Evolution of man's erect posture (preliminary report)

Animal posture cannot be regarded as an actual inheritance, for it constitutes a current physiological interaction between gravity and an organism, according to the structure and physical powers of the latter. Hence, ‘inherited posture’ merely implies that in a given species physical qualifications are congenitally transmitted, which facilitate a certain characteristic position of the body. Evolution of posture, therefore, has inevitably been associated with corresponding evolutionary changes in organic structures. Evidence furnished by the application of biomechanics to studies of ancient and modern primate structures indicates that man's erectly supported body posture could only have originated from a vertically suspended posture (arboreal). The fact that the prehuman stem passed through an earlier arboreal and brachiating period is attested to by the grasping character of his hands, the ratio of arm‐body length, the extreme mobility of the shoulder‐joints, as well as the extension of his legs on the body. The semierect posture of the great apes is not an advance toward human bipedism, but a modern reversion toward quadrupedism. Postural evidence conforms with the many other lines of testimony which maintain the close relationship of the human and anthropoid stems, and signifies that man has been an erect terrestrial biped since the time of his physical origin.