Ask anybody that question and you will probably get a different answer every time. Most would argue that intelligence is limited to mankind and give examples of brainy people like Einstein or Newton.
Others might identify it as being clever, good in exams or being smart, having a high IQ. But was Einstein particularly intelligent or Newton? Both were very gifted at mathematics and certainly imaginative but outside that, their lives didn’t seem to be any smarter or express particular cleverness than millions of others; in some respects perhaps the opposite.
We don’t know how well either would have done in IQ tests. Although successful people generally have a higher IQ than average, the correlation with success is chequered and not outstanding. So it is hardly surprising one recent article found at least 70 different versions of intelligence and then proceeded to provide a novel summary of its own.
Intelligence is an aspect of behaviour, and behaviour is the response to our environment, more properly the signals we perceive. The word intelligence is derived from the Latin interlegere, which simply means to choose between. Choice implies something in past behaviour has opened up two or more different courses of future action. Skill in assessing and taking the right choice within the present context we should describe as intelligent behaviour.
IQ supposedly measures some intrinsic property of the individual brain but actually it was set up simply to identify pupils with special needs. The present test sets problems requiring some numeracy, spatial recognition, and logic; it is largely academic in character but also strongly cultural.
We can see more clearly what intelligence is about if we take away the present cultural bias for intelligence. Go back 50-100,000 years to earlier mankind. The problems he/she faced were basic: finding food and mates, and avoiding predators. Failure led to premature death; success increased sibling number thus fulfilling the basic biological property we call fitness. Advanced society has simply removed the fundamental base of intelligence.
No wonder it is so difficult to characterise. One psychologist Howard Gardener has imaginatively identified all kinds of intelligence, emotional and physical intelligence, linguistic, musical and spatial intelligence, and logico-mathematical intelligence. All except the last one would be crucial for early mankind’s survival.
But I don’t see Einstein or Newton genius though they are in logico-mathematical intelligence as doing particularly well 100,000 years ago. Furthermore mathematics simply didn’t exist then except perhaps simple numeracy. It is a modern day activity in a society in which the fundamentals of survival are no longer pressing.
The most common view amongst psychologists is that intelligence relates to problem-solving and given that the quality does vary amongst individuals, a capacity for problem-solving. But then we are faced with a conundrum. All living things from bacteria plants to animals face the same basic issues of life, finding food whatever it is, finding mates, and avoiding predators; all these require problem-solving and the sheer variety of them for any one individual means the solution can’t be fixed in the genes as some sort of homunculus but necessitates assessment, a process that in some way incorporates knowledge of past history and the ability to choose between alternatives.
Even swimming bacteria have to choose between swimming towards food and away from poisons. To do the opposite is guaranteed disaster, the decision leading to survival and fitness is obvious. But the assessment there does not involve brains or neural pathways; bacteria simply use a protein network whereas animals use a neural network.
It is the complexity of networks of interacting molecules or cells that provide for intelligent behaviour. In swarm intelligence interactions relatively simple in number occur between effectively cloned organisms in the self-organising beehive or colony.
Similar problems are faced by higher plants. Plant behaviour is not familiar to many; are they not often considered still life?
But higher plants simply work on a different time scale. They lack a nervous system but have complex chemical communication between millions of cells that forms the basis of assessment and leads to decisions within the context of detailed environmental perception.
Much visible behaviour requires growth and in virtually all organisms, growth can be a slow business. Plants forage for the resources of light, minerals, and water. They possess self-recognition and recognise competitors. They possess the capabilities of what we call learning and memory, particularly in response to herbivory. But all this in molecules, not nerves, although electrical connection occurs and is used to transfer information. Intelligent behaviour is as essential for them as any other organism.
The underpinning behaviour is just as surprising. Leaves maintain a relatively constant internal temperature, roots sense and seek out resources, the cambium (a kind of inner skin) comparatively assesses the behaviour of branch roots or shoots and awards additional resources to those which are more likely to be profitable in the future.
These are positive responses to signals in their environment that will increase fitness. Selection also operates in mating by a variety of methods to ensure the most fit do mate. Self-organisation is a fundamental plant attribute. Intelligent behaviour is a holistic quality expressed only by the individual and in plants it finds its most surprising expression but without it plants would not be here.
Headline image credit: Photograph of a carnivorous plant, cultivated by Martha Miller, part of a display featured at a First Friday event at the Chemical Heritage Foundation, Philadelphia, PA, USA, on November 6, 2009. Photograph by Conrad Erb, Chemical Heritage Foundation. CC BY-SA 3.0 via Wikimedia Commons.