# Popular Science Monthly/Volume 50/January 1897/Affections and Jealousies of Lizards

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* AFFECTIONS AND JEALOUSIES OF LIZARDS.
By M. J. DELBOEUF.
WHILE the possession of articulate language marks man as distinct from other animals, it seems certain to me that he and they are formed upon the same pattern so far as relates to sensations and feelings. This will hardly be contested as to sensations. Animals that have no eyes have of course no sensations of sight such as clear-seeing ones possess, and we have not the highly developed sense of direction of birds of passage and carrier pigeons; but these may be cultivated, and we are told that the American Indians have the sense of direction in an astonishing degree and can track their enemy as a dog does a hare. We have, it is true, some difficulty in conceiving the nature of the dog's power of scent, and it is possible that ants and bees have other senses than those we have; but these differences, marked as they may be, are at the bottom quantitative and not qualitative. Perhaps a slight modification of some part or another of the sensorial apparatus would give us sensations now strange to us.
Of the feelings, we find in all the higher animals those of love, friendship, hatred, anger, devotion, courage, suspicion, jealousy, cunning, fear, rancor, and pity. Some hens show a marked predilection for their chickens. The contrary also appears. There are stepmothers among hens, dogs, and cats. There are also feelings devious as to their object. The child adores its doll; a dog may be attached to a stick.
These various feelings are manifest also in the lower animals, as my continuous observations on my captive lizards, concerning which I have published several articles, have tended to prove.
My first two lizards had been captured, one in the Spanish Pyrenees and the other at Tarn, in France; wherefore I called them the Spanish and the French lizards, but afterward gave them the names of Pedro and Pierre. I was surprised on the very first day that I occupied myself with their education to observe the absolute contrariety of their characters and dispositions. Pierre, won over at once by the honeyed dainties I offered him, soon became accustomed to let himself be handled without trying to bite or run away, and to hide himself in my clothes, preferring the back, where it was warmer. Pedro, wild and untamable, if one tried to catch him, withdrew into a corner, and then stretching his paws in front of him, his eye glistening and his mouth wide open, hissing, springing at the hand that came near him, and, if he bit it, holding firmly and causing the blood to flow, revealed a resolution that even impressed the young men in my laboratory.
​I made a cage for the lizards of iron wire, open above, and, having a large room in my country house into which the sun shone all day on three sides, I put them in it. Pierre soon learned to leave his cage, to climb up to the windows by some rags I had hung to them, and passed from one to another, following the sun. In the evening he returned to the cage. Pedro, more stupid, tried vainly to get out of his prison, and, when I put him on the ledge of a window in the sun, let himself be overtaken by the shade, persisted for hours in efforts to get through the glass, and finally went to sleep where he had been left. Pierre, always in motion and investigating, discovered an old mattress in the room that had a hole in the cover, and took a liking to the hole. The mattress was put where it could not be reached except over a bridge of cords connecting it with the cage. Pierre, always expert, learned very soon to pass over this bridge to his hiding place. Pedro never could understand what the cords were good for, and his love of comfort never carried him to the point of finding the luxurious mattress. More recently Pierre, when at Liége, found a hole in the lining of a thick portière curtain, of which he became acquainted with the most minute folds and turns, and when he is there there is no means of getting him away.
The physiognomies of the two correspond with their characters. Pierre's eye is black, mild, intelligent, and scrutinizing. In Pedro's, the pupil, surrounded with a golden yellow circle, reflects distrust, hostility, and ferocity. It took six months to tame Pedro, and it was quite two years before he ceased to show his fierce temper when I came upon him too abruptly.
Pierre and Pedro lived on the best of terms with one another. At Liége they slept side by side, often interlocked. Pedro was fond of following Pierre in his wanderings and escapades. One day Pierre was lost. He had got out of my desk, had gone down several steps of the stairway, and had slipped in under the carpet, where he was casually found about three weeks afterward. During the whole time of his disappearance Pedro refused all food, and had no relish for insects and earthworms, till Pierre was restored to him. Seeing him so melancholy, I made an appeal to all my friends in the south of France to get me a new companion for him. M. H. Dineur, an engineer of Prades, sent me a lizard, October 1, 1891, three months after Pierre had been found. From that day on a great change was noticed. I had not learned the sex of my animals, but I observed now that they were both males, while the new one was a female. Pedro conceived a great antipathy for Pierre, which became more evident every day. Between the pursuits and bitings he suffered from Pedro, Pierre led a martyr's life till I was obliged to make a separate cage for him, and when Pierre was let out for an airing Pedro had to be shut up.
​Both, however, became very familiar with me, but Pedro more than Pierre. They would run to me, when I called them, from one end of the room to the other; but I had to hold out a meal worm for bait to bring Pierre, while Pedro would come when my hands were empty. This was not because he was stupid, for when he saw that I had no worm, and I drew back, he would follow me like a dog, and would climb upon me when I stretched out my leg.
M. Dineur sent me the next year several lizards at different times, all of which were received with an ill grace. Among them was a much larger one than Pedro, which he disliked along with the others. One day this lizard took Pedro up and gave him a good shaking, after which Pedro was very cautious in his annoyances, and would run away the instant the other turned toward him.
One lizard was respected by Pedro. It had been sent me from Algeria by M. Forel, of Zurich, of a species we had not been able to identify—a tree liver, small but even fiercer than Pedro, and quite untamable. After devouring one fine specimen and half eating another, it became a marked terror to all the other members of the collection. Only one of my lizards was fond of gentles; the others spit them out as soon as they had tasted them. As we may say of a company of men, "So many heads, so many minds," so we might say, with a little variation, of my pets, "So many lizards, so many dispositions."
Several of my lizards have died; Pedro, a few months ago, of a disease that first affected the eyes, after having been with me five years. Pierre is still living with me, but has long had a tumor on his leg, has lost his tail once by my fault and twice by his own, and no longer likes honey, but shakes his head with an air of disgust when it is put upon his nose—a fact that shows that the taste of lizards, too, may change with the years.
As to the longevity of lizards: I do not think I am much mistaken when I suppose that they may live twenty or thirty years, or even longer. As they advance in years the plates of the head, smooth when they are young, show wrinkles and cavities which become more marked and numerous. Those with me have not grown much, and though I weighed them often—usually about once a month—the results were too irregular to permit of any conclusions being drawn from them. The weight of the larger lizards varied to the extent of thirty grammes, according as they were well or sparingly fed. Pierre now weighs one hundred and six grammes, another one one hundred and twenty-eight grammes, and another thirty-eight grammes—weights which are evidently proportional to the cubes of their lengths; but, according to my figures, they have not gained any in five years. I conclude from this that many years must have passed before the larger ones attained the weight they have.
​The bifid extremity of their tongues, soft and always moist, is most probably an organ delicate to touch and probably to taste. They never cease to project it forward on to all the things within their reach, and although accustomed to meal worms, they begin generally by feeling them—at least the first one—in this way before taking them. The whip-tails (Uromastix) do the same, and when set down in the grass test all the flowers with their tongue. I should observe further that these animals did not hibernate with me, and that they were as lively and active in winter as in summer. The same may be said of two jerboas which I kept in captivity for three years and a half. Hibernation, therefore, does not seem to be a physiological necessity, but to be rather a natural effect of the cold, like the depression of the thermometer. The lizards were very fond of keeping themselves in front of the registers.
I now come to a trait which on reflection appears to me to be characteristic in the highest degree. Jealousy is a feeling not less natural to animals than to us. The males compete in strength, beauty, or talent to conquer the females. Beasts of prey, from spiders to lions and eagles, enforce respect of their hunting grounds. All defend their bed, their burrow, or their nest; and probably, too, herbivorous animals living in herds do not permit other herds to trespass upon their pastures. The jealousy of the dog is well known; if he is left alone, he will eat the part of the cat, and even rob the pigs of their messes. I have kept two jerboas for three years, all very familiar. Every evening we give each of them an almond, which they come and take out of the hand, and even ask for. But hardly has one received hers than, without paying any more attention to us, the other pursues her, takes it away from her, and a struggle ensues—a struggle which is otherwise courteous. The same play is acted when dandelions are given to them; hardly has one detached a leaf when the other tries to snatch it from her.
My lizards did not vary from the general rule. The best worm was always the one that a comrade had. If it was long, we might witness such a steeplechase as is seen sometimes in poultry yards.
Pedro was jealous of my preference and caresses. When he was on my sleeve, I could keep him for hours motionless by passing my hand lightly along his body; but if I took Pierre or another lizard up, his rage broke out at once, and he would jump upon him with his mouth menacingly wide open. If, however, I chose the large lizard, he gradually drew back, as if regretfully, without leaving me. Now, what good do caresses do to a lizard? Dogs and cats, they tell us, are delighted with them. But these animals, when they were young, were caressed by their mothers, who licked, bit, and amused them, and it is not strange ​that they should find in our cajolery a kind of recollection of motherly tenderness. They play together, embrace one another, and press against one another. The man who plays with them is like a companion of a little more respectable species, and that is all. In menageries, monkeys, bears, lions, tigers, and hyenas indulge in caresses to the point that some animals seek them and provoke them. But lizards, with their scaly skin, unaccustomed to embracing, feeling, and licking, hatched in the sun! My Pedro therefore presented a deviation of the feeling of jealousy. We not rarely see parrots that like to be stroked on the neck or the head. I once accustomed a vulture in the zoölogical garden of Ghent to pass his head out between the bars of his cage in order to have it held and caressed. My friend Prof. Gilkinet tamed a wild rabbit till it became as familiar as a dog, and learned to like the hand that stroked it. All these creatures have known the pleasures of the nest and of maternal contact. But again, a lizard? I suppose that when cuddled between my handkerchief and my hand, it felt in that kind of moist and easy cavity a renewal of the pleasure of the days when it was free, and had a secure refuge in the shelter of the leaves against a burning sun. On the other hand, when another lizard comes, it displays envy or anger as if it were threatened with dislodgment. Is it that? It alone can tell what is passing in its darkened psychic sensibility, for man can not penetrate the animal mind. But could he penetrate the human soul if he had not language; can he penetrate the soul of one whose language he is not acquainted with? If we met a savage in the midst of a virgin forest, should we be better able to divine his intentions than we should those of an alligator?
Does it not result from these observations that, aside from the faculty of abstract, artificial, and conventional language, which seems up to this time to be the exclusive appanage of man, there is no clearly marked difference in general feelings between man and his lower brethren? Or rather, as I have ventured to say on another occasion, I ask if there may not appear in each animal species from time to time scamps, individuals inclined to rapine and murder, like my lizard Ben Youssouf, or simple, uneasy creatures like Pedro?
Furthermore, these minute observations, which may seem puerile in the eyes of many, help to establish the psychological transition from man to animals placed much lower in the zoölogical scale than lizards. In this aspect, they may be considered an humble contribution in support of transformism.—Translated for the Popular Science Montlily from the Revue Scientifique.