Darwin's Theory of Sexual Selection 213 
and as a gibbon, one of the anthropomorphous apes, pours 
forth a whole octave of musical notes and may be said to 
sing, it appears probable that the progenitors of man, either 
the males or females or both sexes, before acquiring the 
power of expressing their mutual love in articulate language, 
endeavored to charm each other with musical notes and 
rhythm. So little is known about the use of the voice by 
the Quadrumana during the season of love, that we have no 
means of judging whether the habit of singing was first 
acquired by our male or female ancestors. Women are 
generally thought to possess sweeter voices than men, and as 
far as this serves as any guide, we may infer that they first 
acquired musical powers in order. to attract the other sex. 
But if so, this must have occurred long ago, before our ances- 
tors had become sufficiently human to treat and value their 
women merely as useful slaves. The impassioned orator, 
bard, or musician, when with his varied tones and cadences 
he excites the strongest emotions in his hearers, little 
suspects that he uses the same means by which his half- 
human ancestors long ago aroused each other’s ardent pas- 
sions during their courtship and rivalry.” 
We have now examined in some detail the evidence that 
Darwin has brought forward in support of his hypothesis of 
sexual selection. A running comment has been made while 
considering the individual cases, but it may be well to sum 
up the matter by briefly indicating the reasons why the hy- 
pothesis seems incompetent to explain the facts. 
GENERAL CRITICISM OF THE THEORY OF SEXUAL SELECTION 
1. Some of the objections that apply to the theory of 
natural selection apply also with equal force to the theory of 
sexual selection in so far as the results in both cases are sup- 
posed to be the outcome of the selection of individual, or 
fluctuating, variations. If these variations appear in only 
