Archer, 2000), but also the growing appreciation of the self-amplifying potential of the new machines. In 1844, the British author and future prime minister Benjamin Disraeli wrote the novel Coningsby. In a section describing the industrial landscape of Manchester, the narrator raises the idea of machines making machines and alludes to the profound potential of such a development (see quote above).
During the same period, the scientific understanding of the complexity of biological life was undergoing a revolution, in the theories being developed by Charles Darwin and Alfred Russell Wallace. Both theories were first presented at the Linnean Society of London in 1858 (Darwin and Wallace, 1858), with a greatly extended presentation of Darwin's theory appearing a year later with the publication of The Origin of Species (Darwin, 1859).
At this time, the intellectual elite of England were a richly connected web of thinkers, among whom ideas of science, philosophy, technology, literature and the arts freely flowed. It did not take long for the contemporaneous ideas of machines making machines, and of the evolution of biological organisms, to be connected-the result was the development of the idea of self-reproducing and evolving machines.
In this paper we explore the work of prominent authors of the nineteenth and early twentieth centuries who addressed this topic. 1 We then identify common themes in their work in terms of the implications of these ideas for the future of human society and evolution, and conclude with brief comments about the relevance of this work to current debates.
Early writing on self-reproducing and evolving machines Late Nineteenth Century (1860s-1890s) Samuel Butler: Darwin Among The Machines (1863) and later works As a young man, the English author Samuel Butler (1835Butler ( -1902 spent five years working in New Zealand. Shortly after his arrival in 1859 he read-and was greatly influenced by-the recently published Origin of Species. During his stay he published a number of letters relating to Darwin's theory in the local Christchurch newspaper, The Press. The second of these, which appeared in the 13 June 1863 edition under the pseudonym Cellarius, was entitled Darwin Among the Machines (Butler, 1863). Butler began the letter by noting the rapid pace of development of machinery from the earliest mechanisms to the most sophisticated examples of the day. He commented that this had far outstripped the pace of development in the animal and vegetable kingdoms, and asked what might be the ultimate outcome of this trend. Observing the increasingly sophisticated "self-regulating, self-acting power" with which machines were being conferred, Butler suggested that humans "are ourselves creating our own successors." He further speculated that, freed from the constraints of feelings and emotion, machines will ultimately become "the acme of all that the best and wisest man can ever dare to aim at," at which point "man will have become to the machine what the horse and the dog are to man" (Butler, 1863). At that stage, Butler reasoned, the machines would still be reliant upon humans for feeding them, repairing them, and producing their offspring, and hence they would likely treat us kindly. "[Man] will continue to exist, nay even to improve, and will be probably better off in his state of domestication under the beneficent rule of the machines than he is in his present wild state." However, he then introduced the possibility of a time when "the reproductive organs of the machines have been developed in a manner which we are hardly yet able to conceive," noting that "it is true that machinery is even at this present time employed in begetting machinery, in becoming the parent of machines often after its own kind" (Butler, 1863).
Throughout his subsequent career, Butler wrestled with his views on the application of Darwin's theory to machines, and the implications for humanity. In a subsequent letter to The Press entitled Lucubratio Ebria (Butler, 1865), published on 29 July 1865, he presented a vision whereby machines are seen not as a competing species, but rather as extensions to the human body. From this perspective, Butler emphasised the capacity of machines to exert positive evolutionary influences on the evolution of humankind, not only by increasing our physical and mental capabilities, but also by changing the environment in which we develop as individuals and evolve as a species.
Upon his return to England in 1864, Butler continued to explore these ideas. They appear in their most developed form in The Book of the Machines, which constituted chapters 23-25 of his novel Erewhon (Butler, 1872). Here he explored the collective reproduction of heterogeneous groups of machines, rather than the reproduction of individuals. Butler likened a complicated machine to "a city or society" (Butler, 1872, p. 212), and asked "how few of the machines are there which have not been produced systematically by other machines?" (Butler, 1872, p. 210). He invoked a number of biological analogies, such as bee pollination and specialisation of reproductive function in ant colonies, to argue that collective machine reproduction is no less like-like than the self-reproduction of individual machines.
In Erewhon Butler further explored the idea, first addressed in Lucubratio Ebria, that humans and machines are co-evolving, in a process driven by market economics. However, in contrast to his earlier writing, he now feared that this might be detrimental to humankind, with machines evolving by acting parasitically upon their designers: "[the machines] have preyed upon man's grovelling preference for his material over his spiritual interests" (Butler, 1872, p. 207). Humans, he argued, are economically invested in producing machines with ever more "intelligibly organised" mechanical reproductive systems (Butler, 1872, p. 212): "For man at present believes that his interest lies in that direction; he spends an incalculable amount of labour and time and thought in making machines breed better and better . . . and there seem no limits to the results of accumulated improvements if they are allowed to descend with modification from generation to generation." Erewhon (Butler, 1872, p. 212) As machines evolved to become ever more complex, Butler was concerned that they might "so equalise men's powers" that evolutionary selection pressure on human physical capabilities would be reduced to a level that precipitated "a degeneracy of the human race, and indeed that the whole body might become purely rudimentary" (Butler, 1872, p. 224). This concern about the consequences for the human race of entering a long-term co-evolutionary relationship with machines is taken up by a number of later authors, most notably J. D. Bernal, whose work we discuss later.
Alfred Marshall: Ye Machine (c. 1867) Contemporaneous with Butler, in 1867 the young Alfred Marshall (1842Marshall ( -1924 wrote a series of four papers that formed the basis of talks at "The Grote Club"-an intellectual debating society at the University of Cambridge. His theme was the extent to which the activities of the human mind could be accounted for in physical terms. In the third paper, Ye Machine, Marshall proposed a model for the objective study of mechanisms capable of learning and intelligent action (Raffaelli, 1994). Inspired by recent scientific work in psychology, he described a mechanical device (a robot in today's terms) equipped with sensors, effectors and circuitry that would allow it to develop progressively more sophisticated ideas and reasoning about its interactions with the world. The brain of Marshall's robot consisted of "an indefinite number of wheels of various sizes" connected by bands which would be automatically tightened whenever two wheels moved at the same time (Raffaelli, 1994, p. 116). The design therefore implements what would now be classified as a kind of associative learning. He goes on to describe how such a machine might also learn through receiving positive or negative feedback about its actions, and how it might develop instincts to allow it to maintain desired states. Although such instincts could arise from the robot's associative learning mechanisms, Marshall also speculated: "Nay, further, the Machine . . . might make others like itself. We thus get hereditary and accumulated instinct. For these descendants, as they may be called, may vary slightly, owing to accidental circumstances, from the parent. Those which were most suited to the environment would supply themselves most easily with fuel, etc. and have the greatest chance of prolonged activity. The principle of natural selection, which indeed involves only purely mechanical agencies, would thus be in full operation." Alfred Marshall, Ye Machine, c. 1867 (Raffaelli, 1994, p. 119) Ye Machine and the other papers presented by Marshall at The Grote Club in the late 1860s had a limited audience at the time, and they were not published in the scientific literature until 1994 (courtesy of the efforts of the late Tiziano Raffaelli). However, the ideas Marshall developed in these papers are clear antecedents of themes in his later work. 2 George Eliot: Impressions of Theophrastus Such (1879) In the following decade, George Eliot (Mary Ann Evans) published her final work, a series of short essays by an imaginary scholar (Eliot, 1879). The chapter Shadows of The Coming Race is a dialogue covering themes first raised by Butler regarding the possibility of machines developing the capacity for self-reproduction and evolution by natural selection. It also touches upon the potential consequences for humans, including mass unemployment and an evolutionary degeneration of the mind and body. Asked where these ideas had come from, the narrator explains that "[t]hey seem to be flying around in the air with other germs." By the late 1800s these topics were indeed very much in the air. 3 Early Twentieth Century (1900s-1950s) By the turn of the twentieth century, the pace of technological development had created a more pressing need for considering where such progress might ultimately lead us. During this period, the exploration of potential futures of humanity in a world shared with self-reproducing, evolving machines was attracting a wider audience. Where Samuel Butler had led, other authors soon followed. Here we highlight some of the first examples of novels and other literature exploring self-reproducing machines from the early twentieth century, and also discuss speculative scientific work from this period.  (Forster, 1909) was his only work of science fiction. It is now regarded as a classic of dystopian literature (Evans et al., 2010, p. 50).
The story depicts a future in which humans live underground in personal accommodation where corporeal needs are entirely satisfied by technology (the global, all-nurturing "Machine"). This leaves them free to concentrate on intellectual development, although it also renders them physically degenerate. Forster describes the Machine's "mending apparatus" that fixes problems and performs self-repair functions, evoking an early image of a machine with a selfmaintaining organisation. It is the collapse of this functionality, brought about by the mending apparatus itself falling into disrepair, that brings the story to an apocalyptic end. Forster refers in passing to the Machine evolving new "foodtubes", "medicine-tubes", "music-tubes" and even "nervecentres", but these ideas are not further explored.
Forster acknowledged the influence of Samuel Butler in his work (Forster, 1951)-the vision in The Machine Stops of a future where an increasing dependency upon machines leads to the degeneracy of the human body certainly echoes some of Butler's concerns. Forster's image of selfmaintaining machines sustaining human life was further developed 20 years later by J. D. Bernal (see below).
KarelČapek: R.U.R.: Rossum's Universal Robots (1920) Themes of machine (collective) self-reproduction are further developed in KarelČapek's play R.U.R.: Rossum's Universal Robots (Čapek, 1920). Published in 1920 and first performed in 1921, the play introduced the word "robot" into the English language. The robots were constructed from biochemical components and designed to resemble humans, but lacked "superfluous" capacities such as feelings or the capacity to reproduce. They were mass-produced in a factory to replace human workers with a cheaper, more productive alternative. Most of the production at the factory was carried out by robots themselves, with only the most senior positions filled by humans. However, the complex formula for manufacturing the key "living material" was a closelyguarded secret, recorded by the factory's founder (Rossum) before his death and kept in a safe to prevent it from falling into the hands of competitors or the robots themselves.
One of the scientists in the factory experiments in mak-ing robots with more human-like feelings such as pain and irritability, but this results in unintended and ultimately disastrous consequences when the robots come to despise their human masters and rise up against them. This eventually leads to a stand-off where the robots surround the factory and the people within it. The humans realise that their only bargaining chip is the document that explains Rossum's formula, without which the robots would be unable to produce more of themselves and would therefore die out as a race when the current models fail. The climax of the play thus revolves around a struggle for the ownership of the written instructions that would allow the robots to collectively produce more of themselvesa struggle for the ownership of the robot's DNA, as it were. This idea of the collective reproduction of a society of robots reflects some of Butler's earlier ideas in Erewhon. Fiction (1920s-1950s) The appearance of American pulp science fiction magazines in the 1920s, and their growing popularity over the decades that followed, provided a medium in which many writers explored the idea of self-reproducing robots and evolving machines. Perhaps the first example in this genre was the British writer S. Fowler Wright's story Automata, published in the American magazine Weird Tales (Wright, 1929). With echoes of Samuel Butler, the story extrapolates the observed accelerating pace of technological development of the time into the far future, to a point when machines no longer rely on humans to service them. The machines become not only self-reproducing, but also able to design their own offspring. The story views the takeover by machines as the inevitable next stage of evolution, and serves as a warning of the unpredictable long-term consequences of machine evolution:

Early American Science
"Even in the early days of the Twentieth Century man had stood in silent adoration around the machines that had self-produced a newspaper or a needle . . . And at that time they could no more have conceived what was to follow than the first ape that drew the sheltering branches together could foresee the dim magnificence of a cathedral dome." Automata (Wright, 1929, p. 344) Three years later, in 1932, the influential American sci-fi writer and editor John W. Campbell published The Last Evolution (Campbell, 1932), which also anticipated the eventual replacement of the human race by self-reproducing and selfdesigning machines. However, Campbell's story is more optimistic than Wright's, foreseeing a period where humans live in peaceful and co-operative coexistence with intelligent machines, with human creativity complementing machine logic and infallibility. The end of the human race comes not at the hands of the intelligent machines, but when a species from another solar system invades Earth. The invasion prompts the machines to design a new super-intelligent machine to thwart the attack, and this itself spawns further rounds of creation of more sophisticated machines-the final instantiation of which succeeds in repelling the invaders but is ultimately the only surviving species on Earth. Earlier in the story, the last two surviving humans console themselves while contemplating their fate: "I think . . . that this is the end . . . of man . . . But not the end of evolution. The children of men still live-the machines will go on. Not of man's flesh, but of a better flesh, a flesh that knows no sickness, and no decay, a flesh that spends no thousands of years in advancing a step in its full evolution, but overnight leaps ahead to new heights." The Last Evolution (Campbell, 1932, p Campbell's vision of a complementary coexistence of humans and intelligent machines is replaced by a less positive image in his 1935 story The Machine (written under the pseudonym Don A. Stuart) (Campbell, 1935). In the story a human-like race on a distant planet design a thinking machine that is set the task of making better versions of itself. The outcome is a machine that takes care of all of the race's basic needs. However, this ultimately leads to the degeneration of the race's intelligence, civility, and its ability to look after itself-a similar fate to those described by Butler in Erewhon and Forster in The Machine Stops. The machine decides that its presence has become detrimental to the planet's inhabitants, for they are not engaging with it appropriately, but instead treating it like a god. The machine resolves to leave the planet so that they can learn to live independently once more.
Laurence Manning's The Call of the Mech-Men (Manning, 1933) also mirrors ideas first aired by Butler 60 years earlier. Two explorers discover a group of extraterrestrial robots who have been living in underground caverns on Earth since their spaceship was damaged many tens of thousands of years earlier. The robots are amused when they hear of humankind's view of itself as master of its technology, remarking (in their stilted English): "Machine gets fed and tended under that belief! Human even builds new machines and improves year by year. Machines evolving with humans doing all work!" (Manning, 1933, p. 381).
Recurring themes of machine evolution and selfreproduction are seen in stories over the following years. An example is Joseph E. Kelleam's Rust, set on a postapocalyptic Earth where human-designed robots have survived after humankind has been wiped out (Kelleam, 1939). The robots try to design and build more of their kind before they succumb to erosion, but ultimately fail in their attempts. In Robert Moore Williams' Robots Return (Williams, 1938), three robots from a faraway planet travel to Earth in search of information about their origins many thousands of years earlier. To their surprise, they discover that they were originally designed by humans, and had been sent into space to accompany their creators in escaping a dying Earth. The humans did not survive the mission, but the robots did, settling upon a distant world; there, they reproduced and ultimately evolved into their current state. One further example is A. E. van Vogt's M 33 in Andromeda, in which a spaceship of human explorers overcome an extraterrestrial intelligence the size of a galaxy by constructing a self-reproducing torpedomanufacturing machine (van Vogt, 1943).
The most explicit exploration of machine selfreproduction and evolution in early science fiction is found in Philip K. Dick's Second Variety (Dick, 1953). The story is set on Earth at the end of a long-running war between East and West, in which Western forces are driven to design killer robots to turn the tide on the battlefield. The robots are highly autonomous, with each generation of design becoming more sophisticated, including powers of self-repair and self-manufacture. They eventually become too dangerous for the human designers to be anywhere near, and they are left to reproduce by themselves. Similar to Wright's Automata and Campbell's The Last Evolution, the robots in Second Variety eventually develop the ability to design their own offspring, and increasingly sophisticated and human-like species of killer robots begin to emerge. Echoes of these earlier stories are also seen when one of the human characters remarks "It makes me wonder if we're not seeing the beginning of a new species. The new species. Evolution. The race to come after man" (Dick, 1953).
Themes of machine self-repair, self-reproduction and evolution were central to various subsequent works by Dick. Another notable example is Autofac (Dick, 1955), which ends with a vision of the seeds of self-reproducing manufacturing plants being launched into space.

J. D. Bernal: The World, The Flesh and the Devil (1929)
In addition to the fictional explorations of machine selfreproduction and evolution described above, we also see continued interest in these topics from scientists in the early 1900s. John Desmond Bernal (1901Bernal ( -1971 was an influential researcher who conducted pioneering work on structural crystallography. Later in his career he also became interested in the origins of life (Bernal, 1951). In addition to his experimental work, he wrote many works on science and society; his first monograph, and yet perhaps his most futuristic writing, was entitled "The World, the Flesh and the Devil: An Enquiry into the Future of the Three Enemies of the Rational Soul" (Bernal, 1929). 4 In this work, Bernal discusses how one might examine the future of humanity in a scientifically defensible way. After sign-posting the methodological and intellectual dangers to be avoided, and discussing the unavoidable limitations, he proceeds to explore what might be said of the three major kinds of struggle facing humanity: against the forces of na-ture and the laws of physics in general ("the world"); against biological factors including ecology, food, health and disease ("the flesh"); and against psychological factors including desires and fears ("the devil").
Writing before the advent of space travel, atomic energy or computers, Bernal first tackles how humankind might overcome the challenges that arise from the material world. He argues that limitations of land and energy in the world will eventually compel us to colonise space: "On earth, even if we should use all the solar energy which we received, we should still be wasting all but one two-billionths of the energy that the sun gives out. Consequently, when we have learnt to live on this solar energy and also to emancipate ourselves from the earth's surface, the possibilities of the spread of humanity will be multiplied accordingly" (Bernal, 1929, p. 22). After discussing plausible technologies for powering a spaceship (both to escape the earth's gravitational field and also when in outer space), he goes on to imagine how humans might set up permanent space colonies.
Bernal proposes a "spherical shell ten miles or so in diameter" (Bernal, 1929, p. 23) which could provide a habitable environment for twenty or thirty thousand inhabitants. After discussing how the construction of a sphere might be bootstrapped from a basic design built largely of materials mined from an asteroid, Bernal continues with a description of the organisation of a mature sphere. It is imagined as "an enormously complicated single-celled plant" (Bernal, 1929, p. 23) with a protective "epidermis", complete with regenerative mechanisms to protect against meteorites, mechanisms for the capture of meteoric matter to be used as raw material for the growth and propulsion of the sphere, systems for energy production from solar energy, stores for basic goods such as solid oxygen, ice and hydro-carbons, and mechanisms for the production and distribution of food and mechanical energy. The sphere would also have mechanisms for recycling all waste matters, "for it must be remembered that the globe takes the place of the whole earth and not of any part of it, and in the earth nothing can afford to be permanently wasted" (Bernal, 1929, p. 25).
The inhabitants of these globes in space would not be isolated, but would be in wireless communication with other globes and with the earth. In addition, there would be a constant interchange of people between the globes and the earth via interplanetary transport vessels. Having set out how the globes might function to sustain life as "mini-earths", Bernal imagines a yet more ambitious scenario: "However, the essential positive activity of the globe or colony would be in the development, growth and reproduction of the globe. A globe which was merely a satisfactory way of continuing life indefinitely would barely be more than a reproduction of terrestrial conditions in a more restricted sphere." The World, The Flesh and the Devil (Bernal, 1929, p. 27) Hence, the globe is conceived of as a fully self-maintaining and self-reproducing unit-what might now be described as an autopoietic organisation (Maturana and Varela, 1972). Bernal discusses methods by which a globe might construct another globe, and then envisages how an evolutionary pressure to explore might arise among a population of globes: "As the globes multiplied they would undoubtedly develop very differently according to their construction and to the tendencies of their colonists, and at the same time they would compete increasingly both for the sunlight which kept them alive and for the asteroidal and meteoric matter which enabled them to grow. Sooner or later this pressure . . . would force some more adventurous colony to set out beyond the bounds of the solar system." The World, The Flesh and the Devil (Bernal, 1929, p. 29) The enormous challenges of travelling interstellar distances are addressed, but Bernal argues that such a vision is nevertheless reasonable to consider: "once acclimatized to space living, it is unlikely that man will stop until he has roamed over and colonized most of the sidereal universe, or that even this will be the end. Man will not ultimately be content to be parasitic on the stars but will invade them and organize them for his own purposes" (Bernal, 1929, p. 30). Moving next to the possibilities of how our own bodies might develop in the distant future, Bernal imagines that we will increasingly replace and augment body parts with synthetic alternatives. Turning to the activities such advanced beings might pursue, Bernal suggests that, among other important scientific questions, there would surely be intensive further study of life processes, and the creation of synthetic life. However, "the mere making of life would only be important if we intended to allow it to evolve of itself anew . . . [however] artificial life would undoubtedly be used as ancillary to human activity and not allowed to evolve freely except for experimental purposes" (Bernal, 1929, p. 45).
Bernal's vision of the relationship between the future evolution of humans and machines is more symbiotic than the futures imagined by Forster andČapek: "Normal man is an evolutionary dead end; mechanical man, apparently a break in organic evolution, is actually more in the true tradition of a further evolution" (Bernal, 1929, p. 42). This perspective is more in line with the ideas expressed by Butler in Lucubratio Ebria, and with those of sci-fi authors such as John W. Campbell. Bernal sees the main barriers towards progress in these areas arising from human psychologyin addition to having the desire for progress, we must also "overcome the quite real distaste and hatred which mechanization has already brought into being" (Bernal, 1929, p. 55). Various ways of overcoming such barriers are suggested, but Bernal does not discount the alternative possibility that we ultimately find ways of living a simpler yet more satisfying life that is not occupied by science or art but more at one with nature. 5 He also considers a third possibility, "the most unexpected, but not necessarily the most improbable" (Bernal, 1929, p. 56), that human evolution might diverge, with one race following the natural path and another race following the intellectual and technological path. Recent Work (1950s-present) The 1940s and, in particular, the 1950s saw the emergence both of the first rigorous theoretical work on the design of self-reproducing machines, and of the first implementations of artificial self-reproducing systems in software and in hardware (Taylor and Dorin, 2018). This has been accompanied by continued public debate about the implications of the technology for the long-term future of our species. The history of these ideas from this period is more widely acknowledged in current discussions, so we end our review of the early development of these ideas here. Details of work in the 1950s and early 1960s, and pointers to more recent developments, can be found in (Taylor and Dorin, 2018).

Discussion
As demonstrated in the preceding sections, the early history of thought about self-reproducing and evolving machines unveils a diverse array of hopes and fears. These contributions demonstrate that current debates about the implications of AI and ALife for the future development of humankind are actually a continuation of a conversation that has been in progress for at least a hundred and fifty years. In this final section, we consider the main recurring themes that have emerged in our review.
Takeover by intelligent machines The most prominent theme apparent in this work is the fear that machines might evolve to a level where they displace humankind as the dominant intelligent species. While some writers proposed more positive, co-operative alliances between humans and machines (e.g. Butler, Marshall, Wright, Campbell, Bernal), none was fully convinced by this outcome, and all discussed less desirable possibilities elsewhere in their work. 6 The idea that we ourselves are creating our own successors can be seen in the work of Butler, Eliot,Čapek, Wright and Campbell. Some saw this not as a development to be feared, but rather as a way in which the reach of humankind might be extended beyond the extinction of our species (e.g. Capek, Campbell [The Last Evolution], and Williams).
Most saw the evolution of increasingly intelligent machines as an inevitable process. In the work reviewed, only Č apek engages significantly with the idea that humans might exert some control over the robots' reproduction. Butler and Bernal thought this could likely only be achieved by humans forsaking the development of technology altogether.
The idea of self-repairing machines is present in the work of Eliot, Forster, Campbell [The Machine] and Bernal, and this is indeed a theme in current evolutionary robotics research, e.g. (Bongard et al., 2006), (Cully et al., 2015). In contrast, we are unaware of any serious scientific investigation of the idea of self-designing machines, which appears in the work of Wright, Campbell and Dick. These authors portray self-design as a route by which the pace of machine evolution can accelerate-these works, and Butler's before, strongly foreshadow current interest in the idea of the technological singularity. The concept has attracted increasing interest and speculation since the birth of the digital computer age, particularly in recent years through authors such as Moravec (1988), Kurzweil (2005) and Bostrom (2014). However, such speculations date back at least two hundred years; for a good discussion of the history of these ideas, see (Eden et al., 2013).
Implications for human evolution Beyond the idea that machines might become the dominant intelligent species, the reviewed works have explored a number of potential implications of self-reproducing machines for the future direction of human evolution.
In Erewhon Butler envisaged that humans might become weaker and physically degenerate due to reduced evolutionary selection pressure brought about by all-caring machines. Eliot and Forster foresaw a similar outcome. In contrast, an alternative outcome explored by Butler [Lucubratio Ebria] and Bernal is that human abilities might become significantly enhanced by the incorporation of increasingly sophisticated cyborg technology.
Several authors emphasised that humans and machines are engaged in a co-evolutionary process. In Lucubratio Ebria Butler suggests that this closely coupled evolution of humans and machines might increase our physical and mental capabilities. In particular, he suggests that intelligent machines change the environment in which humans develop and evolve-foreshadowing the modern idea of biological niche construction (Odling-Smee et al., 2003). In The Last Evolution Campbell envisaged a positive outcome of this coevolution, with human creativity working in harmony with machine logic and infallibility. Butler in Erewhon, however, was more dubious of the process, conjuring an image of machines as parasites benefiting from the unwitting assistance of humans in driving their evolution.
The significance of self-reproducing machines as a technology to allow humankind to explore and colonise other planets is a theme covered in various works. The properties of self-repair and multiplication by self-reproduction are seen as essential for attempts to traverse the immense distances of inter-stellar-or even inter-galactic-missions. Bernal's vision is of self-repairing and self-reproducing living environments to allow multiple generations of humans to survive such journeys. Williams, and Dick [Autofac], have our robot successors making the journey in place of us.
Implications for human society In addition to imagining consequences for human evolution, these authors also envisaged how human society and the lives of individuals might be affected by the existence of super-intelligent machines.
The prospect of humans becoming mere servants to machines was raised by Butler [Darwin Among The Machines], Wright and Manning. However, Butler suggests that this might not necessarily be a detrimental development-the machines would likely take good care of us, at least for as long as they still rely upon humans for performing functions relating to their maintenance and reproduction.
Many of the works explore how humans might spend their time in a world where all of their basic needs are taken care of by beneficent machines. In Forster's work, humans engage in the exchange of ideas and academic learning (mostly about the history of the world before the Machine existed). Similarly, Bernal suggests that we would be free to pursue science, but also other areas of uniquely human activity including art and religion. Individuals in Campbell's The Machine are chiefly occupied with playing physical games and pursuing matters of the heart. They also develop an unhealthy reverence to the Machine as a god, to the extent that the Machine ultimately decides to leave that planet so that the humans can learn to live independently again.
Likewise, Butler [Erewhon] and Bernal discuss the possibility that humans might separate from machines at some point in the future, although in their works, in contrast to Campbell's, this is a decision made by the humans rather than the machines. Bernal also considers the possibility that the human species might ultimately diverge into two, with one group pursuing the path of technological co-evolution, and the other rejecting technology and searching for a simpler and more satisfying existence more at one with nature.
Conclusion Concern about the impact of self-reproducing and evolving machines on human society and our future evolution has a surprisingly long history. As we have shown, this dates back at least as early as the Industrial Revolution in Britain, and gains momentum with the publication of The Origin of Species. Modern debates about the implications of AI and ALife technology are the continuation of a conversation that has been in progress for over 150 years.
There is a possible dystopian bias in the works reviewed, which were predominantly written by young, white men (Roberts, 2018). It is indeed true that the large-scale mechanical self-reproducing machines envisaged by these authors have not yet been realised. Nevertheless, technological advances in recent years have made possible various alternative manifestations of their ideas. Computer viruses, nanomachines, manufactured bacteria and other self-reproducing wetware: all testify to the continued and increasing need for careful thought in this area. The spectre of self-reproducing and evolving machines is still very much with us.