1 The Zero-Force Evolutionary Law 2 Randomness, Hierarchy, and Constraint 3 Diversity 4 Complexity 5 Evidence, Predictions, and Tests 6 Philosophical Foundations 7 Implications.

Is life a purely physical process? What is human nature? Which of our traits is essential to us? In this volume, Daniel McShea and Alex Rosenberg – a biologist and a philosopher, respectively – join forces to create a new gateway to the philosophy of biology; making the major issues accessible and relevant to biologists and philosophers alike. Exploring concepts such as supervenience; the controversies about genocentrism and genetic determinism; and the debate about major transitions central to contemporary thinking about (...) macroevolution; the authors lay out the broad terms in which we should assess the impact of biology on human capacities, social institutions and ethical values. (shrink)

Teleology has a complicated history in the biological sciences. Some have argued that Darwin’s theory has allowed biology to purge itself of teleological explanations. Others have been content to retain teleology and to treat it as metaphorical, or have sought to replace it with less problematic notions like teleonomy. And still others have tried to naturalize it in a way that distances it from the vitalism of the nineteenth century, focusing on the role that function plays in teleological explanation. No (...) consensus has seemed possible in this debate. This paper takes a different approach. It argues that teleology is a perfectly acceptable scientific notion, but that the debate took an unfortunate misstep some 2300 years ago, one that has confused things ever since. The misstep comes in the beginning of Aristotle’s Physics when a distinction is made between two types of teleological explanation. One type pertains to artifacts while the other pertains to entities in nature. For Aristotle, artifacts are guided by something external to themselves, human intentions, while natural entities are guided by an internal nature. We aim to show that there is, in fact, only one type of legitimate teleological explanation, what Aristotle would have considered a variant of an artifact model, where entities are guided by external fields. We begin with an analysis of the differences between the two types of explanation. We then examine some evidence in Aristotle’s biological works suggesting that on account of his natural-artifactual distinction, he encountered difficulties in trying to provide teleological accounts of spontaneous generation. And we show that it is possible to resolve these difficulties with a more robust version of an artifact model of teleology, in other words, with an externalist teleology. This is McShea’s model, in which goal-directed entities are guided by a nested series of upper-level fields. To explain teleological behavior, this account invokes only external physical forces rather than mysterious internal natures. We then consider how field theory differs from other efforts to naturalize teleology in biology. And finally, we show how the account enables us to grapple with certain difficult cases – genes and intentions – where, even in biology today, the temptation to posit internal natures remains strong. (shrink)

The consensus among evolutionists seems to be that the morphological complexity of organisms increases in evolution, although almost no empirical evidence for such a trend exists. Most studies of complexity have been theoretical, and the few empirical studies have not, with the exception of certain recent ones, been especially rigorous; reviews are presented of both the theoretical and empirical literature. The paucity of evidence raises the question of what sustains the consensus, and a number of suggestions are offered, including the (...) possibility that certain cultural and/or perceptual biases are at work. In addition, a shift in emphasis from theoretical to empirical inquiry is recommended for the study of complexity, and guidelines for future empirical studies are proposed. (shrink)

How shall we understand apparently teleological systems? What explains their persistence and their plasticity? Here I argue that all seemingly goal-directed systems—e.g., a food-seeking organism, human-made devices like thermostats and torpedoes, biological development, human goal seeking, and the evolutionary process itself—share a common organization. Specifically, they consist of an entity that moves within a larger containing structure, one that directs its behavior in a general way without precisely determining it. If so, then teleology lies within the domain of the theory (...) of compositional hierarchies. (shrink)

Barrett et al. present four puzzles for the ZFEL-view of evolution that we present in our 2010 book, Biology’s First Law: The Tendency for Diversity and Complexity to Increase in Evolutionary Systems. Our intent in writing this book was to present a radically different way to think about evolution. To the extent that it really is radical, it will be easy to misunderstand. We think Barrett et al. have misunderstood several crucial points and so we welcome the opportunity to clarify.

The conventional wisdom declares that evolution is not goal directed, that teleological considerations play no part in our understanding of evolutionary trends. Here I argue that, to the contrary, under a current view of teleology, field theory, most evolutionary trends would have to be considered goal directed to some degree. Further, this view is consistent with a modern scientific outlook, and more particularly with evolutionary theory today. Field theory argues that goal directedness is produced by higher-level fields that direct entities (...) contained within them to behave persistently and plastically, that is, returning them to a goal-directed trajectory following perturbations (persistence) and directing them to a goal-directed trajectory from a large range of alternative starting points (plasticity). The behavior of a bacterium climbing a chemical food gradient is persistent and plastic, with guidance provided by the external “food field,” the chemical gradient. Likewise, an evolutionary trend that is produced by natural selection is a lineage behaving persistently and plastically under the direction of its local ecology, an “ecological field.” Trends directed by selection-generated boundaries, thermodynamic gradients, and certain internal constraints, would also count as goal directed. In other words, most of the causes of evolutionary trends that have been proposed imply goal directedness. However, under field theory, not all trends are goal directed. Examples are discussed. Importantly, nothing in this view suggests that evolution is guided by intentionality, at least none at the level of animal intentionality. Finally, possible implications for our thinking about evolutionary directionality in the history of life are discussed. (shrink)

Wants, preferences, and cares are physical things or events, not ideas or propositions, and therefore no chain of pure logic can conclude with a want, preference, or care. It follows that no pure-logic machine will ever want, prefer, or care. And its behavior will never be driven in the way that deliberate human behavior is driven, in other words, it will not be motivated or goal directed. Therefore, if we want to simulate human-style interactions with the world, we will need (...) to first understand the physical structure of goal-directed systems. I argue that all such systems share a common nested structure, consisting of a smaller entity that moves within and is driven by a larger field that contains it. In such systems, the smaller contained entity is directed by the field, but also moves to some degree independently of it, allowing the entity to deviate and return, to show the plasticity and persistence that is characteristic of goal direction. If all this is right, then human want-driven behavior probably involves a behavior-generating mechanism that is contained within a neural field of some kind. In principle, for goal directedness generally, the containment can be virtual, raising the possibility that want-driven behavior could be simulated in standard computational systems. But there are also reasons to believe that goal-direction works better when containment is also physical, suggesting that a new kind of hardware may be necessary. (shrink)

In this Element, we extend our earlier treatment of biology's first law. The law says that in any evolutionary system in which there is variation and heredity, there is a tendency for diversity and complexity to increase. The law plays the same role in biology that Newton's first law plays in physics, explaining what biological systems are expected to do when no forces act, in other words, what happens when nothing happens. Here we offer a deeper explanation of certain features (...) of the law, develop a quantitative version of it, and explore its consequences for our understanding of diversity and complexity. (shrink)

When behaviors assemble into combinations, then synergies have a central role in the discovery of productive patterns of behavior. In our view—what we call the Synergy Emergence Principle (SEP)—synergies are dynamic attractors, drawing interactions toward greater returns as they happen, in the moment. This Principle offers an alternative to the two conventionally acknowledged routes to discovery: directed problem solving, involving forethought and planning; and the complete randomness of trial and error. Natural selection has a role in the process, in humans (...) favoring the maintenance and improvement of certain key underlying capabilities, such as prosocial helping and episodic foresight, but selection is not required for discovery by synergy (which occurs too rapidly for selection anyway). Here we discuss the consequences of the SEP for the evolution in humans of key synergies such as tool usage and interactions that reward cooperation, show how discovery by synergy and the selection of synergy-supporting abilities formed a positive feedback loop, and show how synergies can combine, forming clusters and packages that are the core of institutions and cultures. Finally, clusters and packages represent an intermediate level of organization above the individual and below whole society, with consequences for our understanding of the major transitions in evolution. (shrink)

The view that complexity increases in evolution is uncontroversial, yet little is known about the possible causes of such a trend. One hypothesis, the Zero Force Evolutionary Law (ZFEL), predicts a strong drive toward complexity, although such a tendency can be overwhelmed by selection and constraints. In the absence of strong opposition, heritable variation accumulates and complexity increases. In order to investigate this claim, we evaluate the gross morphological complexity of laboratory mutants in Drosophila melanogaster, which represent organisms that arise (...) in a context where selective forces are greatly reduced. Complexity was measured with respect to part types, shape, and color over two independent focal levels. Compared to the wild type, we find that D. melanogaster mutants are significantly more complex. When the parts of mutants are categorized by degree of constraint, we find that weakly constrained parts are significantly more complex than more constrained parts. These results support the ZFEL hypothesis. They also represent a first step in establishing the domain of application of the ZFEL and show one way in which a larger empirical investigation of the principle might proceed. (shrink)

What would a Grand Unified Theory of big-scale evolution look like? Here is one answer. It would unify the various trends that have been documented and suspected, the features of life that have been said to increase over its history—body size, fitness, intelligence, versatility, evolvability, energy intensiveness, energy rate density, and complexity-in-the-sense-of-part-types, and complexity-in-the-sense-of-hierarchy. It would show us how these putative trends are related to each other, how they are all the product of some single simple principle or some small (...) set of principles. It would identify and connect all of the variables that are expected to increase over the long haul in evolution, perhaps in a single equation, or if not yet quantifiable, perhaps in a single breath.The obvious unifying candidate is fitness. Natural selection acts to adapt organisms to local circumstances, of course, but it might also act over the long term to produce adaptation on a bigger scale, to produce or .. (shrink)

The functional complexity, or the number of functions, of organisms hasfigured prominently in certain theoretical and empirical work inevolutionary biology. Large-scale trends in functional complexity andcorrelations between functional complexity and other variables, such assize, have been proposed. However, the notion of number of functions hasalso been operationally intractable, in that no method has been developedfor counting functions in an organism in a systematic and reliable way.Thus, studies have had to rely on the largely unsupported assumption thatnumber of functions can be (...) measured indirectly, by using number ofmorphological, physiological, and behavioral parts as a proxy. Here, amodel is developed that supports this assumption. Specifically, the modelpredicts that few parts will have many functions overlapping in them, andtherefore the variance in number of functions per part will be low. If so,then number of parts is expected to be well correlated with number offunctions, and we can use part counts as proxies for function counts incomparative studies of organisms, even when part counts are low. Alsodiscussed briefly is a strategy for identifying certain kinds of parts inorganisms in a systematic way. (shrink)