Artificial evolution, when freely allowed to manipulate a physical silicon medium, does indeed share many of the same problems that natural evolution faces in crafting systems able to operate over a wide range of ambient temperatures. A number of engineering proposals have been constructed by analysing these correspondences.
In analogy to biochemical compensation, it was suggested that an electronic system could be composed of many subcircuits, and that there be alternatives for each subcircuit. For a particular subcircuit, the alternatives would operate over different ranges of temperature, and would automatically come into play as appropriate. All the alternative subcircuits need not reside on the silicon simultaneously: the fast reconfiguration of an FPGA could be used to `swap' them in and out, possibly with the intervention of a high-level controller. Indeed, several whole systems could be evolved for different temperature ranges, and the system in its entirety swapped with another in response to a temperature change (there is even a biological counterpart for that). It was also seen how a system can stabilise its behavioural timescales by interaction with external timegivers, either implicit in the input, or explicitly supplied.
Temperature-altering mechanisms were discussed. The behavioural responses heavily relied upon by many animals are to a large extent not applicable in electronic applications other than autonomous mobile robotics. Several of the most important heat-exchange mechanisms found in nature are already in use in the electronics industry, with the exception of evaporative cooling, which seems inappropriate. The use of circuit activity adaptively to generate heat in analogy with thermogenic tissues in animals is highly promising, though there seems to be no precedent for the case where subcircuits with `nervous' function also adapt their activity for thermal considerations.
The most radical suggestion to come from the biological literature was that precise homeostatic control of internal temperature is almost essential for a complex behavioural and physiological organisation. It is straightforward to arrange for this in electronic systems, but in the current climate of extreme low cost and low power consumption, the benefits will need to be great for commercial acceptance. Dormancy, and the use of collective regulation behaviours, are possibilities for reducing the power consumption of a homeostatically thermoregulated electronic system.
In conclusion, biology provides a wealth of new ideas for combining the new possibilities of extreme efficiency through the unconstrained exploitation of physical resources with an adequate thermal stability. Some of these are suitable for immediate inclusion into research programmes in evolutionary electronics. The fact that thermal considerations cannot be neglected as an inconsequential implementation detail is also worthy of note to ALife researchers interested in animal behaviour, evolution, and neuroethology.
ACKNOWLEDGEMENTS: This work is supported by Xilinx Inc., and the Centre for Computational Neuroscience & Robotics: many thanks to each. Thanks also to John Gray, Phil Husbands, Dave Cliff, Inman Harvey, and everyone.