186 CHARLES MIDLO AND HAROLD CUMMINS 



primitive morphologic plan of the configurations, more closely 

 than any of the great apes. The retention of this primitive- 

 ness is especially evident in the distal portions of the palm 

 and sole. It is of interest to note that Pongo, the ape which 

 most nearly resembles Homo in reference to retention of the 

 primitive plan, is much farther from the primitive in the 

 sole than in the palm, while in man this aspect of primitive- 

 ness is about equally distributed in the two members. As 

 pointed out previously, we have regarded likeness of hand 

 and foot as indicating primitiveness or equal advance in 

 specialization of the two members. While in man both palm 

 and sole present some modification of the basic plan, both 

 members are unquestionably more primitive than the sole 

 of Pongo. It seems quite probable that man and the great 

 apes sprang from a common stem, man being closer to the 

 primitive, as noted aHove, each genus then proceeding along 

 an independent line of dermatoglyphic specialization associ- 

 ated with differential locomotor and prehensile uses of the 

 members and the attendant unlike gross structural modifica- 

 tions. As based upon the total pattern intensities of palm 

 and sole, it is suggested that Pongo retained the character- 

 istic functional membral distinctions of the ancestral type, and 

 that these distinctions were progressively obliterated in 

 Gorilla and Pan, and reversed in Homo, where the sole rather 

 than the palm presents the higher intensity. The primitive- 

 ness of the sole, as indicated in high total intensity as well 

 as close adherence to the morphologic plan, may be credited 

 to the retention (or acquisition) of the walking habit. In 

 Gorilla and Homo there would have been similar evolution in 

 the uses of the soles, hence in their pattern intensities. The 

 palms of Gorilla and man, in contrast, must have proceeded 

 along divergent courses, that of Gorilla retaining a larger 

 share of original primitiveness and that in man becoming in 

 many respects highly specialized. This dissociation of palm 

 and sole in evolutionary sequence did not occur in chimpanzee, 

 where palm and sole were equally involved in reduction of 



