The historical diversity of opinion regarding human nature is what has led me to the attempt to give an exposition of human nature in its strength and in its weakness. But, before dealing with the man himself, we must survey the lower forms of life.
The facts of the organised world, before the appearnace of man, teach us that though we find change and development, development does not always take a progressive march. We are bound to believe, for instance, that the latest products of evolution are not human beings, but certain parasites which live only upon, or in, the human body. The law in nature is not of constant progress, but of constant tendency towards adaptation. Exquisite adaptations, or harmonies, in nature are constantly met with in the world of living beings. But, on the other hand, any close investigation of organisation and life reveals that beside many most perfect harmonies, there are facts which prove the existence of incomplete harmony, or even absolute disharmony. Rudimentary and useless organs are widely distributed. Many insects are exquisitely adapted for sucking the nectar of flowers; many others would wish to do the same, but their want of adaptation baffles them.
It is plain that an instinct, or any other form of disharmony, leading to destruction, cannot increase or even endure very long. The perversion of the maternal instinct, tending to abandonment of the young, is destructive to the stock. In consequence, individuals affected by it do not have the opportunity of transmitting the perversion. If all rabbits, or a majority of them, left their young to die through neglect, it is evident that the species would soon die out. On the contrary, mothers guided by their instinct to nourish and foster their offspring will produce a vigorous generation capable of transmitting the healthy maternal instinct so essential for the preservation of the species. For such a reason harmonious characters are more abundant in nature than injurious peculiarities. The latter, because they are injurious to the individual and to the species, cannot perpetuate themselves indefinitely.
In this way there comes about a constant selection of characters. The useful qualities are handed down and preserved, while noxious characters perish and so disappear. Although disharmonies tend to the destruction of a species, they may themselves disappear without having destroyed the race in which they occur.
This continuous process of natural selection, which offers so good an explanation of the transmutation and origin of species by means of preservation of useful and destruction of harmful characters, was discovered by Darwin and Wallace, and was established by the splendid researches of the former of these.
Long before the appearance of man on the face of the earth, there were some happy beings well adapted to their environment, and some unhappy creatures that followed disharmonious instincts so as to imperil or to destroy their lives. Were such creatures capable of reflection and communication, plainly the fortunate among them, such as orchids and certain wasps, would be on the side of the optimists; they would declare this the best of all possible worlds, and insist that to secure happiness it is necessary only to follow natural instincts. On the other hand, the disharmonious creatures, those ill adapted to the conditions of life, would be pessimistic philosophers. Consider the case of the ladybird, driven by hunger and with a preference for honey, which searches for it on flowers and meets only with failure, or of insects driven by their instincts into the flames, only to lose their wings and their lives; such creatures, plainly, would express as their idea of the world that it was fashioned abominably, and that existence was a mistake.
II.—Disharmonies in Man
As for man, the creature most interesting to us, in what category does he fall? Is he a being whose nature is in harmony with the conditions in which he has to live, or is he out of harmony with his environment? A critical examination is needed to answer these questions, and to such an examination the pages to follow are devoted.
Science has proved that man is closely akin to the higher monkeys or anthropoid apes—a fact which we must reckon with if we are to understand human nature. The details of anatomy which show the kinship between man and the apes are numerous and astonishing. All the facts brought to light during the last forty years have supported this truth, and no single fact has been brought against it. Quite lately it has been shown that there are remarkable characters in the blood, such that, though by certain tests the fluid part of human blood can be readily distinguished from that of any other creature, the anthropoid apes, and they alone, furnish an exception to this rule. There is thus verily a close blood-relationship between the human species and the anthropoid apes.
But how man arose we do not know. It is probable that he owes his origin to a mutation—a sudden change comparable with that which De Vries observed in the case of the evening primrose. The new creature possessed a brain of abnormal size placed in a spacious cranium which allowed a rapid development of intellectual faculties. This peculiarity would be transmitted to the descendants, and as it was a very considerable advantage in the struggle for existence, the new race would hold its own, propagate, and prevail.