Moving and Thinking
Living organisms move. Some jump and run, others fly or slither, some crawl or burrow whilst some swim or hop, some walk on two legs, other canter on four. Dogs and cats and horses and fish and other obviously moving beings are the stars of the ambulatory show, and in the slow motion world of geological and ecological time their get-up-and-go attracts a lot of attention. But movement is not restricted to creatures with legs or wings and even the most sessile and sedentary lifeforms which seem to spend their entire time passively waiting do so in relation to an active and changing environment. Sunflowers turn their heads in lockstep with the motion of the nearest star, pond algae floats to the surface where oxygen and light can be found, dandelion seeds drift in the wind, trees send out roots into the earth and moss grows by inches along the north side of those trees.
Movement brings change; some spots are warmer than others, some are more plentiful in resources, some are safer, and movement toward these spots brings a positive change in the likely survival of the organism making these moves. Change of fortune through the change in location brought by movement may also be negative however; an organism blindly on the move may find itself in the waiting jaws of a predator, or in area of toxicity, or stranded far from its kin. Therefore, those rolling, tumbling, floating, drifting organisms which are able to somehow take control of this motion are more likely to survive and prosper than those which stumble randomly and fatalistically between famine and plenty, predator and prey. Incessant movement is part of the environmental conditions in which organisms operate and offers a set of possibilities for evolutionary development.
Strategies for taking advantage of this ambient movement vary across the animal and vegetable kingdom. Some organisms have settled for simple one-stop solutions such as phototropism, the facility of plants to grow toward the light. Others have used slightly more complex mechano-chemical processes, such as the amoeba which has a cell wall that is sensitive to the presence of chemicals in the water around it that signal the proximity of a nutrient source, usually a smaller organism. This sentivity is realised in the amoeba by the chemical composition of its cell wall changing such that it becomes less rigid and bulges in the direction of the food source. Eventually the amoeba makes contact, surrounding and absorbing it.
The strategy for exploiting locomotion which is of most interest and relevance to us however is the one preferred by those organisms which we regard as truly mobile and which we might feel we have most in common (at least to the extent that we vegetarians try not to eat them). These are creatures which have avoided putting all their evolutionary eggs in one basket and have gone for the building of a central nervous system.
The core principle of a central nervous system is that it connects faculties for collecting data from the outside world, call them ‘senses’, with mechanisms for movement and action in relation to that data. So for example, a simple organisms may have sensors which can detect the presence of food at a particular place in its local environment, and it may also have some means of moving through that environment, a flagellum for example. A central nervous system connecting these faculties coordinates the sense input with the motor output into an integrated sensorimotor system that allows the organism to move in the direction of the food source.
A creature with a slightly more complex central nervous system may have additional features that those other organisms do not. As well as being able to move and to respond to movement in a way which coordinates action with environment, this central nervous system may be able to evaluate the changing environment and make predictions based on ‘perceived’ differences in those values. This structure of evaluation and perception effectively ‘represents’ salient parts of the environment as processes within the central nervous system. This is broadly the view put forward by Pat Churchland in the book ‘Neurophilosophy’ (1986) in which she points out that this ability to coordinate representing the world with movement in the world is not only tactically useful but is also an eminently scaleable solution to the problems of survival. As she puts it “With increased complexity of behavioural repertoire comes increased capacity for representing the environment” (1986: 1). As the variety and multiplicity of sensorimotor activity increases, so the ability of the organism to not only exist within the world but also to model parts of that world within itself also increases.
Churchland goes on to link this ability to coordinate sense and movement within a sensorimotor system with the development of brains and something like intelligence or thought. She claims that
“If you root yourself to the ground, you can afford to be stupid. But if you move, you must have mechanisms for moving, and mechanisms to ensure that the movement is not utterly arbitrary and independent of what’s going on outside …. Neurons….are evolution’s solution to the problem of adaptive movement” (Churchland, 1986:13-14)
This is also the view put forward by Rodolfo Llinas in “i of the Vortex” (2002), a theory which he further develops into a possible account of the development of ‘the self’. He sums up this theory in the memorable and apposite aphorism “that which we call thinking is the evolutionary internalisation of movement“. This is something which I may be returning to later.
On youtube at http://www.youtube.com/watch?v=bpyKDmTtHdk
Churchland, P. (1986) Neurophilosophy: Toward a Unified Science of the Mind-Brain. Cambridge, Massachusetts: The MIT Press.
Llinás, Rodolfo R. (2001) I of the Vortex: From Neurons to Self. Massachusetts: The MIT Press.