THE LINEAGE OF MAN 



is meagre it tends to show that the various groups appeared 

 in the following succession: (l) tree shrews, (2) lemuroids 

 and tarsioids, (3) monkeys, (4) pro-anthropoids, (5) 

 diversified anthropoids, (6) primitive man, (7) modernized 

 man. But this is also precisely what one would predict from 

 a comprehensive comparative study of the surviving families 

 of Primates, with special reference to the structure of their 

 brains, skull, teeth, hands and feet, and other parts of the 

 body. The main branches of the order are all represented 

 to-day by surviving members. By making comparisons first 

 within each group and then between groups, including both 

 the fossil and the recent forms, it has been possible to deci- 

 pher the main record of evolution of the brain, teeth, and 

 various parts of the skeleton. 



Taking the series as a whole, it shows a remarkable grada- 

 tion of forms and structures, culminating in various side 

 branches and also in man. It will remain for future palaeon- 

 tologists to correct errors and to amplify the details of the 

 process of evolution, but the general sequence of events has 

 been worked out independently by a number of investigators, 

 whose results yield a remarkably concordant, consistent story. 

 Thus Keith has shown that when we pass from the monkeys 

 to the gibbons, which stand near the base of the anthropoid- 

 man radiation, we find that the gibbon has already effected 

 profound readjustments of the viscera and skeleton to its 

 habit of sitting upright and of brachiating, or extending the 

 arms upward and leaping from branch to branch. Keith 

 finds that on the whole the gibbon is nearer to man in this 

 internal readjustment to the upright position than it is to 

 the lower primates. Elliott Smith and his students in England 

 and Tilney in America have worked out the sequence in 

 brain structure from tree-shrew to lemur to monkey, gibbon, 

 orang, chimpanzee, gorilla, man, and they find progressive 



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