654 proceedings: antheopological society 



cal constituents of the human body and those of other mammals; and 

 (6) the frequent presence in man of vestiges of or reversions to anatom- 

 ical features still functional in some lower animals. 



The physical evidence of man's evolution consists of a large series of 

 skeletal remains dating from the early Pleistocene to the last prehis- 

 toric peri'od. These remains show in general that the farther back we 

 proceed the more primitive are the human features and the more closely 

 they are related to those of the lower primates. This evidence alone 

 is quite conclusive, although there are still, of course, many important 

 gaps in the line of evidence, especially relating to the earlier periods; 

 these however are gradually being filled in. 



The historical and recent changes in man show us that his evolution 

 has not as yet been fully accomplished but is still progressing, and that 

 possibly among civilized white men it is progressing more rapidly than 

 it has during most of its course. We see that the higher civilized 

 white man has already in some respects outdistanced others, that he 

 is rapidly diversifying, and that those who can not keep the acceler- 

 ated pace are being eliminated by nature. Probably the most obvious 

 changes are taking place in his teeth, which are gradually lessening in 

 resistance, in size, and even in numbers — changes which in turn condi- 

 tion weakening and numerous disharmonies in the whole facial structure. 



The process of human evolution has close relations to medicine — 

 much closer, in fact, than are commonly appreciated by even the sur- 

 geon and physician. Evolution is not only constructive, but elimina- 

 tive, involving weakening, degeneration, and eventual loss of parts which 

 have become less useful, less functional. The progressive and retro- 

 gressive changes are not always harmonious or generally beneficial 

 to the individual, and they bring about many conditions which demand 

 medical or surgical intervention. The process of evolution bears, 

 however, still other relations to medicine. It has prolonged the periods 

 of infancy, childhood, and senility in man, the most dangerous periods 

 of an organism; the assumption of the erect posture had necessarily 

 adverse consequences, which probably have not yet been completely 

 overcome, on the circulatory system and in seriously modifying the 

 abdominal and pelvic drags as well as pressure, especially in pregnancy; 

 it has intensified the sexual functions in man, the results of which are 

 frequently untoward and even dangerous ; it has caused an enlargement 

 in the size of the head in the human foetus which necessitated a con- 

 sequent enlargement of the pelvic cavity, and there are doubtless still 

 disharmonies between the two conditions ; it has resulted in greater rela- 

 tive slenderness of bones, even in the skull, rendering them proportion- 

 ately more liable to injuries; it has brought about greater delicacy of 

 skin, with a consequent less resistance of the body to exposure; it has 

 induced especially a great enlargement of the brain, a process the re- 

 sults of which to this day offer many imperfections; and, finally, while 

 evolution has doubtless improved various immunities in man, it is 

 still very incomplete in this respect, and on the other hand it has evi- 

 dently led to new dangers and predispositions. There seem to exist 



