Of the many presumably instinctive modes of behavior which were
observed, only those which have to do with social relations seem
especially worth reporting. From among them I shall select for
description a few which have already been referred to in connection with
the experimental observations.
_Maternal Instinct_
Aspects of the maternal instinct I had opportunity to observe in Gertie,
who on February 27 gave birth to a male infant, I present below the
substance of a previously published note on her behavior (Yerkes, 1915).
"On February 27 one of the monkeys of our collection gave birth, in the
cages at Montecito, to a male infant. The mother is a _Macacus
cynomolgus rhesus_ (_P. irus rhesus_) who has been described by Hamilton
(1914, p. 298) as 'Monkey 9, Gertie, _M. cynomolgus rhesus_ (_P. irus
rhesus_). Age, 3 years 2 months. (She is now, May 1, 1915, 4 years and 6
months.) Daughter of monkeys 3 and 10. First pregnancy began September,
1913.' The result of this pregnancy was, I am informed, a still-birth.
"The second pregnancy, which shall now especially concern us, resulted
likewise in a still-birth. Parturition occurred Saturday night, and the
writer first observed the behavior of the mother the following Monday
morning. In the meantime the laboratory attendant had obtained the data
upon which I base the above statements.
"At the time of parturition Gertie was in a 6 by 6 by 12 foot out-door
cage containing a small shelter box, with an exceptionally quiet and
gentle male (not the father of the infant) who is designated in
Hamilton's paper as Monkey 28, Scotty.
"My notes record the following exceptionally interesting and genetically
important behavior. On March 1, when I approached her cage, Gertie was
sitting on the floor with the infant held in one hand while she fingered
its eyelids and eyes with the other. Scotty sat close beside her
watching intently. When disturbed by me the mother carried her infant to
a shelf at the top of the cage. Repeatedly attempts were made to remove
the dead baby, but they were futile because Gertie either held it in her
hands or sat close beside it ready to seize it at the slightest
disturbance.
"Especially noteworthy on this, the second day after the birth of the
infant, are the male's, as well as the female's, keen interest in the
body and their frequent examinations of the eyes, as if in attempts to
open them. Often, also, the mother searched the body for fleas.
"Observations were made from day to day, and each day opportunity was
sought to remove the body without seriously frightening or exciting the
female. No such opportunity came, and during the second week the corpse
so far decomposed that, with constant handling and licking by the
adults, it rapidly wore away. By the third week there remained only the
shriveled skin covering a few fragments of bone, and the open skull from
the cavity of which the brain had been removed. This the mother never
lost sight of: even when eating she either held it in one hand or foot,
or laid it beside her within easy reach.
"Gradually this remnant became still further reduced until on March 31
there existed only a strip of dry skin about four inches long with a
tail-like appendage of nearly the same length.
"The male, Scotty, on this date was removed to another cage. Gertie made
a great fuss, jumping about excitedly and uttering plaintive cries when
she discovered that her mate was gone. Whenever I approached her cage
she scurried into the shelter box and stayed there while I was near.
This behavior I never before had observed. It continued for two days. On
April 2, it was noted that she had lost her recently acquired shyness
and she no longer made any attempts to avoid me. As usual, on this date,
she was carrying the remnant about with her.
"The following day, April 3, Gertie was lured from her cage to a large
adjoining compartment for certain experimental observations. After she
had been returned to her own cage the remnant was noticed on the floor
of the large cage. I picked it up. Gertie evidently noticed my act; for
although at a distance of at least ten feet from me, she made a sharp
outcry and sprang to the side of the cage nearest me. I held the piece
of skin (it looked more like a bit of rat skin than the remains of a
monkey) out to her and she immediately seized it and rushed with it to
the shelf at the top of the cage.
"Two days later the remnant was missing, and careful search failed to
discover it in the cage. It is probable that Gertie had carelessly left
it lying on the floor whence it was washed out when the cages were
cleaned. On this date Gertie seemed quieter than for weeks previously.
"Thus it appears that during a period of five weeks the instinct to
protect her offspring impelled this monkey to carry its gradually
vanishing remains about with her and to watch over them so assiduously
that it was utterly impossible to take them from her except by force.
"After reading this note in manuscript, Doctor Hamilton informed me that
Gertie had behaved toward her first still-birth as toward her second.
And, further, that Grace, a baboon, also carried a still-birth about for
weeks.
"I am now heartily glad that my early efforts to remove the corpse were
futile, for this record of the persistence of maternal behavior seems to
me of very unusual interest to the genetic psychologist."
_Fear_
In connection with the multiple-choice experiments Skirrl exhibited what
seemed to be instinctive fear as a result of his unfortunate experience
with nails in the floor of box 1. He seemingly referred his misadventure
to some unseen enemy under the floor, and this in spite of the fact that
he was given abundant opportunity to examine the floor of the box, but
not until after the dangerous nails had been clinched. His long
continued avoidance of the experiment boxes and his still more
persistent hesitancy in entering them, coupled with his almost ludicrous
efforts to see beneath the floor through the holes cut for the staples
on the doors, gave me the impression of superstitious fear of the
unseen. As I watched and recorded his behavior day after day during the
period of most pronounced fear, I could not avoid the thought that the
instinctive fear of snakes had something to do with his peculiar
actions, and although I have never studied either the natural or the
acquired responses of monkeys to snakes, I suspect that lacking such
instinctive equipment, Skirrl would have behaved differently as a result
of the pricks which he received from the nails. It is needless to
redescribe his acquired fear of whiteness as it manifested itself in the
freshly painted apparatus. Accompanying these instructive modes of
response and their emotions are suggestions of peculiarly interesting
problems as well as of modes of attacking them. As a matter of fact,
Skirrl's fear-reactions did much to alter my conception of the
constitution of his mind. I should not have been surprised by the
features of behavior exhibited, but I was by no means prepared for their
persistence, and for the highly emotional attitude toward the particular
situation. Only an organism of complexly constituted nervous system and
fairly highly developed affective life could be expected to respond as
did this monkey. As has been suggested above, I find the appeal to
instinct, modified by experience, a natural mode of accounting for the
unexpected features of Skirrl's behavior.
_Sympathy_
The instinctive playfulness of the young monkey Tiny contrasted most
strikingly with the more serious, if not more sedate, modes of behavior
of the older individuals.
During the greater part of my period of observation Tiny was cage-mate
of Scotty, the most calm and apparently lazy of all the monkeys. Tiny
delighted in teasing Scotty, and her varied modes of mildly tormenting
him and of stirring him to pursuit or to retaliation were as interesting
as they were amusing. Her most common trick was to steal up behind him
and pull the hair of his back, or seize his tail with her hands or
teeth. Often when he was asleep she would suddenly run to him, give a
sudden jerk at a handful of hairs, and leap away. He was surprisingly
patient, and I never saw him treat her roughly in retaliation.
Another of Tiny's favorite forms of amusement was that of trying to stir
up the other monkeys to attacks on one another. She very cleverly did
this by pretending that she herself was being attacked. The instant the
older animals began to show hostility toward one another she would leap
out of the way and watch the disturbance with evident satisfaction. It
was this mode of behavior in the little animal which ultimately provided
opportunity for the observations which I wish now to report as
indicative of sympathetic, possibly I may say altruistic, emotions.
Tiny was confined with Scotty in a cage adjoining the one in which
Jimmie and Gertie were being kept. The cages were separated by wire
netting of half-inch mesh.
One morning as I was watching the behavior of the animals in the several
cages, I noticed Tiny dressing with her teeth a wounded finger. It had
evidently been bitten by one of the other animals, in all probability
either by Jimmie or Gertie. Tiny was trimming away the loose bits of
skin very neatly and cleansing the wound. After working at this task for
a few minutes, she quickly climbed up to the shelf near the top of her
cage, and by rushing to the partition wire between the two cages, she
lured Gertie to an attempted attack on her. Gertie sprang up to the
partition, placed her hands on it, with the fingers projecting through
the meshes, and attempted to seize Tiny's fingers with her teeth. But
the latter was too quick for her, and withdrawing her hands, like a
flash seized in her teeth the middle finger of Gertie's left hand. She
then bit it severely and with all her might, at the same time pulling
and twisting violently, often placing the entire weight of her body on
the finger. Her sharp teeth cut to the bone, and it was impossible for
the larger and stronger monkey to tear away. For several seconds this
continued, then Gertie succeeded in escaping, whereupon she at once
retreated to the opposite end of her shelf and proceeded to attend to
her injured finger. She cried, wrung her hands, and from time to time
placed the finger in her mouth as though in an effort to relieve the
pain. By this time Jimmie's attention had been attracted by the
disturbance and he rushed up to the shelf, and facing Gertie, watched
her intently for a few seconds. The look of puzzled concern on his face
was most amusing. Apparently he felt dimly that something in which he
should have intelligent interest was going on, but was unable wholly to
understand the situation. After watching Gertie for a time and trying to
discover what she was doing, which was rendered difficult by her
tendency to turn away from him, in order to shield her injured finger,
he rushed over to the wire partition and made strenuous efforts to seize
Tiny with his hands and teeth. But although she continued close to the
partition and often crowded against it with face and hands flattened on
the wires, he was not able to get hold of her, and after a few vain
attempts he returned to his mate, and again with evident solicitousness
and the most troubled expression, watched her wringing her hands and
chewing or sucking at her injured finger. Shortly he again returned to
the partition and renewed his attempts to seize the young monkey. Thus
he went back and forth from one place of interest to the other several
times, but being unable to achieve anything at either point, he finally
gave up and returned to his breakfast on the floor of the cage.
I report this incident fully because the behavior of Jimmie was in
marked contrast with the usual behavior of the monkeys. Selfishness
seemed everywhere dominant, while clear indications of sympathetic
emotions were rare indeed. The above is undoubtedly the best evidence of
anything altruistic that I obtained.
It is possible that Tiny's action was retaliatory, but although it is
practically certain that either Gertie or Jimmie inflicted the wound on
her finger, I of course cannot be sure that the spirit of revenge
stirred her to punish Gertie so severely. Jimmie's part in the whole
affair is, however, perfectly intelligible from our human point of view,
and there seems no reason to doubt that he did experience something like
a feeling of sympathy with his mate, coupled with a feeling of
resentment or anger against Tiny.