. The paper studies the role of neutrality in the fitness landscapes associated with the evolutionary design of digital circuits and particularly the three-bit binary multiplier. For the purpose of the study, digital circuits are evolved extrinsically on an array of logic cells. To evolve on an array of cells, a genotype-phenotype mapping has been devised by which neutrality can be embedded in the resulting fitness landscape. It is argued that landscape neutrality is beneficial for digital circuit evolution. 1 Introduction Digital circuit evolution is a process of evolving configurations of logic gates for some prespecified computational program. Often the aim is for a highly efficient electronic circuit to emerge in a population of instances of the program. Digital electronic circuits have been evolved intrinsically [1] and extrinsically [2--6]. The former is associated with an evolutionary process in which each evolved electronic circuit is built and tested on hardware, whil...

The birth of a new form of business organization, the partnership system, in Renaissance Florence is examined closely in order to discover the social processes of invention in that extraordinarily inventive place. Stated generally, the processes of invention the authors discover there are transposition, refunctionality, and catalysis across multiple social networks. Specifically, political co-optation of cambio bankers in the aftermath of the Ciompi revolt induced the transposition of domestic guild methods to the international plane, thereby changing their purpose and their reach. Subsequent social absorption through marriage of these elevated bankers into the victorious political alliance infused partnership with the multiplex logic (and often money) of dowry, thereby reproducing partnership systems as an integral component in post-Ciompi republicanism. Medieval organizational logics of patrilineage and guild were transformed into Renaissance organizational logics of marriage and clientage. The origins of financial capitalism are partly rooted in this elite social-network response to class revolt.

A neural network with fixed topology can be regarded as a parametrization of functions, which decides on the correlations between functional variations when parameters are adapted. We propose an analysis, based on a differential geometry point of view, that allows to calculate these correlations. In practise, this describes how one response is unlearned while another is trained. Concerning conventional feed-forward neural networks we find that they generically introduce strong correlations, are predisposed to forgetting, and inappropriate for task decomposition. Perspectives to solve these problems are discussed.

2 The problem of speciation 2 Rugged adaptive landscapes 3 Nearly neutral networks and holey adaptive landscapes 6 The origin of the idea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Simple models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Russian roulette model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Uniformly rugged landscape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Multiplicative fitnesses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Stabilizing selection on an additive trait . . . . . . . . . . . . . . . . . . . . . . . . 10 NK model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Conclusions from models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Experimental evidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 A metaphor of holey adapt...

Epistasis is defined as the influence of the genotype at one locus on the effect of a mutation at another locus. As such it plays a crucial role in a variety of evolutionary phenomena such as speciation, population bottle necks and the evolution of genetic architecture (i.e. the evolution of dominance, canalization and genetic correlations). In mathematical population genetics, however, epistasis is often represented as a mere noise term in an additive model of gene effects. In this paper it is argued that epistasis needs to be scaled in a way that is more directly related to the mechanisms of evolutionary change. A review of general measurement theory shows that the scaling of a quantitative concepts has to reflect the empirical relationships among the objects. To apply these ideas to epistatic mutation effects it is proposed to scale AxA epistatic effects as the change in the magnitude of the additive effect of a mutation at one locus due to a mutation at a second locus. It is shown ...

. Morphospace studies are rich in pattern and process. Techniques for adequate description and mapping of morphologies have been increasingly refined and applied, the same being true of metrics for relevant parameters (like disparity). However, the testing of process hypotheses for specific patterns of morphospace occupation in time and space is less refined and demands more intensive scrutiny. The polarization of ecological and developmental explanations entails a need to properly tease apart their respective contributions. There are different ways to go about this problem. Here I describe one approach: the isolation of development as a target for testing via the construction of developmental morphospaces. Comparison of differently constructed morphospaces (one reflecting development directly, the other indirectly) provides a way of consistently studying the impact of development in constraining or facilitating changes in diversity. Congruence in range and/or location of "developmenta...

SUMMARY In this paper, I argue that the ultimate causes of morphological, and hence developmental, evolution are scale independent. In other words, micro- and macroevolutionary patterns show fundamental similarities and therefore are most simply explained as being caused by the same kinds of evolutionary forces. I begin by examining the evolution of single lineages and argue that dynamics of adaptive evolution are the same for bacteria in test-tube evolution experiments and fossil lineages. Similarly, I argue that the essential features of adaptive radiations large and small can be

Abstract. Many representations have been presented to enable the effective evolution of computer programs. Turing was perhaps the first to present a general scheme by which to achieve this end. Significantly, Turing proposed a form of discrete dynamical system and yet dynamical representations remain almost unexplored within conventional genetic programming. This paper presents results from an initial investigation into using simple dynamical genetic programming representations within a Learning Classifier System. It is shown possible to evolve ensembles of dynamical Boolean function networks to solve versions of the well-known multiplexer problem. Both synchronous and asynchronous systems are considered.

Central notions in evolutionary biology are intrinsically topological. This claim is maybe most obvious for the discontinuities associated with punctuated equilibria. Recently, a mathematical framework has been developed that derives the concepts of phenotypic characters and homology from the topological structure of the phenotype space. This structure in turn is determined by the genetic operators and their interplay with the properties of the genotype-phenotype map.

This paper explores the connections between inheritance systems, evolvability and modularity. I argue that the transmission of symbiotic micro-organisms is an inheritance system, and one that is evolutionarily significant because symbionts generate biologically crucial aspects of their hosts ’ organisation through modular developmental pathways. More specifically, I develop and defend five theses. 2 (i) I defend a multiple inheritance model. Any mechanism whereby members of generation N influence their offspring in generation N+1 in ways that tend to make those offspring resemble their parents is an inheritance mechanism. But not all inheritance mechanisms are of equal importance in the evolution of biological diversity and complex adaptation. Genetic inheritance is only one of the systems that supports cross-generation similarity. But it is one of exceptional importance. It is ancient. It is (almost) universal. And it is highly evolvable. (ii) But the vertical transmission of symbionts, especially of symbiotic microorganisms,