Ninth International Conference on the Simulation and Synthesis of Living Systems (ALIFE9)

Boston, Massachusetts

September 12-15th 2004

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Artwork by Dr. Cliff Pickover used by permission





Evolution of Sensors
Tutorial at Alife IX

Daniel Polani
Department of Computer Science
University of Hertfordshire
United Kingdom



An individual or agent usually is seen as an essentially distinguished subentity of a larger system, its environment. The environment can exert its influence on the agent in a manifold variety of different ways. Sensors and actors constitute the interface between environment and agent, enabling the latter to identify its current state and, using this knowledge, to gain certain control over its own fate. Since information is central for the ability to perform effective actions, an efficient utilization of available state information is vital to survive in an environment governed by selection.

The principle of accessing new sensory channels and to make use of the implicit information coded there has been exploited in nature to a formidable degree. Olfactory, tactile, auditive and visual, but also e.g. electric and even magnetic senses have been realized in a vast multitude of variants, often utilizing organs not originally "intended" for the purpose they serve. At the same time, as already Darwin points out, it seems difficult to believe that an organ of such complexity as e.g. the eye "could have been formed by natural selection". Nevertheless photoreceptors of widely different degree of differentiation have evolved in at least forty independent lines of descent.

Several motivations drive the study of sensor evolution. One is to understand the mechanisms that drive the creation of sensors
exploiting information sources in such a large variety of ways; this aspect has intimate connections with questions of evolvability. The
second is to develop agents that can adapt themselves with a higher degree of flexibility to their environment. Thirdly, there are strong indications that understanding the acquisition of sensory information can provide deep and far-reaching insights into role and mechanisms of intelligent information processing and of embodiment.

Aims of the Tutorial

In this tutorial the audience will be introduced to the general topic of sensor evolution. The interface role that sensors in the
interaction between agents and environment will be discussed and different views of the sensor concept will be developed. An overview over sensors evolved in nature and the role of different types of mechanisms of evolvability; we will devote special attention to several particularly intriguing examples of sensor development to illustrate the spectrum of phenomena. Focusing on sensory information processing we will stress and discuss the tight connection between sensor evolution and that of information processing (e.g. neural) systems. This tutorial strives to give the audience insights into the scope, the philosophy, the models, and the methods of sensor evolution research as well as the implications the study of sensor evolution has for other fields in Artificial Life, Biology and Robotics.

Target Audience

The targeted audience includes a broad range of people, in particular, people interested in: general evolutionary mechanisms for sensor development, also with respect to perspectives for hardware evolution; general questions of (embodiment) evolution and evolvability; fundamental questions of information processing in embodied action-perception loops and its role for modelling life-like systems.