Part of the ALife enterprise is to use computer simulations as a tool in theoretical biology [27]. Animal behaviour, evolution, and neuroethology are studied. As is essential in any model, some of the complexity of the real system is left behind, and it might be thought that thermal considerations can safely be ignored as a `mere implementation detail' with no impact on the essence of behaviour and evolution. It seems clear from the biological literature summarised here that this is not the case. Behavioural mechanisms for thermal regulation are ubiquitous and can be a significant component of an animal's lifestyle. This is especially the case when water economy, not considered above, is taken into account: to use evaporative cooling, one must have drunk sufficiently or be adjacent to an external liquid source.
We have even seen that thermal considerations can have an influence on the evolution of body size: small animals have a greater surface-area to volume ratio, which affects heat transfer with the environment [6, Chap. 32 ,]. They also have smaller reserves of food, water, or energy (important for dormancy), but can easily seek thermal shelter by behaviours like burrowing [28]. Small animals can change their body temperature more rapidly than larger ones, so can suspend or resume thermoregulation relatively rapidly.
Thermal considerations can even influence macroevolution. Recently, physiological and morphological adaptations to climatic conditions in the house sparrow (Passer domesticus) in N. America have led to the differentiation of new sub-species living at distinct localities [15]. Such population dynamics cannot be understood without considering animals' responses to temperature.
It can be concluded that there is a wide range of biological phenomena within the scope of ALife which can only be fully understood with reference to animals' thermal responses.