Nov. 2, 1876] 



NATURE 



10 



read an article by Job. von Fischer, of Gotha, published in Der 



Zoolos;ische Garten, April, 1876, on the expression of monkeys 

 under various emotions, which is well worthy of study by any 

 one interested in the subject, and which shows that the author is 

 a careful and acute observer. In this article there is an account 

 of the behaviour of a young male mandrill when he first beheld 

 himself in a looking-glass, and it is added, that after a time he 

 turned round and T>resented his red hinder end to the glass. 

 Accordin<;ly I wrote to Herr J. von Fischer to ask what he sup- 

 posed was the meaning of this strange action, and he has sent 

 me two long letters full of new and curious detail?, which will, 

 I hope, be hereafter published. He says that he was himself at 

 first perplexed by the above action, and was thus led carefully 

 to observe several individuals of various other species of mon- 

 keys , which he has long kept in his house. He finds that not 

 only the mandrill (Cynccephahts Diormov) but the drill (C letico- 

 fhaus) ard three other kinds of baboons (C haniadryas, sphinx, 

 and bahoiiin), also Cynopithecns nign; and Afacacus rhesus and 

 nevustrinus, turn this part of their bodies, which in all these 

 species is more or less brightly coloured, to him when they are 

 pleased, and to other persons as a sort of greeting. He took 

 ^ pains to cure a Macacus rhesus, which he had kept for five years, 

 of this indecorous habit, and at last succeeded. These monkeys 

 are particularly apt to act in this manner, grinning at the same 

 time, when first introduced to a new monkey, but often also to 

 their old monkey friends ; and after this mutual display they 

 begin to play together. The young mandrill ceased spon- 

 taneously after a time to act in this manner towards his master, 

 von Fischer, but continued to do so towards persons who were 

 strangers and to new monkeys. A young Cynopithecns niger 

 never acted, excepting on one occasion, in this way towards his 

 master, but frequently towards strangers, and continues to do so 

 up to the present time. From these facts von Fischer concludes 

 that the monkeys which behaved in this manner before a look- 

 ing-glass (viz., the mandrill, drill, Cynopithecns niger, Macacus 

 rhesus, and nemestrmus) acted as if their reflection were anew ac- 

 quaintance. The mandrill and drill, which have their hinder ends 

 especially ornamented, display it even whilst quite young, more 

 frequently and more ostentatiously than do the other kinds. 

 Next in order comes Cynocephalus hamadryas, whilst the other 

 species act in this manner seldomer. The individuals, however, 

 of the same species, vary in this respect, and some which were 

 very shy never displayed their hinder ends. It deserves especial 

 attention that von Fischer has never seen any species purposely 

 exhibit the hinder part of its body, if not at all coloured. 

 This remark applies to many individuals of Macacus cynomolgus 

 and Cercocebus radiatits (which is closely allied to M. rhesus), to 

 three species of Cercopithecus and several American monkeys. 

 The habit of turning the hinder ends as a greeting to an old 

 friend or new acquaintance, which seems to us so odd, is not 

 really more so than the habits of many savages, for instance that 

 of rubbing their bellies with their hands, or rubbing noses to- 

 gether. The habit with the mandrill and drill seems to be 

 instinctive or inherited, as it was followed by very young 

 animals ; but it is modified or guided, like so many other 

 instincts, by observation, for von Fischer says that they take 

 pains to make their display fully, and if made before !wo 

 observers, they turn to him who seems to pay the most atten- 

 tion. 



With respect to the origin of the habit, von Fischer remarks 

 that his monkeys like to have their naked hinder ends patted or 

 stroked, and that they then grunt with pleasure. They often 

 ftlso turn this part of their bodies to other monkeys to have bits 

 of dirt picked off, and so no doubt it would be with respect to 

 thorns. But the habit with adult animals is connected to a 

 •-•ertain extent with sexual feelings, for von Fischer watched 

 through a glass door a female Cynopithecus niger, and she 

 during several days, " umdrehte und dem Mannchen mit gur- 

 gelnden Tonen die stark gerothete Sitzflache zeigte, was ich 

 friiher nie an diesem Thier bemerkt hatte. Beim Anblick dieses 

 Gegenstandes erregte sich das Mannchen sichtlich, denn es 

 polterte heftig an den St'aben, ebenfalls gurgelnde Laute aus- 

 stossend." As all the monkeys which have the hinder parts 

 of their bodies more or less bright coloured live, accord- 

 ing to von Fischer, in open rocky places, he thinks that these 

 colours serve to render one sex conspicuous at a distance 

 to the other ; but as monkeys are such gregarious animals, I 

 should have thought that there was no need for the sexes to 

 recognise each other at a distance. It seems to me more pro- 

 bable that the bright colours, whether on the face or hinder end, 

 or, as in the mandrill, on both, serve as a sexual ornament and 



attraction. Anyhow, as we now know that monkeys have the 

 habit of turning their hinder ends towards other monkeys, it 

 ceases to be at all surprising that it should liavebeen this part of 

 their bodies which has been more or less decorated. The fact 

 that it is only the monkeys thus characterised which, as far a? 

 at present known, act in this manner as a greeting towards other 

 monkeys, renders it doubtful whether the habit was first acquired 

 from some independent cause, and that afterwards the parts in 

 question were coloured as a sexual ornament ; or whether the 

 colouring and the habit of turning round were first acquired 

 through variation and sexual selection, and that afterwards the 

 habit was retained as a sign of pleasure or as a greeting, through 

 the principle of inherited association. This principle apparently 

 comes into play on many occasions : thus it is generally admitted 

 that the songs of birds serve mainly as an attraction during the 

 season of love, and that the leks, or great congregations of the 

 black grouse, are connected with their courtship ; but the liabit 

 of singing has been retained by some birds when they feel happy, 

 for instance by the common robin, and the habit of congregating 

 has been retained by the black grouse, during other seasons of 

 the year. 



I beg leave to refer to one other point in relation to sexual 

 selection. It has been objected that this form of selection, as 

 far as the ornaments of the males are concerned, implies that all 

 the females within the same district must possess and exercise 

 exactly the same taste. It should, however, be observed in the 

 first place, that although the range of variation of a species may 

 be very large, it is by no means indefinite. I have elsewhere 

 given a good instance of this fact in the pigeon, of which there 

 are at least a hundred varieties differing widely in their colours, 

 and at least a score of varieties of the fowl diflering in the same 

 manner ; but the range of colour in these two species is 

 extremely distinct. Therefore the females of natural species 

 cannot have an unlimited scope for their taste. In the second 

 place, I presume that no supporter of the principle of sexual 

 selection believes that the females select particular points of 

 beauty in the males ; they are merely excited or attracted in a 

 greater degree by one male than by another, and this seems often 

 to depend, especially with birds, on brilliant colouring. Even 

 man, excepting perhaps an artist, does not analyse the slight 

 differences in the features of the woman whom he may admire, 

 on which her beauty depends. The male mandrill has not only 

 the hinder end of his body, but his face gorgeously coloured 

 and marked with oblique ridges, a yellow beard, and other orna- 

 ments. We may infer from what we see of the variation of 

 animals under domestication, that the above several ornaments 

 of the mandrill were gradually acquired by one individual vary- 

 ing a little in one way, and another individual in another way. 

 The males which were the handsomest or the most attractive in 

 any manner to the females would pair oftenest, and would leave 

 rather more offspring than other males. The offspring of the 

 former, although variously intercrossed, would either inherit the 

 peculiarities of their fathers, or transmit an increased tendency 

 to vary in the same manner. Consequently the whole body of 

 males inhabiting the sam.e country, would tend from the effects 

 of constant intercrossing to become modified almost uniformly, 

 but sometimes a little more in one character and sometimes in 

 another, though at an extremely slow rate ; all ultimately being 

 thus rendered more attractive to the females. The process is 

 like that which I have called unconscious selection by man, and 

 of which I have given several instances. In one country the 

 inhabitants value a fleet or light dog or horse, and in another 

 country a heavier and more powerful one ; in neither country is 

 there any selection of the individual animals with lighter or 

 stronger bodies and limbs ; nevertheless after a considerable lapse 

 of time the individuals are found to have been modified in the 

 desired manner almost uniformly, though differently in each 

 country. In two absolutely distinct countries inhabited by the 

 same species, the individuals of which can never during long 

 ages have intermigrated and intercrossed, and where, moreover, 

 the variations will probably not have been identically the same, 

 sexual selection might cause the males to differ. Nor does the 

 belief appear to me altogether fanciful that two sets of females, 

 surrounded by a very different environment, would be apt to 

 acquire somewhat different tastes with respect to form, sound, 

 or colour. However this may be, I have given in my " Descent 

 of Man" instances of closely-allied birds inhabiting distinct 

 countries, of which the young and the females cannot be distin- 

 guished, whilst the adult males differ considerably, and this may 

 be attributed with much probability to the action of sexual selec- 

 tion. Charles Darwin 



