It does make you (me) wonder about animal research. I have a remarkable book "The Soul of the Ape" by Eugène Marais
http://en.wikipedia.org/wiki/Eug%C3%A8ne_Marais which records the experiences and observations of three years of living at close quarters with a troop of chacma baboons after the Boer war. He was a pioneer in this kind of documented observation and is often refered to as the father of ethology A fascinating man whose studies of the white ant was plagerized by a Nobel prize laureate.
There is an unforgettable passage in the chapter
Hesperian Depression in the Chacma:
(...)
With the setting of the sun and the first deepening of the shadows a singular transformation came over the entire scene. Silence fell upon them gradually. The "talking" ceased, the little ones crept cuddlingly into the protecting arms of their mothers. The romping young folk joined different groups, generally on the higher flat rocks from which a view could be had of the western horizon. The older ones assumed attitudes of profound dejection, and for a long intervals the silence would be unbroken except for the soft whimpering complaints of the little ones and the consoling gurgling of the mothers. And then from all sides would come the sound of mourning, a sound never uttered otherwise than on occasions of great sorrow--of death or parting. I do not think there is any possibility of mistaking the state of mind which determines this behaviour--even by one not well acquainted with the character and ways of the animal. One need only compare with a native village under the same conditions to realize beyond any shadow of doubt that you have here a representation of the same inherent pain of consciousness at the height of its dinural rhythm. In the case of the chacma the condition also disappears with the settling darkness. When the troop finally moved on to the krans or to the entrance of the sleeping cave, the games were resumed and sometimes on moonlight nights continued for several hours.
In the presence of these proofs, it is hardly possible to avoid the conclusion that the chacma sufers from the same attribute of pain which is such an important ingredient of human mentality, and that the condition is due to the same cause.
(...)
One can also compare the habit of city-dwellers who. with a little shiver, turn on the lights at dusk or the origins of taking a "sundowner".
I've always been fascinated by that book. My copy is Penguin 1972, but the original was published in 1969. The original documents are from the end of the the 1800s (after the Boer War).