18 THE HISTORY OF CREATION. 
ter (vol. i. p. 365). But the post glacial period, or the more 
recent diluvial period, during which the temperature again 
increased and the ice retreated towards the poles, was 
also highly important in regard to the present state of 
chorological relations. 
The biological characteristic of the quaternary epoch lies 
essentially in the development and dispersion of the human 
organism and his culture. Man has acted with a greater 
transforming, destructive, and modifying influence upon the 
animal and vegetable population of the earth than any other 
organism. For this reason, and not because we assign to man 
a privileged exceptional position in nature in other matters, 
we may with full justice designate the development of man 
and his civilization as the beginning of a special and last 
main division of the organic history of the earth. It is 
probable indeed that the corporeal development of primeval 
man out of man-like apes took place as far back as the earlier 
pliocene period, perhaps even in the miocene tertiary period. 
But the actual development of human speech, which we look 
upon as the most powerful agency in the development of the 
peculiar characteristics of man and his dominion over other 
organisms, probably belongs to that period which on 
geological grounds is distinguished from the preceding 
pliocene period as the pleistocene or diluvial. In fact the 
time which has elapsed from the development of human 
speech down to the present day, though it may comprise 
many thousands and perhaps hundreds of thousands of years, 
almost vanishes into nothing as compared with the im- 
measurable length of the periods which have passed from 
the beginning of organic life on the earth down to the 
origin of the human race. 
