“What makes the old sow grunt and the piggies sing and whine?” said a little girl to a portly substantial farmer. “I suppose they does it for company, my dear,” was the simple and cautious reply. So far as appearances went, that farmer looked as guiltless of theories as man could be. And yet he gave terse expression to what may perhaps be regarded as the most satisfactory hypothesis as to the primary purpose of animal sounds. They are a means by which each indicates to others the fact of his comforting presence; and they still, to a large extent, retain their primary function. The chirping of grasshoppers, the song of the cicada, the piping of frogs in the pool, the bleating of lambs at the hour of dusk, the lowing of contented cattle, the call-notes of the migrating host of birds--all these, whatever else they may be, are the reassuring social links of sound, the grateful signs of kindred presence. Arising thus in close relation to the primitive feelings of social sympathy, they would naturally be called into play with special force and suggestiveness at times of strong emotional excitement, and the earliest differentiations would, we may well believe, be determined along lines of emotional expression. Thus would originate mating cries, male and female after their kind; and parental cries more or less differentiated into those of mother and offspring, the deeper note of the ewe differing little save in pitch and timbre from the bleating of her lamb, while the cluck of the hen differs widely from the peeping note of the chick in down. Thus, too, would arise the notes of anger and combat, of fear and distress, of alarm and warning. If we call these the instinctive language of emotional expression, we must remember that such “language” differs markedly from the “language” of which the sentence is the recognized unit.
It is, however, not improbable that, through association in the conscious situation, sounds, having their origin in emotional expression and evoking in others like emotional states, may acquire a new value in suggesting, for example, the presence of particular enemies. An example will best serve to indicate my meaning. “In the early dawn of a grey morning,” says Mr. H. B. Medlicott,[82] “I was geologizing along the base of the Muhair Hills in South Behar, when all of a sudden there was a stampede of many pigs from the fringe of the jungle, with porcine shrieks of _sauve-qui-peut_ significance. After a short run in the open they took to the jungle again, and in a few minutes there was another uproar, but different in sound and in action; there was a rush, presumably of the fighting members, to the spot where the row began, and after some seconds a large leopard sprang from the midst of the scuffle. In a few bounds he was in the open, and stood looking back, licking his chaps. The pigs did not break cover, but continued on their way. They were returning to their lair after a night’s feeding on the plain, several families having combined for mutual protection; while the beasts of prey were evidently waiting for the occasion. I was alone, and, though armed, I did not care to beat up the ground to see if in either case a kill had been effected. The numerous herd covered a considerable space, and the scrub was thick. The prompt concerted action must in each case have been started by the special cry. I imagine that the first assailant was a tiger, and the case was at once known to be hopeless, the cry prompting instant flight, while in the second case the cry was for defence. It can scarcely be doubted that in the first case each adult pig had a vision of a tiger, and in the second of a leopard or some minor foe.”