Why engineer systems simulating living creatures and their societies? Well, it helps us
understand better those living creatures and their societies. But in the process, we obtain
artificial creatures with the same capabilities as the ones simulated from the living creatures.
So we have a benefit, both for engineering and biology (Maes, 1991).
Also, understanding adaptive behaviour paves the road for understanding higher
cognition.
0.1. Behaviour and the Evolution of Cognition
“The more we can find out about how our brains evolved from those of simpler animals,
the easier the task will be”
—Marvin Minsky
We can classify adaptive (animal) behaviour in the following types of behaviours:
vegetative, reflex, reactive, and motivated behaviours. Vegetative behaviours would be the ones
that are in the organism by “default”, such as breathing, heart beating, metabolizing, etc. They
can be seen as implicit, internal behaviours, that are not noticed by an observer because they
are always there. They do not require to be modelled, because they are “obvious1”. Reflex
behaviours would be action-response-based behaviours, such as the response to a burn, that
is to move the injured part from the heating source. We would argue that bacteria’s behaviours
are controlled only by reflex behaviours. We could say that in vertebrate animals, reflex
behaviours are controlled at a medular level. We can see that there is no problem of action
selection in the previous behaviour types, as it is in the following. Reactive behaviours would
be the ones that depend strongly of an external stimulus, or a set or sequence of external stimuli
(McFarland, 1981). For example, if I perceive a tasty chocolate cake, even if I am not hungry
(no internal motivation), I might reactively eat it; but also I might decide not to eat it, because
I have other internal needs to be satisfied (such as vanity). Most simple social behaviours could
be classified as reactive, such as flock and school formations, stampedes, and crowd behaviours.
This is because each individual in the society imitates the neighbours, but without the “need”
of doing so (it is not that they do not need it, but that they can live without it). We can see that
reflex and reactive behaviours are similar, but the difference is that the reactive behaviours go
through an action selection process, which may cause that they will not be executed, and the
reflex behaviours will always be executed. Motivated behaviours would be the ones that need
an internal motivation and an external stimulus (which might be also the absence of a stimulus)
in order to be executed. For example, the searching for water by an animal may be caused by
his thirst. We understand by internal motivations those that are needed to be satisfied so that
the entity will be in a “comfort zone”. Not only those motivations needed for survival are
internal motivations. Emotions can also be seen as internal motivations, or as expressions of
1They are obvious at the level of the individual, for example, hunger decreasing because of feeding is
obvious at an individual level, but quite complex at a protein or cellular level.