Publications

Understanding the origins of complexity is a key challenge in many sciences. Although networks are known to underlie most systems, showing how they contribute to well-known phenomena remains an issue. Here, we show that recurrent phase transitions in network connectivity underlie emergent phenomena in many systems. We identify properties that are typical of systems in different connectivity phases, as well as characteristics commonly associated with the phase transitions. We synthesize these common features into a common framework, which we term dual-phase evolution (DPE). Using this framework, we review the literature from several disciplines to show that recurrent connectivity phase transitions underlie the complex properties of many biological, physical and human systems. We argue that the DPE framework helps to explain many complex phenomena, including perpetual novelty, modularity, scale-free networks and criticality. Our review concludes with a discussion of the way DPE relates to other frameworks, in particular, self-organized criticality and the adaptive cycle.

This is a republication of this 2009 paper.

Evidence from several fields suggests that dual phase evolution (DPE) may account for distinctive features associated with complex adaptive systems. Here, we review empirical and theoretical evidence for DPE in natural systems and examine the relationship of DPE to self-organized criticality and adaptive cycles. A general model for DPE in networks is outlined, with preliminary data illustrating the emergence of phase changes.

This is a republication of this 2009 paper.

Data show that human-like cognitive traits do not evolve in animals through natural selection. Rather, human-like cognition evolves through runaway selection for social skills. Here, we discuss why social selection may be uniquely effective for promoting human-like cognition, and the conditions that facilitate it. These observations suggest future directions for artificial life research aimed at generating human-like cognition in digital organisms.

Data show that human-like cognitive traits do not evolve in animals through natural selection. Rather, human-like cognition evolves through runaway selection for social skills. Here, we discuss why social selection may be uniquely effective for promoting human-like cognition, and the conditions that facilitate it. These observations suggest future directions for artificial life research aimed at generating human-like cognition in digital organisms.

Evidence from several fields suggests that Dual Phase Evolution (DPE) may account for distinctive features associated with complex adaptive systems. We review empirical and theoretical evidence for DPE in natural systems and examine the relationship of DPE to other complexity theories such self-organised criticality and adaptive cycles.

Evidence from several fields suggests that dual phase evolution (DPE) may account for distinctive features associated with complex adaptive systems. Here, we review empirical and theoretical evidence for DPE in natural systems and examine the relationship of DPE to self-organized criticality and adaptive cycles. A general model for DPE in networks is outlined, with preliminary data illustrating the emergence of phase changes.

Analytical models show that high-dimensional fitness landscapes form “holey” rather than “rugged” topographies, but the implications of this finding for biological and artificial life systems remain largely unexplored. One of the reasons for this gap can be attributed to serious difficulties in the implementation of individual-based holey fitness landscape (HFL) models. Here, we introduce a method for simulating HFLs in spatially explicit individual-based models that overcomes these difficulties. We examine how the HFL changes predictions for the maintenance of genetic diversity in the face of migration. Previous models suggest that ecologically-based reproductive isolation will rapidly collapse under migration. Our results indicate that an underlying HFL can often maintain diversity in this situation. Hybrid species emerge frequently when HFL genetics are simulated, but are usually doomed to extinction because of small population sizes. However, hybridisation can also lead to novel adaptations and potentially the exploitation of new ecological niches. More generally, the results imply that HFL genetics should not be neglected in studies of adaptation and diversity.

During the last three decades, the field of Intelligent and Evolutionary Systems (IES) has established itself as a key research area, with the ability to address common problems across diverse disciplines. Many challenges arise from the massive volumes of data provided by widespread automation, and from the increasingly complex webs of interaction that arise as local events scale up to generate global phenomena. Inspiration from biology – the core concept of IES research - underlies key advances in engineering systems that respond with adaptive intelligence and resilience in such noisy, dynamic environments.

Today, IES continues to develop, as traditional neural and genetic computation techniques are supplemented with new ideas from a diverse range of areas that include swarm computing, artificial life, complex systems and many others. Advances on key theoretical fronts are complemented by close ties to applications within specific areas, ensuring that IES retain relevance across disciplines.

The Asia Pacific Symposium on Intelligent and Evolutionary Systems is an annual event that brings together researchers from the Asia-Pacific Rim and other areas to discuss emerging ideas as well as on-going research in intelligent and evolutionary computation, and to deepen and extend links and collaboration in the community.

The 2008 event is the 12th meeting in a series of IES symposia that originated in 1997. This year, the event was held in Melbourne, Australia in conjunction with the 7th International Conference on Simulated Evolution and Learning (SEAL'08). The work presented at the symposium is indicative of the diverse areas touched by IES research, with applications in architecture, horticulture, epidemiology, software development and traffic control among others. In addition to exploring several new applications of genetic algorithms, papers here develop novel approaches to data assimilation, examine the theory and application of learning systems, and explore the evolution of culture and cooperation in multi-agent simulations. Key ideas such as non-dominance and entropy evolution are also further developed.

We are very grateful to the many people who have helped to make this year's symposium a success. First of all we thank the authors for their work and participation, and for providing manuscripts on time and in a standard format. All papers were carefully reviewed by at least two independent members of the program committee to ensure quality and consistency, and the time and effort contributed by the program committee are much appreciated. We are particularly grateful to Prof. David Green whose experience from previous IES meetings was invaluable for ensuring the success of this year's event. We also thank Ms Dianne Nguyen for her assistance with the event coordination and the production of these proceedings.

In this study, we describe an evolutionary mechanism – Dual Phase Evolution (DPE) – and argue that it plays a key role in the emergence of internal structure in complex adaptive systems (CAS). Our DPE theory proposes that CAS exhibit two well-defined phases – selection and variation – and that shifts from one phase to the other are triggered by external perturbations. We discuss empirical data which demonstrates that DPE processes play a prominent role in species evolution within landscapes and argue that processes governing a wide range of self-organising phenomena are similar in nature. In support, we present a simulation model of adaptive radiation in landscapes. In the model, organisms normally exist within a connected landscape in which selection maintains them in a stable state. Intermittent disturbances (such as fires, commentary impacts) flip the system into a disconnected phase, in which populations become fragmented, freeing up areas of empty space in which selection pressure lessens and genetic variation predominates. The simulation results show that the DPE mechanism may indeed facilitate the appearance of complex diversity in a landscape ecosystem.

Recent studies suggest that macro-evolutionary patterns such as punctuated equilibrium may be generated by a process termed Dual Phase Evolution (DPE). According to the DPE hypothesis, evolution in landscapes exhibits two phases – selection and variation. Disturbances such as mass extinctions can flip the landscape from selection to variation phases. Similar processes occur in a wide range of artificial, natural and social complex systems. Here, we show that mass extinctions induce DPE in a simulation model of adaptive radiation. The model is based on a previous model of adaptive radiation which did not incorporate Dual Phase Evolution. Results confirm that mass extinctions caused by external disturbances can trigger periods of rapid species turnover and adaptive radiation (variation phases), which are followed by long periods without innovation (selection phases). Our simulations also show that the spatial configuration of disasters leading to mass extinctions strongly influences whether and to what extent such disasters are capable of inducing evolutionary variation phases.

A primary motivation for research in digital ecosystems is the desire to exploit the self-organising properties of natural ecosystems. Ecosystems are thought to be robust, scalable architectures that can automatically solve complex, dynamic problems. However, the biological processes that contribute to these properties have not been made explicit in digital ecosystem research. Here, we discuss how biological properties contribute to the self-organising features of natural ecosystems. These properties include populations of evolving agents, a complex dynamic environment, and spatial distributions which generate local interactions. The potential for exploiting these properties in artificial systems is then considered. An example architecture, the Digital Business Ecosystem (DBE), is considered in detail. Simulation results imply that the DBE performs better at large scales than a comparable service-oriented architecture. These results suggest that incorporating ideas from theoretical ecology can contribute to useful self-organising properties in digital ecosystems.