2.5 Living systems and information flows
Understanding the role of information flows in feedback relationships is often confusing. It is relatively easy to visualise flows of energy and matter (ecosystem food webs, water flowing through a rainforest ecosystem, etc). But how does information ‘flow’ within feedback loops, and how does this affect systems?
The first point to make clear is that information is only meaningful to those systems that can perceive it. In other words, these systems need to have components that act as sensors tuned to the particular form of signal that is arriving. On receiving this signal, these sensors must initiate changes in other flows, which may include flows of energy, matter or more information. Information, therefore, is something that does not already ‘exist’ in the environment. It is a reaction by a living system to flows of energy and matter round it. Flows of information are thus always associated with flows of matter and/or energy and a sensor within the living system. What is more, we not only have to have the sensors to receive that particular form of signal from the environment, but we have to have an internal model which can interpret that signal as information and assess its relevance with regards to its various goals. For example, feeling uncomfortably warm in a room is associated with the flow of heat energy into our bodies, but sensing this warmth commits us to an action such as removing an item of clothing or opening a window until we achieve the desired body temperature. This action is a direct result of our temperature regulation system – firstly our skin senses the change in temperature and secondly our nervous system and brain recognises the significance of that change and turns the signal into information. Other reactions resulting directly from the transfer of heat energy into our body may include an increase in our metabolic rate. This increase in metabolic rate is directly related to a flow of energy into the body and has nothing to do with information flow – chemical reactions speed up with increasing temperature.
But why is information flow only important to living systems? In order to survive, living systems have evolved the ability to sense changes and react pre-emptively. We sense heat and take off clothing, in order to prevent our bodies from overheating. Information allows living systems to actively promote their survival and adapt, rather than being passive recipients of changes in energy and material flows within their environment. Maintaining an active information subsystem requires additional expenditure of energy.
But what about things like room thermostats? They are inanimate control systems that rely on information (comparing room temperature to the temperature setting). They too sense a change in temperature, and the manufacturer has built in a model which ensures that this change is recognised and uses it as information to adjust a source of heat or cooling. But, in fact, these inanimate systems are only an extension of other living systems. The room temperature is only meaningful to the living system that occupies that room, and the room thermostat is essentially an extension of that living system’s information subsystem. As artificial intelligence devices become more sophisticated, this distinction may become blurred, and eventually we may even be able to define some robots as being ‘alive’.