Chapter II — On the Differentiation of the Human From the Anthropoid Mind
§ 1 Heredity, Adaptation, Accommodation
Following the general belief that Man is descended from a stock nearly allied to the greater anthropoids—Orang, Chimpanzee, Gorilla—we may assume that his mental endowments were once much the same as theirs; and that, so far as they are still the same, heredity sufficiently explains his having them. Thus the senses, perception, the simpler forms of comparison and inference, the appetites and many of the instincts and emotions are common to us with the apes, are seen in our children under three years old, and (in short) constitute that generic consciousness (as I have called it) from which the human mind in general and the peculiar traits of races and individuals are differentiated.
So much for heredity; but the differences of the human from the anthropoid mind, alike in intelligence and in character, are enormous, and must be accounted for in some other way. Allowing for some original specific difference which we can hardly hope to discover, the changes that have taken place may be considered as the result of adaptation to those habits of life under which our species (now ranking zoologically as a Family) has been developed. And this adaptation I shall assume to have been brought about under conditions of natural selection: human races, as we now see them, being the survivors of many variations, more or less successful, and the others having been destroyed. For good judges are of opinion that, amongst the discovered remains of ancient specimens of the human family, some that exhibit marked deviations from the modern type—Neanderthalensis, Eoanthropus, Pithecanthropus—should be regarded not as belonging to our ancestral line, but rather as representing distinct species that have failed in the struggle for existence.28
But besides the innate dispositions of human nature determined by heredity and natural selection, which are found in some measure universally, because they are adaptations to conditions that, at one time and not long ago, weighed upon the ancestors of all of us, there are numerous traits (some of them quite superficial) that vary from country to country and from age to age, according to the economic or political type of the society in which a man lives, his place therein, geographical circumstances, religious institutions and the countless causes that govern manners and customs. In the lives of most men these traits are not necessary; they may be adopted and cast aside more than once in an individual’s career: they are temporary accommodations due to education, imitation, tradition; and, in fact, are often the disguises of human nature. Still, as society grows more and more complex, orderly and stable, there is, no doubt, again some natural selection of those individuals who are capable of undergoing the requisite accommodations. Those that cannot endure the restraints of civilisation, wander away; the extremely lazy, improvident, dishonest, or aggressive, in considerable numbers, perish.