Man is pre-eminently a social animal. He seeks companionship and depends largely upon his fellows for security and happiness. Nor is this dependence upon others confined to the human species. Association, or combination of interests, is manifested throughout the entire organic scale. From Mr. Darwin’s reasoning it is evident that he regards association as the basic principle underlying progress. He also thinks that combination is impossible without sympathy or a desire for the welfare of others outside of self. He is certain that associated animals have a feeling of affection for the group and that “they sympathize with one another in times of distress and danger.”[41] [41] _The Descent of Man_, 1877, p. 102. This writer thinks that an animal like the gorilla, which possessing great size and strength is able to defend itself against all its enemies, would not become social and therefore would be unable to advance. And this too, notwithstanding the fact that such an animal has already developed pugnacity, courage, and perseverance, the characters which are regarded as the source of the remarkable mental endowment of man. We have seen that the greater size of the male is the result of Sexual Selection and is therefore a secondary sexual character. “All the secondary sexual characters of man are highly variable.”[42] In dealing with this subject we must not lose sight of the fact that variability denotes low organization. It shows that the organs of the body have not become specialized to perform their legitimate functions. [42] _The Descent of Man_, 1877, p. 559. Among monogamous animals difference in size between the sexes is slight, but among polygamous species the male is considerably larger than the female, this difference being correlated with numerous variations of structure. Among early races males were considerably in excess of females so it was customary for the former to fight desperately to win the favour of the latter in much the same manner as their animal progenitors had fought to secure their mates. These struggles were enacted in the presence of the females, they always choosing the strongest and best endowed leaving the weaker and uglier members of the group unmated and therefore unable to propagate their misfortunes. This exercise of choice by the female in pairing is the primary fact in the history of human progress. The appalling effects of the withdrawal from women of this fundamental prerogative will be referred to later in these pages. That pugnacity, courage, and perseverance are the result of man’s strong sexual nature is shown wherever this subject is touched upon in _The Descent of Man_. Special attention is directed to the fact that eunuchs are deficient in these qualities.