The Outline of Science, Volume 1

We speak of the wisdom of the serpent; but it is not very easy to justify the phrase. Among all the multitude of reptiles—snakes, lizards, turtles, and crocodiles, a motley crowd—we cannot see much more than occasional traces of intelligence. The inner life remains a tiny rill. No doubt many reptiles are very effective; but it is an instinctive rather than an intelligent efficiency. The well-known "soft-shell" tortoise of the United States swims with powerful strokes and runs so quickly that it can hardly be overtaken. It hunts vigorously for crayfish and insect larv in the rivers. It buries itself in the mud when cold weather comes. It may lie on a floating log ready to slip into the water at a moment's notice; it may bask on a sunny bank or in the warm shallows. Great wariness is shown in choosing times and places for egg-laying. The mother tramps the earth down upon the buried eggs. All is effective.[Pg 219] Similar statements might be made in regard to scores of other reptiles; but what we see is almost wholly of the nature of instinctive routine, and we get little glimpse of more than efficiency and endeavour. In a few cases there is proof of reptiles finding their way back to their homes from a considerable distance, and recognition of persons is indubitable. Gilbert White remarks of his tortoise: "Whenever the good old lady came in sight who had waited on it for more than thirty years, it always hobbled with awkward alacrity towards its benefactress, while to strangers it was altogether inattentive." Of definite learning there are a few records. Thus Professor Yerkes studied a sluggish turtle of retiring disposition, taking advantage of its strong desire to efface itself. On the path of the darkened nest of damp grass he interposed a simple maze in the form of a partitioned box. After wandering about constantly for thirty-five minutes the turtle found its way through the maze by chance. Two hours afterwards it reached the nest in fifteen minutes; and after another interval of two hours it only required five minutes. After the third trial, the routes became more direct, there was less aimless wandering. The time of the twentieth trial was forty-five seconds; that of the thirtieth, forty seconds. In the thirtieth case, the path followed was quite direct, and so it was on the fiftieth trip, which only required thirty-five seconds. Of course, the whole thing did not amount to very much; but there was a definite learning, a learning from experience, which has played an important part in the evolution of animal behaviour. Comparing reptiles with amphibians, we may recognise an increased masterliness of behaviour and a hint of greater plasticity. The records of observers who have made pets of reptiles suggest that the life of feeling or emotion is growing stronger, and so do stories, if they can be accepted, which suggest the beginning of conjugal affection. The error must be guarded against of interpreting in terms[Pg 220] of intelligence what is merely the outcome of long-continued structure adaptation. When the limbless lizard called the Slow-worm is suddenly seized by the tail, it escapes by surrendering the appendage, which breaks across a preformed weak plane. But this is a reflex action, not a reflective one. It is comparable to our sudden withdrawal of our finger from a very hot cinder. The Egg-eating African snake Dasypeltis gets the egg of a bird into its gullet unbroken, and cuts the shell against downward-projecting sharp points of the vertebr . None of the precious contents is lost and the broken "empties" are returned. It is admirable, indeed unsurpassable; but it is not intelligent.