Reading 1.6: Models in nature
Resource Reading 1.4 focused on different models that humans use to help them think through and act in a complex world. This provokes the questions: but what about other living things? Do they model their environment?
A mental model is an example of an internalised model, a model contained within a brain. This idea of an internalised model gives surprising insights.
Internalised models seem to be at the heart of life itself. One of the simplest examples is that of a protein molecule that can be said to model the shape of another molecule. This similarity of shape enables them to selectively interact. This is a mechanism that is one of the fundamental bases of life. A second example in a relatively simple life form is a bacterium that can detect a chemical gradient over its body length so that it can swim up the gradient to where food is plentiful. I can interpret this as the bacterium containing a model whose purpose is to enable it to find food. A more complex example is a fly that can detect and is sensitive to a small black moving patch, its model of another fly, a potential mate. So here you can consider models driving behaviour.
In more complex organisms models not only drive behaviour but are used for communication. Karl von Frisch (von Frisch, 1967) describes bees at work. When a bee returns to the hive carrying nectar from a newly-found source it needs to communicate this to other bees. Bees communicate using a model of where a food source is located.
They dance a special dance usually performed on a vertical surface of the hive, communicating the direction of a potential food source and its distance from the hive to other bees around (see Figure 4). The distance the food source is from the hive is represented by the proportion of time the bee spends wagging its tail in the dance and the direction is represented by the angle to the vertical the bee adopts for the wagging portion of the dance. The spatial location of the source is modelled so that communication can take place. The bee converts its experience into the dance, and the watching bees reconvert what they see into action. The internal model is converted to an external manifestation and then reconverted to action by watching bees.
If a bee arrives back at the hive loaded with nectar and there are no available bees around to unload it and take the nectar back to the storage area, then it does a different trembling dance, the purpose being to attract more helpers to the storage task. These two dances keep the collection system in balance.
In the primitive animal world, the internalised models of an individual cannot change. Individual animals cannot learn, but of course the species can, since internal structures can and do change through the mechanisms of evolution to enable adaptation to a changing environment. In higher animals, i.e. species with advanced cognitive abilities, internalised models can change – higher animals have a nervous system that is plastic, and that can change through an individual animal's lifetime. So individuals can learn, can change internal models to match a changing environment. Clearly this is a necessary development to enable longer lifetimes for more complex individual animals – if the environment changes then so must the internal models to enable the animal to survive. Humans have developed this ability par excellence, and therein lies our supreme adaptability. Humans can change any of their mental models through learning.