Prologue – In Silico – Full Text
- The creatures cruise silently, skimming the surface of their world with the elegance of ice skaters. They move at varying speeds, some with the variegated cadence of vacillation, others with what surely must be firm purpose. Their bodies – flecks of colors that resemble paper airplanes or pointed confetti – betray their needs. Green ones are hungry. Blue ones seek mates. Red ones want to fight.
- They see. A so-called neural network bestows on them vision, and they can perceive the colors of their neighbors and something of the world around them. They know something about their own internal states and can sense fatigue. They learn. Experience teaches them what might make them feel better or what might relieve a pressing need.
- They reproduce. Two of them will mate, their genes will merge, and the combination determines the characteristics of the offspring. Over a period of generations, the mechanics of natural selection assert themselves, and fitter creatures roam the landscape.
- They die, and sometimes before their bodies decay, others of their ilk devour the corpses. In certain areas, at certain times, cannibal cults arise in which this behavior is the norm. The carcasses are nourishing, but not as much as the food that can be serendipitously discovered on the terrain.
- The name of this ecosystem is PolyWorld, and it is located in the chips and disk drives of a Silicon Graphics Iris Workstation. The sole creator of this realm is a researcher named Larry Yaeger, who works for Apple Computer. It is a world inside a computer, whose inhabitants are, in effect, made of mathematics. The creatures have digital DNA. Some of these creatures are more fit than others, and those are the ones who eventually reproduce, forging a path that eventually leads to several sorts of organisms who successfully exploit the peccadilloes of PolyWorld.
- "The species have their own unique behaviors and group dynamics," notes Yaeger. One group seems on the edge of psychosis – the "frenetics," who, zipping compulsively through the landscape, constantly desire food and sex and expend energy on little else. Then there is "the cannibal cult," members of which seek their own to mate with, fight with, and eat. They form grotesque clumps from which they need not move in order to fulfill any of those needs. A third species is the "edge runner”. Owing to a peculiarity in the landscape – unlike our own spherical planet, PolyWorld can be programmed to have a distinct end of the world – there is a benefit in lurking on the brim of oblivion. Once a respectable number of fellow creatures adopt this behavior, there will always be an ample supply of conjugal partners, as well as old carcasses now turned to food.
- Yaeger is cautious about sweeping statements; he prefers to describe what he has done and what might immediately follow from it. "So far what PolyWorld has shown is that successful organisms in a biologically motivated and only somewhat complex environment have evolved adaptive strategies for living in this environment," he says. When it comes to describing the creatures themselves, Yaeger is less tentative.
- "I see them," he says, "as artificial life."
- In September 1987, more than one hundred scientists and technicians gathered in Los Alamos, New Mexico, to establish the new science of artificial life. The event celebrated a technological and scientific watershed. A deepened understanding of biological mechanisms, along with the exponentially increasing power of digital computers, had brought humankind to the threshold of duplicating nature's masterpiece, living systems. The pioneers were both thrilled at the prospect and humbled by previous speculations of what lay ahead. The legacy of Mary Shelley, who wrote of Frankenstein and his monster, as well as the dark accomplishments hatched on the very site of the conference, hovered over the proceedings like, as one participant put it, a bugaboo.
- Nevertheless, the mood was exuberant. Many of the scientists drawn to Los Alamos had long dreamed of an aggregate effort to create a new form of life; their individual labors had looked toward that day. Now it had arrived. The significance of the moment was later framed by a physicist named James Doyne Farmer, who coauthored a paper about the implications of this new science. Its abstract alone was perhaps as striking a description of nascent technology at the lab as any since the development of the atomic bomb. Those who read it would have been well advised to take a deep breath – and perhaps suspend disbelief until resuming aspiration – before reading the following prediction:
Within fifty to a hundred years a new class of organisms is likely to emerge. These organisms will be artificial in the sense that they will originally be designed by humans. However, they will reproduce, and will evolve into something other than their original form; they will be "alive" under any reasonable definition of the word. . . . The advent of artificial life will be the most significant historical event since the emergence of human beings. ...
- Artificial life, or a-life, is devoted to the creation and study of lifelike organisms and systems built by humans. The stuff of this life is nonorganic matter, and its essence is information: computers are the kilns from which these new organisms emerge. Just as medical scientists have managed to tinker with life's mechanisms in vitro, the biologists and computer scientists of a-life hope to create life in silico.
- The degree to which this resembles real, "wet" life varies; many experimenters admit freely that their laboratory creations are simply simulations of aspects of life. The goal of these practitioners of "weak" a-life is to illuminate and understand more clearly the life that exists on earth and possibly elsewhere. As astronomer A. S. Eddington has said, "the contemplation in natural science of a wider domain than the actual leads to a far better understanding of the actual." By simulating a kind of life different from that with which we are familiar, a-life scientists seek to explore paths that no form of life in the universe has yet taken, the better to understand the concepts and limits of life itself.
- Hoping that the same sorts of behavior found in nature will spontaneously emerge from the simulations, sometimes scientists attempt to model directly processes characteristic of living systems. Biologists treat these artificial systems as the ultimate laboratory animals; their characteristics illuminate the traits of known organisms, but, since their composition is transparent, they are much more easily analyzed than rats, plants, or E. coli. Physicists pursue a-life in the hope that the synthesis of life will shed light on a related quest: the understanding of all complex nonlinear systems, which are thought to be ruled by universal forces not yet comprehended. By studying phenomena such as self-organization in a-life, these mysteries may soon be unraveled.
- The boldest practitioners of this science engage in "strong" a-life. They look toward the long-term development of actual living organisms whose essence is information. These creatures may be embodied in corporeal form – a-life robots – or they may live within a computer. Whichever, these creations, as Farmer insisted, are intended to be "alive under every reasonable definition of the word" – as much as bacteria, plants, animals, and human beings.
- Many might consider this an absurd claim on the face of it.
- How could something inside a computer ever be considered alive?
- Could anything synthesized by humans ever aspire to such a classification?
- Should not the term "life" be restricted to nature's domain?
- The1 question is difficult to answer, largely because we have no "reasonable definition" of life. Nearly two thousand years ago, Aristotle made the observation that by "possessing life," one implied that "a thing can nourish itself and decay." Most everyone also agreed that the capacity for self-reproduction2 is a necessary condition for life. From there, opinions diverged and still do. One could devise a laundry list3 of qualities characteristic of life, but these inevitably fail. They are either overly discriminating or excessively lenient. The creatures in PolyWorld, for instance, are in many ways lifelike – they grow, reproduce, adapt, and evolve. Yet even their creator dares not claim that they are truly alive.
- Some scientists suggest that the definition-of-life question is a red herring. Life, they say, should be gauged on a continuum, and not granted according to a binary decision. A rock would certainly be low on any continuum4 of aliveness, and a dog, a tree, and a human being would rank highly. More ambiguous systems would fall in a middle region of semi-aliveness – somewhere below bacteria, which almost everyone agrees are alive, and somewhere above rocks. Viruses, which some biologists consider living and others do not, would reside in the upper reaches of this middle ground. Below that would be complex systems that no one really considers to be alive but that display some behaviors consistent with living organisms – things such as the economy and automobiles. The PolyWorld organisms would fall somewhere between Chevrolets and the flu. There is a particular advantage in regarding life in this manner: using systems that no one would classify as truly alive, biologists could nonetheless isolate the qualities of life.
- But this, too, is unsatisfying. One feels that it should mean something to be alive, even as one concedes the apparent impossibility in fixing the borderline between life and nonlife. Part of the difficulty arises from culture's refusal to yield the province of life to the realm of science. For centuries, a mystical component, if not an unabashed nod to divinity, loitered in whatever definition one chose to use. Despite attempts by iconoclasts and visionaries to use empirical means to recognize life, for most of history people felt that a supernatural component bestowed the property of life on otherwise-inert materials.
- As scientists came to discard those beliefs, their idea of life shifted to accommodate new discoveries. After the identification of the cell, they thought differently about how matter organized itself into living structures. And once it was understood how critical Darwin's contribution was to the life sciences, evolution became a central issue in defining life. To some, evolution remains the central issue. "Life should be defined by the possession of those properties which are needed to ensure evolution by natural selection," writes John Maynard Smith, not surprisingly an evolutionary biologist. "That is, entities with the properties of multiplication, variation, and heredity are alive, and entities lacking one or more of those properties are not." The more recent discovery of DNA as a pervasive and essential component in all matter generally regarded as living added another wrinkle: not only did living things contain blueprints for their operation and reproduction, but also these unique collections of molecules contained elements of the history of all life. "The possession of a genetic program provides for an absolute difference between organisms and inanimate matter," writes Ernst Mayr. "Nothing comparable exists in the inanimate world, except for manmade computers." (Note the sole, but significant, exception.)
- The latest twist on our perception of the necessary conditions for aliveness comes from the recognition of complex systems theory as a key component in biology. A complex system is one whose component parts interact with sufficient intricacy that they cannot be predicted by standard linear equations; so many variables are at work in the system that its overall behavior can only be understood as an emergent consequence of the holistic sum of all the myriad behaviors embedded within. Reductionism does not work with complex systems5, and it is now clear that a purely reductionist approach cannot be applied when studying life: in living systems, the whole is more than the sum of its parts. As we shall see, this is the result not of a mysterious dram of vital life-giving fluid but rather the benefits of complexity, which allow certain behaviors and characteristics to emerge unbidden. The mechanics of this may have been hammered out by evolution, but the engine of evolution cannot begin to fire until a certain degree of complexity is present. Living systems epitomize complexity, so much so that some scientists now see complexity as a defining characteristic of life.
- But complexity is only one more item on the laundry list6. Despite all our scientific knowledge, "there is no generally accepted definition of life," as Carl Sagan flatly states in his Encyclopedia Britannica essay on the topic. Philosopher Mark A. Bedau contends that the question "should be considered one of the fundamental concepts of philosophy, but philosophers haven't thought of it much. Nor have biologists. They typically throw up their hands. It's not a natural property like water – you can investigate water and say, 'there's H2O, that's its essence.' But life isn't material, it's ephemeral7."
- Philosophers, too, can throw up their hands at the dilemma. "I really doubt that a purely philosophical answer to these questions is possible," writes Elliott Sober. The University of Wisconsin philosopher contends that ultimately, the question is not important8. "If a machine can extract energy from its environment, grow, repair damage to its body, and reproduce," he asks, "what remains of the issue9 whether it is 'really' alive?"
- Yet such a machine would not close the issue but open it. Many people would find it threatening to consider an artificial organism as described above as literally alive. Now most human beings will not regard anything as living if it is not composed of the same matter as natural biological organisms. Physicist Gerald Feinberg and biologist Robert Shapiro have coined a term for those who "believe that all life must be based on the chemistry of carbon compounds and must operate in an aqueous (water) medium": "carbaquists." Yet no one has effectively argued that life could never exist in other forms.
- The things we now consider alive are possibly only a subset of a larger class of organisms. By chance, by an unfortunate accident of history, we have been presented with this limited spectrum of possible life-forms and no others. Our challenge, then, is to anticipate which characteristics of life as we know it are peculiar to that subset, and which are universal of all life, even the potential forms we have yet to see or, as the case may be, to build – to contemplate, and then create, life-as-it-could-be (to use the term coined by Christopher Langton, who organized the first a-life conference).
- "If scientists are going to develop a broad theory of life, it's going to require them to accept radically non-organic things as being alive" says Langton. "Most biologists are generally hesitant to do this now. It will take a while to get processes like this that will convince biologists that these things are alive, in the sense that people are alive10. But we're going to get them."
- This book is about that quest: the effort to create the processes of life itself, with the intended effect of changing the way the world thinks. If Langton and his colleagues achieve their goals, human beings will see themselves in a different light. We will not be standing at the pinnacle of some self-defined evolutionary hierarchy but will rank as particularly complex representatives of one subset of life among many possible alternatives.
- Our uniqueness11 will lie in the ability to create our own successors.
- Artificial life is something quite different from genetic engineering12, which uses fully evolved wet life as its starting point. The scientists of a-life are devising the means by which actual living systems can be generated, evolved, and observed. Theirs is an effort to engineer the course of evolution and extend the range of living systems on planet earth and beyond. From this grand experiment, a more profound understanding of life itself, an ability to use its mechanisms to perform our work and, perhaps, the discovery of powerful laws of nature that govern not only biological systems but also any series of complex nonlinear self-organizing interactions may ultimately arise.
- What drives men and women engaged in the quest for a-life is a desire to decipher the vast tangle of obscurities that nature has laid before us, particularly in regard to the deepest question of all, What is life?
- Working in different disciplines these researchers have concluded that the way to answer that question is not merely to observe but to create. The first step is believing it can be done, and there is convincing evidence that it can be done. The next step is doing it. Though it may take many years in terms of the life span in human individuals, in the scope of evolutionary time the result could be accomplished within an instant. In any case, this fearsome work is underway, and this book will introduce you to the remarkable people performing it.
- With the fruits of their labors, we may come to know what it means to be alive. By making life, we may finally know what life is.
- There are three distinct questions, as noted above.
- This appears to imply that the impotent are literally – as well as maybe metaphorically “dead” – which is deeply implausible.
- No doubt there’s a caveat along the lines of “typical individuals”.
- This is a good point, analogous to that for Personhood.
- There’s more than a hint of arbitrariness (and retrofitting) about this procedure.
- This is analogous to the approach taken to Consciousness by the panpsychists such as Galen Strawson.
- Rocks don’t rate highly in either the “life” or “consciousness” stakes – but they are really a “reductio” of the position, because they aren’t alive – or conscious – “period” (as they say).
Footnote 6: Agreed. Ad hoc.
- I think this confuses explanatory reduction – which doesn’t work in the predictive sense – and ontological reduction, which is fine.
- See my Note of Reductionism.
Footnote 7: What does this mean?
- I think I might agree – especially if we’re just going to gerrymander a shopping list of supposedly necessary and sufficient conditions.
- This reminds me of Derek Parfit’s denial that there’s any “further fact” for personal identity over and above Relation R.
- Crumbs! That’s a bit of a leap!
- It’d take a lot of credulity to believe they are alive in the way that viruses are alive – if they are!
- ‘These things” are the machines (yet to be built) described above by Elliott Sober.
- Why? This sounds like the latest straw to grasp at.
- Also, how would we know this ability was “unique”?
Text Colour Conventions (see disclaimer)
- Blue: Text by me; © Theo Todman, 2019
- Mauve: Text by correspondent(s) or other author(s); © the author(s)