developed mammals, such as the Carnivora and Ungulata, have a much longer ancestry and have really attained a far higher stage of development. In the matter of digits it is maintained that true progress is characterized by a reduction in their number, and that the highest stage is not reached until they are reduced to one, as in the horse. In this respect man is a slight advance upon the apes in the first toe having lost the character of a thumb. No one can deny that the power of flight would have been an immense advantage to man, yet few mammals possess this power, and it is chiefly confined to creatures of low organization.
It is difificult to conceive abeing entirely different in form from man taking the place that he has acquired, but if any one of the structurally higher races possessed the same brain development it would have had the same intelligence, and although its achievements would doubtless have been very different from his, they would have had the same rank and secured for that race the same mastery over animate and inanimate nature. This will become clearer when we consider the second of the above propositions which we may now proceed to do.
To what extent has brain development reacted upon man's physical nature? I cannot, of course, go fully into this question here, but nothing is better known to anatomists than that the erect posture is not the natural or primary one. It has been acquired by man within a comparatively recent time. It is a legitimate inference that it is chiefly due to brain development, physiologically as a means of supporting the enlarged and correspondingly heavier head, which it would be difficult to carry in the horizontal position, and psychologically as the natural result of a growing intelligence and self-consciousness which seeks to lift the head and raise it to a position from which it can command its surroundings. It is a common observation that those persons who possess the greatest amount of self-esteem stand straightest, and it is this same principle that has bperated from the beginning to bring the human body more and more nearly into a vertical position.
