WORLD-POWER AND EVOLUTION 
A Review of Dr. Ellsworth Huntington’s Evidence of how Climate has Affected 
the Development of the Human Race and Determined the Periods of 
Greatest Achievement 
PauL PorpENOE 
HE effect of changes of climate 
on human activity, not only 
physical but more particularly 
mental, is the thesis of this’ as 
of several preceding books by Ells- 
worth Huntington. 
Beginning with present-day condi- 
tions, he shows that business cycles, as 
measured by bank clearings, financial 
depressions, periods of credit expan- 
sion, and the like, correlate with the 
general conditions of health in the 
eastern United States. He measures 
health, for this purpose, by fluctuations 
in the death-rate, and then proceeds to 
show that these fluctuations correlate 
positively with changes in temperature, 
so that even a small deviation from 
the optimum temperature in either 
direction causes an increase of deaths. 
The most favorable conditions under 
which human beings can live, he con- 
cludes, are a mean temperature of 
64°F, for physical activity, with a good 
deal of humidity and frequent changes 
in temperature, while for mental 
activity he finds a mean of 40°F. better 
suited. 
These conclusions are based on ex- 
tensive statistical data, partly analysed 
in the book under review and partly 
in previous volumes. ‘The statistical 
methods used are somewhat crude, but 
probably the data available are not suf- 
ficiently precise to justify more refined 
treatment. Dr. Huntington has made 
out a plausible and interesting case for 
the importance of climatic changes .in 
daily life; future and more exact in- 
vestigation will determine the limits. 
In his latest book, Dr. Huntington 
inquires why there is a difference be- 
tween the most favorable temperature 
for mental activity and that for physical 
activity. He explains by saying that 
these adaptations were made at differ- 
ent periods in the history of the race, 
when the air was different. 
THE IMPORTANCE OF AIR 
“Long before man’s earliest ancestors 
had become different from the beasts 
the whole world of life had realized the 
necessity of air,” he remarks. “Even 
the creatures that inhabit the water can 
live only by taking from it the dissolved 
air. Otherwise the chemical activities 
which are the basis of all life come 
promptly to an end. Before these 
primitive animals could give rise to 
higher forms, however, it was neces- 
sary that they should pass through a 
series of crises. Each of these crises 
was a step forward in the estate of man. 
Each has left its impress not only upon 
the animal world but upon the human 
race. 
“A few of these crises, such as the 
development of vertebrates from in- 
vertebrates, were due to causes other 
than climate, but most arose directly 
from the conditions of the air which we 
call climate. Let us consider three of 
the chief crises. 
“The first was the emergence of the 
earliest vertebrates from the water. 
This was a most momentous step, for 
only in the highly varied environment 
of the land does brain power develop 
rapidly. Creatures like the seal, the 
whale, and the manatee, which have 
gone back to the water from the land, 
*World-Power and Evolution,” by Ellsworth Huntington, Ph. D., Research Associate 
in Geography, Yale University; author of “Civilization and Climate,” ete. 
Price $2.50. New Haven, Conn.: Yale University Press, 1919. 
maps, etc. 
Pp. 287, with 
137 
