“Baboons often show their passion, and threaten their enemies in a very odd manner, namely, by opening their mouths widely, as in the act of yawning. Mr. Bartlett has often seen two Baboons, when first placed in the same compartment, sitting opposite to each other, and thus alternately opening their mouths; and this action seems frequently to end in a real yawn. Mr. Bartlett believes that both animals wished to show to each other that they are provided with a formidable set of teeth, as is undoubtedly the case. As I could hardly credit the reality of this yawning gesture, Mr. Bartlett insulted an old Baboon, and put him into a violent passion, and he almost immediately thus acted. Some species of Macacus and of Cercopithecus behave in the same manner. Baboons likewise show their anger—as was observed by Brehm with those which he kept alive in Abyssinia—in another manner, namely, by striking the ground with one hand, like an angry man striking the table with his fist. I have seen this movement with the Baboons in the Zoological Gardens, but sometimes the action seems rather to represent the searching for a stone or other objects in their beds of straw. Mr. Sutton has often observed the face of the Rhesus Monkey, when much enraged, growing red. As he was mentioning this to me another Monkey attacked a Rhesus, and I saw its face redden as plainly as that of a man in a violent passion. In the course of a few minutes after the battle the face of this Monkey recovered its natural tint; at the same time that the face reddened, the naked posterior part of the body, which is always red, seemed to grow still redder, but I cannot positively assert that this was the case. When the Mandrill is any way excited the brilliantly-coloured naked parts of the skin are said to become still more vividly coloured.
“With several species of Baboons the ridge of the forehead projects much over the eyes, and is studded with a few long hairs representing our eyebrows. These animals are always looking about them, and in order to look upwards they raise their eyebrows. They have thus, as it would appear, acquired the habit of frequently moving their eyebrows. However this may be, many kinds of Monkeys, especially the Baboons, when angered or in any way excited, rapidly and incessantly move their eyebrows up and down, as well as the hairy skin of their foreheads. As we associate in the case of man raising and lowering of the eyebrows with definite states of the mind, the almost incessant movement of the eyebrows by Monkeys gives them a senseless expression. I once observed a man who had a trick of continually raising his eyebrows with any corresponding emotion, and this gave to him a foolish appearance; so it is with some persons who keep the corners of their mouths a little drawn backwards and upwards, as if by an incipient smile, though at the time they are not amused or pleased.
“A young Orang, made jealous by her keeper attending to another Monkey, slightly uncovered her teeth, and uttering a peevish noise, like ‘tish-shist,’ turned her back on him. Both Orangs and Chimpanzees when a little more angered protrude their lips greatly, and make a harsh barking noise. A young female Chimpanzee in a violent passion presented a curious resemblance to a child in the same state. She screamed loudly, with widely-open mouth, the lips being retracted so that the teeth were fully exposed. She threw her arms wildly about, sometimes clasping them over her head. She rolled on the ground, sometimes on her back, sometimes on her belly, and hit everything within reach. A young Gibbon in a passion has been described as behaving in almost exactly the same manner. The lips of young Orangs and Chimpanzees are protruded sometimes to a wonderful degree under various circumstances. They act thus not only when slightly angered, sulky, or disappointed, but when alarmed at anything—in one instance at the sight of a Turtle—and likewise when pleased. But neither the degree of protrusion nor the shape of the mouth is exactly the same, as I believe, in all cases; and the sounds which are then uttered are different.
“Frowning, which is one of the most important of all the expressions in man, is due to the contraction of the corrugations by which the eyebrows are covered and brought together, so that vertical furrows are formed on the forehead. Both the Orang and Chimpanzee are said to possess this muscle, but it seems rarely brought into action, at least in a conspicuous manner. I made my hands into a sort of cage, and placing some tempting fruit within, allowed both a young Orang and Chimpanzee to try their utmost to get it out; but, although they grew rather cross, they showed not a trace of a frown, nor was there any frown when they were enraged. Twice I took two Chimpanzees from their rather dark room suddenly into bright sunshine, which would certainly have caused us to frown. They blinked and winked their eyes, but only once did I see a very slight frown. On another occasion I tickled the nose of a Chimpanzee with a straw, and, as it crumpled up its face, slight vertical furrows appeared between the eyebrows. I have never seen a frown on the forehead of the Orang.
“A fresh-water Turtle was placed, at my request, in the same compartment in the Zoological Gardens with many Monkeys, and they showed unbounded astonishment, as well as some fear. This was displayed by their remaining motionless, staring intently with widely-opened eyes, their eyebrows being often moved up and down. Their faces seemed somewhat lengthened. They occasionally raised themselves on their hind legs to get a better view. They often retreated a few feet, and then, turning their heads over one shoulder, again stared intently. It was curious to observe how much less afraid they were of the Turtle than of a living Snake, which I had formerly placed in their compartment, for in the course of a few minutes some of the Monkeys ventured to approach and touch the Turtle. On the other hand some of the larger Baboons were greatly terrified, and grinned as if on the point of screaming out. When I showed a little dressed-up doll to the black Baboon, it stood motionless, stared intently with widely-opened eyes, and advanced its ears a little forwards; but when the Turtle was placed in its compartment, this Monkey also moved its lips in an odd, rapid, jabbering manner, which the keeper declared was meant to conciliate or please the Turtle. I was never able clearly to perceive that the eyebrows of astonished Monkeys were kept permanently raised, though they were frequently moved up and down. Attention, which precedes astonishment, is expressed by man by a slight raising of the eyebrows, and Dr. Duchenne informs me that when he gave to the Monkey formerly mentioned some quite new article of food, it elevated its eyebrows a little, thus assuming an appearance of close attention. It then took the food in its fingers, and with lowered or rectilinear eyebrows scratched, smelt, and examined it, an expression of reflection being thus exhibited. Sometimes it would throw back its head a little, and again with suddenly-raised eyebrows re-examine, and finally taste, the food.
“In no case did any Monkey keep its mouth open when it was astonished. Mr. Sutton observed for me a young Orang and Chimpanzee during a considerable length of time; and, however much they were astonished, or whilst listening intently to some strange sound, they did not keep their mouths open. This fact is surprising, as with mankind hardly any expression is more general than a widely-open mouth, under the sense of astonishment. As far as I have been able to observe, Monkeys breathe more freely through their nostrils than men do, and this may account for their not opening their mouths when they are astonished, for, as can be discovered with care, man apparently acts in this manner when startled, at first for the sake of quickly drawing a full inspiration, and afterwards for the sake of breathing as quietly as possible.
“Terror is expressed by many kinds of Monkeys by the utterance of shrill screams, the lips being drawn back so that the teeth are exposed. The hair becomes erect, especially when some anger is likewise felt. Mr. Sutton has distinctly seen the face of the Rhesus Monkey grow pale from fear. Monkeys also tremble from fear, and sometimes they void their excretions. I have seen one which, when caught, almost fainted from an excess of terror.”
Rengger, who studied the American Monkeys carefully, says that they evidently understand each others’ gestures, and this is plain enough to all who spend a little time in a large collection of them. They have their likes and dislikes, and submit to be teased and bullied by some favourite, although of a different species; the contrary, however, is the usual occurrence, and they resent familiarities very readily. Perhaps the most amusing instance of this fondness is given by Mr. Darwin, who had it from the Superintendent of the Zoological Gardens. Two Chimpanzees, rather older animals than those usually brought to England, were introduced to each other for the first time:—“They sat opposite, touching each other with their much-protruding lips, and the one put his hand on the shoulder of the other. They then mutually folded each other in their arms. Afterwards they stood up, each with one arm on the shoulder of the other, lifted up their heads, opened their mouths, and yelled with delight.”
