[Read before the Texas Academy of Science , May 6, 1898 . ] 
THE ESSENTIAL DIFFERENCES BETWEEN MAN AND OTHER 
ANIMALS. 
By S. E. Mezes. 
Although the problem to he considered in this paper has been re- 
peatedly discussed since it was first faced by Aristotle, it is not neces- 
sary to undertake a review of opinions, most of which, important and 
useful as they were in their day, have become quite inadequate since 
modern, science came into possession of precise methods and instru- 
ments of observation. Darwin’s great discovery as set forth in his 
Origin of Species , and later in his Descent of Man , has rendered earlier 
speculations obsolete. Accordingly the reader’s attention is to he direct- 
ed only to investigations and discussions made and incited by Darwin. 
In the full discussion^of the subject in his Descent of Man , Darwin 
well says that man manifestly owes his immense superority “to his in- 
tellectual faculties, to his social habits, which lead him to aid and de- 
fend his fellows, and to his corporeal structure.” Passing over man’s 
social habits, the discussion of which, though admittedly of the highest 
importance, since they are the basis of his moral nature, would lead too 
far, the plan of this paper contemplates a few words on his corporeal 
structure, preliminary to the main discussion of his intellectual facul- 
ties, a suggestion being made in conclusion as to the interrelation of 
the two. 
Darwin not only mentions man’s chief differences in bodily structure 
from other animals, hut also suggests the probable order in which the 
change of the latter into the former took place. In his account, there are 
two points of departure, the hand and the brain. First, as he suggests, 
the forefeet of the horn mine apes were somehow transformed into the 
wonderful human hand; the most skillful and adaptable single instru- 
ment that Nature has ever devised, for without the hand man never 
could have become the tool-making animal. As the hand, deviating 
from the forefoot, grew in utility and came to he more used, its effective 
[ 23 ] 
