MANS PLACE IN aaIURE 



4:>.; 



>l)|iil|lll/iH|i'l 



Fit:. 280.— ^ ..miu«>»i' 

 all u. MrnncIihcU; .i 

 life by Dr. Heck of licrliij.) 



\\ fit- 



ly derived from a oomnion 

 stock, and each species in 

 its ramifications modified 

 by the forces and condi- 

 tions inchuhnl unthT the 

 general lieads of variation, 

 heredity, segregation, selec- 

 tion, and the impact of 

 environment precisely as 

 species in other groups are 

 affected. It is clear that if 

 there is an origin of species 

 through natural causes 

 among the lower animals 

 and plants, there is an 

 origin of species among 

 men. If homology among 

 animals and i)lants is the 

 stamp of blood relation- 

 ship, the same rule holds 

 with man as well. Man is connected with tlie lower aninial.s 

 by the most perfect of homologies. These are traceable in 

 every bone and muscle, in every blood vessel ami glaiul. in 



every i)ha.<e of .structure, 

 even inchiding tho.*ie of 

 the brain and nervou.s 

 system. Tlir common 

 heredity of man with other 

 vertebrate animals is a5 

 well estal)lisln'<l a.«< any fact 

 in j)hylogeny can l)e. 



In working out the 

 details of the <»rigin of 

 man. we have once more 

 tlie tlire<» '*anc«^tral docu- 

 ments " of biology, conipar- 

 ativ(» anatomy, embry<»l- 

 ogy. ami paleontoiog^y. 

 Considereti structur- 

 17 OQ, r' ♦ u 1 . f I .w. Jdlv, man forms a single 



Fig. 281. — Foot skeleton of chiinpiiiiwH? at Irft, • 



and of man at right, (.\ftcr Wiedor..lieim.) gelUlS, Iiomo, tllC SOlc n»|> 



80 



