The General Formula of Heredity

length divided by the lower leg length) diminishes from 140% during mid foetal months to about 90% at birth. In the adult boy it has diminished to 65%, while it remains at about 80% in the gibbon and about 90% in the adult gorilla and chimpanzee. This relatively shortened foot may be regarded as a more effective adaptation to bipedal locomotion than the longer foot of the gorilla. We see, then, that even after birth genetic changes occur, which are parallel to the later phylogenetic stages; that is to say, man passes through the same embryological stages that the lower forms do, and even some of the stages in pre-adolescent development are the same in man and the lower primates. But man, as the higher form, goes beyond the point at which the less evolved species stop their development. That is to say, he shows in the proportions of his body special adaptations to the special functions he has to perform as a non-aboreal biped.