Very few really satisfactory experiments have been made in this direction, but the history of the negroes in America shows that the pure, unmixed negro brain is capable of showing high mathematical power, musical gifts of the best, and moral and philosophic activities equal to those of the best, or all but the exceptionally gifted, individuals of European race. It seems that the large educable brain gained by man in a relatively early period of his development from the ape has now entered on a new phase of importance. The pressure of natural selection no longer favours an increased educability (and therefore size) of brain, but the later progress of man has depended on the actual administration by each generation to its successors of an increasingly systematized exercise of that brain; in short, it has depended on education itself, and on the gigantic new possibilities of education, which have followed from the development, first, of language, then of writing, and lastly of printing, together with the accompanying growth and development of social organization, the inter-communication of all races, and the carrying on, by means of the Great Record--the written and printed documents of humanity--of the experience and knowledge of each passing generation of men from them to the men of the present moment.
Huxley agreed with Cuvier in the opinion that the possession of articulate speech is the grand distinctive character of man. It was no sudden acquirement, but was slowly, step by step, evolved from the significant grunts and cries of apes in the course of long ages, and corresponded in its progress with a parallel progress in mental capacities. Once attained, it led to the formation of vast educative products, namely, to oral tradition, to written and then to printed memorials and records. It is not desirable in our present state of knowledge to speculate as to whether the transitional ape-man acquired the use of fire before or after he had invented articulate speech. It probably was acquired very soon after some skill in the flaking of flints had been attained, and was of immense value, both as a defence against predatory animals and as a means of preparing food. Man probably learnt at a very early period to cover himself with clothing made from the skins of other animals, and thus to tolerate cold climates. The use of clothing was correlated with the diminution of his natural hairy covering. As to the circumstances which led to the reduction in size of his canine teeth and the diminution of the projection of his jaws, it is impossible to say more than that this was favoured by the increased skill of his hand and by the use of weapons, and probably was directly correlated with an increased growth of the brain. It is an interesting fact that very young children still exhibit the ancestral tendency to bite when angry, and that the use of the teeth as weapons of attack is more frequent among lower races with "prognathous" jaws than among Europeans.