288 SECRETS OF ANIMAL LIFE 
it in performing bipedal dogs and bears. But 
bipedal progression is one thing and the upright 
position is something more. The problem is: What 
induced man and his relatives to attempt it and 
persevere in it successfully? We think that the 
answer is given in Professor F. Wood Jones’ 
recent brilliant study of “ Arboreal Man,” and in an 
earlier not less brilliant study by Dr. R. Anthony, 
a French zoologist. 
Professor Wood Jones has worked out very con- 
vincingly the thesis that Man had no quadrupedal 
ancestry, but that the Primate stock to which he be- 
longs was, from the first, bipedal and arboreal, and 
that the leading peculiarities of man and his distant 
relatives were wrought out during a long arboreal 
apprenticeship. When we say “ from the first” we 
mean from the time when the Primate race diverged 
from a stock of generalized placental mammals, or 
from a stock of bipedal arboreal reptiles, represented 
perhaps by some of the extinct Therapsids. It is 
interesting to remember the view of some experts 
that birds were also evolved from an ancient stock 
of arboreal reptiles. All these pedigrees are hidden 
in the mist, but this need not hinder a discussion 
of the organic lessons that may have been learned 
in the primeval school of the tree-tops. The first 
great gain of arboreal life on bipedal erect lines 
(and not in the fashion of sloths, bats, and the like) 
was the emancipation of the hand. The typical 
quadruped needs its fore limb as a stable supporting 
pillar and organ of progression upon the earth, but 
