PSYCHE 
Vol. 54 June, 1947 
No. 2 
EARLY INSECT LIFE* 
By Frank M. Carpenter 
Harvard University 
Most entomologists, whether concerned with insect con- 
trol or taxonomy, are convinced that we have enough 
living insects to contend with, without bothering about 
those of prehistoric times. Paradoxical as it may be, how- 
ever, man apparently owes his very existence to the early 
insects. Some three hundred million years ago, as the 
first Amphibia abandoned the aquatic environment of 
their ancestors and explored the possibilities of terres- 
trial life, they were obliged to find a new source of food. 
By that time, the insects had already become established 
on land and, being especially abundant near water, were 
readily available to them. The amphibians were thus 
able to survive in their new environment and eventually 
their descendants gave rise to reptiles, birds and mam- 
mals. Many geologic periods later — only a few million 
years ago, in fact — man evolved within the mammalian 
complex. Cannot the insects claim, therefore, that if it 
were not for their early ancestors, the vertebrates might 
have failed to gain a foot-hold on land and man might 
not have come into existence? 
Let us consider the nature and extent of the earlv insect 
life to which we presumably owe so much. 4 ‘Early” is 
of course a relative term, and to define my present use of 
it, I must refer to the conventional geologic timetable. 
Figure 1 lists the eras and periods of that part of geologic 
time with which paleontology is chiefly concerned. Of 
the three eras, the Paleozoic is the earliest and longest, 
* Annual Public Address of the Entomological Society of America, Rich- 
mond, Virginia, December 9, 1946. Published with the aid of a grant from 
the Museum of Comparative Zoology at Harvard College. 
