CHAPTER VI.

THE ORIGIN OF LAUGHTER.

Problem of the origin of laughter in the race • 155

Supposed rudiments of mirth in animals • 156

The dog’s manifestations of a sense of fun • 159

The mirthful displays of the ape • 162

First appearance of laughter in child: date of the first smile • 164

Date of the first laugh • 166

The laugh as following the smile • 168

Order of the two in the evolution of the race • 170

Conjecture as to genesis of the human smile • 171

How the primitive smile may have grown into the laugh • 173

Problem of the evolution of the laughter of tickling • 176

Effects of tickling in animals • 177

Date of first response to tickling in the child • 177

Tickling as inheritance from remote ancestors • 178

Value of evolutional theories of tickling • 181

How laughter may have come into tickling • 183