PRESENT PROBLEMS IN EVOLUTION AND HEREDITY. olf) 



humble role in our economy we ean ])rove beyond a doubt that they are 

 in course of evolution. .Minor variations in foot structure, whicli are 

 possibly of vital importance to a quadruped whose very existence may 

 depend upon speed, siidc into obscurity as factors in the survival of 

 the modern American. 



The evohition of uran in the most unimportant details of his structure 

 promises, therefore, to attbrd a tar more crucial test of the Lamarckiau 

 vs. the pure natural selection theory, than in the domain of his hij;her 

 faculties, for the reason that selection may operate upon variations in 

 mind, while it taxes our credulity to believe it can operate upon varia- 

 tions in muscle and bone. This is my ground for selecting the skele- 

 ton and muscles for the subject of the introductory lecture. Never- 

 theless, let us review variation in all its forms in luiman anatomy be- 

 fore forming an opinion. Let us remember, too, that congenital and 

 acquired variations are universal as necessities of birth and life; they 

 are exhibited in the body as a whole — in its proportions, in the compo- 

 nents of each limb, linally in the separate parts of each component, as 

 in the divisions of a complex muscle. Thus the possibilities of trans- 

 formism are everywliere. What is the nature and origin of congenital 

 variations? Their causes? Do they follow certain directions? Do 

 they spring from acquired variations by heredity ? These are some 

 of the questions wliich are still unsettled. 



But striking as are the anomalies from type, the repetitions of type 

 as exhibited in atavism and normal inh(u-itance are still more so, and 

 equally difllicult to explain. Tlicreforc our theory must provide both 

 ibr the observed laws of repetition of am-estral form and thb laws of 

 variation from ancestral form, as the pasture-land ofevoluti<m. Add 

 to these, that for a period in each generation this entire legislation of 

 nature is comi)ressed into the tiny nucleus of the fertilized ovum, 

 and tlu' whole problem rises before us in its apparent imi)regnability 

 which only intensifies our ardor of research. 



LKC'irUK I. — THE CONTEMPORAKV EVOLUTION OF MAN. 



The aiitinopologists and anatoniists liave enjoyed a certain monoi>oly 

 of Homo .s(tjn(iis^ while the biologists have directed tlieir energies 

 nminly upon the lower creation. lint under the inspiring intluenccs of 

 the Darwinian theory these originally distinct branches have con- 

 verged, and as man takes his i)lace in the zoological system, conn)ai- 

 ative anatomy is recognized as the inlallible key to human anatomy. 



For our ]>resent pnrpose we nuist sup])ress our sentinu'iili at the out- 

 set and state plainly that the only intei-pretation of our bodily sti'uc- 

 ture li(;s in the theory of our des(-ent from some early member of the 

 primates, such as may have given rise also to the living Anthr(>poidea. 

 This is also the only tenable teleological view, for manj^ of our inher- 

 ited organs ar<' at luesent non purposive, in some cases even harmful, — 

 as the appendix vermiformis. 



